Method and device for processing video data, medium, and method for storing bit stream

Abstract

Methods, systems, and apparatus for video processing are described. An example video processing method includes performing conversion between a video including a video block and a bitstream of the video according to a rule, wherein the rule specifies whether to include a first syntax element in a slice header (SH), the first syntax element indicating whether transform skip based residual codec is disabled for the slice, and wherein the rule specifies whether to include the first syntax element in the SH is selectively based on a second syntax element in a sequence parameter set (SPS), the second syntax element indicating whether transform skip (TS) mode is enabled for the video block.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is filed to claim priority to and the benefit of International Patent Application No. PCT / CN2020 / 078770, filed on March 11, 2020. The entire disclosure of the aforementioned application is incorporated by reference as part of the disclosure of this application. Technical Field

[0003] This patent document relates to image and video encoding and decoding. Background Art

[0004] Digital video accounts for the largest use of bandwidth on the Internet and other digital communications networks. As the number of connected user devices capable of receiving and displaying video increases, bandwidth demand for digital video usage is expected to continue to grow. Summary of the Invention

[0005] This document discloses techniques that can be used by video encoders and decoders for processing a codec representation of a video using control information useful for decoding the codec representation.

[0006] In one example aspect, a video processing method is disclosed. The method includes performing conversion between a video including a video unit and a bitstream of the video according to a rule, wherein the rule specifies whether to include information related to a scaling list of the video in an adaptation parameter set (APS) or how to include information related to a scaling list of the video in the adaptation parameter set (APS) based on a first syntax element and independent of one or more syntax elements in a sequence parameter set (SPS), the first syntax element indicating whether the APS includes syntax elements related to chroma components.

[0007] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that a syntax element is included in an adaptation parameter set (APS), and wherein the rule specifies that the syntax element indicates whether one or more syntax elements for chroma residual scaling are included in the APS.

[0008] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies whether one or more syntax elements for chroma residual scaling are included in an adaptation parameter set (APS) based on a first syntax element indicating whether the APS includes syntax elements related to chroma components.

[0009] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video comprising a video block and a bitstream of the video according to a rule, wherein the rule specifies whether to include a first syntax element in a slice header (SH), the first syntax element indicating whether transform skip based residual codec is disabled for the slice, and wherein the rule specifies whether to include the first syntax element in the SH is selectively based on a second syntax element in a sequence parameter set (SPS), the second syntax element indicating whether transform skip (TS) mode is enabled for the video block.

[0010] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video including a luma block and a bitstream of the video according to a rule, wherein the rule specifies whether a slice header (SH) includes a first syntax element based on a second syntax element, and wherein the first syntax element indicates whether use of a delta quantization parameter (QP) is enabled for one or more codec units (CUs) of a particular slice of the luma block.

[0011] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video comprising a video picture and a bitstream of the video according to a rule, wherein the rule provides that, in response to a first syntax element indicating that each sub-picture of the video picture includes only one rectangular slice: a second syntax element indicating a number of rectangular slices in each video picture of a reference picture parameter set (PPS) plus one is equal to a third syntax element indicating a number of sub-pictures in each video picture in a codec layer video sequence (CLVS) of the bitstream plus one.

[0012] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video including a video picture and a bitstream of the video according to a rule, wherein the rule provides that a picture parameter set (PPS) includes one or more syntax elements, the one or more syntax elements indicating whether the video picture of the video is divided into a first number of slice rows or columns having the same height and a second number of slice rows or columns having different heights or widths, and wherein the first number of slice rows or columns precedes the second number of slice rows or columns in the video picture.

[0013] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video including a video region and a bitstream of the video according to a rule, wherein the rule specifies that adaptive loop filtering operations are allowed for the video region in response to the absence of one or more adaptation parameter set (APS) network abstraction layer (NAL) units including adaptive loop filtering data.

[0014] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video including a video region and a bitstream of the video according to a rule, wherein the rule specifies that in response to the absence of one or more Adaptation Parameter Set (APS) Network Abstraction Layer (NAL) units including adaptive loop filtering data, adaptive loop filtering operations are not allowed on the video region.

[0015] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video comprising video pictures and a bitstream of the video according to a rule, wherein the rule provides that in response to a first value of a first syntax element having a value of 1 indicating that a second value of a second syntax element is equal to 0, adaptive loop filtering operations or cross-component adaptive loop filtering operations are not allowed, wherein the rule provides that a general constraint information syntax structure includes the first syntax element, and wherein the rule provides that a second syntax element having a value of 0 in a sequence parameter set (SPS) indicates that cross-component adaptive loop filtering operations are disabled for all video pictures of the video.

[0016] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video including one or more video pictures and a bitstream of the video according to a rule, wherein the rule specifies whether to include one or more syntax elements indicating a plurality of adaptation parameter sets (APSs) including adaptive loop filtering data and / or one or more syntax elements indicating an APS identifier for an adaptive loop filtering operation or a cross-component adaptive loop filtering operation is based on the presence of a first syntax element indicating an APS network abstraction layer (NAL) unit including the adaptive loop filtering data.

[0017] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies indicating one or more syntax elements in a parameter set, a header, or a syntax structure to indicate disabling any one or more of the following: adaptive loop filtering operations, cross-component adaptive loop filtering operations, luma mapping with chroma scaling (LMCS) operations, or one or more user-defined scaling lists.

[0018] In another example aspect, a video processing method is disclosed. The method includes performing conversion between a video including video pictures and a bitstream of the video according to a rule, wherein the rule provides for omitting a set of consistency window parameters from a picture parameter set (PPS) in response to the following situations: a width in units of luma samples of each video picture that references the PPS is equal to a maximum picture width in units of luma samples indicated in a sequence parameter set (SPS) referenced by each video picture, and a height in units of luma samples of each video picture that references the PPS is equal to a maximum picture height in units of luma samples indicated in the SPS.

[0019] In another example aspect, a video processing method is disclosed. The method includes performing a conversion between a video region of a video and a codec representation of the video; wherein the codec representation conforms to a format rule; wherein the format rule specifies a flag indicating whether a scaling list for a color component in the video is included in an adaptation parameter set, regardless of a syntax field value in a sequence parameter set.

[0020] In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video region of a video and a codec representation of the video region; wherein the codec representation conforms to a format rule; wherein the format rule specifies that one or more adaptation parameter sets are included in the codec representation such that, for each adaptation parameter set, chroma-related syntax elements are omitted due to chroma constraints on the video.

[0021] In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video comprising one or more video regions and a codec representation of the video, the one or more video regions comprising one or more video units; wherein the codec representation conforms to a format rule; wherein the format rule specifies whether a first transform codec syntax field is included in the codec representation at the level of the video unit of the video region and / or its value depends on the value of a second transform codec syntax field at the level of the video region.

[0022] In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video comprising one or more video regions and a codec representation of the video, each video region comprising one or more video units; wherein the codec representation conforms to a format rule; wherein the format rule specifies that a flag at the video unit level controls whether differential signaling of a quantization parameter is enabled for the conversion.

[0023] In another example aspect, another video processing method is disclosed, the method comprising performing conversion between a video comprising one or more video regions and a codec representation of the video, each video region comprising one or more video units, wherein the codec representation conforms to a format rule, wherein the format rule dictates interpretation of a first flag at a picture level indicating a number of sub-pictures and a second flag at a sub-picture level indicating a number of slices in the sub-picture.

[0024] In another example aspect, another video processing method is disclosed, the method including performing conversion between a video comprising one or more video pictures and a codec representation of the video, each video picture comprising one or more slices and / or one or more slices, wherein the codec representation conforms to a format rule, wherein the format rule specifies that a field in a picture parameter set associated with the video picture indicates whether the video picture is divided into a plurality of slice rows or slice columns of different heights or widths.

[0025] In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video comprising one or more video pictures and a codec representation of the video, each video picture comprising one or more slices and / or one or more slices; wherein the codec representation conforms to a format rule; wherein the format rule specifies that, if an adaptation parameter set excludes an indication of adaptive loop filtering, applicability of adaptive loop filtering to a region of the video is based on a second rule.

[0026] In another example aspect, another video processing method is disclosed. The method includes performing conversion between a video comprising one or more video pictures and a codec representation of the video, each video picture comprising one or more slices and / or one or more slices; wherein the codec representation conforms to a format rule; wherein the format rule specifies skipping explicit signaling of a consistency window parameter in a picture parameter set for a picture having a width and height, a maximum width, and a maximum height of the video.

[0027] In yet another exemplary aspect, a video encoder apparatus is disclosed. The video encoder includes a processor configured to implement the above method.

[0028] In yet another exemplary aspect, a video decoder apparatus is disclosed. The video decoder includes a processor configured to implement the above method.

[0029] In yet another exemplary aspect, a computer-readable medium having stored thereon code is disclosed. The code is in the form of processor-executable code embodying one of the methods described herein.

[0030] These and other features are described in this document. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a block diagram of an example video processing system.

[0032] Figure 2 A block diagram of a video processing device.

[0033] Figure 3 A flowchart of an example method for video processing is provided.

[0034] Figure 4 is a block diagram illustrating a video encoding and decoding system according to some embodiments of the present disclosure.

[0035] Figure 5 is a block diagram illustrating an encoder according to some embodiments of the present disclosure.

[0036] Figure 6 is a block diagram illustrating a decoder according to some embodiments of the present disclosure.

[0037] Figures 7 to 19 is a flow chart of an example method of video processing. DETAILED DESCRIPTION

[0038] The section headings used in this document are for ease of understanding and do not limit the applicability of the techniques and embodiments disclosed in each section to that section. Furthermore, the use of H.266 terminology in some descriptions is for ease of understanding only and is not intended to limit the scope of the disclosed techniques. Therefore, the techniques described herein are also applicable to other video codec protocols and designs.

[0039] 1. Introduction

[0040] This document relates to video codec technology. Specifically, it is about the design of the SH, PPS, APS, and GCI syntax elements in video codecs. These ideas can be applied, alone or in various combinations, to any video codec standard or non-standard video codec that supports multi-layer video codecs (e.g., the Versatile Video Codec (VVC) under development).

[0041] 2. Abbreviation

[0042] APS Adaptive Parameter Set

[0043] AU Access Unit

[0044] AUD Access Unit Delimiter

[0045] AVC Advanced Video Codec

[0046] CLVS codec layer video sequence

[0047] CPB Codec Picture Buffer

[0048] CRA Clean Random Access

[0049] CTU Codec Tree Unit

[0050] CVS codec video sequence

[0051] DPB decoded picture buffer

[0052] DPS decoding parameter set

[0053] EOB End of bitstream

[0054] EOS sequence ends

[0055] GCI General Constraints Information

[0056] GDR Gradual Decode Refresh

[0057] HEVC High-Efficiency Video Codec

[0058] HRD Hypothesized Reference Decoder

[0059] IDR Instant Decode Refresh

[0060] JEM Joint Exploration Model

[0061] MCTS Motion Constraint Patch

[0062] NAL Network Abstraction Layer

[0063] OLS output layer set

[0064] PH Image Header

[0065] PPS picture parameter set

[0066] PTL grade, level, and grade

[0067] PU picture unit

[0068] RBSP Raw Byte Sequence Payload

[0069] SEI Supplemental Enhancement Information

[0070] SH Strip Header

[0071] SPS sequence parameter set

[0072] SVC Scalable Video Codec

[0073] VCL video codec layer

[0074] VPS Video Parameter Set

[0075] VTM VVC test model

[0076] VUI Video Availability Information

[0077] VVC multifunctional video codec

[0078] 3. Preliminary Discussion

[0079] Video codec standards have evolved primarily through the development of the well-known ITU-T and ISO / IEC standards. ITU-T produced the H.261 and H.263 standards, ISO / IEC produced the MPEG-1 and MPEG-4 Visual standards, and the two organizations jointly produced the H.262 / MPEG-2 Video standard, the H.264 / MPEG-4 Advanced Video Codec (AVC) standard, and the H.265 / HEVC standard. Starting with H.262, video codec standards have been based on a hybrid video codec architecture that utilizes temporal prediction and transform coding. To explore future video codec technologies beyond HEVC, the Joint Video Exploration Team (JVET) was jointly established by VCEG and MPEG in 2015. Since then, JVET has adopted many new methods and incorporated them into reference software called the Joint Exploration Model (JEM). JVET meetings are held concurrently every quarter, with the goal of reducing the bitrate of new codecs by 50% compared to HEVC. The new video codec standard was officially named Versatile Video Coding (VVC) at the JVET meeting in April 2018, and the first version of the VVC Test Model (VTM) was also released at that time. As VVC standardization continues, new codec technologies are incorporated into the VVC standard at each JVET meeting. The VVC working draft and test model (VTM) are updated after each meeting. The VVC project is currently aiming for technical completion (FDIS) at the July 2020 meeting.

[0080] 3.1. GCI Syntax and Semantics

[0081] In the latest VVC draft text, GCI syntax and semantics are as follows:

[0082]

[0083]

[0084]

[0085] general_progressive_source_flag and general_interlaced_source_flag are interpreted as follows:

[0086] If general_progressive_source_flag is equal to 1 and general_interlaced_source_flag is equal to 0, the source scan type of the picture in OlsInScope shall be interpreted as progressive scan only.

[0087] Otherwise, if general_progressive_source_flag is equal to 0 and general_interlaced_source_flag is equal to 1, the source scan type of the picture in OlsInScope shall be interpreted as interlaced only.

[0088] Otherwise, if general_progressive_source_flag is equal to 0 and general_interlaced_source_flag is equal to 0, the source scan type of the picture in OlsInScope shall be interpreted as unknown or unspecified.

[0089] Otherwise (general_progressive_source_flag is equal to 1 and general_interlaced_source_flag is equal to 1), the source scan type for each picture in OlsInScope is indicated at the picture level using the syntax element source_scan_type in the frame field information SEI message. A bitstream conformance requirement is that when general_progressive_source_flag is equal to 1 and general_interlaced_source_flag is equal to 1, a frame field information SEI message shall be present in each AU.

[0090] NOTE 1 - The decoder may ignore the values of general_progressive_source_flag and general_interlaced_source_flag. Furthermore, the actual source scan type of a picture is outside the scope of this specification, and the method by which the encoder selects the values of general_progressive_source_flag and general_interlaced_source_flag is unspecified.

[0091] general_non_packed_constraint_flag equal to 1 specifies that there shall not be any frame packing arrangement SEI message in the OlsInScope bitstream. general_non_packed_constraint_flag equal to 0 does not impose such a constraint.

[0092] NOTE 2 – A decoder may ignore the value of general_non_packed_constraint_flag since there are no decoding process requirements related to the presence or interpretation of the frame packing arrangement SEI message.

[0093] general_frame_only_constraint_flag equal to 1 specifies that OlsInScope transmits pictures representing frames. general_frame_only_constraint_flag equal to 0 specifies that OlsInScope transmits pictures that may or may not represent frames.

[0094] NOTE 3 – A decoder may ignore the value of general_frame_only_constraint_flag since there are no decoding process requirements associated with it.

[0095] general_non_projected_constraint_flag equal to 1 specifies that there shall not be any equirectangular projection SEI message or generalized cubemap projection SEI message in the bitstream for OlsInScope. general_non_projected_constraint_flag equal to 0 does not impose such a constraint.

[0096] NOTE 4 - A decoder may ignore the value of general_non_projected_constraint_flag since there are no decoding process requirements related to the presence or interpretation of the equirectangular projection SEI message and the generalized cubemap projection SEI message.

[0097] intra_only_constraint_flag equal to 1 specifies that slice_type should be equal to 1. intra_only_constraint_flag equal to 0 does not impose such a constraint.

[0098] max_bitdepth_constraint_idc specifies that bit_depth_minus8 should be in the range of 0 to max_bitdepth_constraint_idc (inclusive).

[0099] max_chroma_format_constraint_idc specifies that chroma_format_idc should be in the range of 0 to max_chroma_format_constraint_idc (inclusive).

[0100] no_res_change_in_clvs_constraint_flag equal to 1 specifies that res_change_in_clvs_allowed_flag shall be equal to 0. no_res_change_in_clvs_constraint_flag equal to 0 does not impose such a constraint.

[0101] one_tile_per_pic_constraint_flag equal to 1 specifies that each picture should contain only one tile. one_tile_per_pic_constraint_flag equal to 0 does not impose such a constraint.

[0102] one_slice_per_pic_constraint_flag equal to 1 specifies that each picture shall contain only one slice. one_slice_per_pic_constraint_flag equal to 0 does not impose such a constraint.

[0103] one_subpic_per_pic_constraint_flag equal to 1 specifies that each picture shall contain only one sub-picture. one_subpic_per_pic_constraint_flag equal to 0 does not impose such a constraint. When one_slice_per_pic_constraint_flag is equal to 1, the value of one_subpic_per_pic_constraint_flag shall be equal to 1.

[0104] no_qtbtt_dual_tree_intra_constraint_flag equal to 1 specifies that qtbtt_dual_tree_intra_flag should be equal to 0. no_qtbtt_dual_tree_intra_constraint_flag equal to 0 does not impose such a constraint.

[0105] no_partition_constraints_override_constraint_flag equal to 1 specifies that partition_constraints_override_enabled_flag shall be equal to 0. no_partition_constraints_override_constraint_flag equal to 0 does not impose such constraints.

[0106] no_sao_constraint_flag equal to 1 specifies that sps_sao_enabled_flag should be equal to 0. no_sao_constraint_flag equal to 0 does not impose such a constraint.

[0107] no_alf_constraint_flag equal to 1 specifies that sps_alf_enabled_flag should be equal to 0. no_alf_constraint_flag equal to 0 does not impose such a constraint.

[0108] no_ccalf_constraint_flag equal to 1 specifies that sps_ccalf_enabled_flag shall be equal to 0. no_ccalf_constraint_flag equal to 0 does not impose such a constraint.

[0109] no_joint_cbcr_constraint_flag equal to 1 specifies that sps_joint_cbcr_enabled_flag should be equal to 0. no_joint_cbcr_constraint_flag equal to 0 does not impose such a constraint.

[0110] no_ref_wraparound_constraint_flag equal to 1 specifies that sps_ref_wraparound_enabled_flag shall be equal to 0. no_ref_wraparound_constraint_flag equal to 0 does not impose such a constraint.

[0111] no_temporal_mvp_constraint_flag equal to 1 specifies that sps_temporal_mvp_enabled_flag shall be equal to 0. no_temporal_mvp_constraint_flag equal to 0 does not impose such a constraint.

[0112] no_sbtmvp_constraint_flag equal to 1 specifies that sps_sbtmvp_enabled_flag should be equal to 0. no_sbtmvp_constraint_flag equal to 0 does not impose such a constraint.

[0113] no_amvr_constraint_flag equal to 1 specifies that sps_amvr_enabled_flag should be equal to 0. no_amvr_constraint_flag equal to 0 does not impose such a constraint.

[0114] no_bdof_constraint_flag equal to 1 specifies that sps_bdof_enabled_flag should be equal to 0. no_bdof_constraint_flag equal to 0 does not impose such a constraint.

[0115] no_dmvr_constraint_flag equal to 1 specifies that sps_dmvr_enabled_flag shall be equal to 0. no_dmvr_constraint_flag equal to 0 does not impose such a constraint.

[0116] no_cclm_constraint_flag equal to 1 specifies that sps_cclm_enabled_flag shall be equal to 0. no_cclm_constraint_flag equal to 0 does not impose such a constraint.

[0117] no_mts_constraint_flag equal to 1 specifies that sps_mts_enabled_flag should be equal to 0. no_mts_constraint_flag equal to 0 does not impose such a constraint.

[0118] no_sbt_constraint_flag equal to 1 specifies that sps_sbt_enabled_flag should be equal to 0. no_sbt_constraint_flag equal to 0 does not impose such a constraint.

[0119] no_affine_motion_constraint_flag equal to 1 specifies that sps_affine_enabled_flag should be equal to 0. no_affine_motion_constraint_flag equal to 0 does not impose such a constraint.

[0120] no_bcw_constraint_flag equal to 1 specifies that sps_bcw_enabled_flag should be equal to 0. no_bcw_constraint_flag equal to 0 does not impose such a constraint.

[0121] no_ibc_constraint_flag equal to 1 specifies that sps_ibc_enabled_flag should be equal to 0. no_ibc_constraint_flag equal to 0 does not impose such a constraint.

[0122] no_ciip_constraint_flag equal to 1 specifies that sps_ciip_enabled_flag should be equal to 0. no_cipp_constraint_flag equal to 0 does not impose such a constraint.

[0123] no_fpel_mmvd_constraint_flag equal to 1 specifies that sps_fpel_mmvd_enabled_flag should be equal to 0. no_fpel_mmvd_constraint_flag equal to 0 does not impose such a constraint.

[0124] no_gpm_constraint_flag equal to 1 specifies that sps_gpm_enabled_flag should be equal to 0. no_gpm_constraint_flag equal to 0 does not impose such a constraint.

[0125] no_ladf_constraint_flag equal to 1 specifies that sps_ladf_enabled_flag shall be equal to 0. no_ladf_constraint_flag equal to 0 does not impose such a constraint.

[0126] no_transform_skip_constraint_flag equal to 1 specifies that sps_transfrom_skip_enabled_flag should be equal to 0. no_transform_skip_constraint_flag equal to 0 does not impose such a constraint.

[0127] no_bdpcm_constraint_flag equal to 1 specifies that sps_bdpcm_enabled_flag should be equal to 0. no_bdpcm_constraint_flag equal to 0 does not impose such a constraint.

[0128] no_qp_delta_constraint_flag equal to 1 specifies that it is a requirement for bitstream conformance that cu_qp_delta_enabled_flag shall be equal to 0. no_qp_delta_constraint_flag equal to 0 imposes no such constraint.

[0129] no_dep_quant_constraint_flag equal to 1 specifies that it is a requirement for bitstream conformance that sps_dep_quant_enabled_flag shall be equal to 0. no_dep_quant_constraint_flag equal to 0 does not impose such a constraint.

[0130] no_sign_data_hiding_constraint_flag equal to 1 specifies that it is a requirement for bitstream conformance that sps_sign_data_hiding_enabled_flag shall be equal to 0. no_sign_data_hiding_constraint_flag equal to 0 does not impose such a constraint.

[0131] no_mixed_nalu_types_in_pic_constraint_flag equal to 1 specifies that it is a bitstream conformance requirement that mixed_nalu_types_in_pic_flag shall be equal to 0. no_mixed_nalu_types_in_pic_constraint_flag equal to 0 does not impose such a constraint.

[0132] no_trail_constraint_flag equal to 1 specifies that NAL units with nuh_unit_type equal to TRAIL_NUT shall not be present in OlsInScope. no_trail_constraint_flag equal to 0 does not impose such a constraint.

[0133] no_stsa_constraint_flag equal to 1 specifies that NAL units with nuh_unit_type equal to STSA_NUT shall not be present in OlsInScope. no_stsa_constraint_flag equal to 0 does not impose such a constraint.

[0134] no_rasl_constraint_flag equal to 1 specifies that no NAL units with nuh_unit_type equal to RASL_NUT shall be present in OlsInScope. no_rasl_constraint_flag equal to 0 does not impose such a constraint.

[0135] no_radl_constraint_flag equal to 1 specifies that NAL units with nuh_unit_type equal to RADL_NUT shall not be present in OlsInScope. no_radl_constraint_flag equal to 0 does not impose such a constraint.

[0136] no_idr_constraint_flag equal to 1 specifies that NAL units with nuh_unit_type equal to IDR_W_RADL or IDR_N_LP shall not be present in OlsInScope. no_idr_constraint_flag equal to 0 imposes no such constraint.

[0137] no_cra_constraint_flag equal to 1 specifies that NAL units with nuh_unit_type equal to CRA_NUT shall not be present in OlsInScope. no_cra_constraint_flag equal to 0 does not impose such a constraint.

[0138] no_gdr_constraint_flag equal to 1 specifies that NAL units with nuh_unit_type equal to GDR_NUT shall not be present in OlsInScope. no_gdr_constraint_flag equal to 0 does not impose such a constraint.

[0139] no_aps_constraint_flag equal to 1 specifies that NAL units with nuh_unit_type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT shall not be present in OlsInScope. no_aps_constraint_flag equal to 0 does not impose such a constraint.

[0140] gci_alignment_zero_bits shall be equal to 0.

[0141] num_reserved_constraint_bytes specifies the number of reserved constraint bytes. The value of num_reserved_constraint_bytes shall be 0. Other values of num_reserved_constraint_bytes are reserved for future use by ITU-T | ISO / IEC and shall not appear in bitstreams conforming to this version of this specification.

[0142] gci_reserved_constraint_byte[i] can have any value. Its presence and value do not affect the conformance of a decoder to the profile specified in this version of this specification. Decoders conforming to this version of this specification shall ignore all values of the gci_reserved_constraint_byte[i] syntax element.

[0143] 3.2. SPS Syntax and Semantics

[0144] In the latest VVC draft text, SPS syntax and semantics are as follows:

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154] The SPS RBSP shall be available to the decoding process before it is referenced, either by being included in at least one AU with TemporalId equal to 0, or by being provided by external means.

[0155] All SPS NAL units in a CVS with a specific value of sps_seq_parameter_set_id shall have the same content.

[0156] sps_seq_parameter_set_id provides an identifier for the SPS for reference by other syntax elements.

[0157] Regardless of the nuh_layer_id value, SPS NAL units share the same value space of sps_seq_parameter_set_id.

[0158] Assume that spsLayerId is the value of nuh_layer_id of a specific SPS NAL unit, and vclLayerId is the value of nuh_layer_id of a specific VCL NAL unit. The specific VCL NAL unit shall not reference the specific SPS NAL unit unless spsLayerId is less than or equal to vclLayerId and the layer with nuh_layer_id equal to spsLayerId is included in at least one OLS that contains a layer with nuh_layer_id equal to vclLayerId.

[0159] When sps_video_parameter_set_id is greater than 0, it specifies the value of vps_video_parameter_set_id of the VPS referenced by the SPS.

[0160] When sps_video_parameter_set_id is equal to 0, the following applies:

[0161] --SPS does not refer to VPS.

[0162] --When decoding each CLVS that refers to the SPS, the VPS is not referred to.

[0163] The value of --vps_max_layers_minus1 is inferred to be equal to 0.

[0164] -- A CVS shall contain only one layer (i.e., all VCL NAL units in a CVS shall have the same nuh_layer_id value).

[0165] --The value of GeneralLayerIdx[nuh_layer_id] is inferred to be equal to 0.

[0166] The value of --vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is inferred to be equal to 1.

[0167] When vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1, the nuh_layer_id of the SPS referenced by the CLVS with a specific nuh_layer_id value nuhLayerId shall be equal to nuhLayerId.

[0168] The value of sps_video_parameter_set_id shall be the same in all SPSs referenced by CLVS in CVS.

[0169] sps_max_sublayers_minus1 plus 1 specifies the maximum number of time domain sublayers that may be present in each CLVS of the reference SPS. The value of sps_max_sublayers_minus1 shall be in the range of 0 to vps_max_sublayers_minus1, inclusive.

[0170] In bitstreams conforming to this version of this specification, sps_reserved_zero_4bits shall be equal to 0. Other values of sps_reserved_zero_4bits are reserved for future use by ITU-T | ISO / IEC.

[0171] sps_ptl_dpb_hrd_params_present_flag equal to 1 specifies the presence of the profile_tier_level() syntax structure and the dpb_parameters() syntax structure in the SPS. Furthermore, the general_hrd_parameters() syntax structure and the ols_hrd_parameters() syntax structure may also be present in the SPS. sps_ptl_dpb_hrd_params_present_flag equal to 0 specifies the absence of these four syntax structures in the SPS. The value of sps_ptl_dpb_hrd_params_present_flag shall be equal to vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]].

[0172] gdr_enabled_flag equal to 1 specifies that GDR pictures may be present in the CLVS referencing the SPS. gdr_enabled_flag equal to 0 specifies that GDR pictures are not present in the CLVS referencing the SPS.

[0173] chroma_format_idc specifies the chroma samples relative to the luma samples, as specified in clause 6.2.

[0174] separate_colour_plane_flag equal to 1 specifies that the three color components of the 4:4:4 chroma format are coded separately. separate_colour_plane_flag equal to 0 specifies that the color components are not coded separately. When separate_colour_plane_flag is not present, it is inferred to be equal to 0. When separate_colour_plane_flag is equal to 1, the codec picture consists of three separate components, each consisting of coded samples of one color plane (Y, Cb, or Cr), and uses the monochrome codec syntax. In this case, each color plane is associated with a specific colour_plane_id value.

[0175] NOTE 1 – The decoding process has no dependencies between color planes with different colour_plane_id values. For example, the decoding process of a monochrome picture with one colour_plane_id value does not use any data from a monochrome picture with a different colour_plane_id value for inter prediction.

[0176] Depending on the value of separate_colour_plane_flag, the value of the variable ChromaArrayType is assigned as follows:

[0177] If separate_colour_plane_flag is equal to 0, ChromaArrayType is set equal to chroma_format_idc.

[0178] --Otherwise (separate_colour_plane_flag is equal to 1), ChromaArrayType is set equal to 0.

[0179] res_change_in_clvs_allowed_flag equal to 1 specifies that the picture spatial resolution may change within a CLVS referencing an SPS. res_change_in_clvs_allowed_flag equal to 0 specifies that the picture spatial resolution may not change within any CLVS referencing an SPS.

[0180] pic_width_max_in_luma_samples specifies the maximum width of each decoded picture that references the SPS, in units of luma samples. pic_width_max_in_luma_samples shall not be equal to 0 and shall be an integer multiple of Max(8,MinCbSizeY).

[0181] A bitstream conformance requirement is that for any OLS with OLS index i that contains one or more layers that reference an SPS, the value of pic_width_max_in_luma_samples shall be less than or equal to the value of ols_dpb_pic_width[i].

[0182] pic_height_max_in_luma_samples specifies the maximum height of each decoded picture that references the SPS, in units of luma samples. pic_height_max_in_luma_samples shall not be equal to 0 and shall be an integer multiple of Max(8,MinCbSizeY).

[0183] A bitstream conformance requirement is that for any OLS with OLS index i that contains one or more layers of a reference SPS, the value of pic_height_max_in_luma_samples shall be less than or equal to the value of ols_dpb_pic_height[i].

[0184] sps_conformance_window_flag equal to 1 indicates that the conformance cropping window offset parameter immediately follows in the SPS. sps_conformance_window_flag equal to 0 indicates that the conformance cropping window offset parameter is not present in the SPS.

[0185] sps_conf_win_left_offset, sps_conf_win_right_offset, sps_conf_win_top_offset, and sps_conf_win_bottom_offset specify the cropping window that applies to pictures with pic_width_in_luma_samples equal to pic_width_max_in_luma_samples and pic_height_in_luma_samples equal to pic_height_max_in_luma_samples. When sps_conformance_window_flag is equal to 0, the values of sps_conf_win_left_offset, sps_conf_win_right_offset, sps_conf_win_top_offset, and sps_conf_win_bottom_offset are inferred to be equal to 0.

[0186] The conforming cropping window contains luma samples with horizontal picture coordinates from SubWidthC*sps_conf_win_left_offset to pic_width_max_in_luma_samples-(SubWidthC*sps_conf_win_right_offset+1) (inclusive) and vertical picture coordinates from SubHeightC*sps_conf_win_top_offset to pic_height_max_in_luma_samples-(SubHeightC*sps_conf_win_bottom_offset+1) (inclusive).

[0187] The value of SubWidthC*(sps_conf_win_left_offset+sps_conf_win_right_offset) should be less than pic_width_max_in_luma_samples, and the value of SubHeightC*(sps_conf_win_top_offset+sps_conf_win_bottom_offset) should be less than pic_height_max_in_luma_samples.

[0188] When ChromaArrayType is not equal to 0, the corresponding specified samples of the two chroma arrays are samples with picture coordinates (x / SubWidthC, y / SubHeightC), where (x, y) are the picture coordinates of the specified luma sample.

[0189] NOTE 2 – The consistency crop window offset parameter applies only to output. All internal decoding processes are applied to the uncropped picture size.

[0190] sps_log2_ctu_size_minus5 plus 5 specifies the luma codec treeblock size for each CTU. The value of sps_log2_ctu_size_minus5 shall be in the range of 0 to 2 (inclusive). The value of sps_log2_ctu_size_minus5 of 3 is reserved for future use by ITU-T | ISO / IEC.

[0191] The variables CtbLog2SizeY and CtbSizeY are exported as follows:

[0192] CtbLog2SizeY=sps_log2_ctu_size_minus5+5 (43)

[0193] CtbSizeY=1< <CtbLog2SizeY (44)

[0194] subpic_info_present_flag equal to 1 specifies that sub-picture information of CLVS is present, and there may be one or more sub-pictures in each picture of CLVS. subpic_info_present_flag equal to 0 specifies that sub-picture information of CLVS is not present, and there is only one sub-picture in each picture of CLVS.

[0195] When res_change_in_clvs_allowed_flag is equal to 1, the value of subpic_info_present_flag shall be equal to 0.

[0196] NOTE 3 – When the bitstream is the result of a sub-bitstream extraction process and contains only a subset of the sub-pictures of the input bitstream of the sub-bitstream extraction process, it may be necessary to set the value of subpic_info_present_flag equal to 1 in the RBSP of the SPS.

[0197] sps_num_subpics_minus1 plus 1 specifies the number of subpictures in each picture in the CLVS. The value of sps_num_subpics_minus1 shall be in the range of 0 to Ceil(pic_width_max_in_luma_samples ÷ CtbSizeY)*Ceil(pic_height_max_in_luma_samples ÷ CtbSizeY)-1, inclusive. When not present, the value of sps_num_subpics_minus1 is inferred to be equal to 0.

[0198] sps_independent_subpics_flag equal to 1 specifies that intra prediction, inter prediction, and loop filtering operations may not be performed across any sub-picture boundaries in the CLVS. sps_independent_subpics_flag equal to 0 specifies that inter prediction or loop filtering operations may be allowed across sub-picture boundaries in the CLVS. When not present, the value of sps_independent_subpics_flag is inferred to be equal to 0.

[0199] subpic_ctu_top_left_x[i] specifies the horizontal position of the top left CTU of the i-th sub-picture in units of CtbSizeY. The length of the syntax element is Ceil(Log2((pic_width_max_in_luma_samples+CtbSizeY-1)>>CtbLog2SizeY)) bits. When not present, the value of subpic_ctu_top_left_x[i] is inferred to be equal to 0.

[0200] subpic_ctu_top_left_y[i] specifies the vertical position of the top left CTU of the i-th sub-picture in units of CtbSizeY. The length of the syntax element is Ceil(Log2((pic_height_max_in_luma_samples+CtbSizeY-1)>>CtbLog2SizeY)) bits. When not present, the value of subpic_ctu_top_left_y[i] is inferred to be equal to 0.

[0201] subpic_width_minus1[i] plus 1 specifies the width of the i-th sub-picture in units of CtbSizeY. The length of this syntax element is Ceil(Log2((pic_width_max_in_luma_samples + CtbSizeY - 1) >> CtbLog2SizeY)) bits. When not present, the value of subpic_width_minus1[i] is inferred to be equal to ((pic_width_max_in_luma_samples + CtbSizeY - 1) >> CtbLog2SizeY) - subpic_ctu_top_left_x[i] - 1.

[0202] subpic_height_minus1[i] plus 1 specifies the height of the i-th sub-picture in units of CtbSizeY. The length of this syntax element is Ceil(Log2((pic_height_max_in_luma_samples + CtbSizeY - 1) >> CtbLog2SizeY)) bits. When not present, the value of subpic_height_minus1[i] is inferred to be equal to ((pic_height_max_in_luma_samples + CtbSizeY - 1) >> CtbLog2SizeY) - subpic_ctu_top_left_y[i] - 1.

[0203] subpic_treated_as_pic_flag[i] equal to 1 specifies that the i-th sub-picture of each codec picture in the CLVS is treated as a picture with excluded loop filtering operations during decoding. subpic_treated_as_pic_flag[i] equal to 0 specifies that the i-th sub-picture of each codec picture in the CLVS is not treated as a picture with excluded loop filtering operations during decoding. When not present, the value of subpic_treated_as_pic_flag[i] is inferred to be equal to sps_independent_subpics_flag.

[0204] When subpic_treated_as_pic_flag[i] is equal to 1, bitstream conformance is that, for every output layer in an OLS that includes as an output layer the layer containing the i-th sub-picture and its reference layers, all of the following are true:

[0205] --All pictures in the output layer and its reference layers should have the same pic_width_in_luma_samples value and the same pic_height_in_luma_samples value.

[0206] --For each value of j in the range of 0 to sps_num_subpics_minus1 (inclusive), all SPSs referenced by the output layer and its reference layers shall have the same value of sps_num_subpics_minus1 and shall have the same values of subpic_ctu_top_left_x[j], subpic_ctu_top_left_y[j], subpic_width_minus1[j], subpic_height_minus1[j], and loop_filter_cross_subpic_enabled_flag[j], respectively.

[0207] --For each value of j in the range 0 to sps_num_subpics_minus1 (inclusive), all pictures in each access unit in the output layer and its reference layers shall have the same value of SubpicIdVal[j].

[0208] loop_filter_across_subpic_enabled_flag[i] equal to 1 specifies that loop filtering operations may be performed across the boundaries of the i-th sub-picture in each codec picture in the CLVS. loop_filter_across_subpic_enabled_flag[i] equal to 0 specifies that loop filtering operations are not performed across the boundaries of the i-th sub-picture in each codec picture in the CLVS. When not present, the value of loop_filter_across_subpic_enabled_pic_flag[i] is inferred to be equal to 1-sps_independent_subpics_flag.

[0209] A bitstream conformance requirement is that the shape of the sub-pictures should be such that each sub-picture, when decoded, should have its entire left and top borders consisting of either picture boundaries or the boundaries of previously decoded sub-pictures.

[0210] sps_subpic_id_len_minus1 plus 1 specifies the number of bits used to represent the syntax element sps_subpic_id[i], the syntax element pps_subpic_id[i] (if present), and the syntax element slice_subpic_id (if present). The value of sps_subpic_id_len_minus1 shall be in the range of 0 to 15 (inclusive). The value of 1<<(sps_subpic_id_len_minus1+1) shall be greater than or equal to sps_num_subpics_minus1+1.

[0211] subpic_id_mapping_explicitly_signaled_flag equal to 1 specifies that sub-picture ID mapping is explicitly signaled in the SPS or in the PPS referenced by the coded picture of the CLVS. subpic_id_mapping_explicitly_signalled_flag equal to 0 specifies that sub-picture ID mapping is not explicitly signaled for the CLVS. When not present, the value of subpic_id_mapping_explicitly_signalled_flag is inferred to be equal to 0.

[0212] subpic_id_mapping_in_sps_flag equal to 1 specifies that sub-picture ID mapping is signaled in the SPS when subpic_id_mapping_explicitly_signaled_flag is equal to 1. subpic_id_mapping_in_sps_flag equal to 0 specifies that sub-picture ID mapping is signaled in the PPS referenced by the coded picture of the CLVS when subpic_id_mapping_explicitly_signaled_flag is equal to 1.

[0213] sps_subpic_id[i] specifies the sub-picture ID of the i-th sub-picture. The length of the sps_subpic_id[i] syntax element is sps_subpic_id_len_minus1+1 bits.

[0214] bit_depth_minus8 specifies the bit depth BitDepth of the luminance and chrominance array samples, and the value of the luminance and chrominance quantization parameter range offset QpBdOffset, as shown below:

[0215] BitDepth=8+bit_depth_minus8 (45)

[0216] QpBdOffset=6*bit_depth_minus8 (46)

[0217] bit_depth_minus8 should be in the range of 0 to 8 (inclusive).

[0218] sps_entropy_coding_sync_enabled_flag equal to 1 specifies that a specific synchronization process of context variables is called before decoding the CTU including the first CTB of a row of CTBs in each slice of each picture referencing the SPS, and a specific storage process of context variables is called after decoding the CTU including the first CTB of a row of CTBs in each slice of each picture referencing the SPS. sps_entropy_coding_sync_enabled_flag equal to 0 specifies that a specific synchronization process of context variables does not need to be called before decoding the CTU including the first CTB of a row of CTBs in each slice of each picture referencing the SPS, and a specific storage process of context variables does not need to be called after decoding the CTU including the first CTB of a row of CTBs in each slice of each picture referencing the SPS.

[0219] sps_wpp_entry_point_offsets_present_flag equal to 1 specifies that signaling of entry point offsets for CTU rows may be present in the slice header of pictures referencing the SPS when sps_entropy_coding_sync_enabled_flag is equal to 1. sps_wpp_entry_point_offsets_present_flag equal to 0 specifies that signaling of entry point offsets for CTU rows is not present in the slice header of pictures referencing the SPS. When not present, the value of sps_wpp_entry_point_offsets_present_flag is inferred to be equal to 0.

[0220] sps_weighted_pred_flag equal to 1 specifies that weighted prediction may be applied to P slices referencing the SPS. sps_weighted_pred_flag equal to 0 specifies that weighted prediction may not be applied to P slices referencing the SPS.

[0221] sps_weighted_bipred_flag equal to 1 specifies that explicit weighted prediction may be applied to B slices referencing the SPS. sps_weighted_bipred_flag equal to 0 specifies that explicit weighted prediction may not be applied to B slices referencing the SPS.

[0222] log2_max_pic_order_cnt_lsb_minus4 specifies the value of the variable MaxPicOrderCntLsb used in the decoding process of the picture order count, as shown below:

[0223] MaxPicOrderCntLsb=2 (log2_max_pic_order_cnt_lsb_minus4+4)(47)

[0224] The value of log2_max_pic_order_cnt_lsb_minus4 should be in the range of 0 to 12 (inclusive).

[0225] sps_poc_msb_flag equal to 1 specifies that the ph_poc_msb_present_flag syntax element is present in the PH referencing the SPS. sps_poc_msb_flag equal to 0 specifies that the ph_poc_msb_present_flag syntax element is not present in the PH referencing the SPS.

[0226] poc_msb_len_minus1 plus 1 specifies the length (in bits) of the poc_msb_val syntax element when it is present in the PH of the referenced SPS. The value of poc_msb_len_minus1 shall be in the range of 0 to 32-log2_max_pic_order_cnt_lsb_minus4-5 (inclusive).

[0227] num_extra_ph_bits_bytes specifies the number of bytes of extra bits in the PH syntax structure of a codec picture that references the SPS. In bitstreams conforming to this version of this specification, the value of num_extra_ph_bits_bytes shall be equal to 0. Although this version of this specification requires the value of num_extra_ph_bits_bytes to be equal to 0, decoders conforming to this version of this specification shall allow the value of num_extra_ph_bits_bytes to be equal to 1 or 2 to appear in the syntax.

[0228] num_extra_sh_bits_bytes specifies the number of bytes of extra bits in the slice header of codec pictures that reference the SPS. In bitstreams conforming to this version of this specification, the value of num_extra_sh_bits_bytes shall be equal to 0. Although this version of this specification requires the value of num_extra_sh_bits_bytes to be equal to 0, decoders conforming to this version of this specification shall allow the value of num_extra_sh_bits_bytes equal to 1 or 2 to appear in the syntax.

[0229] sps_sublayer_dpb_params_flag is used to control the presence of the max_dec_pic_buffering_minus1[i], max_num_reorder_pics[i], and max_latency_increase_plus1[i] syntax elements in the dpb_parameters() syntax structure in the SPS. When not present, the value of sps_sub_dpb_params_info_present_flag is inferred to be equal to 0.

[0230] long_term_ref_pics_flag equal to 0 specifies that no LTRP is used for inter prediction of any codec picture in the CLVS. long_term_ref_pics_flag equal to 1 specifies that LTRP can be used for inter prediction of one or more codec pictures in the CLVS.

[0231] inter_layer_ref_pics_present_flag equal to 0 specifies that no ILRP is used for inter prediction of any codec picture in the CLVS. inter_layer_ref_pic_flag equal to 1 specifies that ILRP may be used for inter prediction of one or more codec pictures in the CLVS. When sps_video_parameter_set_id is equal to 0, the value of inter_layer_ref_pics_present_flag is inferred to be equal to 0. When vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1, the value of inter_layer_ref_pics_present_flag shall be equal to 0. [Ed.(YK): Check if there is a better name for this syntax element.]

[0232] sps_idr_rpl_present_flag equal to 1 specifies that the reference picture list syntax element is present in the slice header of the IDR picture. sps_idr_rpl_present_flag equal to 0 specifies that the reference picture list syntax element is not present in the slice header of the IDR picture.

[0233] rpl1_same_as_rpl0_flag equal to 1 specifies that the syntax element num_ref_pic_lists_in_sps[1] and the syntax structure ref_pic_list_struct(1, rplsIdx) are not present, and the following applies:

[0234] --The value of num_ref_pic_lists_in_sps[1] is inferred to be equal to the value of num_ref_pic_lists_in_sps[0].

[0235] --For rplsIdx in the range from 0 to num_ref_pic_lists_in_sps[0]-1, the value of each syntax element in ref_pic_list_struct(1, rplsIdx) is inferred to be equal to the value of the corresponding syntax element in ref_pic_list_struct(0, rplsIdx).

[0236] num_ref_pic_lists_in_sps[i] specifies the number of ref_pic_list_struct(listIdx, rplsIdx) syntax structures included in the SPS with listIdx equal to i. The value of num_ref_pic_lists_in_sps[i] shall be in the range of 0 to 64 (inclusive).

[0237] NOTE 4 – For each value of listIdx (equal to 0 or 1), the decoder shall allocate memory for a total of num_ref_pic_lists_in_sps[i]+1 ref_pic_list_struct(listIdx, rplsIdx) syntax structures, since there may be one ref_pic_list_struct(listIdx, rplsIdx) syntax structure signaled directly in the slice header of the current picture.

[0238] qtbtt_dual_tree_intra_flag equal to 1 specifies that, for I slices, each CTU is partitioned into codec units with 64x64 luma samples using implicit quadtree partitioning, and these codec units are the roots of two separate coding_tree syntax structures for luma and chroma. qtbtt_dual_tree_intra_flag equal to 0 specifies that separate coding_tree syntax structures are not used for I slices. When qtbtt_dual_tree_intra_flag is not present, it is inferred to be equal to 0.

[0239] log2_min_luma_coding_block_size_minus2 plus 2 specifies the minimum luma coding block size. The value of log2_min_luma_coding_block_size_minus2 shall be in the range of 0 to Min(4, sps_log2_ctu_size_minus5+3), inclusive.

[0240] The variables MinCbLog2SizeY, MinCbSizeY, IbcBufWidthY, IbcBufWidthC, and Vsize are exported as follows:

[0241] MinCbLog2SizeY=log2_min_luma_coding_block_size_minus2+2 (48)

[0242] MinCbSizeY=1< <MinCbLog2SizeY (49)

[0243] IbcBufWidthY=256*128 / CtbSizeY (50)

[0244] IbcBufWidthC=IbcBufWidthY / SubWidthC (51)

[0245] VSize=Min(64,CtbSizeY) (52)

[0246] The value of MinCbSizeY should be less than or equal to VSize.

[0247] The variables CtbWidthC and CtbHeightC, which specify the width and height of the array of each chroma CTB respectively, are derived as follows:

[0248] --If chroma_format_idc is equal to 0 (monochrome) or separate_colour_plane_flag is equal to 1, CtbWidthC and CtbHeightC are both equal to 0.

[0249] Otherwise, CtbWidthC and CtbHeightC are derived as follows:

[0250] CtbWidthC=CtbSizeY / SubWidthC (53)

[0251] CtbHeightC=CtbSizeY / SubHeightC (54)

[0252] For log2BlockWidth ranging from 0 to 4 (including the end values) and log2BlockHeight ranging from 0 to 4 (including the end values), call the upper right diagonal scan order array initialization process as specified in Clause 6.5.2, where 1 << log2BlockWidth and 1 << log2BlockHeight are used as inputs, and the output is assigned to DiagScanOrder[log2BlockWidth][log2BlockHeight].

[0253] For log2BlockWidth ranging from 0 to 6 (including the end values) and log2BlockHeight ranging from 0 to 6 (including the end values), call the horizontal and vertical traversal scan order array initialization process as specified in Clause 6.5.3, where 1 << log2BlockWidth and 1 << log2BlockHeight are used as inputs, and the outputs are respectively assigned to HorTravScanOrder[log2BlockWidth][log2BlockHeight] and VerTravScanOrder[log2BlockWidth][log2BlockHeight].

[0254] That partition_constraints_override_enabled_flag equals 1 stipulates the existence of partition_constraints_override_flag in the PH of the reference SPS. That partition_constraints_override_enabled_flag equals 0 stipulates the non - existence of partition_constraints_override_flag in the PH of the reference SPS.

[0255] sps_log2_diff_min_qt_min_cb_intra_slice_luma specifies the default difference between the base 2 logarithm of the minimum size of luma samples of the luma leaf blocks resulting from the quadtree partitioning of the CTU and the base 2 logarithm of the minimum decoded block size of the luma samples of the luma CU in the slice with slice_type equal to 2(I) of the reference SPS. The default difference can be overridden by ph_log2_diff_min_qt_min_cb_luma present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_log2_diff_min_qt_min_cb_intra_slice_luma should be in the range of 0 to CtbLog2SizeY - MinCbLog2SizeY (inclusive). The base 2 logarithm of the minimum size of luma samples of the luma leaf blocks resulting from the quadtree partitioning of the CTU is derived as follows:

[0256] MinQtLog2SizeIntraY=sps_log2_diff_min_qt_min_cb_intra_slice_luma+MinCbLog2SizeY (55)

[0257] sps_max_mtt_hierarchy_depth_intra_slice_luma specifies the default maximum hierarchy depth for codec units resulting from multi-type tree partitioning of quadtree leaves in slices with slice_type equal to 2(I) of the reference SPS. When partition_constraints_override_enabled_flag is equal to 1, the default maximum hierarchy depth can be overridden by ph_max_mtt_hierarchy_depth_intra_slice_luma present in the PH of the reference SPS. The value of sps_max_mtt_hierarchy_depth_intra_slice_luma shall be in the range of 0 to 2*(CtbLog2SizeY - MinCbLog2SizeY), inclusive.

[0258] sps_log2_diff_max_bt_min_qt_intra_slice_luma specifies the default difference between the base-2 logarithm of the maximum size (width or height) of the luma samples of a luma codec block that can be partitioned using binary partitioning and the base-2 logarithm of the minimum size (width or height) of the luma samples of a luma leaf block resulting from a quadtree partitioning of a CTU of a slice with slice_type equal to 2(I) of the reference SPS. The default difference can be overridden by ph_log2_diff_max_bt_min_qt_luma present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_log2_diff_max_bt_min_qt_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeIntraY, inclusive. When sps_log2_diff_max_bt_min_qt_intra_slice_luma is not present, the value of sps_log2_diff_max_bt_min_qt_intra_slice_luma is inferred to be equal to 0.

[0259] sps_log2_diff_max_tt_min_qt_intra_slice_luma specifies the default difference between the base-2 logarithm of the maximum size (width or height) of the luma samples of a luma codec block that can be partitioned using ternary partitioning and the base-2 logarithm of the minimum size (width or height) of the luma samples of a luma leaf block resulting from a quadtree partitioning of a CTU in a slice with slice_type equal to 2(I) of the reference SPS. The default difference can be overridden by ph_log2_diff_max_tt_min_qt_luma present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_log2_diff_max_tt_min_qt_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeIntraY, inclusive. When sps_log2_diff_max_tt_min_qt_intra_slice_luma is not present, the value of sps_log2_diff_max_tt_min_qt_intra_slice_luma is inferred to be equal to 0.

[0260] sps_log2_diff_min_qt_min_cb_inter_slice specifies the default difference between the base 2 logarithm of the minimum size of luma samples of the luma leaf blocks resulting from a quadtree partitioning of a CTU and the base 2 logarithm of the minimum luma codec block size of the luma samples of the luma CU in slices for which slice_type is equal to 0 (B) or 1 (P) of the reference SPS. The default difference can be overridden by ph_log2_diff_min_qt_min_cb_luma present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_log2_diff_min_qt_min_cb_inter_slice shall be in the range of 0 to CtbLog2SizeY - MinCbLog2SizeY, inclusive. The base 2 logarithm of the minimum size of luma samples of the luma leaf blocks resulting from a quadtree partitioning of a CTU is derived as follows:

[0261] MinQtLog2SizeInterY=sps_log2_diff_min_qt_min_cb_inter_slice+MinCbLog2SizeY (56)

[0262] sps_max_mtt_hierarchy_depth_inter_slice specifies the default maximum hierarchy depth for codecs resulting from multi-type tree partitioning of quad leaves of slices with slice_type equal to 0 (B) or 1 (P) of the reference SPS. The default maximum hierarchy depth can be overridden by ph_max_mtt_hierarchy_depth_inter_slice present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_max_mtt_hierarchy_depth_inter_slice shall be in the range of 0 to 2*(CtbLog2SizeY - MinCbLog2SizeY), inclusive.

[0263] sps_log2_diff_max_bt_min_qt_inter_slice specifies the default difference between the base-2 logarithm of the maximum size (width or height) of the luma samples of a luma codec block that can be partitioned using binary partitioning and the base-2 logarithm of the minimum size (width or height) of the luma samples of a luma leaf block resulting from a quadtree partitioning of a CTU in a slice with slice_type equal to 0 (B) or 1 (P) of the reference SPS. The default difference can be overridden by ph_log2_diff_max_bt_min_qt_luma present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_log2_diff_max_bt_min_qt_inter_slice should be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeInterY, inclusive. When sps_log2_diff_max_bt_min_qt_inter_slice is not present, the value of sps_log2_diff_max_bt_min_qt_inter_slice is inferred to be equal to 0.

[0264] sps_log2_diff_max_tt_min_qt_inter_slice specifies the default difference between the base-2 logarithm of the maximum size (width or height) of the luma samples of a luma codec block that can be partitioned using ternary partitioning and the base-2 logarithm of the minimum size (width or height) of the luma samples of a luma leaf block resulting from a quadtree partitioning of a CTU in a slice with slice_type equal to 0 (B) or 1 (P) of the reference SPS. The default difference can be overridden by ph_log2_diff_max_tt_min_qt_luma present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_log2_diff_max_tt_min_qt_inter_slice should be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeInterY, inclusive. When sps_log2_diff_max_tt_min_qt_inter_slice is not present, the value of sps_log2_diff_max_tt_min_qt_inter_slice is inferred to be equal to 0.

[0265] sps_log2_diff_min_qt_min_cb_intra_slice_chroma specifies the default difference between the base-2 logarithm of the minimum size of luma samples of chroma leaf blocks resulting from quadtree partitioning of chroma CTUs with treeType equal to DUAL_TREE_CHROMA and the base-2 logarithm of the minimum decoded block size of luma samples of chroma CUs with treeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2(I) of the reference SPS. The default difference can be overridden by ph_log2_diff_min_qt_min_cb_chroma present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_log2_diff_min_qt_min_cb_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY - MinCbLog2SizeY, inclusive. When not present, the value of sps_log2_diff_min_qt_min_cb_intra_slice_chroma is inferred to be equal to 0. The base-2 logarithm of the minimum size of luma samples of chroma leaf blocks resulting from a quadtree partition of a CTU with treeType equal to DUAL_TREE_CHROMA is derived as follows:

[0266] MinQtLog2SizeIntraC=sps_log2_diff_min_qt_min_cb_intra_slice_chroma+MinCbLog2SizeY (57)

[0267] sps_max_mtt_hierarchy_depth_intra_slice_chroma specifies the default maximum hierarchical depth for chroma codec units resulting from multi-type tree partitioning of chroma quadtree leaves with treeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2(I) of the reference SPS. The default maximum hierarchical depth may be overridden by ph_max_mtt_hierarchy_depth_chroma present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_max_mtt_hierarchy_depth_intra_slice_chroma shall be in the range of 0 to 2*(CtbLog2SizeY - MinCbLog2SizeY), inclusive. When not present, the value of sps_max_mtt_hierarchy_depth_intra_slice_chroma is inferred to be equal to 0.

[0268] sps_log2_diff_max_bt_min_qt_intra_slice_chroma specifies the default difference between the base-2 logarithm of the maximum size (width or height) of the luma samples of a chroma codec block that can be partitioned using binary partitioning and the base-2 logarithm of the minimum size (width or height) of the luma samples of a chroma leaf block resulting from a quadtree partition of a chroma CTU with treeType equal to DUAL_TREE_CHROMA in a slice with slice_type equal to 2(I) of the reference SPS. The default difference can be overridden by ph_log2_diff_max_bt_min_qt_chroma present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_log2_diff_max_bt_min_qt_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeIntraC, inclusive. When sps_log2_diff_max_bt_min_qt_intra_slice_chroma is not present, the value of sps_log2_diff_max_bt_min_qt_intra_slice_chroma is inferred to be equal to 0.

[0269] sps_log2_diff_max_tt_min_qt_intra_slice_chroma specifies the default difference between the base-2 logarithm of the maximum size (width or height) of the luma samples of a chroma codec block that can be partitioned using ternary partitioning and the base-2 logarithm of the minimum size (width or height) of the luma samples of a chroma leaf block resulting from a quadtree partitioning of a chroma CTU with treeType equal to DUAL_TREE_CHROMA in a slice with slice_type equal to 2(I) of the reference SPS. The default difference can be overridden by ph_log2_diff_max_tt_min_qt_chroma present in the PH of the reference SPS when partition_constraints_override_enabled_flag is equal to 1. The value of sps_log2_diff_max_tt_min_qt_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeIntraC, inclusive. When sps_log2_diff_max_tt_min_qt_intra_slice_chroma is not present, the value of sps_log2_diff_max_tt_min_qt_intra_slice_chroma is inferred to be equal to 0.

[0270] sps_max_luma_transform_size_64_flag equal to 1 specifies that the maximum transform size of luma samples is equal to 64. sps_max_luma_transform_size_64_flag equal to 0 specifies that the maximum transform size of luma samples is equal to 32.

[0271] When CtbSizeY is less than 64, the value of sps_max_luma_transform_size_64_flag shall be equal to 0.

[0272] The variables MinTbLog2SizeY, MaxTbLog2SizeY, MinTbSizeY, and MaxTbSizeY are exported as follows:

[0273] MinTbLog2SizeY=2 (58)

[0274] MaxTbLog2SizeY=sps_max_luma_transform_size_64_flag? 6:5 (59)

[0275] MinTbSizeY=1< <MinTbLog2SizeY (60)

[0276] MaxTbSizeY=1< <MaxTbLog2SizeY (61)

[0277] sps_joint_cbcr_enabled_flag equal to 0 specifies disabling of joint coding of chroma residual. sps_joint_cbcr_enabled_flag equal to 1 specifies enabling of joint coding of chroma residual. When not present, the value of sps_joint_cbcr_enabled_flag is inferred to be equal to 0.

[0278] same_qp_table_for_chroma equal to 1 specifies that only one chroma QP mapping table is signaled, and that this table applies to both the Cb residual and the Cr residual, and also to the joint Cb-Cr residual, when sps_joint_cbcr_enabled_flag is equal to 1. same_qp_table_for_chroma equal to 0 specifies that when sps_joint_cbcr_enabled_flag is equal to 1, the chroma QP mapping table is signaled in the SPS, two for Cb and Cr, and one for the joint Cb-Cr. When same_qp_table_for_chroma is not present in the bitstream, the value of same_qp_table_for_chroma is inferred to be equal to 1.

[0279] qp_table_start_minus26[i] plus 26 specifies the starting luma and chroma QPs for describing the i-th chroma QP map. The value of qp_table_start_minus26[i] shall be in the range of -26 - QpBdOffset to 36 (inclusive). When qp_table_start_minus26[i] is not present in the bitstream, the value of qp_table_start_minus26[i] is inferred to be equal to 0.

[0280] num_points_in_qp_table_minus1[i] plus 1 specifies the number of points used to describe the i-th chroma QP map table. The value of num_points_in_qp_table_minus1[i] shall be in the range of 0 to 63+QpBdOffset, inclusive. When num_points_in_qp_table_minus1[0] is not present in the bitstream, the value of num_points_in_qp_table_minus1[0] is inferred to be equal to 0.

[0281] delta_qp_in_val_minus1[i][j] specifies the incremental value used to derive the input coordinates of the j-th pivot point of the i-th chroma QP map. When delta_qp_in_val_minus1[0][j] is not present in the bitstream, the value of delta_qp_in_val_minus1[0][j] is inferred to be equal to 0.

[0282] delta_qp_diff_val[i][j] specifies the delta value used to derive the output coordinates of the j-th pivot point of the i-th chroma QP map.

[0283] The i-th chroma QP mapping table ChromaQpTable[i] for i=0..numQpTables-1 is derived as follows:

[0284]

[0285]

[0286] When same_qp_table_for_chroma is equal to 1, ChromaQpTable[1][k] and ChromaQpTable[2][k] are set equal to ChromaQpTable[0][k] for k in the range of -QpBdOffset to 63 (inclusive).

[0287] The bitstream conformance requirement is that for i in the range 0 to numQpTables-1 (inclusive) and for j in the range 0 to num_points_in_qp_table_minus1[i]+1 (inclusive), the values of qpInVal[i][j] and qpOutVal[i][j] shall be in the range -QpBdOffset to 63 (inclusive).

[0288] sps_sao_enabled_flag equal to 1 specifies that the sample adaptive offset process is applied to the reconstructed picture after the deblocking filtering process. sps_sao_enabled_flag equal to 0 specifies that the sample adaptive offset process is not applied to the reconstructed picture after the deblocking filtering process.

[0289] sps_alf_enabled_flag equal to 0 specifies that the adaptive loop filter is disabled. sps_alf_enabled_flag equal to 1 specifies that the adaptive loop filter is enabled.

[0290] sps_ccalf_enabled_flag equal to 0 specifies that the cross-component adaptive loop filter is disabled. sps_ccalf_enabled_flag equal to 1 specifies that the cross-component adaptive loop filter is enabled.

[0291] sps_transform_skip_enabled_flag equal to 1 specifies that transform_skip_flag may be present in the transform unit syntax. sps_transform_skip_enabled_flag equal to 0 specifies that transform_skip_flag is not present in the transform unit syntax.

[0292] log2_transform_skip_max_size_minus2 specifies the maximum block size for transform skipping and should be in the range of 0 to 3 (inclusive).

[0293] The variable MaxTsSize is set equal to 1<<(log2_transform_skip_max_size_minus2+2).

[0294] sps_bdpcm_enabled_flag equal to 1 specifies that intra_bdpcm_luma_flag and intra_bdpcm_chroma_flag may be present in the codec unit syntax of an intra codec unit. sps_bdpcm_enabled_flag equal to 0 specifies that intra_bdpcm_luma_flag and intra_bdpcm_chroma_flag are not present in the codec unit syntax of an intra codec unit. When not present, the value of sps_bdpcm_enabled_flag is inferred to be equal to 0.

[0295] sps_ref_wraparound_enabled_flag equal to 1 specifies that horizontal wraparound motion compensation is applied in inter prediction. sps_ref_wraparound_enabled_flag equal to 0 specifies that horizontal wraparound motion compensation is not applied. When the value of (CtbSizeY / MinCbSizeY+1) is greater than (pic_width_in_luma_samples / MinCbSizeY-1), where pic_width_in_luma_samples is the value of pic_width_in_luma_samples in any PPS that references the SPS, the value of sps_ref_wraparound_enabled_flag shall be equal to 0. [Ed.(YK): The semantics here still depend on the PPS syntax elements.]

[0296] sps_temporal_mvp_enabled_flag equal to 1 specifies that the temporal motion vector predictor can be used in CLVS. sps_temporal_mvp_enabled_flag equal to 0 specifies that the temporal motion vector predictor is not used in CLVS.

[0297] sps_sbtmvp_enabled_flag equal to 1 specifies that the subblock based temporal motion vector predictor can be used for decoding pictures with all slices whose slice_type in CLVS is not equal to 1. sps_sbtmvp_enabled_flag equal to 0 specifies that the subblock based temporal motion vector predictor is not used in CLVS. When sps_sbtmvp_enabled_flag is not present, it is inferred to be equal to 0.

[0298] sps_amvr_enabled_flag equal to 1 specifies that adaptive motion vector difference resolution is used in motion vector coding and decoding. amvr_enabled_flag equal to 0 specifies that adaptive motion vector difference resolution is not used in motion vector coding and decoding.

[0299] sps_bdof_enabled_flag equal to 0 specifies that bidirectional optical flow inter prediction is disabled. sps_bdof_enabled_flag equal to 1 specifies that bidirectional optical flow inter prediction is enabled.

[0300] sps_bdof_pic_present_flag equal to 1 specifies that ph_disable_bdof_flag is present in the PH referencing the SPS. sps_bdof_pic_present_flag equal to 0 specifies that ph_disable_bdof_flag is not present in the PH referencing the SPS. When sps_bdof_pic_present_flag is not present, the value of sps_bdof_pic_present_flag is inferred to be equal to 0.

[0301] sps_smvd_enabled_flag equal to 1 specifies that symmetric motion vector differences can be used in motion vector decoding. sps_smvd_enabled_flag equal to 0 specifies that symmetric motion vector differences are not used in motion vector encoding and decoding.

[0302] sps_dmvr_enabled_flag equal to 1 specifies that inter bi-prediction based on decoder motion vector refinement is enabled. sps_dmvr_enabled_flag equal to 0 specifies that inter bi-prediction based on decoder motion vector refinement is disabled.

[0303] sps_dmvr_pic_present_flag equal to 1 specifies that ph_disable_dmvr_flag is present in the PH referencing the SPS. sps_dmvr_pic_present_flag equal to 0 specifies that ph_disable_dmvr_flag is not present in the PH referencing the SPS. When sps_dmvr_pic_present_flag is not present, the value of sps_dmvr_pic_present_flag is inferred to be equal to 0.

[0304] sps_mmvd_enabled_flag equal to 1 specifies that the merge mode with motion vector difference is enabled. sps_mmvd_enabled_flag equal to 0 specifies that the merge mode with motion vector difference is disabled.

[0305] sps_isp_enabled_flag equal to 1 specifies that intra prediction with subpartitioning is enabled. sps_isp_enabled_flag equal to 0 specifies that intra prediction with subpartitioning is disabled.

[0306] sps_mrl_enabled_flag equal to 1 specifies that intra prediction with multiple reference lines is enabled. sps_mrl_enabled_flag equal to 0 specifies that intra prediction with multiple reference lines is disabled.

[0307] sps_mip_enabled_flag equal to 1 specifies that matrix-based intra prediction is enabled. sps_mip_enabled_flag equal to 0 specifies that matrix-based intra prediction is disabled.

[0308] sps_cclm_enabled_flag equal to 0 specifies that cross-component linear model intra prediction from luma components to chroma components is disabled. sps_cclm_enabled_flag equal to 1 specifies that cross-component linear model intra prediction from luma components to chroma components is enabled. When sps_cclm_enabled_flag is not present, it is inferred to be equal to 0.

[0309] sps_chroma_horizontal_collocated_flag equal to 1 specifies that the prediction process operates in a manner designed for chroma sample positions that are not horizontally shifted relative to the corresponding luma sample positions. sps_chroma_horizontal_collocated_flag equal to 0 specifies that the prediction process operates in a manner designed for chroma sample positions that are right-shifted by 0.5 luma samples relative to the corresponding luma sample positions. When sps_chroma_horizontal_collocated_flag is not present, it is inferred to be equal to 1.

[0310] sps_chroma_vertical_collocated_flag equal to 1 specifies that the prediction process operates in a manner designed for chroma sample positions that are not vertically shifted relative to the corresponding luma sample positions. sps_chroma_vertical_collocated_flag equal to 0 specifies that the prediction process operates in a manner designed for chroma sample positions that are shifted downward by 0.5 in units of luma samples relative to the corresponding luma sample positions. When sps_chroma_vertical_collocated_flag is not present, it is inferred to be equal to 1.

[0311] sps_mts_enabled_flag equal to 1 specifies that sps_explicit_mts_intra_enabled_flag is present in the sequence parameter set RBSP syntax and sps_explicit_mts_inter_enabled_flag is present in the sequence parameter set RBSP syntax. sps_mts_enabled_flag equal to 0 specifies that sps_explicit_mts_intra_enabled_flag is not present in the sequence parameter set RBSP syntax and sps_explicit_mts_inter_enabled_flag is not present in the sequence parameter set RBSP syntax.

[0312] sps_explicit_mts_intra_enabled_flag equal to 1 specifies that mts_idx may be present in intra codec unit syntax. sps_explicit_mts_intra_enabled_flag equal to 0 specifies that mts_idx is not present in intra codec unit syntax. When not present, the value of sps_explicit_mts_intra_enabled_flag is inferred to be equal to 0.

[0313] sps_explicit_mts_inter_enabled_flag equal to 1 specifies that mts_idx may be present in inter-codec unit syntax. sps_explicit_mts_inter_enabled_flag equal to 0 specifies that mts_idx is not present in inter-codec unit syntax. When not present, the value of sps_explicit_mts_inter_enabled_flag is inferred to be equal to 0.

[0314] six_minus_max_num_merge_cand specifies the maximum number of merging motion vector prediction (MVP) candidates supported in the SPS, subtracted from 6. The value of six_minus_max_num_merge_cand should be in the range of 0 to 5 (inclusive).

[0315] The maximum number of merging MVP candidates, MaxNumMergeCand, is derived as follows:

[0316] MaxNumMergeCand=6-six_minus_max_num_merge_cand (63)

[0317] sps_sbt_enabled_flag equal to 0 specifies that sub-block transform for inter-predicted CUs is disabled. sps_sbt_enabled_flag equal to 1 specifies that sub-block transform for inter-predicted CUs is enabled.

[0318] sps_affine_enabled_flag specifies whether affine-based motion compensation can be used for inter prediction. If sps_affine_enabled_flag is equal to 0, the syntax should be constrained so that affine-based motion compensation is not used in CLVS, and inter_affine_flag and cu_affine_type_flag are not present in the codec syntax of CLVS. Otherwise (sps_affine_enabled_flag is equal to 1), affine-based motion compensation can be used in CLVS.

[0319] five_minus_max_num_subblock_merge_cand specifies the maximum number of sub-block based merge motion vector prediction candidates supported in the SPS, subtracted from 5.

[0320] sps_affine_type_flag specifies whether motion compensation based on a 6-parameter affine model can be used for inter prediction. If sps_affine_type_flag is equal to 0, the syntax should be constrained so that motion compensation based on a 6-parameter affine model is not used in CLVS, and cu_affine_type_flag is not present in the codec unit syntax in CLVS. Otherwise (sps_affine_type_flag is equal to 1), motion compensation based on a 6-parameter affine model can be used in CLVS. When not present, the value of sps_affine_type_flag is inferred to be equal to 0.

[0321] sps_affine_amvr_enabled_flag equal to 1 specifies the use of adaptive motion vector difference resolution in motion vector coding for affine inter mode. sps_affine_amvr_enabled_flag equal to 0 specifies the use of adaptive motion vector difference resolution in motion vector coding for affine inter mode. When not present, the value of sps_affine_amvr_enabled_flag is inferred to be equal to 0.

[0322] sps_affine_prof_enabled_flag specifies whether prediction refinement using optical flow can be used for affine motion compensation. If sps_affine_prof_enabled_flag is equal to 0, affine motion compensation will not use optical flow for refinement. Otherwise (sps_affine_prof_enabled_flag is equal to 1), affine motion compensation can use optical flow for refinement. When not present, the value of sps_affine_prof_enabled_flag is inferred to be equal to 0.

[0323] sps_prof_pic_present_flag equal to 1 specifies that ph_disable_prof_flag is present in the PH referencing the SPS. sps_prof_pic_present_flag equal to 0 specifies that ph_disable_prof_flag is not present in the PH referencing the SPS. When sps_prof_pic_present_flag is not present, the value of sps_prof_pic_present_flag is inferred to be equal to 0.

[0324] sps_palette_enabled_flag equal to 1 specifies that pred_mode_plt_flag may be present in the codec unit syntax. sps_palette_enabled_flag equal to 0 specifies that pred_mode_plt_flag is not present in the codec unit syntax. When sps_palette_enabled_flag is not present, it is inferred to be equal to 0.

[0325] sps_act_enabled_flag equal to 1 specifies that adaptive color transform can be used and cu_act_enabled_flag may be present in the codec unit syntax. sps_act_enabled_flag equal to 0 specifies that adaptive color transform is not used and cu_act_enabled_flag is not present in the codec unit syntax. When sps_act_enabled_flag is not present, it is inferred to be equal to 0.

[0326] min_qp_prime_ts_minus4 specifies the minimum allowed quantization parameter for transform skip mode as follows:

[0327] QpPrimeTsMin=4+min_qp_prime_ts_minus4 (64)

[0328] The value of min_qp_prime_ts_minus4 should be in the range of 0 to 48 (inclusive).

[0329] sps_bcw_enabled_flag specifies whether bidirectional prediction with CU weights can be used for inter prediction. If sps_bcw_enabled_flag is equal to 0, the syntax should be constrained so that bidirectional prediction with CU weights is not used in CLVS and bcw_idx is not present in the codec unit syntax of CLVS. Otherwise (sps_bcw_enabled_flag is equal to 1), bidirectional prediction with CU weights can be used in CLVS.

[0330] sps_ibc_enabled_flag equal to 1 specifies that IBC prediction mode can be used for decoding of pictures in CLVS. sps_ibc_enabled_flag equal to 0 specifies that IBC prediction mode is not used in CLVS. When sps_ibc_enabled_flag is not present, it is inferred to be equal to 0.

[0331] six_minus_max_num_ibc_merge_cand specifies the maximum number of IBC merge block vector prediction (BVP) candidates supported in the SPS subtracted from 6. The value of six_minus_max_num_ibc_merge_cand shall be in the range of 0 to 5, inclusive.

[0332] The maximum number of IBC merging BVP candidates, MaxNumIbcMergeCand, is derived as follows:

[0333]

[0334] sps_ciip_enabled_flag specifies that ciip_flag may be present in the codec unit syntax of an inter codec unit. sps_ciip_enabled_flag equal to 0 specifies that ciip_flag is not present in the codec unit syntax of an inter codec unit.

[0335] sps_fpel_mmvd_enabled_flag equal to 1 specifies that the merge mode with motion vector difference uses integer sample precision. sps_fpel_mmvd_enabled_flag equal to 0 specifies that the merge mode with motion vector difference can use fractional sample precision.

[0336] sps_gpm_enabled_flag specifies whether geometric partitioning-based motion compensation can be used for inter prediction. sps_gpm_enabled_flag equal to 0 specifies that the syntax should be constrained so that geometric partitioning-based motion compensation is not used in CLVS and merge_gpm_partition_idx, merge_gpm_idx0, and merge_gpm_idx1 are not present in the codec unit syntax of CLVS. sps_gpm_enabled_flag equal to 1 specifies that geometric partitioning-based motion compensation can be used in CLVS. When not present, the value of sps_gpm_enabled_flag is inferred to be equal to 0.

[0337] max_num_merge_cand_minus_max_num_gpm_cand specifies the maximum number of geometric partition merge mode candidates supported in the SPS subtracted from MaxNumMergeCand.

[0338] The maximum number of geometric segmentation merge mode candidates MaxNumGpmMergeCand is derived as follows:

[0339]

[0340] The value of MaxNumGpmMergeCand should be in the range of 2 to MaxNumMergeCand (including the end values).

[0341] sps_lmcs_enabled_flag equal to 1 specifies that luma mapping with chroma scaling is used in CLVS. sps_lmcs_enabled_flag equal to 0 specifies that luma mapping with chroma scaling is not used in CLVS.

[0342] sps_lfnst_enabled_flag equal to 1 specifies that lfnst_idx may be present in the intra codec unit syntax. sps_lfnst_enabled_flag equal to 0 specifies that lfnst_idx is not present in the intra codec unit syntax.

[0343] sps_ladf_enabled_flag is equal to 1, which specifies that sps_num_ladf_intervals_minus2, sps_ladf_lowest_interval_qp_offset, sps_ladf_qp_offset[i], and sps_ladf_delta_threshold_minus1[i] are present in the SPS.

[0344] sps_num_ladf_intervals_minus2 plus 1 specifies the number of sps_ladf_delta_threshold_minus1[i] and sps_ladf_qp_offset[i] syntax elements present in the SPS. The value of sps_num_ladf_intervals_minus2 shall be in the range of 0 to 3 (inclusive).

[0345] sps_ladf_lowest_interval_qp_offset specifies the offset used to derive the variable qP as specified in clause 8.8.3.6.1. The value of sps_ladf_lowest_interval_qp_offset shall be in the range of -63 to 63 (inclusive).

[0346] sps_ladf_qp_offset[i] specifies the offset array used to derive the variable qP as specified in clause 8.8.3.6.1. The value of sps_ladf_qp_offset[i] shall be in the range of -63 to 63 (inclusive).

[0347] sps_ladf_delta_threshold_minus1[i] is used to calculate the value of SpsLadfIntervalLowerBound[i], which specifies the lower bound of the ith luminance intensity level interval. The value of sps_ladf_delta_threshold_minus1[i] should be between 0 and 2. BitDepth -3 (inclusive) range.

[0348] The value of SpsLadfIntervalLowerBound[0] is set equal to 0.

[0349] For each value of i in the range from 0 to sps_num_ladf_intervals_minus2 (inclusive), the variable SpsLadfIntervalLowerBound[i+1] is derived as follows:

[0350]

[0351] log2_parallel_merge_level_minus2 plus 2 specifies the value of the variable Log2ParMrgLevel, which is used for the derivation of spatial merge candidates as specified in clause 8.5.2.3, the derivation of motion vectors and reference indices in sub-block merge mode as specified in clause 8.5.5.2, and controls the invocation of the update procedure for the history-based motion vector predictor list as specified in clause 8.5.2.1. The value of log2_parallel_merge_level_minus2 shall be in the range of 0 to CtbLog2SizeY–2 (inclusive). The variable Log2ParMrgLevel is derived as follows:

[0352] Log2ParMrgLevel=log2_parallel_merge_level_minus2+2 (68)

[0353] sps_scaling_list_enabled_flag equal to 1 specifies that the scaling list is used for the scaling process of transform coefficients. sps_scaling_list_enabled_flag equal to 0 specifies that the scaling list is not used for the scaling process of transform coefficients.

[0354] sps_dep_quant_enabled_flag equal to 0 specifies that dependent quantization is disabled for pictures that reference the SPS. sps_dep_quant_enabled_flag equal to 1 specifies that dependent quantization can be enabled for pictures that reference the SPS.

[0355] sps_sign_data_hiding_enabled_flag equal to 0 specifies that sign bit hiding is disabled for pictures that reference the SPS. sps_sign_data_hiding_enabled_flag equal to 1 specifies that sign bit hiding may be enabled for pictures that reference the SPS. When sps_sign_data_hiding_enabled_flag is not present, it is inferred to be equal to 0.

[0356] sps_virtual_boundaries_enabled_flag equal to 1 specifies that loop filtering with disabled cross-virtual boundaries may be applied in coded pictures in CLVS. sps_virtual_boundaries_enabled_flag equal to 0 specifies that loop filtering with disabled cross-virtual boundaries is not applied in coded pictures in CLVS. Loop filtering operations include deblocking filter, sample adaptive offset filter, and adaptive loop filter operations.

[0357] sps_virtual_boundaries_present_flag equal to 1 specifies that virtual boundaries are signaled in the SPS. sps_virtual_boundaries_present_flag equal to 0 specifies that virtual boundaries are not signaled in the SPS. When one or more virtual boundaries are signaled in the SPS, loop filtering operations are disabled across virtual boundaries in pictures that reference the SPS. Loop filtering operations include deblocking filter, sample adaptive offset filter, and adaptive loop filter operations.

[0358] A bitstream conformance requirement is that when the value of res_change_in_clvs_allowed_flag is equal to 1, the value of sps_virtual_boundaries_present_flag shall be equal to 0.

[0359] sps_num_ver_virtual_boundaries specifies the number of sps_virtual_boundaries_pos_x[i] syntax elements present in the SPS. When sps_num_ver_virtual_boundaries is not present, it is inferred to be equal to 0.

[0360] sps_virtual_boundaries_pos_x[i] specifies the position of the i-th vertical virtual boundary in units of luma samples divided by 8. The value of sps_virtual_boundaries_pos_x[i] shall be in the range of 1 to Ceil(pic_width_in_luma_samples ÷ 8) – 1, inclusive. [Ed.(VD): pic_width_in_luma_samples is in PPS, not SPS.]

[0361] sps_num_hor_virtual_boundaries specifies the number of sps_virtual_boundaries_pos_y[i] syntax elements present in the SPS. When sps_num_hor_virtual_boundaries is not present, it is inferred to be equal to 0.

[0362] When sps_virtual_boundaries_enabled_flag is equal to 1 and sps_virtual_boundaries_present_flag is equal to 1, the sum of sps_num_ver_virtual_boundaries and sps_num_hor_virtual_boundaries shall be greater than 0.

[0363] sps_virtual_boundaries_pos_y[i] specifies the position of the i-th horizontal virtual boundary in units of luma samples divided by 8. The value of sps_virtual_boundaries_pos_y[i] shall be in the range of 1 to Ceil(pic_height_in_luma_samples ÷ 8) – 1, inclusive. [Ed.(VD): pic_height_in_luma_samples is in PPS, not SPS.]

[0364] sps_general_hrd_params_present_flag equal to 1 specifies that the syntax structure general_hrd_parameters() is present in the SPS RBSP syntax structure. sps_general_hrd_params_present_flag equal to 0 specifies that the syntax structure general_hrd_parameters() is not present in the SPS RBSP syntax structure.

[0365] sps_sublayer_cpb_params_present_flag equal to 1 specifies that the syntax structure old_hrd_parameters() in the SPS RBSP includes the HRD parameters of the sublayer representation whose TemporalId is in the range of 0 to sps_max_sublayers_minus1 (inclusive). sps_sublayer_cpb_params_present_flag equal to 0 specifies that the syntax structure ols_hrd_parameters() in the SPS RBSP includes only the HRD parameters of the sublayer representation whose TemporalId is equal to sps_max_sublayers_minus1. When sps_max_sublayers_minus1 is equal to 0, the value of sps_sublayer_cpb_params_present_flag is inferred to be equal to 0.

[0366] When sps_sublayer_cpb_params_present_flag is equal to 0, the HRD parameters of the sublayer representation with TemporalId in the range of 0 to sps_max_sublayers_minus1-1 (inclusive) are inferred to be the same as the HRD parameters of the sublayer representation with TemporalId equal to sps_max_sublayers_minus1. This includes the HRD parameters starting with the fixed_pic_rate_general_flag[i] syntax element up to the sublayer_hrd_parameters(i) syntax structure immediately following the conditional "if (general_vcl_hrd_params_present_flag)" in the ols_hrd_parameters syntax structure.

[0367] field_seq_flag equal to 1 instructs CLVS to transmit pictures representing fields. field_seq_flag equal to 0 instructs CLVS to transmit pictures representing frames. When general_frame_only_constraint_flag is equal to 1, the value of field_seq_flag shall be equal to 0.

[0368] When field_seq_flag is equal to 1, a frame field information SEI message shall be present for each codec picture in the CLVS.

[0369] NOTE 5 – The specified decoding process does not treat pictures representing fields or frames differently. Therefore, a sequence of pictures representing a field will be encoded or decoded with the picture dimensions of a single field. For example, a picture representing a 1080i field will typically have cropped output dimensions of 1920x540, and the sequence picture rate will typically represent the source field rate (typically between 50 Hz and 60 Hz) rather than the source frame rate (typically between 25 Hz and 30 Hz).

[0370] vui_parameters_present_flag equal to 1 specifies that the syntax structure vui_parameters() is present in the SPS RBSP syntax structure. vui_parameters_present_flag equal to 0 specifies that the syntax structure vui_parameters() is not present in the SPS RBSP syntax structure.

[0371] sps_extension_flag equal to 0 specifies that the sps_extension_data_flag syntax element is not present in the SPS RBSP syntax structure. sps_extension_flag equal to 1 specifies that the sps_extension_data_flag syntax element is present in the SPS RBSP syntax structure.

[0372] sps_extension_data_flag can have any value. Its presence and value do not affect decoder conformance to the profile specified in this version of this specification. Decoders conforming to this version of this specification shall ignore all sps_extension_data_flag syntax elements.

[0373] 3.1.PPS Syntax and Semantics

[0374] In the latest VVC draft text, the PPS syntax and semantics are as follows:

[0375]

[0376]

[0377]

[0378]

[0379]

[0380] The PPS RBSP shall be available to the decoding process before being referenced, included in at least one AU with a TemporalId less than or equal to the TemporalId of the PPS NAL unit, or provided by external means.

[0381] All PPS NAL units within a PU with a specific value of pps_pic_parameter_set_id shall have the same content.

[0382] pps_pic_parameter_set_id identifies the PPS referenced by other syntax elements. The value of pps_pic_parameter_set_id shall be in the range of 0 to 63 (inclusive).

[0383] Regardless of the nuh_layer_id value, PPS NAL units share the same value space of pps_pic_parameter_set_id.

[0384] Let ppsLayerId be the value of nuh_layer_id of a specific PPS NAL unit, and vclLayerId be the value of nuh_layer_id of a specific VCL NAL unit. A specific VCL NAL unit shall not refer to a specific PPS NAL unit unless ppsLayerId is less than or equal to vclLayerId and the layer with nuh_layer_id equal to ppsLayerId is contained in at least one OLS that includes a layer with nuh_layer_id equal to vclLayerId.

[0385] pps_seq_parameter_set_id specifies the value of sps_seq_parameter_set_id of the SPS. The value of pps_seq_parameter_set_id should be in the range of 0 to 15 (inclusive). The value of pps_seq_parameter_set_id should be the same in all PPSs referenced by a codec picture in CLVS.

[0386] mixed_nalu_types_in_pic_flag equal to 1 specifies that each picture of the referenced PPS has multiple VCL NAL units, the VCL NAL units do not have the same nal_unit_type value, and the picture is not an IRAP picture. mixed_nalu_types_in_pic_flag equal to 0 specifies that each picture of the referenced PPS has one or more VCL NAL units, and the VCL NAL units of each picture of the referenced PPS have the same nal_unit_type value.

[0387] When no_mixed_nalu_types_in_pic_constraint_flag is equal to 1, the value of mixed_nalu_types_in_pic_flag shall be equal to 0.

[0388] For each slice having a nal_unit_type value nalUnitTypeA in the range IDR_W_RADL to CRA_NUT (inclusive) in a picture picA that also contains one or more slices having another value of nal_unit_type (i.e., the value of mixed_nalu_types_in_pic_flag of picture picA is equal to 1), the following applies:

[0389] - The slice shall belong to the sub-picture subpicA with the corresponding value of subpic_treated_as_pic_flag[i] equal to 1.

[0390] - A slice shall not belong to a sub-picture of picA containing a VCL NAL unit whose nal_unit_type is not equal to nalUnitTypeA.

[0391] - If nalUnitTypeA is equal to CRA, then for all subsequent PUs in the CLVS that follow the current picture in decoding order and output order, the RefPicList[0] and RefPicList[1] of the slices in subpicA in these PUs shall not include any pictures that precede picA in decoding order in the active entry.

[0392] Otherwise (i.e., nalUnitTypeA is equal to IDR_W_RADL or IDR_N_LP), for all PUs in the CLVS that follow the current picture in decoding order, neither the RefPicList[0] nor the RefPicList[1] of the slices in subpicA in these PUs shall include any pictures that precede picA in decoding order in the active entry.

[0393] NOTE 1 – mixed_nalu_types_in_pic_flag is equal to 1 to indicate that the picture referencing the PPS contains slices with different NAL unit types, for example, a codec picture resulting from a sub-picture bitstream merge operation, and the encoder must ensure matching of the bitstream structure and further alignment of the parameters of the original bitstream. An example of such alignment is as follows: When the value of sps_idr_rpl_flag is equal to 0 and mixed_nalu_types_in_pic_flag is equal to 1, the picture referencing the PPS shall not have slices with nal_unit_type equal to IDR_W_RADL or IDR_N_LP.

[0394] pic_width_in_luma_samples specifies the width of each decoded picture that references the PPS, in units of luma samples. pic_width_in_luma_samples shall not be equal to 0, shall be an integer multiple of Max(8, MinCbSizeY), and shall be less than or equal to pic_width_max_in_luma_samples.

[0395] When res_change_in_clvs_allowed_flag is equal to 0, the value of pic_width_in_luma_samples shall be equal to pic_width_max_in_luma_samples.

[0396] pic_height_in_luma_samples specifies the height in luma samples of each decoded picture that references the PPS. pic_height_in_luma_samples shall not be equal to 0 and shall be an integer multiple of Max(8, MinCbSizeY) and shall be less than or equal to pic_height_max_in_luma_samples.

[0397] When res_change_in_clvs_allowed_flag is equal to 0, the value of pic_height_in_luma_samples shall be equal to pic_height_max_in_luma_samples.

[0398] The variables PicWidthInCtbsY, PicHeightInCtbsY, PicSizeInCtbsY, PicWidthInMinCbsY, PicHeightInMinCbsY, PicSizeInMinCbsY, PicSizeInSamplesY, PicWidthInSamplesC, and PicHeightInSamplesC are derived as follows:

[0399] PicWidthInCtbsY=Ceil(pic_width_in_luma_samples÷CtbSizeY) (69)

[0400] PicHeightInCtbsY=Ceil(pic_height_in_luma_samples÷CtbSizeY) (70)

[0401] PicSizeInCtbsY=PicWidthInCtbsY*PicHeightInCtbsY (71)

[0402] PicWidthInMinCbsY=pic_width_in_luma_samples / MinCbSizeY (72)

[0403] PicHeightInMinCbsY=pic_height_in_luma_samples / MinCbSizeY (73)

[0404] PicSizeInMinCbsY=PicWidthInMinCbsY*PicHeightInMinCbsY (74)

[0405] PicSizeInSamplesY=pic_width_in_luma_samples*pic_height_in_luma_samples (75)

[0406] PicWidthInSamplesC=pic_width_in_luma_samples / SubWidthC (76)

[0407] PicHeightInSamplesC=pic_height_in_luma_samples / SubHeightC (77)

[0408] pps_conformance_window_flag equal to 1 indicates that the conformance cropping window offset parameter follows immediately in the PPS. pps_conformance_window_flag equal to 0 indicates that the conformance cropping window offset parameter does not exist in the PPS.

[0409] pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset specify the samples of the picture in the CLVS output from the decoding process, output according to the rectangular area specified in picture coordinates. When pps_conformance_window_flag is equal to 0, the values of pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset are inferred to be equal to 0.

[0410] The conforming cropping window contains luma samples with horizontal picture coordinates from SubWidthC*pps_conf_win_left_offset to pic_width_in_luma_samples-(SubWidthC*pps_conf_win_right_offset+1), and vertical picture coordinates from SubHeightC*pps_conf_win_top_offset to pic_height_in_luma_samples-(SubHeightC*pps_conf_win_bottom_offset+1), inclusive.

[0411] The value of SubWidthC*(pps_conf_win_left_offset+pps_conf_win_right_offset) should be less than pic_width_in_luma_samples, and the value of SubHeightC*(pps_conf_win_top_offset+pps_conf_win_bottom_offset) should be less than pic_height_in_luma_samples.

[0412] When ChromaArrayType is not equal to 0, the corresponding specified samples of the two chroma arrays are samples with picture coordinates (x / SubWidthC, y / SubHeightC), where (x, y) are the picture coordinates of the specified luma sample.

[0413] NOTE 2 - The consistency crop window offset parameter applies only to output. All internal decoding processes are applied to the uncropped picture size.

[0414] Assume that ppsA and ppsB are any two PPSs that reference the same SPS. The bitstream conformance requirement is that when ppsA and ppsB have the same values of pic_width_in_luma_samples and pic_height_in_luma_samples, respectively, ppsA and ppsB shall have the same values of pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset, respectively.

[0415] When pic_width_in_luma_samples is equal to pic_width_max_in_luma_samples and pic_height_in_luma_samples is equal to pic_height_max_in_luma_samples, the bitstream conformance requirement is that pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset are equal to sps_conf_win_left_offset, sps_conf_win_right_offset, sps_conf_win_top_offset, and sps_conf_win_bottom_offset, respectively.

[0416] scaling_window_explicit_signaling_flag equal to 1 specifies that the scaling window offset parameters are present in the PPS. scaling_window_explicit_signaling_flag equal to 0 specifies that the scaling window offset parameters are not present in the PPS. When res_change_in_clvs_allowed_flag is equal to 0, the value of scaling_window_explicit_signaling_flag shall be equal to 0.

[0417] scaling_win_left_offset, scaling_win_right_offset, scaling_win_top_offset, and scaling_win_bottom_offset specify offsets to the picture size that should be used for scaling calculations. When not present, the values of scaling_win_left_offset, scaling_win_right_offset, scaling_win_top_offset, and scaling_win_bottom_offset are inferred to be equal to pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset, respectively.

[0418] The value of SubWidthC*(scaling_win_left_offset+scaling_win_right_offset) should be less than pic_width_in_luma_samples, and the value of SubHeightC*(scaling_win_top_offset+scaling_win_bottom_offset) should be less than pic_height_in_luma_samples.

[0419] The variables PicOutputWidthL and PicOutputHeightL are derived as follows:

[0420]

[0421]

[0422] Assume that refPicOutputWidthL and refPicOutputHeightL are the PicOutputWidthL and PicOutputHeightL of the reference picture of the current picture that refers to this PPS. The bitstream conformance requirement is that all of the following conditions are met:

[0423] -PicOutputWidthL*2 should be greater than or equal to refPicWidthInLumaSamples.

[0424] -PicOutputHeightL*2 should be greater than or equal to refPicHeightInLumaSamples.

[0425] -PicOutputWidthL should be less than or equal to refPicWidthInLumaSamples*8.

[0426] -PicOutputHeightL should be less than or equal to refPicHeightInLumaSamples*8.

[0427] - PicOutputWidthL*pic_width_max_in_luma_samples should be greater than or equal to refPicOutputWidthL*(pic_width_in_luma_samples-Max(8,MinCbSizeY)).

[0428] - PicOutputHeightL*pic_height_max_in_luma_samples should be greater than or equal to refPicOutputHeightL*(pic_height_in_luma_samples-Max(8,MinCbSizeY)).

[0429] output_flag_present_flag equal to 1 indicates that the pic_output_flag syntax element is present in the slice header of the referenced PPS. output_flag_present_flag equal to 0 indicates that the pic_output_flag syntax element is not present in the slice header of the referenced PPS.

[0430] subpic_id_mapping_in_pps_flag equal to 1 specifies that sub-picture ID mapping is signaled in the PPS. subpic_id_mapping_in_pps_flag equal to 0 specifies that sub-picture ID mapping is not signaled in the PPS. If subpic_id_mapping_explicitly_signalled_flag is 0 or subpic_id_mapping_in_sps_flag is 1, then the value of subpic_id_mapping_in_pps_flag shall be equal to 0. Otherwise (subpic_id_mapping_explicitly_signalled_flag is 1 and subpic_id_mapping_in_sps_flag is 0), the value of subpic_id_mapping_in_pps_flag shall be equal to 1.

[0431] pps_num_subpics_minus1 shall be equal to sps_num_subpics_minus1.

[0432] pps_subpic_id_len_minus1 shall be equal to sps_subpic_id_len_minus1.

[0433] pps_subpic_id[i] specifies the sub-picture ID of the i-th sub-picture. The length of the pps_subpic_id[i] syntax element is pps_subpic_id_len_minus1+1 bits.

[0434] For each value of i in the range from 0 to sps_num_subpics_minus1 (inclusive), the variable SubpicIdVal[i] is derived as follows:

[0435]

[0436] The requirement for bitstream conformance is that the following two constraints apply:

[0437] --For any two different values of i and j in the range of 0 to sps_num_subpics_minus1 (inclusive), SubpicIdVal[i] shall not be equal to SubpicIdVal[j].

[0438] --When the current picture is not the first picture of the CLVS, for each value of i in the range of 0 to sps_num_subpics_minus1 (inclusive), if the value of SubpicIdVal[i] is not equal to the value of SubpicIdVal[i] of the previous picture in the same layer in decoding order, the nal_unit_type of all codec slice NAL units of the subpictures in the current picture with subpicture index i shall be equal to the specified value in the range of IDR_W_RADL to CRA_NUT (inclusive).

[0439] no_pic_partition_flag equal to 1 specifies that no picture partitioning is applied to each picture of the referenced PPS. no_pic_partition_flag equal to 0 specifies that each picture of the referenced PPS may be partitioned into multiple slices or slices.

[0440] The bitstream conformance requirement is that the value of no_pic_partition_flag shall be the same for all PPSs referenced by a codec picture within a CLVS.

[0441] A bitstream conformance requirement is that when the value of sps_num_subpics_minus1+1 is greater than 1, the value of no_pic_partition_flag shall not be equal to 1.

[0442] pps_log2_ctu_size_minus5 plus 5 specifies the luma codec treeblock size for each CTU. pps_log2_ctu_size_minus5 shall be equal to sps_log2_ctu_size_minus5.

[0443] num_exp_tile_columns_minus1 plus 1 specifies the number of explicitly provided tile column widths. The value of num_exp_tile_columns_minus1 shall be in the range of 0 to PicWidthInCtbsY–1, inclusive. When no_pic_partition_flag is equal to 1, the value of num_exp_tile_columns_minus1 is inferred to be equal to 0.

[0444] num_exp_tile_rows_minus1 plus 1 specifies the number of explicitly provided tile row heights. The value of num_exp_tile_rows_minus1 shall be in the range of 0 to PicHeightInCtbsY–1, inclusive. When no_pic_partition_flag is equal to 1, the value of num_tile_rows_minus1 is inferred to be equal to 0.

[0445] tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column for i in the range 0 to num_exp_tile_columns_minus1-1 (inclusive) in units of CTBs. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1 as specified in clause 6.5.1. The value of tile_column_width_minus1[i] shall be in the range 0 to PicWidthInCtbsY–1 (inclusive). When not present, the value of tile_column_width_minus1[0] is inferred to be equal to PicWidthInCtbsY-1.

[0446] tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row for i in the range 0 to num_exp_tile_rows_minus1-1 (inclusive) in units of CTBs. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows for indices greater than or equal to num_exp_tile_rows_minus1 as specified in clause 6.5.1. The value of tile_row_height_minus1[i] shall be in the range 0 to PicHeightInCtbsY–1 (inclusive). When not present, the value of tile_row_height_minus1[0] is inferred to be equal to PicHeightInCtbsY-1.

[0447] rect_slice_flag equal to 0 specifies that the slices within each slice are in raster scan order and that slice information is not signaled in the PPS. rect_slice_flag equal to 1 specifies that the slices within each slice cover a rectangular area of the picture and that slice information is signaled in the PPS. When not present, rect_slice_flag is inferred to be equal to 1. When subpic_info_present_flag is equal to 1, the value of rect_slice_flag shall be equal to 1.

[0448] single_slice_per_subpic_flag equal to 1 specifies that each sub-picture consists of one and only one rectangular slice. single_slice_per_subpic_flag equal to 0 specifies that each sub-picture may consist of one or more rectangular slices. When single_slice_per_subpic_flag is equal to 1, num_slices_in_pic_minus1 is inferred to be equal to sps_num_subpics_minus1. When not present, the value of single_slice_per_subpic_flag is inferred to be equal to 0.

[0449] num_slices_in_pic_minus1 plus 1 specifies the number of rectangular slices in each picture referencing the PPS. The value of num_slices_in_pic_minus1 shall be in the range of 0 to MaxSlicesPerPicture–1, inclusive, where MaxSlicesPerPicture is specified in Annex A. When no_pic_partition_flag is equal to 1, the value of num_slices_in_pic_minus1 is inferred to be equal to 0.

[0450] tile_idx_delta_present_flag equal to 0 specifies that tile_idx_delta values are not present in the PPS, and all rectangular slices in pictures referencing the PPS are specified in raster order according to the procedure defined in clause 6.5.1. tile_idx_delta_present_flag equal to 1 specifies that tile_idx_delta values may be present in the PPS, and all rectangular slices in pictures referencing the PPS are specified in the order indicated by the tile_idx_delta values. When not present, the value of tile_idx_delta_present_flag is inferred to be equal to 0.

[0451] slice_width_in_tiles_minus1[i] plus 1 specifies the width of the i-th rectangular strip in units of tile columns. The value of slice_width_in_tiles_minus1[i] should be in the range of 0 to NumTileColumns–1 (inclusive).

[0452] When slice_width_in_tiles_minus1[i] is not present, the following applies:

[0453] --If NumTileColumns is equal to 1, the value of slice_width_in_tiles_minus1[i] is inferred to be equal to 0.

[0454] -- Otherwise, the value of slice_width_in_tiles_minus1[i] is inferred as specified in clause 6.5.1.

[0455] slice_height_in_tiles_minus1[i] plus 1 specifies the height of the i-th rectangular strip in units of tile rows. The value of slice_height_in_tiles_minus1[i] should be in the range of 0 to NumTileRows–1 (inclusive).

[0456] When slice_height_in_tiles_minus1[i] is not present, the following applies:

[0457] --If NumTileRows is equal to 1, or tile_idx_delta_present_flag is equal to 0, and tileIdx%NumTileColumns is greater than 0, then the value of slice_height_in_tiles_minus1[i] is inferred to be equal to 0.

[0458] Otherwise (NumTileRows is not equal to 1, and tile_idx_delta_present_flag is equal to 1 or tileIdx%NumTileColumns is equal to 0), when tile_idx_delta_present_flag is equal to 1 or tileIdx%NumTileColumns is equal to 0, the value of slice_height_in_tiles_minus1[i] is inferred to be equal to slice_height_in_tiles_minus1[i-1].

[0459] num_exp_slices_in_tile[i] specifies the number of explicitly provided strip heights in the current slice containing multiple rectangular strips. The value of num_exp_slices_in_tile[i] shall be in the range of 0 to RowHeight[tileY]-1 (inclusive), where tileY is the index of the slice row containing the i-th strip. When not present, the value of num_exp_slices_in_tile[i] is inferred to be equal to 0. When num_exp_slices_in_tile[i] is equal to 0, the value of the variable NumSlicesInTile[i] is derived to be equal to 1.

[0460] exp_slice_height_in_ctus_minus1[j] plus 1 specifies the height of the j-th rectangular slice in the current slice in units of CTU rows. The value of exp_slice_height_in_ctus_minus1[j] should be in the range of 0 to RowHeight[tileY]-1 (inclusive), where tileY is the slice row index of the current slice.

[0461] When num_exp_slices_in_tile[i] is greater than 0, the variables NumSlicesInTile[i] and SliceHeightInCtusMinus1[i+k] with k in the range of 0 to NumSlicesInTile[i]-1 (inclusive) are derived as follows:

[0462]

[0463] tile_idx_delta[i] specifies the difference between the tile index of the first tile in the i-th rectangular stripe and the tile index of the first tile in the i+1-th rectangular stripe. The value of tile_idx_delta[i] shall be in the range -NumTilesInPic+1 to NumTilesInPic-1 (inclusive). When not present, the value of tile_idx_delta[i] is inferred to be equal to 0. When present, the value of tile_idx_delta[i] shall not be equal to 0.

[0464] loop_filter_across_tiles_enabled_flag equal to 1 specifies that loop filtering operations may be performed across slice boundaries in pictures that reference the PPS. loop_filter_cross_tiles_enabled_flag equal to 0 specifies that loop filtering operations are not performed across slice boundaries in pictures that reference the PPS. Loop filtering operations include deblocking filter, sample adaptive offset filter, and adaptive loop filter operations. When not present, the value of loop_filter_cross_tiles_enabled_flag is inferred to be equal to 1.

[0465] loop_filter_cross_slices_enabled_flag equal to 1 specifies that loop filtering operations may be performed across slice boundaries in pictures that reference the PPS. loop_filter_cross_slice_enabled_flag equal to 0 specifies that loop filtering operations are not performed across slice boundaries in pictures that reference the PPS. Loop filtering operations include deblocking filter, sample adaptive offset filter, and adaptive loop filter operations. When not present, the value of loop_filter_cross_slices_enabled_flag is inferred to be equal to 0.

[0466] cabac_init_present_flag equal to 1 specifies that cabac_init_flag is present in the slice header of the referenced PPS. cabac_init_present_flag equal to 0 specifies that cabac_init_flag is not present in the slice header of the referenced PPS.

[0467] num_ref_idx_default_active_minus1[i] incremented by 1, when equal to 0, specifies the inferred value of the variable NumRefIdxActive[0] for P slices or B slices with num_ref_idx_active_override_flag equal to 0, and when i is equal to 1, specifies the inferred value of NumRefIdxActive[1] for B slices with num_ref_idx_active_override_flag equal to 0. The value of num_ref_idx_default_active_minus1[i] shall be in the range of 0 to 14, inclusive.

[0468] rpl1_idx_present_flag equal to 0 specifies that ref_pic_list_sps_flag[1] and ref_pic_list_idx[1] are not present in the PH syntax structure or the slice header of the picture referencing the PPS. rpl1_idx_present_flag equal to 1 specifies that ref_pic_list_sps_flag[1] and ref_pic_list_idx[1] may be present in the PH syntax structure or the slice header of the picture referencing the PPS.

[0469] init_qp_minus26 plus 26 specifies the SliceQp of each slice of the reference PPS Y When a non-zero value of ph_qp_delta is decoded, SliceQp Y The initial value of SliceQp is modified at the picture level, or when a non-zero value of slice_qp_delta is decoded. Y The initial value of init_qp_minus26 is modified at the stripe level. The value of init_qp_minus26 should be in the range of -(26+QpBdOffset) to +37 (inclusive).

[0470] cu_qp_delta_enabled_flag equal to 1 specifies that the ph_cu_qp_delta_subdiv_intra_slice and ph_cu_qp_delta_subdiv_inter_slice syntax elements are present in the PH referencing the PPS and that cu_qp_delta_abs may be present in the transform unit syntax. cu_qp_delta_enabled_flag equal to 0 specifies that the ph_cu_qp_delta_subdiv_intra_slice and ph_cu_qp_delta_subdiv_inter_slice syntax elements are not present in the PH referencing the PPS and that cu_qp_delta_abs is not present in the transform unit syntax.

[0471] pps_chroma_tool_offsets_present_flag equal to 1 specifies that syntax elements related to chroma tool offsets are present in the PPS RBSP syntax structure. pps_chroma_tool_offsets_present_flag equal to 0 specifies that syntax elements related to chroma tool offsets are not present in the PPS RBSP syntax structure. When ChromaArrayType is equal to 0, the value of pps_chroma_tool_offsets_present_flag shall be equal to 0.

[0472] pps_cb_qp_offset and pps_cr_qp_offset are defined to derive Qp′ Cb and Qp′ Cr The luminance quantization parameter Qp′ Y The value of pps_cb_qp_offset and the value of pps_cr_qp_offset should be in the range of -12 to +12 (inclusive). When ChromaArrayType is equal to 0, pps_cb_qp_offset and pps_cr_qp_offset are not used in the decoding process and the decoder should ignore their values. When not present, the values of pps_cb_qp_offset and pps_cr_qp_offset are inferred to be equal to 0.

[0473] pps_joint_cbcr_qp_offset_present_flag equal to 1 specifies that pps_joint_cbcr_qp_offset_value and joint_cbcr_qp_offset_list[i] are present in the PPS RBSP syntax structure. pps_joint_cbcr_qp_offset_present_flag equal to 0 specifies that pps_joint_cbcr_qp_offset_value and joint_cbcr_qp_offset_list[i] are not present in the PPS RBSP syntax structure. When ChromaArrayType is equal to 0 or sps_joint_cbcr_enabled_flag is equal to 0, the value of pps_joint_cbcr_qp_offset_present_flag shall be equal to 0. When not present, the value of pps_joint_cbcr_qp_offset_present_flag is inferred to be equal to 0.

[0474] pps_joint_cbcr_qp_offset_value is specified for deriving Qp′ CbCr The luminance quantization parameter Qp′ YThe value of pps_joint_cbcr_qp_offset_value shall be in the range of -12 to +12 (inclusive). When ChromaArrayType is equal to 0 or sps_joint_cbcr_enabled_flag is equal to 0, pps_joint_cbcr_qp_offset_value is not used during decoding and the decoder shall ignore its value. When pps_joint_cbcr_qp_offset_present_flag is equal to 0, pps_joint_cbcr_qp_offset_value is not present and is inferred to be equal to 0.

[0475] pps_slice_chroma_qp_offsets_present_flag equal to 1 specifies that the slice_cb_qp_offset and slice_cr_qp_offset syntax elements are present in the associated slice header. pps_slice_chroma_qp_offsets_present_flag equal to 0 specifies that the slice_cb_qp_offset and slice_cr_qp_offset syntax elements are not present in the associated slice header. When not present, the value of pps_slice_chroma_qp_offsets_present_flag is inferred to be equal to 0.

[0476] pps_cu_chroma_qp_offset_list_enabled_flag equal to 1 specifies that the ph_cu_chroma_qp_offset_subdiv_intra_slice and ph_cu_chroma_qp_offset_subdiv_inter_slice syntax elements are present in the PH referencing the PPS, and that cu_chroma_qp_offset_flag may be present in transform unit syntax and palette codec syntax. pps_cu_chroma_qp_offset_list_enabled_flag equal to 0 specifies that the ph_cu_chroma_qp_offset_subdiv_intra_slice and ph_cu_chroma_qp_offset_subdiv_inter_slice syntax elements are not present in the PH referencing the PPS, and that cu_chroma_qp_offset_flag is not present in transform unit syntax and palette codec syntax. When not present, the value of pps_cu_chroma_qp_offset_list_enabled_flag is inferred to be equal to 0.

[0477] chroma_qp_offset_list_len_minus1 plus 1 specifies the number of syntax elements cb_qp_offset_list[i], cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i] present in the PPS RBSP syntax structure. The value of chroma_qp_offset_list_len_minus1 shall be in the range of 0 to 5 (inclusive).

[0478] cb_qp_offset_list[i], cr_qp_offset_list[i] and joint_cbcr_qp_offset_list[i] respectively specify Qp′ Cb , Qp′ Cr and Qp′ CbCr The offsets used in the derivation of . The values of cb_qp_offset_list[i], cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i] shall be in the range -12 to +12 (inclusive). When pps_joint_cbcr_qp_offset_present_flag is equal to 0, joint_cbcr_qp_offset_list[i] is not present and is inferred to be equal to 0.

[0479] pps_weighted_pred_flag equal to 0 specifies that weighted prediction is not applied to P slices that reference the PPS. pps_weighted_pred_flag equal to 1 specifies that weighted prediction is applied to P slices that reference the PPS. When sps_weighted_pred_flag is equal to 0, the value of pps_weighted_pred_flag shall be equal to 0.

[0480] pps_weighted_bipred_flag equal to 0 specifies that explicit weighted prediction is not applied to B slices referencing the PPS. pps_weighted_bipred_flag equal to 1 specifies that explicit weighted prediction is applied to B slices referencing the PPS. When sps_weighted_bipred_flag is equal to 0, the value of pps_weighted_bipred_flag shall be equal to 0.

[0481] deblocking_filter_control_present_flag equal to 1 specifies that the deblocking filter control syntax element is present in the PPS. deblocking_filter_control_present_flag equal to 0 specifies that the deblocking filter control syntax element is not present in the PPS.

[0482] deblocking_filter_override_enabled_flag equal to 1 specifies that ph_deblocking_filter_override_flag is present in the PH of the referenced PPS, or slice_deblocking_filter_override_flag is present in the slice header of the referenced PPS. deblocking_filter_override_enabled_flag equal to 0 specifies that ph_deblocking_filter_override_flag is not present in the PH of the referenced PPS, or slice_deblocking_filter_override_flag is not present in the slice header of the referenced PPS. When not present, the value of deblocking_filter_override_enabled_flag is inferred to be equal to 0.

[0483] pps_deblocking_filter_disabled_flag equal to 1 specifies that the operation of the deblocking filter is not applied to slices referencing a PPS for which slice_deblocking_filter_disabled_flag is not present. pps_deblocking_filter_disabled_flag equal to 0 specifies that the operation of the deblocking filter is applied to slices referencing a PPS for which slice_deblocking_filter_disabled_flag is not present. When not present, the value of pps_deblocking_filter_disabled_flag is inferred to be equal to 0.

[0484] pps_beta_offset_div2 and pps_tc_offset_div2 specify default deblocking parameter offsets for β and tC (divided by 2). These parameter offsets are applied to the luma component of slices referencing the PPS, unless the default deblocking parameter offsets are overridden by deblocking parameter offsets present in the picture header or slice header of slices referencing the PPS. The values of pps_beta_offset_div2 and pps_tc_offset_div2 shall both be in the range -12 to 12 (inclusive). When not present, the values of pps_beta_offset_div2 and pps_tc_offset_div2 are both inferred to be equal to 0.

[0485] pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 specify default deblocking parameter offsets for β and tC (divided by 2). These parameter offsets are applied to the Cb component of the slices referencing the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the picture header or slice header of the slices referencing the PPS. The values of pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 shall both be in the range -12 to 12 (inclusive). When not present, the values of pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 are both inferred to be equal to 0.

[0486] pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 specify default deblocking parameter offsets for β and tC (divided by 2). These parameter offsets are applied to the Cr component of the slices referencing the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the picture header or slice header of the slices referencing the PPS. The values of pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 shall both be in the range -12 to 12 (inclusive). When not present, the values of pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 are both inferred to be equal to 0.

[0487] rpl_info_in_ph_flag equal to 1 specifies that the reference picture list information is present in the PH syntax structure and not in the slice headers referencing PPSs that do not contain the PH syntax structure. rpl_info_in_ph_flag equal to 0 specifies that the reference picture list information is not present in the PH syntax structure and may be present in the slice headers referencing PPSs that do not contain the PH syntax structure.

[0488] dbf_info_in_ph_flag equal to 1 specifies that deblocking filter information is present in the PH syntax structure, but not in slice headers referencing PPSs that do not contain a PH syntax structure. dbf_info_in_ph_flag equal to 0 specifies that deblocking filter information is not present in the PH syntax structure, and may be present in slice headers referencing PPSs that do not contain a PH syntax structure. When not present, the value of dbf_info_in_ph_flag is inferred to be equal to 0.

[0489] sao_info_in_ph_flag equal to 1 specifies that the SAO filter information is present in the PH syntax structure, but not in slice headers referencing PPSs that do not contain the PH syntax structure. sao_info_in_ph_flag equal to 0 specifies that the SAO filter information is not present in the PH syntax structure, and may be present in slice headers referencing PPSs that do not contain the PH syntax structure.

[0490] alf_info_in_ph_flag equal to 1 specifies that ALF information is present in the PH syntax structure and not in slice headers referencing PPSs that do not contain a PH syntax structure. alf_info_in_ph_flag equal to 0 specifies that ALF information is not present in the PH syntax structure and may be present in slice headers referencing PPSs that do not contain a PH syntax structure.

[0491] wp_info_in_ph_flag equal to 1 specifies that weighted prediction information may be present in the PH syntax structure, but not in slice headers referencing PPSs that do not contain a PH syntax structure. wp_info_in_ph_flag equal to 0 specifies that weighted prediction information is not present in the PH syntax structure, and may be present in slice headers referencing PPSs that do not contain a PH syntax structure. When not present, the value of wp_info_in_ph_flag is inferred to be equal to 0.

[0492] qp_delta_info_in_ph_flag equal to 1 specifies that QP delta information is present in the PH syntax structure, but not in slice headers referencing PPSs that do not contain a PH syntax structure. qp_delta_info_in_ph_flag equal to 0 specifies that QP delta information is not present in the PH syntax structure, and may be present in slice headers referencing PPSs that do not contain a PH syntax structure.

[0493] pps_ref_wraparound_enabled_flag equal to 1 specifies that horizontal wrap motion compensation is applied in inter prediction. pps_ref_wraparound_enabled_flag equal to 0 specifies that horizontal wrap motion compensation is not applied. When the value of CtbSizeY / MinCbSizeY+1 is greater than pic_width_in_luma_samples / MinCbSizeY-1, the value of pps_ref_wraparound_enabled_flag shall be equal to 0. When sps_ref_wraparound_enabled_flag is equal to 0, the value of pps_ref_wraparound_enabled_flag shall be equal to 0.

[0494] pps_ref_wraparound_offset plus (CtbSizeY / MinCbSizeY)+2 specifies the offset used to calculate the horizontal wrap position in units of MinCbSizeY luma samples. The value of pps_ref_wraparound_offset shall be in the range of 0 to (pic_width_in_luma_samples / MinCbSizeY)-(CtbSizeY / MinCbSizeY)-2, inclusive.

[0495] The variable PpsRefWraparoundOffset is set equal to pps_ref_wraparound_offset+(CtbSizeY / MinCbSizeY)+2.

[0496] picture_header_extension_present_flag equal to 0 specifies that the PH extension syntax element is not present in the PH referencing the PPS. picture_header_extension_present_flag equal to 1 specifies that the PH extension syntax element is present in the PH referencing the PPS. In bitstreams conforming to this version of this specification, picture_header_extension_present_flag shall be equal to 0.

[0497] slice_header_extension_present_flag equal to 0 specifies that the slice header extension syntax element is not present in the slice headers of the codec pictures referencing the PPS. slice_header_extension_present_flag equal to 1 specifies that the slice header extension syntax element is present in the slice headers of the codec pictures referencing the PPS. slice_header_extension_present_flag shall be equal to 0 in bitstreams conforming to this version of this specification.

[0498] pps_extension_flag equal to 0 specifies that the pps_extension_data_flag syntax element is not present in the PPS RBSP syntax structure. pps_extension_flag equal to 1 specifies that the pps_extension_data_flag syntax element is present in the PPS RBSP syntax structure.

[0499] The pps_extension_data_flag can have any value. Its presence and value do not affect decoder conformance to the profiles specified in this version of this specification. Decoders conforming to this version of this specification shall ignore all pps_extension_data_flag syntax elements.

[0500] 3.4.APS Syntax and Semantics

[0501] In the latest VVC draft text, APS syntax and semantics are as follows:

[0502]

[0503]

[0504] APS RBSP contains the ALF syntax structure, namely alf_data().

[0505]

[0506]

[0507]

[0508] The APS RBSP contains the LMCS syntax structure, namely lmcs_data().

[0509]

[0510]

[0511] The APS RBSP contains a scaling list data syntax structure, namely scaling_list_data().

[0512]

[0513]

[0514] Each APS RBSP shall be available to the decoding process before being referenced, be included in at least one AU with a TemporalId less than or equal to the TemporalId of the codec slice NAL unit referencing it, or be provided by external means.

[0515] All APS NAL units with a specific value of adaptation_parameter_set_id and a specific value of aps_params_type within a PU, regardless of whether they are prefix APS NAL units or suffix APS NAL units, should have the same content.

[0516] adaptation_parameter_set_id provides an identifier for the APS for reference by other syntax elements.

[0517] When aps_params_type is equal to ALF_APS or SCALING_APS, the value of adaptation_parameter_set_id shall be in the range of 0 to 7 (inclusive).

[0518] When aps_params_type is equal to LMCS_APS, the value of adaptation_parameter_set_id shall be in the range of 0 to 3 (inclusive).

[0519] Let apsLayerId be the value of nuh_layer_id of a particular APS NAL unit, and vclLayerId be the value of nuh_layer_id of a particular VCL NAL unit. A particular VCL NAL unit shall not reference a particular APS NAL unit unless apsLayerId is less than or equal to vclLayerId and the layer with nuh_layer_id equal to apsLayerId is contained in at least one OLS that contains a layer with nuh_layer_id equal to vclLayerId.

[0520] aps_params_type specifies the type of APS parameters carried in the APS, as specified in Table 6.

[0521] Table 6 – APS parameter type codes and APS parameter types

[0522]

[0523] All APS NAL units with a particular value of aps_params_type, regardless of the value of nuh_layer_id, share the same value space for adaptation_parameter_set_id. APS NAL units with different values of aps_params_type use separate value spaces for adaptation_parameter_set_id.

[0524] NOTE 1 – APS NAL units (with a specific value of adaptation_parameter_set_id and a specific value of aps_params_type) may be shared across pictures, and different slices within a picture may reference different ALF APSs.

[0525] NOTE 2 - A suffix APS NAL unit associated with a particular VCL NAL unit that precedes the suffix APS NAL unit in decoding order is not used for the particular VCL NAL unit, but is used for the VCL NAL units that follow the suffix APS NAL unit in decoding order.

[0526] aps_extension_flag equal to 0 specifies that the aps_extension_data_flag syntax element is not present in the APS RBSP syntax structure. aps_extension_flag equal to 1 specifies that the aps_extension_data_flag syntax element is present in the APS RBSP syntax structure.

[0527] aps_extension_data_flag can have any value. Its presence and value do not affect decoder conformance to the profiles specified in this version of this specification. Decoders conforming to this version of this specification shall ignore all aps_extension_data_flag syntax elements.

[0528] alf_luma_filter_signal_flag equal to 1 specifies that the luma filter set is signaled. alf_luma_filter_signal_flag equal to 0 specifies that the luma filter set is not signaled.

[0529] alf_chroma_filter_signal_flag equal to 1 specifies that the chroma filter is signaled. alf_chroma_filter_signal_flag equal to 0 specifies that the chroma filter is not signaled. When ChromaArrayType is equal to 0, alf_chroma_filter_signal_flag shall be equal to 0.

[0530] At least one of the values of alf_luma_filter_signal_flag, alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag, and alf_cc_cr_filter_signal_flag shall be equal to 1.

[0531] The variable NumAlfFilters, which specifies the number of different adaptive loop filters, is set equal to 25.

[0532] alf_luma_clip_flag equal to 0 specifies that linear adaptive loop filtering is applied to the luma component. alf_luma_clip_flag equal to 1 specifies that nonlinear adaptive loop filtering may be applied to the luma component.

[0533] alf_luma_num_filters_signalled_minus1 plus 1 specifies the number of adaptive loop filter categories for which luma coefficients may be signaled. The value of alf_luma_num_filters_signalled_minus1 shall be in the range of 0 to NumAlfFilters–1, inclusive.

[0534] alf_luma_coeff_delta_idx[filtIdx] specifies the index of the signaled adaptive loop filter luma coefficient delta for the filter class indicated by filtIdx, which ranges from 0 to NumAlfFilters-1. When alf_luma_coeff_delta_idx[filtIdx] is not present, it is inferred to be equal to 0. The length of alf_luma_coeff_delta_idx[filt idx] is Ceil(Log2(alf_luma_num_filters_signalled_minus1+1)) bits. The value of alf_luma_coeff_delta_idx[filtIdx] shall be in the range of 0 to alf_luma_num_filters_signalled_minus1, inclusive.

[0535] alf_luma_coeff_abs[sfIdx][j] specifies the absolute value of the j-th coefficient of the signaled luma filter indicated by sfIdx. When alf_luma_coeff_abs[sfIdx][j] is not present, it is inferred to be equal to 0. The value of alf_luma_coeff_abs[sfIdx][j] should be in the range of 0 to 128 (inclusive).

[0536] alf_luma_coeff_sign[sfIdx][j] specifies the sign of the j-th luma coefficient of the filter indicated by sfIdx as follows:

[0537] --If alf_luma_coeff_sign[sfIdx][j] is equal to 0, the corresponding luma filter coefficient has a positive value.

[0538] Otherwise (alf_luma_coeff_sign[sfIdx][j] is equal to 1), the corresponding luma filter coefficient has a negative value.

[0539] When alf_luma_coeff_sign[sfIdx][j] is not present, it is inferred to be equal to 0.

[0540] The variable filtCoeff[sfIdx][j] with sfIdx=0..alf_luma_num_filters_signalled_minus1 and j=0..11 is initialized as follows:

[0541]

[0542] With element AlfCoeff L [adaptation_parameter_set_id][filtIdx][j] (where filtIdx = 0..NumAlfFilters-1 and j = 0..11) the luma filter coefficients AlfCoeff L [adaptation_parameter_set_id] is derived as follows:

[0543] Alf Coeff L [adaptation_parameter_set_id][filtIdx][j]=filtCoeff[alf_luma_coeff_delta_id

[0544] x[filtIdx]][j](94)

[0545] The fixed filter coefficients AlfFixFiltCoeff[i][j] with i=0..64, j=0..11 and the class-to-filter maps AlfClassToFiltMap[m][n] with m=0..15 and n=0..24 are derived as follows:

[0546]

[0547]

[0548]

[0549]

[0550]

[0551] The bitstream consistency requirement is that filtIdx = 0..NumAlfFilters-1, j = 0..11 AlfCoeff L The value of [adaptation_parameter_set_id][filtIdx][j] should be between -2 7 to 2 7 The range is -1 (including the end value).

[0552] alf_luma_clip_idx[sfIdx][j] specifies the clip index of the clipping value to be used before multiplying the j-th coefficient of the signaled luma filter indicated by sfIdx. A bitstream conformance requirement is that the value of alf_luma_clip_idx[sfIdx][j] for sfIdx = 0..alf_luma_num_filters_signalled_minus1 and j = 0..11 shall be in the range 0 to 3 (inclusive).

[0553] Element AlfClip with filtIdx=0..NumAlfFilters-1 and j=0..11 L [adaptation_parameter_set_id][filtIdx][j] Luma filter clipping value AlfClip L [adaptation_parameter_set_id] is derived from BitDepth and clipIdx set equal to alf_luma_clip_idx[alf_luma_coeff_delta_idx[filtIdx]][j], as specified in Table 8.

[0554] alf_chroma_clip_flag equal to 0 specifies that linear adaptive loop filtering is applied to the chroma components; alf_chroma_clip_flag equal to 1 specifies that non-linear adaptive loop filtering is applied to the chroma components. When not present, alf_chroma_clip_flag is inferred to be equal to 0.

[0555] alf_chroma_num_alt_filters_minus1 specifies the number of alternative filters for the chroma components plus 1. The value of alf_chroma_num_alt_filters_minus1 shall be in the range of 0 to 7 (inclusive).

[0556] alf_chroma_coeff_abs[altIdx][j] specifies the absolute value of the j-th chroma filter coefficient of the alternative chroma filter with index altIdx. When alf_chroma_coeff_abs[altIdx][j] is not present, it is inferred to be equal to 0. The value of alf_chroma_coeff_abs[sfIdx][j] shall be in the range of 0 to 128 (inclusive).

[0557] alf_chroma_coeff_sign[altIdx][j] specifies the sign of the j-th chroma filter coefficient of the alternative chroma filter with index altIdx as follows:

[0558] --If alf_chroma_coeff_sign[altIdx][j] is equal to 0, the corresponding chroma filter coefficient has a positive value.

[0559] Otherwise (alf_chroma_coeff_sign[altIdx][j] is equal to 1), the corresponding chroma filter coefficient has a negative value.

[0560] When alf_chroma_coeff_sign[altIdx][j] is not present, it is inferred to be equal to 0.

[0561] With element AlfCoeff C [adaptation_parameter_set_id][altIdx][j] chroma filter coefficient AlfCoeff C [adaptation_parameter_set_id][altIdx] (where altIdx=0..alf_chroma_num_alt_filters_minus1 and j=0..5) is derived as follows:

[0562] Alf Coeff C [adaptation_parameter_set_id][altIdx][j]=alf_chroma_coeff_abs[altIdx][j]

[0563] *(1-2*alf_chroma_coeff_sign[altIdx][j])(97)

[0564] The bitstream conformance requirement is that AlfCoeff altIdx = 0..alf_chroma_num_alt_filters_minus1, j = 0..5 C The value of [adaptation_parameter_set_id][altIdx][j] should be between -2 7 to 2 7 The range is -1 (including the end value).

[0565] alf_cc_cb_filter_signal_flag equal to 1 specifies that the cross-component filter of the Cb color component is signaled. alf_cc_cb_filter_signal_flag equal to 0 indicates that the cross-component filter of the Cb color component is not signaled. When ChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shall be equal to 0.

[0566] alf_cc_cb_filters_signalled_minus1 plus 1 specifies the number of cross-component filters for the Cb color component signaled in the current ALF APS. The value of alf_cc_cb_filters_signalled_minus1 shall be in the range of 0 to 3 (inclusive).

[0567] alf_cc_cb_mapped_coeff_abs[k][j] specifies the absolute value of the j-th mapping coefficient of the signaled k-th cross-component filter for the Cb color component. When alf_cc_cb_mapped_coeff_abs[k][j] is not present, it is inferred to be equal to 0.

[0568] alf_cc_cb_coeff_sign[k][j] specifies the sign of the j-th coefficient of the k-th cross-component filter signaled for the Cb color component as follows:

[0569] --If alf_cc_cb_coeff_sign[k][j] is equal to 0, the corresponding cross-component filter coefficient has a positive value.

[0570] Otherwise (alf_cc_cb_sign[k][j] is equal to 1), the corresponding cross-component filter coefficient has a negative value.

[0571] When alf_cc_cb_coeff_sign[k][j] is not present, it is inferred to be equal to 0.

[0572] Cb color component CcAlfApsCoeff for j=0..6 Cb The k-th cross-component filter coefficient signaled by [adaptation_parameter_set_id][k][j] is derived as follows:

[0573] --If alf_cc_cb_mapped_coeff_abs[k][j] is equal to 0, then CcAlfApsCoeff Cb [adaptation_parameter_set_id][k][j] is set equal to 0.

[0574] --Otherwise, CcAlfApsCoeff Cb [adaptation_parameter_set_id][k][j] is set equal to (1-2*alf_cc_cb_coeff_sign[k][j])*2 alf_cc_cb_mapped_coeff_abs[k][j]-1 .

[0575] alf_cc_cr_filter_signal_flag equal to 1 specifies that cross-component filters for Cr color components are signaled. alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-component filters for Cr color components are not signaled. When ChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall be equal to 0.

[0576] alf_cc_cr_filters_signalled_minus1 plus 1 specifies the number of cross-component filters for the Cr color component signaled in the current ALF APS. The value of alf_cc_cr_filters_signalled_minus1 shall be in the range of 0 to 3 (inclusive).

[0577] alf_cc_cr_mapped coeff_abs[k][j] specifies the absolute value of the j-th mapping coefficient of the signaled k-th cross-component filter for the Cr color component. When alf_cc_cr_mapped coeff_abs[k][j] is not present, it is inferred to be equal to 0.

[0578] alf_cc_cr_coeff_sign[k][j] specifies the sign of the j-th coefficient of the k-th cross-component filter signaled for the Cr color component, as follows:

[0579] --If alf_cc_cr_coeff_sign[k][j] is equal to 0, the corresponding cross-component filter coefficient has a positive value.

[0580] Otherwise (alf_cc_cr_sign[k][j] is equal to 1), the corresponding cross-component filter coefficient has a negative value.

[0581] When alf_cc_cr_coeff_sign[k][j] is not present, it is inferred to be equal to 0.

[0582] Signaled k-th cross-component filter coefficient CcAlfApsCoeff for Cr color components j=0..6 Cr [adaptation_parameter_set_id][k][j] is derived as follows:

[0583] --If alf_cc_cr_mapped_coeff_abs[k][j] is equal to 0, then CcAlfApsCoeff Cr [adaptation_parameter_set_id][k][j] is set equal to 0.

[0584] --Otherwise, CcAlfApsCoeff Cr [adaptation_parameter_set_id][k][j] is set equal to (1-2*alf_cc_cr_coeff_sign[k][j])*2 alf_cc_cr_mapped_coeff_abs[k][j]-1 .

[0585] alf_chroma_clip_idx[altIdx][j] specifies the clipping index of the clipping value to be used before multiplying the j-th coefficient of the alternative chroma filter with index altIdx. A bitstream conformance requirement is that the value of alf_chroma_clip_idx[altIdx][j] for altIdx = 0..alf_chroma_num_alt_filters_minus1, j = 0..5 shall be in the range 0 to 3 (inclusive).

[0586] Has element AlfClip C [adaptation_parameter_set_id][altIdx][j] (where altIdx = 0..alf_chroma_num_alt_filters_minus1, j = 0..5) chroma filter clipping value AlfClip C [adaptation_parameter_set_id][altIdx] is derived from BitDepth and clipIdx set equal to alf_chroma_clip_idx[altIdx][j], as specified in Table 8.

[0587] Table 8 – Canonical AlfClip depending on BitDepth and clipIdx

[0588]

[0589] lmcs_min_bin_idx specifies the minimum bin index used during the construction of the luma map with chroma scaling. The value of lmcs_min_bin_idx shall be in the range of 0 to 15 (inclusive).

[0590] lmcs_delta_max_bin_idx specifies the delta value between 15 and the maximum bin index LmcsMaxBinIdx for luma map construction with chroma scaling. The value of lmcs_delta_max_bin_idx shall be in the range of 0 to 15 (inclusive). The value of LmcsMaxBinIdx shall be set equal to 15 - lmcs_delta_max_bin_idx. The value of LmcsMaxBinIdx shall be greater than or equal to lmcs_min_bin_idx.

[0591] lmcs_delta_cw_prec_minus1 plus 1 specifies the number of bits used to represent the syntax lmcs_delta_abs_cw[i]. The value of lmcs_delta_cw_prec_minus1 shall be in the range of 0 to BitDepth-2, inclusive.

[0592] lmcs_delta_abs_cw[i] specifies the absolute delta codeword value of the i-th bin.

[0593] lmcs_delta_sign_cw_flag[i] specifies the sign of the variable lmcsDeltaCW[i] as follows:

[0594] --If lmcs_delta_sign_cw_flag[i] is equal to 0, lmcsDeltaCW[i] is a positive value.

[0595] --Otherwise (lmcs_delta_sign_cw_flag[i] is not equal to 0), lmcsDeltaCW[i] is a negative value.

[0596] When lmcs_delta_sign_cw_flag[i] is not present, it is inferred to be equal to 0.

[0597] The variable OrgCW is exported as follows:

[0598] OrgCW=(1< <BitDepth) / 16 (98)

[0599] The variable lmcsDeltaCW[i] where i=lmcs_min_bin_idx..LmcsMaxBinIdx is derived as follows:

[0600] lmcsDeltaCW[i]=(1-2*lmcs_delta_sign_cw_flag[i])*lmcs_delta_abs_cw[i](99)

[0601] The variable lmcsCW[i] is exported as follows:

[0602] -- For i = 0..lmcs_min_bin_idx-1, lmcsCW[i] is set equal to 0.

[0603] --For i = lmcs_min_bin_idx..LmcsMaxBinIdx, the following applies:

[0604] lmcsCW[i]=OrgCW+lmcsDeltaCW[i] (100)

[0605] The value of lmcsCW[i] should be in the range of (OrgCW>>3) to (OrgCW<<3-1) (inclusive).

[0606] -- For i = LmcsMaxBinIdx + 1..15, lmcsCW[i] is set equal to 0.

[0607] The requirements for bitstream conformance are that the following conditions are true:

[0608]

[0609] The variable InputPivot[i] (where i=0..16) is derived as follows:

[0610] InputPivot[i]=i*OrgCW (102)

[0611] The variables LmcsPivot[i] for i=0..16, ScaleCoeff[i] and InvScaleCoeff[i] for i=0..15 are derived as follows:

[0612]

[0613] The requirement for bitstream consistency is that for i = lmcs_min_bin_idx..LmcsMaxBinIdx, when the value of LmcsPivot[i] is not a multiple of 1<<(BitDepth-5), the value of (LmcsPivot[i]>>(BitDepth-5)) should not be equal to the value of (LmcsPivot[i+1]>>(BitDepth-5)).

[0614] lmcs_delta_abs_crs specifies the absolute codeword value of the variable lmcsDeltaCrs. The value of lmcs_delta_abs_crs should be in the range of 0 to 7 (inclusive). When not present, lmcs_delta_abs_crs is inferred to be equal to 0.

[0615] lmcs_delta_sign_crs_flag specifies the sign of the variable lmcsDeltaCrs. When not present, lmcs_delta_sign_crs_flag is inferred to be equal to 0.

[0616] The variable lmcsDeltaCrs is exported as follows:

[0617] lmcsDeltaCrs=(1-2*lmcs_delta_sign_crs_flag)*lmcs_delta_abs_crs (104)

[0618] The bitstream conformance requirement is that when lmcsCW[i] is not equal to 0, (lmcsCW[i] + lmcsDeltaCrs) shall be in the range of (OrgCW>>3) to ((OrgCW<<3)-1) (inclusive).

[0619] The variable ChromaScaleCoeff[i] (where i=0...15) is derived as follows:

[0620]

[0621] scaling_matrix_for_lfnst_disabled_flag equal to 1 specifies that the scaling matrix should not be applied to blocks coded or decoded using LFNST. scaling_matrix_for_lfnst_disabled_flag equal to 0 specifies that the scaling matrix can be applied to blocks coded or decoded using LFNST.

[0622] scaling_list_chroma_present_flag equal to 1 specifies that the chroma scaling list is present in scaling_list_data(). scaling_list_chroma_present_flag equal to 0 specifies that the chroma scaling list is not present in scaling_list_data(). A bitstream conformance requirement is that scaling_list_chroma_present_flag shall be equal to 0 when ChromaArrayType is equal to 0, and shall be equal to 1 when ChromaArrayType is not equal to 0.

[0623] scaling_list_copy_mode_flag[id] equal to 1 specifies that the values of the scaling list are the same as the values of the reference scaling list. The reference scaling list is specified by scaling_list_pred_id_delta[id]. scaling_list_copy_mode_flag[id] equal to 0 specifies that scaling_list_pred_mode_flag is present.

[0624] scaling_list_pred_mode_flag[id] equal to 1 specifies that the values of the scaling list can be predicted from the reference scaling list. The reference scaling list is specified by scaling_list_pred_id_delta[id]. scaling_list_pred_mode_flag[id] equal to 0 specifies that the values of the scaling list are explicitly signaled. When not present, the value of scaling_list_pred_mode_flag[id] is inferred to be equal to 0.

[0625] scaling_list_pred_id_delta[id] specifies the reference scaling list used to derive the prediction scaling matrix ScalingMatrixPred[id]. When not present, the value of scaling_list_pred_id_delta[id] is inferred to be equal to 0. The value of scaling_list_pred_id_delta[id] should be in the range of 0 to maxIdDelta, where maxIdDelta is derived from id as follows:

[0626] maxIdDelta=(id<2)? id:((id<8)?(id-2):(id-8)) (106)

[0627] The variables refId and matrixSize are exported as follows:

[0628] refId=id-scaling_list_pred_id_delta[id] (107)

[0630] matrixSize=(id<2)? 2:((id<8)?4:8) (108)

[0631] The (matrixSize)x(matrixSize) array ScalingMatrixPred[x][y] with x=0..matrixSize-1 and y=0..matrixSize-1 and the variable ScalingMatrixDCPred are derived as follows:

[0632] --When scaling_list_copy_mode_flag[id] and scaling_list_pred_mode_flag[id] are both equal to 0, all elements of ScalingMatrixPred are set equal to 8 and the value of ScalingMatrixDCPred is set equal to 8.

[0633] Otherwise, when scaling_list_pred_id_delta[id] is equal to 0, all elements of ScalingMatrixPred are set equal to 16, and ScalingMatrixDCPred is set equal to 16.

[0634] Otherwise (scaling_list_copy_mode_flag[id] or scaling_list_pred_mode_flag[id] is equal to 1 and scaling_list_pred_id_delta[id] is greater than 0), ScalingMatrixPred is set equal to ScalingMatrixRec[refId], and the following applies to ScalingMatrixDCPred:

[0635] --If refId is greater than 13, ScalingMatrixDCPred is set equal to ScalingMatrixDCRec[refId-14].

[0636] --Otherwise (refId is less than or equal to 13), ScalingMatrixDCPred is set equal to ScalingMatrixPred[0][0].

[0637] scaling_list_dc_coef[id-14] is used to derive the value of the variable ScalingMatrixDC[id-14] when id is greater than 13, as shown below:

[0638] ScalingMatrixDCRec[id-14]=(ScalingMatrixDCPred+

[0639] scaling_list_dc_coef[id-14])&255(109)

[0640] When not present, the value of scaling_list_dc_coef[id-14] is inferred to be equal to 0. The value of scaling_list_dc_coef[id–14] shall be in the range of -128 to 127 (inclusive). The value of ScalingMatrixDCRec[id-14] shall be greater than 0.

[0641] scaling_list_delta_coef[id][i] specifies the difference between the current matrix coefficients ScalingList[id][i] and the previous matrix coefficients ScalingList[id][i-1] when scaling_list_copy_mode_flag[id] is equal to 0. The value of scaling_list_delta_coef[id][i] should be in the range of -128 to 127 (inclusive). When scaling_list_copy_mode_flag[id] is equal to 1, all elements of ScalingList[id] are set to 0.

[0642] The (matrixSize)x(matrixSize) array ScalingMatrixRec[id] is exported as follows:

[0643] ScalingMatrixRec[id][x][y]=(ScalingMatrixPred[x][y]+ScalingList[id][k])&255(110)

[0644] where k = 0..(matrix size * matrix size 1),

[0645] x=DiagScanOrder[Log2(matrix size)][Log2(matrix size)][k][0], and

[0646] y=DiagScanOrder[Log2(matrix size)][Log2(matrix size)][k][1]

[0647] The value of ScalingMatrixRec[id][x][y] should be greater than 0.

[0648] 3.5.PH Syntax and Semantics

[0649] In the latest VVC draft text, PH syntax and semantics are as follows:

[0650]

[0651] The PH RBSP contains the PH syntax structure, namely picture_header_structure().

[0652]

[0653]

[0654]

[0655]

[0656]

[0657]

[0658] The PH syntax structure contains information that is common to all slices of the codec picture associated with the PH syntax structure.

[0659] gdr_or_irap_pic_flag equal to 1 specifies that the current picture is a GDR picture or an IRAP picture. gdr_or_irap_pic_flag equal to 0 specifies that the current picture may or may not be a GDR picture or an IRAP picture.

[0660] gdr_pic_flag equal to 1 specifies that the picture associated with the PH is a GDR picture. gdr_pic_flag equal to 0 specifies that the picture associated with the PH is not a GDR picture. When not present, the value of gdr_pic_flag is inferred to be equal to 0. When gdr_enabled_flag is equal to 0, the value of gdr_pic_flag shall be equal to 0.

[0661] ph_inter_slice_allowed_flag equal to 0 specifies that all codec slices of the picture have slice_type equal to 2. ph_inter_slice_allowed_flag equal to 1 specifies that the picture may or may not have one or more codec slices with slice_type equal to 0 or 1.

[0662] ph_intra_slice_allowed_flag equal to 0 specifies that all codec slices of the picture have slice_type equal to 0 or 1. ph_intra_slice_allowed_flag equal to 1 specifies that the picture may or may not have one or more codec slices with slice_type equal to 2. When not present, the value of ph_intra_slice_allowed_flag is inferred to be equal to 1.

[0663] NOTE 1—For bitstreams where sub-picture based bitstream merging should be performed without changing the PH NAL units, the codec shall set the values of ph_inter_slice_allowed_flag and ph_intra_slice_allowed_flag equal to 1.

[0664] non_reference_picture_flag equal to 1 specifies that the picture associated with the PH is never used as a reference picture. non_reference_picture_flag equal to 0 specifies that the picture associated with the PH may or may not be used as a reference picture.

[0665] ph_pic_parameter_set_id specifies the value of pps_pic_parameter_set_id for the PPS being used. The value of ph_pic_parameter_set_id shall be in the range of 0 to 63 (inclusive).

[0666] The bitstream conformance requirement is that the value of TemporalId of PH shall be greater than or equal to the value of TemporalId of the PPS with pps_pic_parameter_set_id equal to ph_pic_parameter_set_id.

[0667] ph_pic_order_cnt_lsb specifies the picture order count modulo MaxPicOrderCntLsb of the current picture. The length of the ph_pic_order_cnt_lsb syntax element is log2_max_pic_order_cnt_lsb_minus4 + 4 bits. The value of ph_pic_order_cnt_lsb shall be in the range of 0 to MaxPicOrderCntLsb-1 (inclusive).

[0668] no_output_of_prior_pics_flag affects the output of previously decoded pictures in the DPB after decoding a CLVSS picture that is not the first picture in the bitstream as specified in Annex C.

[0669] recovery_poc_cnt specifies the recovery point of the decoded picture in output order. If the current picture is a GDR picture associated with PH, and there is a picture picA that follows the current GDR picture in decoding order in CLVS, whose PicOrderCntVal is equal to the PicOrderCntVal of the current GDR picture plus the value of recovery_poc_cnt, then picture picA is called the recovery point picture. Otherwise, the first picture in output order whose PicOrderCntVal is greater than the PicOrderCntVal of the current picture plus the value of recovery_poc_cnt is called the recovery point picture. In decoding order, the recovery point picture should not precede the current GDR picture. The value of recovery_poc_cnt should be in the range of 0 to MaxPicOrderCntLsb–1 (inclusive).

[0670] When the current picture is a GDR picture, the variable RpPicOrderCntVal is derived as follows:

[0671] RpPicOrderCntVal=PicOrderCntVal+recovery_poc_cnt (82)

[0672] NOTE 2 – When gdr_enabled_flag is equal to 1 and the PicOrderCntVal of the current picture is greater than or equal to the RpPicOrderCntVal of the associated GDR picture, the current and subsequent decoded pictures in output order exactly match the corresponding pictures produced by starting the decoding process from the previous IRAP picture (if any) preceding the associated GDR picture in decoding order.

[0673] ph_extra_bit[i] may be equal to 1 or 0. Decoders conforming to this version of this specification shall ignore the value of ph_extra_bit[i]. Its value does not affect the conformance of the decoder to the profile specified in this version of this specification.

[0674] ph_poc_msb_present_flag equal to 1 specifies that the syntax element poc_msb_val is present in the PH. ph_poc_msb_present_flag equal to 0 specifies that the syntax element poc_msb_val is not present in the PH. The value of ph_poc_msb_present_flag shall be 0 when vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 0 and there is a picture in the current AU in the reference layer of the current layer.

[0675] poc_msb_val specifies the POC MSB value of the current picture. The length of the syntax element poc_msb_val is poc_msb_len_minus1+1 bits.

[0676] ph_alf_enabled_flag equal to 1 specifies that the adaptive loop filter is enabled for all slices associated with the PH and may be applied to the Y, Cb, or Cr color components in the slice. ph_alf_enabled_flag equal to 0 specifies that the adaptive loop filter may be disabled for one or more or all slices associated with the PH. When not present, ph_alf_enabled_flag is inferred to be equal to 0.

[0677] ph_num_alf_aps_ids_luma specifies the number of ALF APSs referenced by the slice associated with the PH.

[0678] ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALF APS, which the luma component of the slice associated with the PH refers to.

[0679] The value of alf_luma_filter_signal_flag shall be equal to 1 for APS NAL units with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i].

[0680] The TemporalId of the APS NAL unit with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i] shall be less than or equal to the TemporalId of the picture associated with the PH.

[0681] ph_alf_chroma_idc equal to 0 specifies that the adaptive loop filter is not applied to the Cb color component and the Cr color component. ph_alf_chroma_idc equal to 1 indicates that the adaptive loop filter is applied to the Cb color component. ph_alf_chroma_idc equal to 2 indicates that the adaptive loop filter is applied to the Cr color component. ph_alf_chroma_idc equal to 3 indicates that the adaptive loop filter is applied to the Cb color component and the Cr color component. When ph_alf_chroma_idc is not present, it is inferred to be equal to 0.

[0682] ph_alf_aps_id_chroma specifies the adaptation_parameter_set_id of the ALF APS that the chroma components of the slice associated with the PH refer to.

[0683] The value of alf_chroma_filter_signal_flag shall be equal to 1 for APS NAL units with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_chroma.

[0684] The TemporalId of the APS NAL unit with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_chroma shall be less than or equal to the TemporalId of the picture associated with the PH.

[0685] ph_cc_alf_cb_enabled_flag equal to 1 specifies that the cross-component filter for the Cb color component is enabled for all slices associated with the PH and may be applied to the Cb color components in the slice. ph_cc_alf_cb_enabled_flag equal to 0 specifies that the cross-component filter for the Cb color component may be disabled for one, multiple, or all slices associated with the PH. When not present, ph_cc_alf_cb_enabled_flag is inferred to be equal to 0.

[0686] ph_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id of the ALF APS referenced by the Cb color component of the slice associated with the PH.

[0687] The value of alf_cc_cb_filter_signal_flag shall be equal to 1 for APS NAL units with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_cc_alf_cb_aps_id.

[0688] The TemporalId of the APS NAL unit with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_cc_alf_cb_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

[0689] ph_cc_alf_cr_enabled_flag equal to 1 specifies that cross-component filters for Cr color components are enabled for all slices associated with the PH and may be applied to Cr color components in a slice. ph_cc_alf_cr_enabled_flag equal to 0 specifies that cross-component filters for Cr color components may be disabled for one, multiple, or all slices associated with the PH. When not present, ph_cc_alf_cr_enabled_flag is inferred to be equal to 0.

[0690] ph_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id of the ALF APS referenced by the Cr color component of the slice associated with the PH.

[0691] The value of alf_cc_cr_filter_signal_flag shall be equal to 1 for APS NAL units with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_cc_alf_cr_aps_id.

[0692] The TemporalId of the APS NAL unit with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to ph_cc_alf_cr_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

[0693] ph_lmcs_enabled_flag equal to 1 specifies that luma mapping with chroma scaling is enabled for all slices associated with the PH, ph_lmcs_enabled_flag equal to 0 specifies that luma mapping with chroma scaling is disabled for one, multiple or all slices associated with the PH, and when not present, the value of ph_lmcs_enabled_flag is inferred to be equal to 0.

[0694] ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APS referenced by the slice associated with the PH. The TemporalId of the APS NAL unit with aps_params_type equal to LMCS_APS and adaptation_parameter_set_id equal to ph_lmcs_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

[0695] ph_chroma_residual_scale_flag equal to 1 specifies that chroma residual scaling is enabled for all slices associated with the PH. ph_chroma_residual_scale_flag equal to 0 specifies that chroma residual scaling may be disabled for one, multiple, or all slices associated with the PH. When ph_chroma_residual_scale_flag is not present, it is inferred to be equal to 0.

[0696] ph_scaling_list_present_flag equal to 1 specifies that the scaling list data for the slices associated with the PH is derived based on the scaling list data contained in the reference scaling list APS. ph_scaling_list_present_flag equal to 0 specifies that the scaling list data for the slices associated with the PH is set equal to 16. When not present, the value of ph_scaling_list_present_flag is inferred to be equal to 0.

[0697] ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of the scaling list APS. The TemporalId of the APS NAL unit with aps_params_type equal to SCALING_APS and adaptation_parameter_set_id equal to ph_scaling_list_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

[0698] ph_virtual_boundaries_present_flag equal to 1 specifies that virtual boundaries are signaled in the PH. ph_virtual_boundaries_present_flag equal to 0 specifies that virtual boundaries are not signaled in the PH. When one or more virtual boundaries are signaled in the PH, loop filtering operations are disabled across the virtual boundaries in the picture. Loop filtering operations include deblocking filter, sample adaptive offset filter, and adaptive loop filter operations. When not present, the value of ph_virtual_boundaries_present_flag is inferred to be equal to 0.

[0699] A bitstream conformance requirement is that when subpic_info_present_flag is equal to 1, the value of ph_virtual_boundaries_present_flag shall be equal to 0.

[0700] The variable VirtualBoundariesPresentFlag is exported as follows:

[0701]

[0702] ph_num_ver_virtual_boundaries specifies the number of ph_virtual_boundaries_pos_x[i] syntax elements present in PH. When ph_num_ver_virtual_boundaries is not present, it is inferred to be equal to 0.

[0703] The variable NumVerVirtualBoundaries is exported as follows:

[0704]

[0705] ph_virtual_boundaries_pos_x[i] specifies the position of the i-th vertical virtual boundary in units of luma samples divided by 8. The value of ph_virtual_boundaries_pos_x[i] shall be in the range of 1 to Ceil(pic_width_in_luma_samples ÷ 8) - 1, inclusive.

[0706] The list VirtualBoundariesPosX[i], where i ranges from 0 to NumVerVirtualBoundaries-1 (inclusive), specifies the position of the vertical virtual boundaries in units of luma samples and is derived as follows:

[0707]

[0708] The distance between any two vertical virtual boundaries should be greater than or equal to CtbSizeY luminance samples.

[0709] ph_num_hor_virtual_boundaries specifies the number of ph_virtual_boundaries_pos_y[i] syntax elements present in PH. When ph_num_hor_virtual_boundaries is not present, it is inferred to be equal to 0.

[0710] The parameter NumHorVirtualBoundaries is derived as follows:

[0711]

[0712] When sps_virtual_boundaries_enabled_flag is equal to 1 and ph_virtual_boundaries_present_flag is equal to 1, the sum of ph_num_ver_virtual_boundaries and ph_num_hor_virtual_boundaries shall be greater than 0.

[0713] ph_virtual_boundaries_pos_y[i] specifies the position of the i-th horizontal virtual boundary in units of luma samples divided by 8. The value of ph_virtual_boundaries_pos_y[i] shall be in the range of 1 to Ceil(pic_height_in_luma_samples ÷ 8) - 1, inclusive.

[0714] The list VirtualBoundariesPosY[i], where i ranges from 0 to NumHorVirtualBoundaries-1 (inclusive), specifies the position of the horizontal virtual boundaries in units of luma samples and is derived as follows:

[0715]

[0716] The distance between any two horizontal virtual boundaries should be greater than or equal to CtbSizeY luminance samples.

[0717] pic_output_flag affects the decoded picture output and removal process as specified in Annex C. When pic_output_flag is not present, it is inferred to be equal to 1.

[0718] partition_constraints_override_flag equal to 1 specifies that the partition constraint parameters are present in the PH. partition_constraints_override_flag equal to 0 specifies that the partition constraint parameters are not present in the PH. When not present, the value of partition_constraints_override_flag is inferred to be equal to 0.

[0719] ph_log2_diff_min_qt_min_cb_intra_slice_luma specifies the difference between the base 2 logarithm of the minimum size of luma samples of the luma leaf blocks resulting from the quadtree partitioning of the CTU and the base 2 logarithm of the minimum decoded block size of luma samples of the luma CU in slices with slice_type equal to 2(1) associated with the PH. The value of ph_log2_diff_min_qt_min_cb_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY - MinCbLog2SizeY, inclusive. When not present, the value of ph_log2_diff_min_qt_min_cb_luma is inferred to be equal to sps_log2_diff_min_qt_min_cb_intra_slice_luma.

[0720] ph_max_mtt_hierarchy_depth_intra_slice_luma specifies the maximum hierarchical depth of codec units resulting from multi-type tree partitioning of quadleafs in slices with slice_type equal to 2(I) associated with the PH. The value of ph_max_mtt_hierarchy_depth_intra_slice_luma shall be in the range of 0 to 2*(CtbLog2SizeY - MinCbLog2SizeY), inclusive. When not present, the value of ph_max_mtt_hierarchy_depth_intra_slice_luma is inferred to be equal to sps_max_mtt_hierarchy_depth_intra_slice_luma.

[0721] ph_log2_diff_max_bt_min_qt_intra_slice_luma specifies the difference between the base-2 logarithm of the maximum dimension (width or height) among the luma samples of a luma codec block that can be partitioned using binary partitioning and the base-2 logarithm of the minimum dimension (width or height) among the luma samples of a luma leaf block resulting from a quadtree partitioning of a CTU in a slice with slice_type equal to 2(1) associated with the PH. The value of ph_log2_diff_max_bt_min_qt_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeIntraY, inclusive. When not present, the value of ph_log2_diff_max_bt_min_qt_intra_slice_luma is inferred to be equal to sps_log2_diff_max_bt_min_qt_intra_slice_luma.

[0722] ph_log2_diff_max_tt_min_qt_intra_slice_luma specifies the difference between the base 2 logarithm of the maximum dimension (width or height) among the luma samples of a luma codec block that can be partitioned using ternary partitioning and the base 2 logarithm of the minimum dimension (width or height) among the luma samples of a luma leaf block resulting from a quadtree partitioning of a CTU in a slice with slice_type equal to 2(1) associated with the PH. The value of ph_log2_diff_max_tt_min_qt_intra_slice_luma shall be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeIntraY, inclusive. When not present, the value of ph_log2_diff_max_tt_min_qt_intra_slice_luma is inferred to be equal to sps_log2_diff_max_tt_min_qt_intra_slice_luma.

[0723] ph_log2_diff_min_qt_min_cb_intra_slice_chroma specifies the difference between the base 2 logarithm of the minimum size among the luma samples of the chroma leaf blocks resulting from the quadtree partitioning of the chroma CTU with treeType equal to DUAL_TREE_CHROMA and the base 2 logarithm of the minimum decoded block size among the luma samples of the chroma CU with treeType equal to DUAL_TREE_CHROMA in the slice with slice_type equal to 2(I) associated with the PH. The value of ph_log2_diff_min_qt_min_cb_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY-MinCbLog2SizeY, inclusive. When not present, the value of ph_log2_diff_min_qt_min_cb_intra_slice_chroma is inferred to be equal to sps_log2_diff_min_qt_min_cb_intra_slice_chroma.

[0724] ph_max_mtt_hierarchy_depth_intra_slice_chroma specifies the maximum hierarchical depth of a chroma codec unit resulting from a multi-type tree partitioning of a chroma quadtree leaf with treeType equal to DUAL_TREE_CHROMA in a slice with slice_type equal to 2(I) associated with the PH. The value of ph_max_mtt_hierarchy_depth_intra_slice_chroma shall be in the range of 0 to 2*(CtbLog2SizeY - MinCbLog2SizeY), inclusive. When not present, the value of ph_max_mtt_hierarchy_depth_intra_slice_chroma is inferred to be equal to sps_max_mtt_hierarchy_depth_intra_slice_chroma.

[0725] ph_log2_diff_max_bt_min_qt_intra_slice_chroma specifies the difference between the base 2 logarithm of the maximum dimension (width or height) among the luma samples of a chroma codec block that can be partitioned using binary partitioning and the base 2 logarithm of the minimum dimension (width or height) among the luma samples of a chroma leaf block resulting from a quadtree partitioning of a chroma CTU with treeType equal to DUAL_TREE_CHROMA in a slice with slice_type equal to 2(I) associated with the PH. The value of ph_log2_diff_max_bt_min_qt_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeIntraC, inclusive. When not present, the value of ph_log2_diff_max_bt_min_qt_intra_slice_chroma is inferred to be equal to sps_log2_diff_max_bt_min_qt_intra_slice_chroma.

[0726] ph_log2_diff_max_tt_min_qt_intra_slice_chroma specifies the difference between the base 2 logarithm of the maximum dimension (width or height) among the luma samples of a chroma codec block that can be partitioned using ternary partitioning and the base 2 logarithm of the minimum dimension (width or height) among the luma samples of a chroma leaf block resulting from a quadtree partitioning of a chroma CTU with treeType equal to DUAL_TREE_CHROMA in a slice with slice_type equal to 2(I) associated with the PH. The value of ph_log2_diff_max_tt_min_qt_intra_slice_chroma shall be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeIntraC, inclusive. When not present, the value of ph_log2_diff_max_tt_min_qt_intra_slice_chroma is inferred to be equal to sps_log2_diff_max_tt_min_qt_intra_slice_chroma.

[0727] ph_cu_qp_delta_subdiv_intra_slice specifies the maximum cbSubdiv value for codec units in intra slices that convey cu_qp_delta_abs and cu_qp_delta_sign_flag. The value of ph_cu_qp_delta_subdiv_intra_slice shall be in the range of 0 to 2*(CtbLog2SizeY - MinQtLog2SizeIntraY + ph_max_mtt_hierarchy_depth_intra_slice_luma), inclusive.

[0728] When not present, the value of ph_cu_qp_delta_subdiv_intra_slice is inferred to be equal to 0.

[0729] ph_cu_chroma_qp_offset_subdiv_intra_slice specifies the maximum cbSubdiv value for codec units in intra slices that convey cu_chroma_qp_offset_flag. The value of ph_cu_chroma_qp_offset_subdiv_intra_slice shall be in the range of 0 to 2*(CtbLog2SizeY - MinQtLog2SizeIntraY + ph_max_mtt_hierarchy_depth_intra_slice_luma), inclusive.

[0730] When not present, the value of ph_cu_chroma_qp_offset_subdiv_intra_slice is inferred to be equal to 0.

[0731] ph_log2_diff_min_qt_min_cb_inter_slice specifies the difference between the base 2 logarithm of the minimum size of luma samples of luma leaf blocks resulting from a quadtree partitioning of a CTU and the base 2 logarithm of the minimum luma codec block size among luma samples of luma CUs in slices with slice_type equal to 0 (B) or 1 (P) associated with the PH. The value of ph_log2_diff_min_qt_min_cb_inter_slice shall be in the range of 0 to CtbLog2SizeY - MinCbLog2SizeY, inclusive. When not present, the value of ph_log2_diff_min_qt_min_cb_luma is inferred to be equal to sps_log2_diff_min_qt_min_cb_inter_slice.

[0732] ph_max_mtt_hierarchy_depth_inter_slice specifies the maximum hierarchy depth of a codec unit resulting from a multi-type tree partitioning of quadtree leaves in slices with slice_type equal to 0 (B) or 1 (P) associated with the PH. The value of ph_max_mtt_hierarchy_depth_inter_slice shall be in the range of 0 to 2*(CtbLog2SizeY - MinCbLog2SizeY), inclusive. When not present, the value of ph_max_mtt_hierarchy_depth_inter_slice is inferred to be equal to sps_max_mtt_hierarchy_depth_inter_slice.

[0733] ph_log2_diff_max_bt_min_qt_inter_slice specifies the difference between the base 2 logarithm of the maximum dimension (width or height) among the luma samples of a luma codec block that can be partitioned using binary partitioning and the base 2 logarithm of the minimum dimension (width or height) among the luma samples of a luma leaf block resulting from a quadtree partitioning of a CTU in a slice with slice_type equal to 0 (B) or 1 (P) associated with the PH. The value of ph_log2_diff_max_bt_min_qt_inter_slice shall be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeInterY, inclusive. When not present, the value of ph_log2_diff_max_bt_min_qt_inter_slice is inferred to be equal to sps_log2_diff_max_bt_min_qt_inter_slice.

[0734] ph_log2_diff_max_tt_min_qt_inter_slice specifies the difference between the base 2 logarithm of the maximum dimension (width or height) among the luma samples of a luma codec block that can be partitioned using ternary partitioning and the base 2 logarithm of the minimum dimension (width or height) among the luma samples of a luma leaf block resulting from a quadtree partitioning of a CTU in a slice with slice_type equal to 0 (B) or 1 (P) associated with the PH. The value of ph_log2_diff_max_tt_min_qt_inter_slice shall be in the range of 0 to CtbLog2SizeY - MinQtLog2SizeInterY, inclusive. When not present, the value of ph_log2_diff_max_tt_min_qt_inter_slice is inferred to be equal to sps_log2_diff_max_tt_min_qt_inter_slice.

[0735] ph_cu_qp_delta_subdiv_inter_slice specifies the maximum cbSubdiv value for codecs that transmit cu_qp_delta_abs and cu_qp_delta_sign_flag in inter slices. The value of ph_cu_qp_delta_subdiv_inter_slice shall be in the range of 0 to 2*(CtbLog2SizeY - MinQtLog2SizeInterY + ph_max_mtt_hierarchy_depth_inter_slice), inclusive.

[0736] When not present, the value of ph_cu_qp_delta_subdiv_inter_slice is inferred to be equal to 0.

[0737] ph_cu_chroma_qp_offset_subdiv_inter_slice specifies the maximum cbSubdiv value of the codec unit that transmits cu_chroma_qp_offset_flag in inter slices. The value of ph_cu_chroma_qp_offset_subdiv_inter_slice shall be in the range of 0 to 2*(CtbLog2SizeY - MinQtLog2SizeInterY + ph_max_mtt_hierarchy_depth_inter_slice), inclusive.

[0738] When not present, the value of ph_cu_chroma_qp_offset_subdiv_inter_slice is inferred to be equal to 0.

[0739] ph_temporal_mvp_enabled_flag specifies whether the temporal motion vector predictor can be used for inter prediction of slices associated with the PH. If ph_temporal_mvp_enabled_flag is equal to 0, the syntax elements of the slices associated with the PH shall be constrained so that the temporal motion vector predictor is not used in the decoding of the slices. Otherwise (ph_temporal_mvp_enabled_flag is equal to 1), the temporal motion vector predictor can be used for decoding the slices associated with the PH. When not present, the value of ph_temporal_mvp_enabled_flag is inferred to be equal to 0. The value of ph_temporal_mvp_enabled_flag shall be equal to 0 when no reference picture in the DPB has the same spatial resolution as the current picture.

[0740] The maximum number of sub-block-based merge MVP candidates, MaxNumSubblockMergeCand, is derived as follows:

[0741]

[0742] The value of MaxNumSubblockMergeCand should be in the range of 0 to 5 (inclusive).

[0743] ph_collocated_from_l0_flag equal to 1 specifies that the collocated picture used for temporal motion vector prediction is derived from reference picture list 0. ph_collocated_from_l0_flag equal to 0 specifies that the collocated picture used for temporal motion vector prediction is derived from reference picture list 1.

[0744] ph_collocated_ref_idx specifies the reference index of the collocated picture used for temporal motion vector prediction.

[0745] When ph_collocated_from_l0_flag is equal to 1, ph_collocated_ref_idx refers to an entry in reference picture list 0, and the value of ph_collocated_ref_idx shall be in the range of 0 to num_ref_entries[0][RplsIdx[0]]−1, inclusive.

[0746] When ph_collocated_from_l0_flag is equal to 0, ph_collocated_ref_idx refers to an entry in reference picture list 1, and the value of ph_collocated_ref_idx shall be in the range of 0 to num_ref_entries[1][RplsIdx[1]]-1 (inclusive).

[0747] When not present, the value of ph_collocated_ref_idx is inferred to be equal to 0.

[0748] mvd_l1_zero_flag equal to 1 indicates that the mvd_coding(x0, y0, 1) syntax structure is not parsed, and for compIdx=0..1 and cpIdx=0..2, MvdL1[x0][y0][compIdx] and MvdCpL1[x0][y0][cpIdx][compIdx] are set equal to 0. mvd_l1_zero_flag equal to 0 indicates that the mvd_coding(x0, y0, 1) syntax structure is parsed.

[0749] ph_fpel_mmvd_enabled_flag equal to 1 specifies that merge mode with motion vector differences uses integer sample precision in slices associated with the PH. ph_fpel_mmvd_enabled_flag equal to 0 specifies that merge mode with motion vector differences may use fractional sample precision in slices associated with the PH. When not present, the value of ph_fpel_mmvd_enabled_flag is inferred to be 0.

[0750] ph_disable_bdof_flag equal to 1 specifies that inter prediction based on bidirectional optical flow is disabled in slices associated with the PH. ph_disable_bdof_flag equal to 0 specifies that inter prediction based on bidirectional optical flow may be enabled or not enabled in slices associated with the PH.

[0751] When ph_disable_bdof_flag is not present, the following applies:

[0752] --If sps_bdof_enabled_flag is equal to 1, the value of ph_disable_bdof_flag is inferred to be equal to 0.

[0753] --Otherwise (sps_bdof_enabled_flag is equal to 0), the value of ph_disable_bdof_flag is inferred to be equal to 1.

[0754] ph_disable_dmvr_flag equal to 1 specifies that decoder motion vector refinement-based inter bi-prediction is disabled in slices associated with the PH. ph_disable_dmvr_flag equal to 0 specifies that decoder motion vector refinement-based inter bi-prediction may or may not be enabled in slices associated with the PH.

[0755] When ph_disable_dmvr_flag is not present, the following applies:

[0756] --If sps_dmvr_enabled_flag is equal to 1, the value of ph_disable_dmvr_flag is inferred to be equal to 0.

[0757] --Otherwise (sps_dmvr_enabled_flag is equal to 0), the value of ph_disable_dmvr_flag is inferred to be equal to 1.

[0758] ph_disable_prof_flag equal to 1 specifies that prediction refinement of optical flow is disabled in slices associated with PH. ph_disable_prof_flag equal to 0 specifies that prediction refinement of optical flow may be enabled or not enabled in slices associated with PH.

[0759] When ph_disable_prof_flag is not present, the following applies:

[0760] --If sps_affine_prof_enabled_flag is equal to 1, the value of ph_disable_prof_flag is inferred to be equal to 0.

[0761] --Otherwise (sps_affine_prof_enabled_flag is equal to 0), the value of ph_disable_prof_flag is inferred to be equal to 1.

[0762] ph_qp_delta specifies the Qp used for the codec blocks in the picture Y The initial value of until it is modified by the value of CuQpDeltaVal in the codec unit layer.

[0763] When qp_delta_info_in_ph_flag is equal to 1, the Qp of all slices of the picture Y The initial value of the quantization parameter SliceQp Y is exported as follows:

[0764] SliceQp Y=26+init_qp_minus26+ph_qp_delta (89)

[0765] SliceQp Y The value should be in the range of -QpBdOffset to +63 (inclusive).

[0766] ph_joint_cbcr_sign_flag specifies whether the collocated residual samples of the two chroma components have reversed signs in a transform unit for which tu_joint_cbcr_residual_flag[x0][y0] is equal to 1. When tu_joint_cbcr_residual_flag[x0][y0] is equal to 1 for the transform unit, ph_joint_cbcr_sign_flag equal to 0 specifies that the sign of each residual sample of the Cr (or Cb) component is the same as the sign of the collocated Cb (or Cr) residual sample, and ph_joint_cbcr_sign_flag equal to 1 specifies that the sign of each residual sample of the Cr (or Cb) component is given by the reverse sign of the collocated Cb (or Cr) residual sample.

[0767] ph_sao_luma_enabled_flag equal to 1 specifies that SAO is enabled for luma components in all slices associated with the PH; ph_sao_luma_enabled_flag equal to 0 specifies that SAO for luma components may be disabled for one, multiple, or all slices associated with the PH, and when ph_sao_luma_enabled_flag is not present, it is inferred to be equal to 0.

[0768] ph_sao_chroma_enabled_flag equal to 1 specifies that SAO is enabled for chroma components in all slices associated with the PH; ph_sao_chroma_enabled_flag equal to 0 specifies that SAO for chroma components may be disabled for one, multiple, or all slices associated with the PH. When ph_sao_chroma_enabled_flag is not present, it is inferred to be equal to 0.

[0769] ph_dep_quant_enabled_flag equal to 0 specifies that dependent quantization is disabled for the current picture. ph_dep_quant_enabled_flag equal to 1 specifies that dependent quantization is enabled for the current picture. When ph_dep_quant_enabled_flag is not present, it is inferred to be equal to 0.

[0770] pic_sign_data_hiding_enabled_flag equal to 0 specifies that sign bit hiding is disabled for the current picture. pic_sign_data_hiding_enabled_flag equal to 1 specifies that sign bit hiding is enabled for the current picture. When pic_sign_data_hiding_enabled_flag is not present, it is inferred to be equal to 0.

[0771] ph_deblocking_filter_override_flag equal to 1 specifies that deblocking parameters are present in PH. ph_deblocking_filter_override_flag equal to 0 specifies that deblocking parameters are not present in PH. When not present, the value of ph_deblocking_filter_override_flag is inferred to be equal to 0.

[0772] ph_deblocking_filter_disabled_flag equal to 1 specifies that the operation of the deblocking filter is not applicable to the slices associated with the PH. ph_deblocking_filter_disabled_flag equal to 0 specifies that the operation of the deblocking filter is applicable to the slices associated with the PH. When ph_deblocking_filter_disabled_flag is not present, it is inferred to be equal to pps_deblocking_filter_disabled_flag.

[0773] ph_beta_offset_div2 and ph_tc_offset_div2 specify the deblocking parameter offsets for β and tC (divided by 2) that are applied to the luma component of the slice associated with the PH. The values of ph_beta_offset_div2 and ph_tc_offset_div2 should both be in the range -12 to 12, inclusive. When not present, the values of ph_beta_offset_div2 and ph_tc_offset_div2 are inferred to be equal to pps_beta_offset_div2 and pps_tc_offset_div2, respectively.

[0774] ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 specify the deblocking parameter offsets for β and tC (divided by 2) that are applied to the Cb component of the slice associated with the PH. The values of ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 should both be in the range -12 to 12, inclusive. When not present, the values of ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 are inferred to be equal to pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2, respectively.

[0775] ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 specify the deblocking parameter offsets for beta and tc (divided by 2) that are applied to the Cr components of the slices associated with the PH. The values of ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 shall both be in the range of -12 to 12, inclusive. When not present, the values of ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 are inferred to be equal to pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2, respectively.

[0776] ph_extension_length specifies the length of the PH extension data in bytes, excluding the bits used to signal the ph_extension_length itself. The value of ph_extension_length shall be in the range of 0 to 256 (inclusive). When not present, the value of ph_extension_length is inferred to be equal to 0.

[0777] The value of ph_extension_data_byte can be any value. Decoders conforming to this version of this specification shall ignore the value of ph_extension_data_byte. Its value does not affect the conformance of the decoder to the profile specified in this version of the specification.

[0778] 3.6.SH Syntax and Semantics

[0779] In the latest VVC draft text, the SH syntax and semantics are as follows:

[0780]

[0781]

[0782]

[0783]

[0784]

[0785] The variable CuQpDeltaVal, which specifies the difference between the luma quantization parameter of a codec containing cu_qp_delta_abs and its prediction, is set equal to 0. The variable CuQpDeltaVal specifies the difference between the luma quantization parameter of a codec containing cu_qp_delta_abs and its prediction when determining the Qp′ of a codec containing cu_chroma_qp_offset_flag. Cb , Qp′ Cr and Qp′ CbCr The value of the variable CuQpOffset to use when the corresponding value of the quantization parameter Cb 、CuQpOffset Cr and CuQpOffset CbCr are all set equal to 0.

[0786] picture_header_in_slice_header_flag equal to 1 specifies that the PH syntax structure is present in the slice header. picture_header_in_slice_header_flag equal to 0 specifies that the PH syntax structure is not present in the slice header.

[0787] A bitstream conformance requirement is that the value of picture_header_in_slice_header_flag shall be the same in all codec slices in a CLVS.

[0788] When picture_header_in_slice_header_flag is equal to 1 for a codec slice, the bitstream conformance requirement is that no VCL NAL unit with nal_unit_type equal to PH_NUT shall be present in the CLVS.

[0789] When picture_header_in_slice_header_flag is equal to 0, all coded slices in the current picture shall have picture_header_in_slice_header_flag equal to 0, and the current PU shall have a PH NAL unit.

[0790] slice_subpic_id specifies the sub-picture ID of the sub-picture containing the slice. If slice_subpic_id exists, the value of the variable CurrSubpicIdx is derived such that SubpicIdVal[CurrSubpicIdx] is equal to slice_subpic_id. Otherwise (slice_subpic_id does not exist), CurrSubpicIdx is derived equal to 0. The length of slice_subpic_id is sps_subpic_id_len_minus1+1 bits.

[0791] slice_address specifies the slice address of the slice. When not present, the value of slice_address is inferred to be equal to 0. When rect_slice_flag is equal to 1 and NumSlicesInSubpic[CurrSubpicIdx] is equal to 1, the value of slice_address is inferred to be equal to 0.

[0792] If rect_slice_flag is equal to 0, the following applies:

[0793] --The stripe address is the raster scan stripe index.

[0794] --slice_address has a length of Ceil(Log2(NumTilesInPic)) bits.

[0795] The value of --slice_address should be in the range of 0 to NumTilesInPic-1 (inclusive).

[0796] Otherwise (rect_slice_flag is equal to 1), the following applies:

[0797] --The strip address is the sub-picture level strip index of the strip.

[0798] --slice_address has a length of Ceil(Log2(NumSlicesInSubpic[CurrSubpicIdx])) bits.

[0799] The value of --slice_address should be in the range of 0 to NumSlicesInSubpic[CurrSubpicIdx]-1 (inclusive).

[0800] The requirements for bitstream conformance are that the following constraints apply:

[0801] --If rect_slice_flag is equal to 0 or subpic_info_present_flag is equal to 0, the value of slice_address shall not be equal to the value of slice_address of any other codec slice NAL unit of the same codec picture.

[0802] -- Otherwise, the pair of slice_subpic_id and slice_address values shall not be equal to the pair of slice_subpic_id and slice_address values of any other codec slice NAL unit of the same codec picture.

[0803] -- The shape of the slices of a picture shall be such that each CTU, when decoded, has its entire left and top boundaries consisting of either picture boundaries or boundaries of previously decoded CTU(s).

[0804] sh_extra_bit[i] may be equal to 1 or 0. Decoders conforming to this version of this specification shall ignore the value of sh_extra_bit[i]. Its value does not affect the conformance of the decoder to the profile specified in this version of this specification.

[0805] num_tiles_in_slice_minus1 plus 1 (if present) specifies the number of tiles in a slice. The value of num_tiles_in_slice_minus1 should be in the range of 0 to NumTilesInPic-1 (inclusive).

[0806] The variable NumCtusInCurrSlice specifies the number of CTUs in the current slice, and the list CtbAddrInCurrSlice[i], where i ranges from 0 to NumCtusInCurrSlice-1 (inclusive), specifies the picture raster scan address of the i-th CTB in the slice, derived as follows:

[0807]

[0808]

[0809] The variables SubpicLeftBoundaryPos, SubpicTopBoundaryPos, SubpicRightBoundaryPos, and SubpicBotBoundaryPos are derived as follows:

[0810]

[0811] slice_type specifies the codec type of the slice according to Table 9.

[0812] Table 9 - Name association with slice_type

[0813] slice_type The name of the slice_type 0 B (B strip) 1 P (P stripe) 2 I(I strip)

[0814] When not present, the value of slice_type is inferred to be equal to 2.

[0815] When ph_intra_slice_allowed_flag is equal to 0, the value of slice_type shall be equal to 0 or 1. When nal_unit_type is in the range of IDR_W_RADL to CRA_NUT (inclusive) and vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1, slice_type shall be equal to 2.

[0816] The variables MinQtLog2SizeY, MinQtLog2SizeC, MinQtSizeY, MinQtSizeC, MaxBtSizeY, MaxBtSizeC, MinBtSizeY, MaxTtSizeY, MaxTtSizeC, MinTtSizeY, MaxMttDepthY and MaxMttDepthC are derived as follows:

[0817] --If slice_type is equal to 2(I), the following applies:

[0818] MinQtLog2SizeY=

[0819] MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_intra_slice_luma (119)

[0820] MinQtLog2SizeC=

[0821] MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_intra_slice_chroma (120)

[0822] MaxBtSizeY=1<<

[0823] (MinQtLog2SizeY+ph_log2_diff_max_bt_min_qt_intra_slice_luma) (121)

[0824] MaxBtSizeC=1<<

[0825] (MinQtLog2SizeC + ph_log2_diff_max_bt_min_qt_intra_slice_chroma) (122)

[0826] MaxTtSizeY = 1 <<

[0827] (MinQtLog2SizeY + ph_log2_diff_max_tt_min_qt_intra_slice_luma) (123)

[0828] MaxTtSizeC = 1 <<

[0829] (MinQtLog2SizeC + ph_log2_diff_max_tt_min_qt_intra_slice_chroma) (124)

[0830] MaxMttDepthY = ph_max_mtt_hierarchy_depth_intra_slice_luma (125)

[0831] MaxMttDepthC = ph_max_mtt_hierarchy_depth_intra_slice_chroma (126)

[0832] CuQpDeltaSubdiv = ph_cu_qp_delta_subdiv_intra_slice (127)

[0833] CuChromaQpOffsetSubdiv = ph_cu_chroma_qp_offset_subdiv_intra_slice (128)

[0834] -- Otherwise (slice_type equals 0 (B) or 1 (P)), the following applies:

[0835] MinQtLog2SizeY = MinCbLog2SizeY + ph_log2_diff_min_qt_min_cb_inter_slice (129)

[0836] MinQtLog2SizeC = MinCbLog2SizeY + ph_log2_diff_min_qt_min_cb_inter_slice (130)

[0837] MaxBtSizeY = 1 <<

[0838] (MinQtLog2SizeY + ph_log2_diff_max_bt_min_qt_inter_slice) (131)

[0839] MaxBtSizeC = 1 <<

[0840] (MinQtLog2SizeC + ph_log2_diff_max_bt_min_qt_inter_slice) (132)

[0841] MaxTtSizeY = 1 <<

[0842] (MinQtLog2SizeY + ph_log2_diff_max_tt_min_qt_inter_slice) (133)

[0843] MaxTtSizeC = 1 <<

[0844] (MinQtLog2SizeC + ph_log2_diff_max_tt_min_qt_inter_slice) (134)

[0845] MaxMttDepthY = ph_max_mtt_hierarchy_depth_inter_slice (135)

[0846] MaxMttDepthC = ph_max_mtt_hierarchy_depth_inter_slice (136)

[0847] CuQpDeltaSubdiv = ph_cu_qp_delta_subdiv_inter_slice (137)

[0848] CuChromaQpOffsetSubdiv = ph_cu_chroma_qp_offset_subdiv_inter_slice (138)

[0849] (MinQtLog2SizeY + ph_log2_diff_max_bt_min_qt_inter_slice) (131) -- The following applies:

[0850] MinQtSizeY = 1 << MinQtLog2SizeY (139)

[0851] MinQtSizeC = 1 << MinQtLog2SizeC (140)

[0852] MinBtSizeY=1< <MinCbLog2SizeY (141)

[0853] MinTtSizeY=1< <MinCbLog2SizeY (142)

[0854] slice_alf_enabled_flag equal to 1 specifies that the adaptive loop filter is enabled and can be applied to the Y, Cb, or Cr color components in the slice. slice_alf_enabled_flag equal to 0 specifies that the adaptive loop filter is disabled for all color components in the slice. When not present, the value of slice_alf_enabled_flag is inferred to be equal to ph_alf_enabled_flag.

[0855] slice_num_alf_aps_ids_luma specifies the number of ALF APSs referenced by the slice. When slice_alf_enabled_flag is equal to 1 and slice_num_alf_aps_ids_luma is not present, the value of slice_num_alf_aps_ids_luma is inferred to be equal to the value of ph_num_alf_aps_ids_luma.

[0856] slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALF APS referenced by the luma component of the slice. The TemporalId of the APS NAL unit with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i] shall be less than or equal to the TemporalId of the coded slice NAL unit. When slice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i] is not present, the value of slice_alf_aps_id_luma[i] is inferred to be equal to the value of ph_alf_aps_id_luma[i].

[0857] The value of alf_luma_filter_signal_flag shall be equal to 1 for APS NAL units with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i].

[0858] slice_alf_chroma_idc equal to 0 specifies that the adaptive loop filter is not applied to the Cb and Cr color components. slice_alf_chroma_idc equal to 1 indicates that the adaptive loop filter is applied to the Cb color component. slice_alf_chroma_idc equal to 2 indicates that the adaptive loop filter is applied to the Cr color components. slice_alf_chroma_idc equal to 3 indicates that the adaptive loop filter is applied to the Cb and Cr color components. When slice_alf_chroma_idc is not present, it is inferred to be equal to ph_alf_chroma_idc.

[0859] slice_alf_aps_id_chroma specifies the adaptation_parameter_set_id of the ALF APS referenced by the chroma components of the slice. The TemporalId of APS NAL units with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_alf_aps_id_chroma shall be less than or equal to the TemporalId of the coded slice NAL unit. When slice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_chroma is not present, the value of slice_alf_aps_id_chroma is inferred to be equal to the value of ph_alf_aps_id_chroma.

[0860] The value of alf_chroma_filter_signal_flag shall be equal to 1 for APS NAL units with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_alf_aps_id_chroma.

[0861] slice_cc_alf_cb_enabled_flag equal to 0 specifies that cross-component filters are not applied to the Cb color component. slice_cc_alf_cb_enabled_flag equal to 1 indicates that cross-component filters are enabled and may be applied to the Cb color component. When slice_cc_alf_cb_enabled_flag is not present, it is inferred to be equal to ph_cc_alf_cb_enabled_flag.

[0862] slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id referenced by the Cb color component of the slice.

[0863] The TemporalId of the APS NAL unit with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_id shall be less than or equal to the TemporalId of the codec slice NAL unit. When slice_cc_alf_cb_enabled_flag is equal to 1 and slice_cc_alf_cb_aps_id is not present, the value of slice_cc_alf_cb_aps_id is inferred to be equal to the value of ph_cc_alf_cb_aps_id.

[0864] The value of alf_cc_cb_filter_signal_flag shall be equal to 1 for APS NAL units with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_id.

[0865] slice_cc_alf_cr_enabled_flag equal to 0 specifies that the cross-component filter is not applied to Cr color components. slice_cc_alf_cb_enabled_flag equal to 1 indicates that the cross-component adaptive loop filter is enabled and can be applied to Cr color components. When slice_cc_alf_cr_enabled_flag is not present, it is inferred to be equal to ph_cc_alf_cr_enabled_flag.

[0866] slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id referenced by the Cr color components of the slice. The TemporalId of the APS NAL unit with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id shall be less than or equal to the TemporalId of the codec slice NAL unit. When slice_cc_alf_cr_enabled_flag is equal to 1 and slice_cc_alf_cr_aps_id is not present, the value of slice_cc_alf_cr_aps_id is inferred to be equal to the value of ph_cc_alf_cr_aps_id.

[0867] The value of alf_cc_cr_filter_signal_flag shall be equal to 1 for APS NAL units with aps_params_type equal to ALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id.

[0868] When separate_colour_plane_flag is equal to 1, colour_plane_id identifies the colour plane associated with the current slice. The value of colour_plane_id shall be in the range of 0 to 2 (inclusive). colour_plane_id values 0, 1 and 2 correspond to the Y, Cb and Cr planes respectively. The value 3 of colour_plane_id is reserved for future use by ITU-T | ISO / IEC.

[0869] NOTE 1 - There is no dependency between the decoding processes of different color planes of a picture.

[0870] num_ref_idx_active_override_flag equal to 1 specifies that the syntax element num_ref_idx_active_minus1[0] is present in P slices and B slices, and the syntax element num_ref_idx_active_minus1[1] is present in B slices. num_ref_idx_active_override_flag equal to 0 specifies that the syntax elements num_ref_idx_active_minus1[0] and num_ref_idx_active_minus1[1] are not present. When not present, the value of num_ref_idx_active_override_flag is inferred to be equal to 1.

[0871] num_ref_idx_active_minus1[i] is used to derive the variable NumRefIdxActive[i] as specified in Equation 143. The value of num_ref_idx_active_minus1[i] shall be in the range of 0 to 14, inclusive.

[0872] For i equal to 0 or 1, when the current slice is a B slice, num_ref_idx_active_override_flag is equal to 1, and num_ref_idx_active_minus1[i] is not present, num_ref_idx_active_minus1[i] is inferred to be equal to 0.

[0873] When the current slice is a P slice, num_ref_idx_active_override_flag is equal to 1, and num_ref_idx_active_minus1[0] is not present, num_ref_idx_active_minus1[0] is inferred to be equal to 0.

[0874] The variable NumRefIdxActive[i] is derived as follows:

[0875]

[0876]

[0877] The value of NumRefIdxActive[i]-1 specifies the maximum reference index of reference picture list i that can be used to decode the slice. When the value of NumRefIdxActive[i] is equal to 0, no reference index of reference picture list i can be used to decode the slice.

[0878] When the current slice is a P slice, the value of NumRefIdxActive[0] should be greater than 0.

[0879] When the current slice is a B slice, both NumRefIdxActive[0] and NumRefIdxActive[1] should be greater than 0.

[0880] cabac_init_flag specifies the method used to determine the initialization table used during the initialization of context variables. When cabac_init_flag is not present, it is inferred to be equal to 0.

[0881] slice_collocated_from_l0_flag equal to 1 specifies that the collocated picture used for temporal motion vector prediction is derived from reference picture list 0. slice_collocated_from_l0_flag equal to 0 specifies that the collocated picture used for temporal motion vector prediction is derived from reference picture list 1.

[0882] When slice_type is equal to B or P, ph_temporal_mvp_enabled_flag is equal to 1, and slice_collocated_from_l0_flag is not present, the following applies:

[0883] --If rpl_info_in_ph_flag is equal to 1, slice_collocated_from_l0_flag is inferred to be equal to ph_collocated_from_l0_flag.

[0884] Otherwise (rpl_info_in_ph_flag is equal to 0 and slice_type is equal to P), the value of slice_collocated_from_l0_flag is inferred to be equal to 1.

[0885] slice_collocated_ref_idx specifies the reference index of the collocated picture used for temporal motion vector prediction.

[0886] When slice_type is equal to P or when slice_type is equal to B and slice_collocated_from_l0_flag is equal to 1, slice_collocated_ref_idx refers to the entry in reference picture list 0, and the value of slice_collocated_ref_idx should be in the range of 0 to NumRefIdxActive[0]-1 (including the end value).

[0887] When slice_type is equal to B and slice_collocated_from_l0_flag is equal to 0, slice_collocated_ref_idx refers to the entry in reference picture list 1, and the value of slice_collocated_ref_idx should be in the range of 0 to NumRefIdxActive[1]-1 (inclusive).

[0888] When slice_collocated_ref_idx is not present, the following applies:

[0889] --If rpl_info_in_ph_flag is equal to 1, the value of slice_collocated_ref_idx is inferred to be equal to ph_collocated_ref_idx.

[0890] Otherwise (rpl_info_in_ph_flag is equal to 0), the value of slice_collocated_ref_idx is inferred to be equal to 0.

[0891] A bitstream conformance requirement is that the picture referenced by slice_collocated_ref_idx shall be the same for all slices of a codec picture.

[0892] Bitstream conformance requirements are that the values of pic_width_in_luma_samples and pic_height_in_luma_samples of the reference picture referred to by slice_collocated_ref_idx shall be equal to the values of pic_width_in_luma_samples and pic_height_in_luma_samples, respectively, of the current picture, and RprConstraintsActive[slice_collocated_from_10_flag?0:1][slice_collocated_ref_idx] shall be equal to 0.

[0893] slice_qp_delta specifies the Qp used for codec blocks in a slice Y The initial value of until it is modified by the value of CuQpDeltaVal in the codec unit layer.

[0894] When qp_delta_info_in_ph_flag is equal to 0, the Qp Y The initial value of the quantization parameter SliceQp Y is exported as follows:

[0895] SliceQp Y =26+init_qp_minus26+slice_qp_delta (144)

[0896] SliceQp Y The value should be in the range of -QpBdOffset to +63 (inclusive).

[0897] When any of the following conditions is true:

[0898] --The value of wp_info_in_ph_flag is equal to 1, the value of pps_weighted_pred_flag is equal to 1, and the value of slice_type is equal to P.

[0899] The value of --wp_info_in_ph_flag is equal to 1, the value of --pps_weighted_bipred_flag is equal to 1, and the value of --slice_type is equal to B.

[0900] The following applies:

[0901] --The value of NumRefIdxActive[0] shall be less than or equal to the value of NumWeightsL0.

[0902] - For each reference picture index RefPicList[0][i] where i is in the range 0 to NumRefIdxActive[0]-1 (inclusive), the luma weight, Cb weight, and Cr weight applied to the reference picture index are LumaWeightL0[i], ChromaWeightL0[0][i], and ChromaWeightL0[1][i], respectively.

[0903] When wp_info_in_ph_flag is equal to 1, pps_weighted_bipred_flag is equal to 1, and slice_type is equal to B, the following applies:

[0904] --The value of NumRefIdxActive[1] shall be less than or equal to the value of NumWeightsL1.

[0905] - For each reference picture index RefPicList[1][i] where i is in the range 0 to NumRefIdxActive[1]-1 (inclusive), the luma weight, Cb weight, and Cr weight applied to the reference picture index are LumaWeightL1[i], ChromaWeightL1[0][i], and ChromaWeightL1[1][i], respectively.

[0906] slice_cb_qp_offset specifies the time to determine Qp′ CbThe value of the quantization parameter is the difference to be added to the value of pps_cb_qp_offset. The value of slice_cb_qp_offset should be in the range of -12 to +12 (inclusive). When slice_cb_qp_offset is not present, it is inferred to be equal to 0. The value of pps_cb_qp_offset + slice_cb_qp_offset should be in the range of -12 to +12 (inclusive).

[0907] slice_cr_qp_offset specifies the time to determine Qp′ Cr The difference to be added to the value of pps_cr_qp_offset when quantizing the parameter value. The value of slice_cr_qp_offset shall be in the range of -12 to +12 (inclusive). When slice_cr_qp_offset is not present, it is inferred to be equal to 0. The value of pps_cr_qp_offset + slice_cr_qp_offset shall be in the range of -12 to +12 (inclusive).

[0908] slice_join_cbcr_qp_offset specifies the offset between the Qp′ and the CbCr The value of slice_joint_cbcr_qp_offset_value is the difference to be added to the value of pps_joint_cbcr_qp_offset_value. The value of slice_joint_cbcr_qp_offset shall be in the range of -12 to +12 (inclusive). When slice_joint_cbcr_qp_offset is not present, it is inferred to be equal to 0. The value of pps_joint_cbcr_qp_offset_value + slice_joint_cbcr_qp_offset shall be in the range of -12 to +12 (inclusive).

[0909] cu_chroma_qp_offset_enabled_flag equal to 1 specifies that cu_chroma_qp_offset_flag may be present in transform unit and palette codec syntax. cu_chroma_qp_offset_enabled_flag equal to 0 specifies that cu_chroma_qp_offset_flag is not present in transform unit or palette codec syntax. When not present, the value of cu_chroma_qp_offset_enabled_flag is inferred to be equal to 0.

[0910] slice_sao_luma_flag equal to 1 specifies that SAO is enabled for the luma components in the current slice; slice_sao_luma_flag equal to 0 specifies that SAO is disabled for the luma components in the current slice. When slice_sao_luma_flag is not present, it is inferred to be equal to ph_sao_luma_enabled_flag.

[0911] slice_sao_chroma_flag equal to 1 specifies that SAO is enabled for the chroma components in the current slice; slice_sao_chroma_flag equal to 0 specifies that SAO is disabled for the chroma components in the current slice. When slice_sao_chroma_flag is not present, it is inferred to be equal to ph_sao_chroma_enabled_flag.

[0912] slice_deblocking_filter_override_flag equal to 1 specifies that deblocking parameters are present in the slice header. slice_deblocking_filter_override_flag equal to 0 specifies that deblocking parameters are not present in the slice header. When not present, the value of slice_deblocking_filter_override_flag is inferred to be equal to ph_deblocking_filter_override_flag.

[0913] slice_deblocking_filter_disabled_flag equal to 1 specifies that the deblocking filter operation is not applied to the current slice. slice_deblocking_filter_disabled_flag equal to 0 specifies that the deblocking filter operation is applied to the current slice. When slice_deblocking_filter_disabled_flag is not present, it is inferred to be equal to ph_deblocking_filter_disabled_flag.

[0914] slice_beta_offset_div2 and slice_tc_offset_div2 specify the deblocking parameter offsets for beta and tc (divided by 2) applied to the luma component of the current slice. The values of slice_beta_offset_div2 and slice_tc_offset_div2 shall both be in the range -12 to 12 (inclusive). When not present, the values of slice_beta_offset_div2 and slice_tc_offset_div2 are inferred to be equal to ph_beta_offset_div2 and ph_tc_offset_div2, respectively.

[0915] slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify the deblocking parameter offsets for beta and tc (divided by 2) applied to the Cb component of the current slice. The values of slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 shall both be in the range -12 to 12 (inclusive). When not present, the values of slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 are inferred to be equal to ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2, respectively.

[0916] slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify the deblocking parameter offsets for beta and tc (divided by 2) applied to the Cr components of the current slice. The values of slice_cr_beta_offset_div2 and slice_cr_tc_offset_div2 shall both be in the range -12 to 12, inclusive. When not present, the values of slice_cr_beta_offset_div2 and slice_cr_tc_offset_div2 are inferred to be equal to ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2, respectively.

[0917] slice_ts_residual_coding_disabled_flag equal to 1 specifies that the residual_coding() syntax structure is used to parse the residual samples of the transform skip blocks of the current slice. slice_ts_residual_coding_disabled_flag equal to 0 specifies that the residual_ts_coding() syntax structure is used to parse the residual samples of the transform skip blocks of the current slice. When slice_ts_residual_coding_disabled_flag is not present, it is inferred to be equal to 0.

[0918] slice_lmcs_enabled_flag equal to 1 specifies that luma mapping with chroma scaling is enabled for the current slice. slice_lmcs_enabled_flag equal to 0 specifies that luma mapping with chroma scaling is not enabled for the current slice. When slice_lmcs_enabled_flag is not present, it is inferred to be equal to 0.

[0919] slice_scaling_list_present_flag equal to 1 specifies that the scaling list data for the current slice is derived based on the scaling list data contained in the reference scaling list APS, where aps_params_type is equal to SCALING_APS and adaptation_parameter_set_id is equal to ph_scaling_list_aps_id. slice_scaling_list_present_flag equal to 0 specifies that the scaling list data for the current picture is the default scaling list data specified in clause 7.4.3.21. When not present, the value of slice_scaling_list_present_flag is inferred to be equal to 0.

[0920] The variable NumEntryPoints specifies the number of entry points in the current strip and is derived as follows:

[0921]

[0922] offset_len_minus1 plus 1 specifies the length in bits of the entry_point_offset_minus1[i] syntax element. The value of offset_len_minus1 shall be in the range of 0 to 31 (inclusive).

[0923] entry_point_offset_minus1[i] plus 1 specifies the i-th entry point offset in bytes and is represented by offset_len_minus1 plus 1 bit. The slice data following the slice header consists of NumEntryPoints+1 subsets, where the subset index values range from 0 to NumEntryPoints (inclusive). The first byte of the slice data is considered to be byte 0. When present, the emulation prevention bytes appearing in the slice data portion of the codec slice NAL unit are counted as part of the slice data for subset identification purposes. Subset 0 consists of bytes 0 to entry_point_offset_minus1[0] (inclusive) of the codec slice data, and subset k (where k ranges from 1 to NumEntryPoints-1 (inclusive)) consists of bytes firstByte[k] to lastByte[k] (inclusive) of the codec slice data, where firstByte[k] and lastByte[k] are defined as:

[0924]

[0925] lastByte[k]=firstByte[k]+entry_point_offset_minus1[k] (147)

[0926] The last subset (where the subset index is equal to NumEntryPoints) consists of the remaining bytes of the codec stripe data.

[0927] When sps_entropy_coding_sync_enabled_flag is equal to 0 and a slice contains one or more complete slices, each subset shall consist of all codec bits of all CTUs in the slice within the same slice, and the number of subsets (i.e., the value of NumEntryPoints+1) shall be equal to the number of slices in the slice.

[0928] When sps_entropy_coding_sync_enabled_flag is equal to 0 and a slice contains a subset of CTU rows from a single slice, NumEntryPoints shall be 0 and the number of subsets shall be 1. The subset shall consist of all codec bits of all CTUs in the slice.

[0929] When sps_entropy_coding_sync_enabled_flag is equal to 1, each subset k in the range of 0 to NumEntryPoints (inclusive) shall consist of all codec bits of all CTUs in the CTU rows in the slice, and the number of subsets (i.e., the value of NumEntryPoints+1) shall be equal to the total number of slice-specific CTU rows in the slice.

[0930] slice_header_extension_length specifies the length of the slice header extension data in bytes, excluding the bits used to signal the slice_header_extension_length itself. The value of slice_header_extension_length shall be in the range of 0 to 256 (inclusive). When not present, the value of slice_header_extension_length is inferred to be equal to 0.

[0931] slice_header_extension_data_byte[i] can have any value. Decoders conforming to this version of this specification shall ignore all values of the slice_header_extension_data_byte[i] syntax element. Its value does not affect the conformance of the decoder to the profile specified in this version of this specification.

[0932] 3.7. Transformation Unit Syntax (Strip Data)

[0933] In the latest VVC draft text, the transform unit syntax and semantics are as follows:

[0934]

[0935]

[0936]

[0937]

[0938]

[0939] The transform coefficient levels are represented by the array TransCoeffLevel[x0][y0][cIdx][xC][yC]. Array indices x0, y0 specify the position (x0, y0) of the top left luma sample of the transform block under consideration relative to the top left luma sample of the picture. Array index cIdx specifies the indicator of the color component; Y is equal to 0, Cb is equal to 1, and Cr is equal to 2. Array indices xC and yC specify the transform coefficient position (xC, yC) within the current transform block. When the value of TransCoeffLevel[x0][y0][cIdx][xC][yC] is not specified in clause 7.3.10.11, it is inferred to be equal to 0.

[0940] tu_cbf_cb[x0][y0] equal to 1 specifies that the Cb transform block contains one or more transform coefficient levels not equal to 0. Array indices x0, y0 specify the top left position (x0, y0) of the transform block under consideration.

[0941] When tu_cbf_cb[x0][y0] is not present, its value is inferred to be equal to 0.

[0942] tu_cbf_cr[x0][y0] equal to 1 specifies that the Cr transform block contains one or more transform coefficient levels not equal to 0. Array indices x0, y0 specify the top left position (x0, y0) of the transform block under consideration.

[0943] When tu_cbf_cr[x0][y0] is not present, its value is inferred to be equal to 0.

[0944] tu_cbf_luma[x0][y0] equal to 1 specifies that the luma transform block contains one or more transform coefficient levels not equal to 0. Array indices x0, y0 specify the position (x0, y0) of the top left luma sample of the transform block under consideration relative to the top left luma sample of the picture.

[0945] When tu_cbf_luma[x0][y0] is not present, its value is inferred as follows:

[0946] --If cu_sbt_flag is equal to 1, and one of the following conditions is true, then tu_cbf_luma[x0][y0] is inferred to be equal to 0:

[0947] –subTuIndex is equal to 0, and cu_sbt_pos_flag is equal to 1.

[0948] –subTuIndex is equal to 1, and cu_sbt_pos_flag is equal to 0.

[0949] Otherwise, if treeType is equal to DUAL_TREE_CHROMA, tu_cbf_luma[x0][y0] is inferred to be equal to 0.

[0950] --Otherwise, tu_cbf_luma[x0][y0] is inferred to be equal to 1.

[0951] tu_joint_cbcr_residual_flag[x0][y0] specifies whether the residual samples of both chrominance components Cb and Cr are coded as a single transform block. The array index x0, y0 specifies the position (x0, y0) of the top left luma sample of the considered transform block relative to the top left luma sample of the picture.

[0952] tu_joint_cbcr_residual_flag[x0][y0] equal to 1 specifies that the transform unit syntax includes the transform coefficient levels of a single transform block from which the residual samples of both Cb and Cr are derived. tu_joint_cbcr_residual_flag[x0][y0] equal to 0 specifies that the transform coefficient levels of the chroma components are coded or decoded as indicated by the syntax elements tu_cbf_cb[x0][y0] and tu_cbf_cr[x0][y0].

[0953] When tu_joint_cbcr_residual_flag[x0][y0] is not present, it is inferred to be equal to 0.

[0954] Based on tu_joint_cbcr_residual_flag[x0][y0], tu_cbf_cb[x0][y0] and tu_cbf_cr[x0][y0], the variable TuCResMode[x0][y0] is derived as follows:

[0955] --If tu_joint_cbcr_residual_flag[x0][y0] is equal to 0, the variable TuCResMode[x0][y0] is set equal to 0.

[0956] --Otherwise, if tu_cbf_cb[x0][y0] is equal to 1 and tu_cbf_cr[x0][y0] is equal to 0, then the variable TuCResMode[x0][y0] is set equal to 1.

[0957] --Otherwise, if tu_cbf_cb[x0][y0] is equal to 1, the variable TuCResMode[x0][y0] is set equal to 2.

[0958] --Otherwise, the variable TuCResMode[x0][y0] is set equal to 3.

[0959] cu_qp_delta_abs specifies the absolute value of the difference CuQpDeltaVal between the quantization parameter of the current codec unit and its prediction.

[0960] cu_qp_delta_sign_flag specifies the sign of CuQpDeltaVal as follows:

[0961] --If cu_qp_delta_sign_flag is equal to 0, the corresponding CuQpDeltaVal has a positive value.

[0962] --Otherwise (cu_qp_delta_sign_flag is equal to 1), the corresponding CuQpDeltaVal has a negative value.

[0963] When cu_qp_delta_sign_flag is not present, it is inferred to be equal to 0.

[0964] When cu_qp_delta_abs exists, the variables IsCuQpDeltaCoded and CuQpDeltaVal are exported as follows:

[0965] IsCuQpDeltaCoded=1 (187)

[0966] CuQpDeltaVal=cu_qp_delta_abs*(1-2*cu_qp_delta_sign_flag) (188)

[0967] The value of CuQpDeltaVal should be in the range of -(32+QpBdOffset / 2) to +(31+QpBdOffset / 2) (inclusive).

[0968] cu_chroma_qp_offset_flag, when present and equal to 1, specifies the entry in cb_qp_offset_list[] used to determine CuQpOffset Cb The corresponding entry in cr_qp_offset_list[] is used to determine the value of CuQpOffset Cr The value of , and the corresponding entry in joint_cbcr_qp_offset_list[] is used to determine CuQpOffset CbCr cu_chroma_qp_offset_flag equal to 0 specifies that these lists are not used to determine CuQpOffset Cb、CuQpOffset Cr and CuQpOffset CbCr The value of .

[0969] cu_chroma_qp_offset_idx (if present) specifies the value used to determine the CuQpOffset Cb 、CuQpOffset Cr and CuQpOffset CbCr cu_chroma_qp_offset_idx is an index into cb_qp_offset_list[], cr_qp_offset_list[], and joint_cbcr_qp_offset_list[] to determine the value of cu_chroma_qp_offset_idx. When present, the value of cu_chroma_qp_offset_idx shall be in the range of 0 to chroma_qp_offset_list_len_minus1, inclusive. When not present, the value of cu_chroma_qp_offset_idx is inferred to be equal to 0.

[0970] When cu_chroma_qp_offset_flag is present, the following applies:

[0971] --The variable IsCuChromaQpOffsetCoded is set equal to 1.

[0972] --Variable CuQpOffset Cb 、CuQpOffset Cr and CuQpOffset CbCr The export is as follows:

[0973] If cu_chroma_qp_offset_flag is equal to 1, the following applies:

[0974] CuQpOffset Cb =cb_qp_offset_list[cu_chroma_qp_offset_idx] (189)

[0975] CuQpOffset Cr =cr_qp_offset_list[cu_chroma_qp_offset_idx] (190)

[0976] CuQpOffset CbCr =joint_cbcr_qp_offset_list[cu_chroma_qp_offset_idx] (191)

[0977] --Otherwise (cu_chroma_qp_offset_flag is equal to 0), CuQpOffset Cb 、CuQpOffset Cr and CuQpOffset CbCr Both are set to 0.

[0978] transform_skip_flag[x0][y0][cIdx] specifies whether the transform is applied to the associated transform block. Array indices x0, y0 specify the position (x0, y0) of the top left luma sample of the transform block under consideration relative to the top left luma sample of the picture. Array index cIdx specifies the indicator of the color component; Y is equal to 0, Cb is equal to 1, and Cr is equal to 2. transform_skip_flag[x0][y0][cIdx] equal to 1 specifies that no transform is applied to the associated transform block. transform_skip_flag[x0][y0][cIdx] equal to 0 specifies that the decision of whether to apply the transform to the associated transform block depends on other syntax elements.

[0979] When transform_skip_flag[x0][y0][cIdx] is not present, it is inferred as follows:

[0980] --If BdpcmFlag[x0][y0][cIdx] is equal to 1, transform_skip_flag[x0][y0][cIdx] is inferred to be equal to 1.

[0981] --Otherwise (BdpcmFlag[x0][y0][cIdx] is equal to 0), transform_skip_flag[x0][y0][cIdx] is inferred to be equal to 0.

[0982] 4. Examples of Technical Problems of Disclosed Embodiments

[0983] The existing design of SH, PPS, and APS syntax elements (SE) has the following problems:

[0984] 1) In the latest VVC draft text, the APS syntax element scaling_list_chroma_present_flag is signaled to control the number of scaling / quantization matrices (QMs) signaled in the SCALING APS, i.e., when scaling_list_chroma_present_flag is equal to 1, 28 QMs are signaled for both luma and chroma; otherwise (when scaling_list_chroma_present_flag is equal to 0), only 10 QMs are signaled for luma. Currently, the value of scaling_list_chroma_present_flag is constrained based on ChromaArrayType (derived from the SPS syntax element), i.e., when ChromaArrayType is not equal to 0, the value of scala_list_chroma_present_flag is required to be equal to 1, and when ChromaArrayType is equal to 0, the value of scala_list_chroma_present_flag is required to be equal to 0. This constraint in the semantics introduces a dependency of the APS on the SPS, which should not happen, because the APS may be applied to pictures (or slices of pictures) that refer to different SPSs, which may be associated with different values of ChromaArrayType.

[0985] Furthermore, currently, once a block is encoded or decoded using a user-defined scaling list, both luma and chroma (if available) should apply the user-defined scaling list. This means that the user-defined scaling lists for luma and chroma cannot be turned on or off independently. This design may be inefficient and inflexible.

[0986] 2) In the latest VVC draft text, when signaling the LMCS APS syntax structure, the APS syntax elements related to chroma residual scaling are always signaled, regardless of whether ChromaArrayType is equal to 0 (for example, there is no chroma component in the video content). When there is no chroma processing in the video content, this may result in unnecessary transmission of chroma-related syntax elements.

[0987] 3) In the latest VVC draft text, the SH syntax element slice_ts_residual_coding_disabled_flag is used to specify whether transform skip based residual coding (TSRC) or regular residual coding (RRC) is used for transform skip blocks. However, slice_ts_residual_coding_disabled_flag is now always signaled in SH, regardless of the disabling of transform skip at the SPS level. If sps_transform_skip_enabled_flag, transform_skip_flag are always equal to 0, and the condition for switching TSRC and RRC (!transform_skip_flag[xC][yC][1]||slice_ts_residual_coding_disabled_flag) will always be true, then in this case, slice_ts_residual_coding_disabled_flag becomes meaningless.

[0988] a. In addition, currently, non-TS blocks can only use RRC and cannot switch between TSRC and RRC, which may not be efficient for non-TS block compression.

[0989] 4) In the latest VVC draft text, multi-level control is used to enable cu_qp_delta for luma blocks. That is, first, the PPS on / off control flag cu_qp_delta_enabled_flag is signaled, then the quantization group (QG) size is specified in the PH, and finally the value of cu_qp_delta_abs in each QG is signaled. With this design, for a picture composed of multiple slices, when some slices use cu_qp delta and other slices never use it, block-level cu_qp_delta_abs still needs to be signaled for each QG. Therefore, there is block-level bit waste that can be avoided.

[0990] 5) In the latest VVC draft text, when the PPS syntax element single_slice_per_subpic_flag is equal to 0, each sub-picture of the picture referencing the PPS can be composed of one or more rectangular slices. When single_slice_per_subpic_flag is equal to 0, for pictures referencing such a PPS, the following situations may occur:

[0991] a. Redundant case: When sps_num_subpics_minus1 is greater than 0 but there is only one slice in each sub-picture. In this case, each picture contains multiple sub-pictures and multiple rectangular slices, but single_slice_per_subpic_flag is equal to 0, so num_slices_in_pic_minus1 needs to be signaled. However, it is redundantly signaled because this case is conceptually equivalent to single_slice_per_subpic_flag being equal to 1, and there is no need to signal this SE at all.

[0992] b. Redundant case: When sps_num_subpics_minus1 is equal to 0 and there is only one slice in each picture of the reference PPS. In this case, each picture contains a sub-picture consisting of only one slice, but single_slice_per_subpic_flag is still allowed to be equal to 0, so num_slices_in_pic_minus1 needs to be signaled. However, it is redundantly signaled because this case is conceptually equivalent to single_slice_per_subpic_flag being equal to 1, and this SE does not need to be signaled at all.

[0993] c. Furthermore, if all of the above redundant cases are prohibited / avoided, it turns out that single_slice_per_subpic_flag equal to 0 is always used for the case where a picture has multiple sub-pictures (each sub-picture contains a single slice or multiple slices) or a picture has multiple slices (each picture contains a single sub-picture or multiple sub-pictures). And for both cases, the value of num_slices_in_pic_minus1 is always greater than 1. It turns out that there is no need to conditionally signal the PPS syntax element tile_idx_delta_present_flag.

[0994] 6) In the latest VVC draft text, slice layouts (such as slice width and height) are designed with explicit signaling coupled with implicit inference. If a picture is divided into multiple slice rows with the same height, the current design allows only the first slice row's height to be signaled, and the heights of the remaining slice rows can be inferred. Otherwise, if the picture is divided into multiple slice rows with different heights, the height of each slice row is explicitly signaled. Otherwise, if the picture is divided into multiple slice rows with different heights for the first few slice rows and the same height for the last few slice rows, the height of the first few slice rows and only one of the last few slice rows is explicitly signaled, and the heights of the remaining slice rows of the same height are inferred without signaling. By combining explicit signaling and implicit inference, the current design works well for these three cases. However, there is another case where a picture is divided into multiple slice rows with the same height for the first few slice rows and different heights for the last few slice rows. In this case, the current design does not seem to be that efficient, as implicit inference cannot be applied to this case, and it still requires explicit signaling of the height of each tile row. Similarly, the same situation exists for tile column signaling and rectangular strip layout signaling, i.e., strip height signaling when the strip is smaller than the tile. Modifications can be applied here to improve this.

[0995] 7) Currently, the GCI syntax element no_aps_constraint_flag is used to disable NAL units with nuh_unit_type equal to PREFIX_APS_NUT or SUFFIX_APS_NUT. If there is no ALF APS, more constraints are expected to be proposed in the draft.

[0996] 8) Currently, the consistency window parameters are always signaled in the PPS, including when the picture width and height are the same as the maximum picture width and height signaled in the SPS referenced by the PPS, while on the other hand, the consistency window parameters for pictures with the maximum picture width and height are also signaled in the SPS. Signaling of the consistency window parameters for pictures with the maximum picture width and height in the PPS is redundant.

[0997] 5. Example List of Embodiments and Techniques

[0998] To solve the above problems and some other problems not mentioned, the following methods are disclosed. The technical solutions should be considered as examples to explain the general concept and should not be interpreted in a narrow way. In addition, these technical solutions can be applied alone or in combination in any way.

[0999] In the following description, regarding changes to the prior text based on the latest working draft JVET-Q2001-vD, deleted parts are highlighted in left and right double brackets (e.g., [[ ]]), where the deleted text is between the double brackets, and added parts are

[1000] 1. Regarding the value of the APS syntax element scaling_list_chroma_present_flag depending on the SPS syntax element, to solve the first problem, one or more of the following methods are disclosed:

[1001] 1) In one example, the VPS ID and / or SPS ID and / or PPS ID may be added to the APS syntax structure, namely adaptation_parameter_set_rbsp(). For example, the syntax structure of adaptation_parameter_set_rbsp() may be changed as follows:

[1002]

[1003] aps_seq_parameter_set_id specifies the value of sps_seq_parameter_set_id of the APS. The value of aps_seq_parameter_set_id should be in the range of 0 to 15 (inclusive). The value of aps_seq_parameter_set_id should be the same in all APSs referenced by a codec picture in CLVS.

[1004] a. Additionally or alternatively, the signaling of the chroma scaling list can be explicitly adjusted based on the value of ChromaArrayType, for example, the syntax table of scaling_list_data() can be changed as follows:

[1005]

[1006] And the semantics of scaling_list_chroma_present_flag is changed as follows:

[1007] [[scaling_list_chroma_present_flag equal to 1 specifies that the chroma scaling list is present in scaling_list_data(). scaling_list_chroma_present_flag equal to 0 specifies that the chroma scaling list is not present in scaling_list_data(). A bitstream conformance requirement is that scaling_list_chroma_present_flag shall be equal to 0 when ChromaArrayType is equal to 0, and shall be equal to 1 when ChromaArrayType is not equal to 0. ]]

[1008] 2) In one example, the VPS and / or SPS and / or PPS associated with the AP may be derived implicitly.

[1009] a. For example, if the APS is referenced by a video unit (such as a picture header or a slice header), and the video unit depends on the VPS and / or SPS and / or PPS, the APS is implicitly associated with the VPS and / or SPS and / or PPS.

[1010] 3) In one example, instead of using a user-defined scaling list (also called an explicit scaling list), flat quantization (default scaling list) can be used for chroma blocks even when an explicit scaling list is applied to luma blocks.

[1011] a. Alternatively, and in addition, even when explicit scaling lists for luma blocks are signaled in the bitstream, explicit scaling lists for chroma blocks may not be signaled.

[1012] 4) Alternatively, the value of scaling_list_chroma_present_flag can be decoupled from the value of ChromaArrayType.

[1013] a. The indication of whether to use explicit scaling lists or default scaling lists for different color components (eg, luma blocks and chroma blocks) may be signaled / controlled separately.

[1014] i. In one example, a syntax element (eg, one or more flags) may be added to the SPS / PPS / PH / SH to specify whether user-defined scaling lists (also referred to as explicit scaling lists) are enabled for luma and / or chroma components.

[1015] ii. For example, a flag could be added to the SPS to enable the luma transform coefficients to be switched between planar quantization (default scaling list) and a user-defined scaling list.

[1016] iii. For example, one or more flags may be added to the SPS to enable the chroma-U and / or chroma-V transform coefficients to be switched between flat quantization (default scaling list) and a user-defined scaling list.

[1017] b. For example, when ChromaArrayType is equal to 0, scaling_list_chroma_present_flag can be equal to 1.

[1018] i. In one example, for a coded picture in 4:0:0 chroma format, N (eg, N=28) groups of scaling matrices may be signaled in the APS.

[1019] ii. In one example, for a coded picture in 4:4:4 chroma format with separate_colour_plane_flag equal to 1, M (eg, M=28) groups of scaling matrices may be signaled in the APS.

[1020] a) For example, when separate_colour_plane_flag is equal to 1 and M (e.g., M=28) groups of scaling matrices are signaled in the APS, each of the Y (luminance), U (Cb), and V (Cr) channel transform coefficients can be regarded as a luminance-Y channel, and the scaling matrix identifier variables id of the Y, U, and V transform coefficients are derived with respect to the color component being equal to the Y component (e.g., value 0).

[1021] b) Alternatively, when separate_colour_plane_flag is equal to 1 and M (e.g., M=28) groups of scaling matrices are signaled in the APS, the scaling matrix identifier variable id of the luma-Y transform coefficient is derived with respect to the color component being equal to the Y component (e.g., value 0), while the scaling matrix identifier variable id of the chroma-U is derived with respect to the color component being equal to the U component (e.g., value 1), and the scaling matrix identifier variable id of the chroma-V is derived with respect to the color component being equal to the V component (e.g., value 2).

[1022] c. For example, when ChromaArrayType is equal to 1, scaling_list_chroma_present_flag can be equal to 0.

[1023] i. In one example, whether chroma transform coefficients are allowed to use a user-defined scaling list may depend on the value of scaling_list_chroma_present_flag.

[1024] a) For example, when scaling_list_chroma_present_flag is equal to 0, user-defined scaling lists are not allowed to be used for chroma transform coefficients regardless of the values of sps_scaling_list_enabled_flag, ph_scaling_list_enabled_flag, and slice_scaling_list_enabled_flag (e.g., the value of the added flag specifying that the user-defined scaling list is used for chroma needs to be equal to a certain number, such as 0 or 1).

[1025] b) For example, when scaling_list_chroma_present_flag is equal to 1, a user-defined scaling list may be allowed for chroma transform coefficients.

[1026] ii. In one example, for coded pictures in 4:2:0 and / or 4:2:2 chroma format and / or 4:4:4 chroma format (where separate_colour_plane_flag is equal to 0), N (eg, N=10) groups of scaling matrices may be signaled in the APS.

[1027] a) For example, when ChromaArrayType is greater than 0 and N (e.g., N=10) sets of scaling matrices are signaled in APS, the scaling matrices for U and / or V transform coefficients can be derived from the signaled N sets of scaling matrices for Y transform coefficients.

[1028] b) Alternatively, when ChromaArrayType is greater than 0 and N (e.g., N=10) sets of scaling matrices are signaled in the APS, the U and / or V transform coefficients may not use a user-defined scaling list (instead, the U and / or V transform coefficients may use flat quantization with a default scaling factor).

[1029] d. For example, the semantic constraints on scaling_list_chroma_present_flag based on ChromaArrayType may not be associated with the syntax element scaling_list_chroma_present_flag, such as as follows:

[1030] scaling_list_chroma_present_flag equal to 1 specifies that the chroma scaling list is present in scaling_list_data(). scaling_list_chroma_present_flag equal to 0 specifies that the chroma scaling list is not present in scaling_list_data(). [[Bitstream conformance requirement is that scaling_list_chroma_present_flag shall be equal to 0 when ChromaArrayType is equal to 0, and shall be equal to 1 when ChromaArrayType is not equal to 0. ]]

[1031] e. For example, the semantic constraints on scaling_list_chroma_present_flag based on ChromaArrayType can be changed as follows:

[1032] scaling_list_chroma_present_flag equal to 1 specifies that the chroma scaling list is present in scaling_list_data(). scaling_list_chroma_present_flag equal to 0 specifies that the chroma scaling list is not present in scaling_list_data(). A bitstream conformance requirement is that when ChromaArrayType is equal to 0, scaling_list_chroma_present_flag shall be equal to 0 [[,

[1033] 5) Alternatively, a constraint associated with the PH and / or SH syntax elements may be added to constrain the value of scaling_list_chroma_present_flag to a certain value (e.g., 0 or 1) according to the ChromaArrayType derived from the PH / SH syntax elements, for example as follows:

[1034] In one example, the semantics of ph_scaling_list_aps_id is changed as follows:

[1035] ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of the scaling list APS. The TemporalId of the APS NAL unit with aps_params_type equal to SCALING_APS and adaptation_parameter_set_id equal to ph_scaling_list_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

[1036]

[1037] Alternatively, the semantics of ph_scaling_list_aps_id are changed as follows:

[1038] ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of the scaling list APS. The TemporalId of the APS NAL unit with aps_params_type equal to SCALING_APS and adaptation_parameter_set_id equal to ph_scaling_list_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

[1039]

[1040] Alternatively, the semantics of ph_scaling_list_aps_id are changed as follows:

[1041] ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of the scaling list APS. The TemporalId of the APS NAL unit with aps_params_type equal to SCALING_APS and adaptation_parameter_set_id equal to ph_scaling_list_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

[1042]

[1043] And the semantics of APS SE is changed as follows:

[1044] scaling_list_chroma_present_flag equal to 1 specifies that the chroma scaling list is present in scaling_list_data(). scaling_list_chroma_present_flag equal to 0 specifies that the chroma scaling list is not present in scaling_list_data(). [[Bitstream conformance requirement is that scaling_list_chroma_present_flag shall be equal to 0 when ChromaArrayType is equal to 0, and shall be equal to 1 when ChromaArrayType is not equal to 0. ]]

[1045] 2. Regarding the unnecessary chroma-related APS syntax element signaling when ChromaArrayType is equal to 0, and to solve the second problem, one or more of the following methods are disclosed:

[1046] 1) In one example, syntax elements (e.g., flags) may be added to the APS syntax structure lmcs_data() to control the presence of APS syntax elements related to chroma residual scaling (e.g., lmcs_delta_abs_crs, lmcs_delta_sign_crs_flag, etc.)

[1047] a. For example, when ChromaArrayType is equal to 0, it is required that signaling of APS syntax elements related to chroma residual scaling (e.g., lmcs_delta_abs_crs, lmcs_delta_sign_crs_flag, etc.) is not allowed, for example, the added flag is required to be equal to a certain value, such as 0 or 1.

[1048] b. For example, when ChromaArrayType is not equal to 0, APS syntax elements related to chroma residual scaling (e.g., lmcs_delta_abs_crs, lmcs_delta_sign_crs_flag, etc.) need to be signaled, for example, the flag that needs to be added is equal to a certain value, such as 0 or 1.

[1049] c. For example, whether the current slice is allowed to use chroma residual scaling may depend on an added flag. For example, if the added flag indicates that APS syntax elements related to chroma residual scaling are not signaled, then chroma residual scaling will never be used regardless of the values of sps_lmcs_enabled_flag, ph_lmcs_enabled_flag, ph_chroma_residual_scale_flag and sh_lmcs_enabled_flag.

[1050] 2) A bitstream constraint may be added under the semantics of the PH / SH / APS syntax element to constrain the value of lmcs_delta_abs_crs with respect to the value of ChromaArrayType, for example as follows:

[1051] ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APS referenced by the slice associated with the PH. The TemporalId of the APS NAL unit with aps_params_type equal to LMCS_APS and adaptation_parameter_set_id equal to ph_lmcs_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

[1052]

[1053] Alternatively, the semantics of ph_lmcs_aps_id are changed as follows:

[1054] ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APS referenced by the slice associated with the PH. The TemporalId of the APS NAL unit with aps_params_type equal to LMCS_APS and adaptation_parameter_set_id equal to ph_lmcs_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

[1055]

[1056] Alternatively, the semantics of ph_lmcs_aps_id are changed as follows:

[1057] ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APS referenced by the slice associated with the PH. The TemporalId of the APS NAL unit with aps_params_type equal to LMCS_APS and adaptation_parameter_set_id equal to ph_lmcs_aps_id shall be less than or equal to the TemporalId of the picture associated with the PH.

[1058]

[1059]

[1060] 3. In the above example, the term "ChromaArrayType" can be replaced with "Check that the color format is equal to 4:0:0".

[1061] 4. Regarding the use of RRC and TSRC to solve the third problem, one or more of the following methods are disclosed:

[1062] 1) Signaling of the TSRC enable / disable flag (eg, slice_ts_residual_coding_disabled_flag) may be conditional on whether transform skipping is enabled (eg, sps_transform_skip_enabled_flag in SPS).

[1063] a. In one example, the following may apply:

[1064]

[1065] b. Alternatively, and additionally, when slice_ts_residual_coding_disabled_flag is not present, it is inferred to be equal to 1.

[1066] 2) Alternatively, the value of the TSRC enable flag (e.g., slice_ts_residual_coding_disabled_flag) may be constrained by sps_transform_skip_enabled_flag in the SPS. For example, the semantics of slice_ts_residual_coding_disabled_flag may be changed as follows:

[1067] slice_ts_residual_coding_disabled_flag is equal to 1 and specifies that the residual_coding() syntax structure is used to parse the residual samples of the transform skip blocks of the current slice. slice_ts_residual_coding_disabled_flag is equal to 0 and specifies that the residual_ts_coding() syntax structure is used to parse the residual samples of the transform skip blocks of the current slice. When [[slice_ts_residual_coding_disabled_flag]] [[Does not exist]] [[It is inferred to be]] equal to [[0]]1.

[1068] 3) Alternatively, if the signaling of the TSRC enable flag (e.g., slice_ts_residual_coding_disabled_flag) is not conditional on any other syntax elements, it may always be present, e.g., the semantics of slice_ts_residual_coding_disabled_flag may be changed as follows:

[1069] slice_ts_residual_coding_disabled_flag equal to 1 specifies that the residual_coding() syntax structure is used to parse the residual samples of the transform skip blocks of the current slice. slice_ts_residual_coding_disabled_flag equal to 0 specifies that the residual_ts_coding() syntax structure is used to parse the residual samples of the transform skip blocks of the current slice. [[When slice_ts_residual_coding_disabled_flag is not present, it is inferred to be equal to 0.]]

[1070] 4) Additionally, TSRC can be applied to non-transform skip (non-TS) codec blocks.

[1071] a. In one example, one or more syntax flags may be added to specify whether TSRC or RRC is enabled for non-TS blocks.

[1072] i. In one example, one or more block-level (CTU / CU / TU) syntax flags may be added to specify whether the current video unit uses TSRC or RRC.

[1073] ii. Additionally or alternatively, one or more high-level (SPS / PPS / PH / SH) syntax flags may be added to specify whether a video unit allows TSRC.

[1074] b. In one example, whether to use TSRC for a non-TS coded block or whether to allow the use of TSRC for a non-TS coded block may depend on codec information, such as the QP value of the block.

[1075] i. In one example, for non-TS blocks with a QP equal to or not greater than X (eg, X=4), residual coding using TSRC or RRC may be allowed.

[1076] 5. Regarding the on / off control of the CU QP increment of the luminance block for solving the fourth problem, one or more of the following methods are disclosed:

[1077] a. A SH level syntax element (e.g., a flag represented by slice_cu_qp_delta_enabled_flag) may be added to control the enabling and / or disabling of cu qp delta for a specific slice.

[1078] i. In one example, the presence of the proposed slice_cu_qp_delta_enabled_flag is conditional on the cu_qp_delta_enabled_flag in the PPS, e.g., the proposed slice_cu_qp_delta_enabled_flag is signaled only when the cu_qp_delta_enabled_flag in the PPS is equal to 1, otherwise (cu_qp_delta_enabled_flag in the PPS is equal to 0), the proposed slice_cu_qp_delta_enabled_flag is not signaled and is inferred to be equal to 0.

[1079] a) Alternatively, the value of the recommended slice_cu_qp_delta_enabled_flag is constrained by the value of cu_qp_delta_enabled_flag in the PPS, i.e., when cu_qp_delta_enabled_flag in the PPS is equal to 0, the value of the recommended slice_cu_qp_delta_enabled_flag should be equal to 0.

[1080] ii. In one example, cu_qp_delta_enabled_flag in the PPS may be used to control the presence of the SH-level cuqp delta enabled flag in the SH, and / or the presence of cu_qp_delta_abs and / or cu_qp_delta_sign_flag in the transform unit syntax and palette codec syntax.

[1081] iii. In one example, the grammatical structure can be changed as follows:

[1082] The PPS syntax structure has been changed as follows:

[1083]

[1084] pps_cu_qp_delta_enabled_flag equal to 1 specifies that the ph_cu_qp_delta_subdiv_intra_slice and ph_cu_qp_delta_subdiv_inter_slice syntax elements are present in the PH of the referenced PPS and that cu_qp_delta_abs may be present in the transform unit syntax. pps_cu_qp_delta_enabled_flag is equal to 0 and specifies that the ph_cu_qp_delta_subdiv_intra_slice and ph_cu_qp_delta_subdiv_inter_slice syntax elements are not present in the PH of the reference PPS, and the transform unit cu_qp_delta_abs does not exist in .

[1085] And the PH syntax structure is changed as follows:

[1086]

[1087]

[1088] And the SH syntax structure changes as follows:

[1089]

[1090]

[1091] b. In addition, the presence of cu_qp_delta_abs in the syntax structure palette_coding() and / or the syntax structure transform_unit() is conditional on the recommended slice_cu_qp_delta_enabled_flag, e.g., cu_qp_delta_abs is signaled only when the value of the recommended slice_cu_qp_delta_enabled_flag is equal to 1; otherwise (recommended slice_cu_qp_delta_enabled_flag is equal to 0), the value of cu_qp_delta_abs is not signaled and is inferred to be equal to 0.

[1092] Alternatively, the chroma cu qp offset may not be controlled by the slice level on / off flag, e.g., whether the chroma cu qp offset is applied to the current slice may depend on the PH / PPS / SPS level flag.

[1093] c. Alternatively, a PH level syntax element (eg, a flag denoted by ph_cu_qp_delta_enabled_flag) may be added to control the enabling and / or disabling of cu qp delta for a specific slice.

[1094] 6. Regarding the design of PPS SE single_slice_per_subpic_flag, num_slices_in_pic_minus1, and tile_idx_delta_present_flag, and to solve the fifth problem, one or more of the following methods are disclosed:

[1095] a. In one example, constraints may be added to the semantics of the PH / SH / PPS syntax elements, such as the following:

[1096] ph_pic_parameter_set_id specifies the value of pps_pic_parameter_set_id for the PPS being used. The value of ph_pic_parameter_set_id shall be in the range of 0 to 63 (inclusive).

[1097] The bitstream conformance requirement is that the value of TemporalId of PH shall be greater than or equal to the value of TemporalId of the PPS with pps_pic_parameter_set_id equal to ph_pic_parameter_set_id.

[1098]

[1099] b. In one example, the semantics of single_slice_per_subpic_flag can be changed as follows:

[1100] single_slice_per_subpic_flag is equal to 1 and specifies that each sub-picture consists of one and only one rectangular slice. single_slice_per_subpic_flag is equal to 0 and specifies that Each sub-image may consist of one or more rectangular strips. When not present, the value of single_slice_per_subpic_flag is inferred to be equal to 0.

[1101] c. In one example, a constraint may be added to the semantics of single_slice_per_subpic_flag, such as as follows:

[1102] single_slice_per_subpic_flag equal to 1 specifies that each sub-picture consists of one and only one rectangular slice. single_slice_per_subpic_flag equal to 0 specifies that each sub-picture may consist of one or more rectangular slices. When not present, the value of single_slice_per_subpic_flag is inferred to be equal to 0.

[1103]

[1104] d. Additionally, or alternatively, a constraint may be added to the semantics of single_slice_per_subpic_flag, for example as follows:

[1105] single_slice_per_subpic_flag equal to 1 specifies that each sub-picture consists of one and only one rectangular slice. single_slice_per_subpic_flag equal to 0 specifies that each sub-picture may consist of one or more rectangular slices. When not present, the value of single_slice_per_subpic_flag is inferred to be equal to 0.

[1106]

[1107] e. In one example, the constraint is that single_slice_per_subpic_flag should be equal to 1 when each sub-picture consists of one and only one rectangular slice.

[1108] f. Additionally, or alternatively, the presence of the PPS syntax element tile_idx_delta_present_flag may not be adjusted based on num_slices_in_pic_minus1, for example, as follows:

[1109]

[1110] g. In one example, it is constrained that when single_slice_per_subpic_flag is equal to 1, num_slices_in_pic_minus1 shall be equal to sps_num_subpics_minus1.

[1111] h. Additionally or alternatively, the PPS syntax element num_slices_in_pic_minus1 may be changed to num_slices_in_pic_minus2.

[1112] i. Additionally, the presence of tile_idx_delta_present_flag is adjusted based on num_slices_in_pic_minus2, for example as follows:

[1113]

[1114] num_slices_in_pic_minus[[1]] Add[[1]] Specifies the number of rectangular slices in each picture of the reference PPS. num_slices_in_pic_minus[[1]] The value should be between 0 and MaxSlicesPerPicture-[[1]] The range is (including the end value), where MaxSlicesPerPicture is specified in Appendix A. When no_pic_partition_flag is equal to 1, Value [[num_slices_in_pic_minus1 is inferred to be equal to 0]]. When single_slice_per_subpic_flag is equal to 1, [[num_slices_in_pic_minus1 is inferred]] is equal to sps_num_subpics_minus1- .

[1115] Additionally, “num_slices_in_pic_minus1” is replaced with “NumSlicesInPic-1” everywhere else in the VVC draft text.

[1116] 7. Regarding the signaling notification of the stripe and slice layout for solving the sixth problem, one or more of the following methods are disclosed:

[1117] a. Syntax elements (e.g., one or more flags) may be added to the PPS to specify whether a picture is divided into multiple slice rows / columns, where the first few slice rows / columns have the same height and the last few slice rows / columns have different heights / widths.

[1118] For example, the suggested syntax flags depend on the no_pic_partition_flag and / or the number of explicit tile rows / columns (e.g., num_exp_tile_columns_minus1 and / or num_exp_tile_rows_minus1), such as the following:

[1119]

[1120]

[1121]

[1122] ii. In addition, when the suggested syntax flag is equal to 1, the slice column width and / or slice row height are derived according to the value of the suggested syntax flag, for example as follows:

[1123] The variable NumTileColumns specifies the number of tile columns, and the list colWidth[i], where i ranges from 0 to NumTileColumns-1 (inclusive), specifies the width of the i-th tile column in CTBs, derived as follows:

[1124]

[1125] The variable NumTileRows specifies the number of tile rows, and the list RowHeight[j], where j ranges from 0 to NumTileRows-1 (inclusive), specifies the height of the jth tile row in CTBs, derived as follows:

[1126]

[1127]

[1128] b. Additionally, similarly, in the case where a slice is divided into multiple slices (in this case, the slice size is smaller than the slice size), a syntax element (e.g., one or more flags) may be added to the PPS to specify whether the slice is divided into multiple slice rows, where the first few slice rows have the same height and the last few slice rows have different heights.

[1129] i. Additionally, when the suggested syntax flag is equal to 1, the slice height is derived according to the value of the suggested syntax flag (eg, SliceHeightInCtusMinus1).

[1130] 8. Regarding the situation where there is no ALF APS to solve the seventh problem, one or more of the following methods are disclosed:

[1131] a. In one example, when there is no ALF APS (eg, no_aps_constraint_flag is equal to 1, or an APS with the required APS ID is not available), then ALF may not be allowed (in this case, sps_alf_enabled_flag and sps_ccalf_enabled_flag need to be equal to 0).

[1132] b. In one example, when there is no ALF APS (eg, no_aps_constraint_flag is equal to 1, or an APS with the required APS ID is not available), ALF may still be enabled (in this case, sps_alf_enabled_flag is allowed to be equal to 0 or 1).

[1133] i. For example, when there is no ALF APS (eg, no_aps_constraint_flag is equal to 1), ph_alf_enabled_flag and / or slice_alf_enabled_flag are allowed to be equal to 0 or 1.

[1134] ii. For example, when there is no ALF APS (eg, no_aps_constraint_flag is equal to 1), chroma ALF and CC-ALF are not allowed, but luma ALF with a fixed filter can be used.

[1135] iii. For example, when there is no ALF APS (eg, no_aps_constraint_flag is equal to 1), the values of ph_num_alf_aps_ids_luma, ph_alf_chroma_idc, slice_num_alf_aps_ids_luma, slice_alf_chroma_idc, and sps_ccalf_enabled_flag are required to be equal to 0.

[1136] c. In one example, when the GCI syntax element no_alf_constraint_flag is equal to 1, then ALF and / or CCALF are not allowed (in this case, sps_alf_enabled_flag and / or sps_ccalf_enabled_flag needs to be equal to 0).

[1137] d. Alternatively, in addition, whether to signal the number of ALF APSs to be used (e.g., ph_num_alf_aps_ids_luma) and / or ALF / CC-ALF APS index (e.g., ph_alf_aps_id_luma, ph_alf_aps_id_chroma, ph_cc_alf_cb_aps_id, ph_cc_alf_cr_aps_id) may depend on whether ALF APS is allowed (e.g., no_aps_constraint_flag).

[1138] i. In one example, when ALF APS is not applied, this information may not be signaled.

[1139] e. In one example, a new syntax element may be signaled in SPS / PPS / PH / SH / GCI to disable ALF, and / or CCALF, and / or LMCS, and / or user-defined scaling lists.

[1140] 9. Regarding the signaling notification of the consistency window parameter used to solve the eighth problem:

[1141] a. In one example, when pic_width_in_luma_samples is equal to pic_width_max_in_luma_samples and pic_height_in_luma_samples is equal to pic_height_in_luma_samples, signaling of conformance window parameters (i.e., pps_conformance_window_flag, pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset) in the PPS may be skipped.

[1142] i. In one example, a flag may be added to the PPS syntax, and when the value of this flag is equal to X (0 or 1), it specifies that pic_width_in_luma_samples is equal to pic_width_max_in_luma_samples and pic_height_in_luma_samples is equal to pic_height_max_in_luma_samples, and when the value of this flag is equal to 1-X, it specifies that pic_width_in_luma_samples is less than pic_width_max_in_luma_samples or pic_height_in_luma_samples is less than pic_height_max_in_luma_samples. However, note that even in the case where pic_width_in_luma_samples is equal to pic_width_max_in_luma_samples and pic_height_in_luma_samples is equal to pic_height_max_in_luma_samples, pic_width_in_luma_samples and pic_height_in_luma_samples still need to be signaled in the PPS to avoid resolving the dependency of the PPS on the SPS.

[1143] In addition, when the above flag is equal to X, the signaling of the consistency window parameters in the PPS (i.e., pps_conformance_window_flag, pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset) is skipped, and the values of the parameters are inferred to be equal to the values of the parameters in the SPS (i.e., sps_conformance_window_flag, sps_conf_win_left_offset, sps_conf_win_right_offset, sps_conf_win_top_offset, and sps_conf_win_bottom_offset).

[1144] Figure 11 is a block diagram of an example video processing system 1900 that may implement the various techniques disclosed herein. Various implementations may include some or all of the components of system 1900. System 1900 may include an input 1902 for receiving video content. The video content may be received in a raw or uncompressed format (e.g., 8- or 10-bit multi-component pixel values), or may be received in a compressed or encoded format. Input 1902 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interfaces include wired interfaces (such as Ethernet, passive optical networks (PONs), etc.) and wireless interfaces (such as Wi-Fi or cellular interfaces).

[1145] System 1900 may include a codec component 1904 that can implement the various codecs or encoding methods described in this document. Codec component 1904 can reduce the average bit rate of the video from input 1902 to the output of codec component 1904 to produce a codec representation of the video. Therefore, codec technology is sometimes referred to as video compression or video transcoding technology. The output of codec component 1904 can be stored or sent via a connected communication, as represented by component 1906. The stored or communicated bitstream (or codec representation) of the video received at input 1902 can be used by component 1908 to generate pixel values or displayable video that is sent to display interface 1910. The process of generating user-visible video from the bitstream is sometimes referred to as video decompression. In addition, although some video processing operations are referred to as "codec" operations or tools, it should be understood that the codec tools or operations are used at the encoder, and the corresponding decoding tools or operations that invert the codec results will be performed by the decoder.

[1146] Examples of peripheral bus interfaces or display interfaces may include Universal Serial Bus (USB), High-Definition Multimedia Interface (HDMI), DisplayPort, etc. Examples of storage interfaces include SATA (Serial Advanced Technology Attachment), PCI, IDE interfaces, etc. The technology described in this document can be implemented in various electronic devices, such as mobile phones, laptop computers, smart phones, or other devices capable of digital data processing and / or video display.

[1147] Figure 23600 is a block diagram of a video processing device 3600. Device 3600 can be used to implement one or more of the methods described herein. Device 3600 can be implemented in a smartphone, tablet, computer, Internet of Things (IoT) receiver, etc. Device 3600 may include one or more processors 3602, one or more memories 3604, and video processing circuitry 3606. Processor(s) 3602 can be configured to implement one or more of the methods described herein. Memory(s) 3604 can be used to store data and code used to implement the methods and techniques described herein. Video processing circuitry 3606 can be used to implement some of the techniques described herein in hardware circuitry.

[1148] Figure 4 is a block diagram illustrating an example video coding system 100 that may utilize the techniques of this disclosure.

[1149] like Figure 4 As shown, the video codec system 100 may include a source device 110 and a destination device 120. The source device 110 generates encoded video data and may be referred to as a video encoding device. The destination device 120 may decode the encoded video data generated by the source device 110 and may be referred to as a video decoding device.

[1150] Source device 110 may include a video source 112 , a video encoder 114 , and an input / output (I / O) interface 116 .

[1151] The video source 112 may include a source such as a video capture device, an interface for receiving video data from a video content provider, and / or a computer graphics system that generates video data, or a combination of these sources. The video data may include one or more pictures. The video encoder 114 encodes the video data from the video source 112 to generate a bitstream. The bitstream may include a sequence of bits that form a codec representation of the video data. The bitstream may include a codec picture and associated data. The codec picture is a codec representation of the picture. The associated data may include a sequence parameter set, a picture parameter set, and other syntax elements. The I / O interface 116 includes a modulator / demodulator (modem) and / or a transmitter. The encoded video data may be sent directly to the destination device 120 via the I / O interface 116 over the network 130a. The encoded video data may also be stored on a storage medium / server 130b for access by the destination device 120.

[1152] Destination device 120 may include an I / O interface 126 , a video decoder 124 , and a display device 122 .

[1153] I / O interface 126 may include a receiver and / or a modem. I / O interface 126 may obtain encoded video data from source device 110 or storage medium / server 130b. Video decoder 124 may decode the encoded video data. Display device 122 may display the decoded video data to a user. Display device 122 may be integrated with destination device 120 or may be external to destination device 120 and configured to interface with an external display device.

[1154] The video encoder 114 and the video decoder 124 may operate according to a video compression standard, such as the High Efficiency Video Codec (HEVC) standard, the Versatile Video Codec (VVC) standard, and other current and / or other standards.

[1155] Figure 5 is a block diagram illustrating an example of a video encoder 200, which may be Figure 4 The video encoder 114 in the system 100 is shown in FIG.

[1156] Video encoder 200 may be configured to perform any or all of the techniques of this disclosure. Figure 5 In the example of FIG, video encoder 200 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of video encoder 200. In some examples, a processor can be configured to perform any or all of the techniques described in this disclosure.

[1157] The functional components of the video encoder 200 may include a segmentation unit 201, a prediction unit 202 (which may include a mode selection unit 203, a motion estimation unit 204, a motion compensation unit 205 and an intra-frame prediction unit 206), a residual generation unit 207, a transform unit 208, a quantization unit 209, an inverse quantization unit 210, an inverse transform unit 211, a reconstruction unit 212, a buffer 213 and an entropy coding unit 214.

[1158] In other examples, the video encoder 200 may include more, fewer, or different functional components. In one example, the prediction unit 202 may include an intra block copy (IBC) unit. The IBC unit may perform prediction in an IBC mode where at least one reference picture is a picture in which the current video block is located.

[1159] Furthermore, some components such as the motion estimation unit 204 and the motion compensation unit 205 may be highly integrated but are not shown for the purpose of explanation. Figure 5 In the example, they are shown separately.

[1160] The partitioning unit 201 may partition a picture into one or more video blocks. The video encoder 200 and the video decoder 300 may support various video block sizes.

[1161] The mode selection unit 203 can, for example, select one of the intra or inter coding modes based on the error result, and provide the resulting intra or inter coding block to the residual generation unit 207 to generate residual block data and to the reconstruction unit 212 to reconstruct the coding block for use as a reference picture. In some examples, the mode selection unit 203 can select a combined intra and inter prediction (CIIP) mode, where the prediction is based on an inter prediction signal and an intra prediction signal. The mode selection unit 203 can also select the resolution of the motion vector for the block in the case of inter prediction (e.g., sub-pixel or whole pixel accuracy).

[1162] To perform inter-frame prediction on the current video block, the motion estimation unit 204 may generate motion information for the current video block by comparing the current video block with one or more reference frames from the buffer 213. The motion compensation unit 205 may determine a predicted video block for the current video block based on the motion information and decoded samples of a picture from the buffer 213 (other than the picture associated with the current video block).

[1163] The motion estimation unit 204 and the motion compensation unit 205 may perform different operations for the current video block, for example, performing different operations depending on whether the current video block is in an I slice, a P slice, or a B slice.

[1164] In some examples, motion estimation unit 204 may perform unidirectional prediction of the current video block, and motion estimation unit 204 may search for a reference video block for the current video block in the reference pictures in list 0 or list 1. Motion estimation unit 204 may then generate a reference index indicating the reference video block in the reference pictures in list 0 or list 1, and a motion vector indicating the spatial displacement between the current video block and the reference video block. Motion estimation unit 204 may output the reference index, prediction direction indicator, and motion vector as motion information for the current video block. Motion compensation unit 205 may generate a predicted video block for the current block based on the reference video block indicated by the motion information for the current video block.

[1165] In other examples, the motion estimation unit 204 may perform bidirectional prediction for the current video block. The motion estimation unit 204 may search for a reference video block for the current video block in the reference pictures in list 0 and may also search for another reference video block for the current video block in the reference pictures in list 1. The motion estimation unit 204 may then generate a reference index indicating the reference video block in the reference pictures in list 0 or list 1 and a motion vector indicating the spatial displacement between the reference video block and the current video block. The motion estimation unit 204 may output the reference index and the motion vector of the current video block as motion information for the current video block. The motion compensation unit 205 may generate a predicted video block for the current video block based on the reference video block indicated by the motion information for the current video block.

[1166] In some examples, motion estimation unit 204 may output the entire set of motion information for use in a decoding process by a decoder.

[1167] In some examples, motion estimation unit 204 may not output the entire set of motion information for the current video. Instead, motion estimation unit 204 may reference the motion information of another video block to signal the motion information of the current video block. For example, motion estimation unit 204 may determine that the motion information of the current video block is sufficiently similar to the motion information of a neighboring video block.

[1168] In one example, motion estimation unit 204 may indicate in a syntax structure associated with the current video block a value that indicates to video decoder 300 that the current video block has the same motion information as another video block.

[1169] In another example, the motion estimation unit 204 may identify another video block and a motion vector difference (MVD) in a syntax structure associated with the current video block. The motion vector difference indicates the difference between the motion vector of the current video block and the motion vector of the indicated video block. The video decoder 300 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[1170] As discussed above, the video encoder 200 may predictively signal motion vectors. Two examples of predictive signaling techniques that may be implemented by the video encoder 200 include advanced motion vector prediction (AMVP) and merge mode signaling.

[1171] The intra-frame prediction unit 206 can perform intra-frame prediction on the current video block. When the intra-frame prediction unit 206 performs intra-frame prediction on the current video block, the intra-frame prediction unit 206 can generate prediction data for the current video block based on decoded samples of other video blocks in the same picture. The prediction data for the current video block can include the predicted video block and various syntax elements.

[1172] The residual generation unit 207 can generate residual data for the current video block by subtracting (e.g., indicated by a minus sign) the predicted video block(s) of the current video block from the current video block. The residual data for the current video block may include residual video blocks corresponding to different sample components of the samples in the current video block.

[1173] In other examples, such as in skip mode, there may be no residual data for the current video block, and the residual generation unit 207 may not perform a subtraction operation.

[1174] Transform processing unit 208 may generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to the residual video block associated with the current video block.

[1175] After transform processing unit 208 generates a transform coefficient video block associated with the current video block, quantization unit 209 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values associated with the current video block.

[1176] The inverse quantization unit 210 and the inverse transform unit 211 may apply inverse quantization and inverse transform, respectively, to the transform coefficient video block to reconstruct a residual video block from the transform coefficient video block. The reconstruction unit 212 may add the reconstructed residual video block to corresponding samples from one or more prediction video blocks generated by the prediction unit 202 to generate a reconstructed video block associated with the current block for storage in the buffer 213.

[1177] After the reconstruction unit 212 reconstructs the video block, a loop filtering operation may be performed to reduce video blocking artifacts in the video block.

[1178] The entropy coding unit 214 may receive data from other functional components of the video encoder 200. When the entropy coding unit 214 receives data, the entropy coding unit 214 may perform one or more entropy coding operations to generate entropy-coded data and output a bitstream including the entropy-coded data.

[1179] Some embodiments of the disclosed technology include making a decision or determining to enable a video processing tool or mode. In one example, when a video processing tool or mode is enabled, the encoder will use or implement the tool or mode in the processing of blocks of video, but will not necessarily modify the resulting bitstream based on the use of the tool or mode. That is, when a video processing tool or mode is enabled based on the decision or determination, the conversion from blocks of video to a bitstream (or bitstream representation) of the video will use the video processing tool or mode. In another example, when a video processing tool or mode is enabled, the decoder will process the bitstream knowing that the bitstream has been modified based on the video processing tool or mode. That is, the conversion from the bitstream of the video to blocks of the video will be performed using the video processing tool or mode enabled based on the decision or determination.

[1180] Figure 6 is a block diagram illustrating an example of a video decoder 300, which may be Figure 4 The video decoder 114 in the system 100 is shown in FIG.

[1181] Video decoder 300 may be configured to perform any or all of the techniques of this disclosure. Figure 6 In the example of FIG, video decoder 300 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of video decoder 300. In some examples, a processor can be configured to perform any or all of the techniques described in this disclosure.

[1182] exist Figure 6 In the example of FIG, the video decoder 300 includes an entropy decoding unit 301, a motion compensation unit 302, an intra-frame prediction unit 303, an inverse quantization unit 304, an inverse transform unit 305, a reconstruction unit 306, and a buffer 307. In some examples, the video decoder 300 can perform the same operation as the video encoder 200 ( Figure 5 ) is a decoding process that is the overall inverse of the encoding process described.

[1183] The entropy decoding unit 301 can retrieve a coded bitstream. The coded bitstream can include entropy-encoded video data (e.g., coded blocks of video data). The entropy decoding unit 301 can decode the entropy-encoded video data, and based on the entropy-encoded video data, the motion compensation unit 302 can determine motion information including motion vectors, motion vector precision, reference picture list index, and other motion information. The motion compensation unit 302 can determine such information, for example, by performing AMVP and merge modes.

[1184] The motion compensation unit 302 may generate a motion compensated block, possibly interpolated based on an interpolation filter. An identifier of the interpolation filter to be used with sub-pixel precision may be included in a syntax element.

[1185] The motion compensation unit 302 may calculate interpolated values of a sub-integer number of pixels of the reference block using the interpolation filter used by the video encoder 200 during encoding of the video block. The motion compensation unit 302 may determine the interpolation filter used by the video encoder 200 based on received syntax information and use the interpolation filter to generate a prediction block.

[1186] The motion compensation unit 302 may use some syntax information to determine: the size of the blocks used to encode the frame(s) and / or slice(s) of the coded video sequence, partitioning information describing how each macroblock of a picture of the coded video sequence is partitioned, a mode indicating how to encode each partition, one or more reference frames (and reference frame lists) for each inter-coded block, and other information for decoding the coded video sequence.

[1187] The intra prediction unit 303 can form a prediction block from spatially neighboring blocks using, for example, an intra prediction mode received in the bitstream. The inverse quantization unit 303 inversely quantizes (i.e., dequantizes) the quantized video block coefficients provided in the bitstream and decoded by the entropy decoding unit 301. The inverse transform unit 303 applies an inverse transform.

[1188] The reconstruction unit 306 can sum the residual block with the corresponding prediction block generated by the motion compensation unit 202 or the intra prediction unit 303 to form a decoded block. If desired, a deblocking filter can also be applied to filter the decoded block to remove blocking artifacts. The decoded video block is then stored in a buffer 307, which provides reference blocks for subsequent motion compensation / intra prediction and also produces decoded video for presentation on a display device.

[1189] A list of preferred solutions for some embodiments is provided below.

[1190] The following solution illustrates an example embodiment of the technique discussed in the previous section (eg, item 1).

[1191] 1. A video processing method (e.g., Figure 3 ), comprising performing a conversion (302) between a video region of a video and a codec representation of the video; wherein the codec representation conforms to a format rule; wherein the format rule provides that a flag indicating whether a scaling list for a color component in the video is included in an adaptation parameter set is independent of a syntax field value in a sequence parameter set.

[1192] 2. The method according to solution 1, wherein the format rule stipulates that a field for identifying a sequence parameter set is included in the adaptation parameter set.

[1193] 3. The method of solution 1, wherein the format rules specify an implicit relationship between the adaptation parameter set and the video parameter set of the sequence parameter set or the picture parameter set, whose control scaling list is included in the codec representation.

[1194] 4. The method of any of solutions 1-3, wherein the format rules specify a format for containing user-defined or explicit scaling lists used during conversion.

[1195] 5. A method according to any of solutions 1-4, wherein the format rules specify that the inclusion of flags in the codec representation is independent of the inclusion of syntax elements of array type indicating chroma components.

[1196] 6. The method of solution 5, wherein the flag indicates that a scaling list is included and a syntax element indicating an array type of chroma components is set to zero.

[1197] 7. The method of solution 5, wherein a flag indicates that the scaling list is excluded, and a syntax element indicating an array type of chroma components is set to 1.

[1198] 8. The method of solution 1, wherein the format rule stipulates that the flag is constrained by a constraint rule to depend on a picture header or a slice header.

[1199] The following solution illustrates an example embodiment of the technique discussed in the previous section (eg, item 2).

[1200] 9. A method for video processing, comprising: performing conversion between a video region of a video and a codec representation of the video region; wherein the codec representation conforms to a format rule; wherein the format rule specifies that one or more adaptation parameter sets are included in the codec representation, such that for each adaptation parameter set, chroma-related syntax elements are omitted due to chroma constraints on the video.

[1201] 10. The method of solution 9, wherein for each adaptation parameter set, syntax element signaling notifies whether chroma-related syntax elements are included in the adaptation parameter set.

[1202] 11. The method of solution 9, wherein the format rules specify conditionally including chroma-related fields in a picture header or slice header or adaptation parameter set if and only if a chroma constraint indicates the presence of chroma in the codec representation of the video.

[1203] The following solution illustrates an example embodiment of the technique discussed in the previous section (eg, item 3).

[1204] 12. A method according to any of solutions 9-11, wherein the chroma constraint is that the chroma array type is equal to zero.

[1205] 13. A method according to any one of solutions 9-11, wherein the chroma constraint is that the format of the video is equal to 4:0:0.

[1206] The following solution illustrates an example embodiment of the technique discussed in the previous section (eg, item 4).

[1207] 14. A video processing method, comprising: performing conversion between a video comprising one or more video regions and a codec representation of the video, the one or more video regions comprising one or more video units; wherein the codec representation complies with a format rule; wherein the format rule specifies whether a first transform codec syntax field is included in the codec representation at the level of the video unit of the video region and / or its value depends on the value of a second transform codec syntax field at the level of the video region.

[1208] 15. The method of solution 14, wherein the first transform codec syntax field is slice_ts_residual_coding_disabled_flag, and wherein the second transform codec syntax field is sps_transform_skip_enabled_flag.

[1209] The following solution illustrates an example embodiment of the technique discussed in the previous section (eg, item 5).

[1210] 16. A video processing method comprising: performing a conversion between a video comprising one or more video regions and a codec representation of the video, each video region comprising one or more video units; wherein the codec representation complies with a format rule; wherein the format rule specifies that a flag at the video unit level controls whether differential signaling of quantization parameters is enabled for the conversion.

[1211] 17. The method of solution 16, wherein a flag at the video unit level controls whether a second flag at the codec unit or transform unit level is included to signal the use of differential quantization parameter signaling.

[1212] The following solution illustrates an example embodiment of the technique discussed in the previous section (eg, item 6).

[1213] 18. A video processing method, comprising: performing conversion between a video comprising one or more video regions and a codec representation of the video, each video region comprising one or more video units; wherein the codec representation conforms to a format rule; wherein the format rule specifies the interpretation of a first flag at the picture level indicating the number of sub-pictures and a second flag at the sub-picture level indicating the number of slices in the sub-picture.

[1214] 19. The method of solution 18, wherein the format rule specifies that if the first flag is set to 1 and the second flag is set to 1, then at least one sub-picture in the picture includes multiple slices.

[1215] 20. The method of solution 18, wherein the format rules dictate that since the first flag is zero and there is a single slice in each picture, the second flag must be set to 1.

[1216] The following solution illustrates an example embodiment of the technique discussed in the previous section (eg, item 7).

[1217] 21. A method for video processing, comprising: performing conversion between a video comprising one or more video pictures and a codec representation of the video, each video picture comprising one or more strips and / or one or more slices; wherein the codec representation conforms to a format rule; wherein the format rule specifies that a field in a picture parameter set associated with the video picture indicates whether the video picture is divided into multiple slice rows or slice columns of different heights or widths.

[1218] 22. The method of solution 21, wherein a second field in the codec representation indicates whether a slice of a video picture is divided into multiple slice rows with different heights.

[1219] 23. The method of solution 22, wherein the second field indicates a stripe height for the plurality of stripe rows.

[1220] The following solution illustrates an example embodiment of the technique discussed in the previous section (eg, item 8).

[1221] 24. A method of video processing, comprising: performing conversion between a video comprising one or more video pictures and a codec representation of the video, each video picture comprising one or more slices and / or one or more tiles; wherein the codec representation conforms to a format rule; wherein the format rule specifies that in a case where an adaptive parameter set excludes an indication of adaptive loop filtering, the applicability of adaptive loop filtering to a video region is based on a second rule.

[1222] 25. The method of solution 24, wherein the second rule specifies disabling adaptive loop filtering for the video region.

[1223] 26. The method of solution 24, wherein the second rule provides for conditionally allowing adaptive loop filtering based on the value of a flag at the sequence parameter set level.

[1224] The following solution illustrates an example embodiment of the technique discussed in the previous section (eg, item 9).

[1225] 27. A method for video processing, comprising: performing conversion between a video comprising one or more video pictures and a codec representation of the video, each video picture comprising one or more strips and / or one or more slices; wherein the codec representation conforms to a format rule; wherein the format rule specifies that for a picture having a width and height, a maximum width and a maximum height of the video, explicit signaling of a consistency window parameter in a picture parameter set is skipped.

[1226] 28. The method of solution 27, wherein the format rule further specifies including a flag indicating whether the width and height are equal to the maximum width and maximum height in case explicit signaling is skipped.

[1227] 29. A method according to any one of solutions 1-28, wherein the video area includes a video picture.

[1228] 30. The method according to any of solutions 1-29, wherein the video unit includes a video slice or a video codec unit.

[1229] 31. A method according to any of solutions 1 to 30, wherein the conversion includes encoding the video into a codec representation.

[1230] 32. A method according to any of solutions 1 to 30, wherein converting includes decoding the codec representation to generate pixel values of the video.

[1231] 33. A video decoding device comprising a processor configured to implement the method described in one or more of solutions 1 to 32.

[1232] 34. A video encoding apparatus comprising a processor configured to implement the method described in one or more of solutions 1 to 32.

[1233] 35. A computer program product having computer code stored thereon, which, when executed by a processor, causes the processor to implement the method of any one of solutions 1 to 32.

[1234] 36. The methods, apparatus, or systems described in this document.

[1235] Figure 77 is a flow chart of an example method 700 for video processing. Operation 702 includes performing conversion between a video including a video unit and a bitstream of the video according to a rule, wherein the rule specifies whether to include information related to a scaling list for the video in an adaptation parameter set (APS) or how to include information related to a scaling list for the video in the adaptation parameter set (APS) based on a first syntax element and independent of one or more syntax elements in a sequence parameter set (SPS), the first syntax element indicating whether the APS includes syntax elements related to chroma components.

[1236] In some embodiments of method 700, information related to scaling lists includes whether a scaling list for a color component is included in an APS. In some embodiments of method 700, rules provide for including one or more fields in the APS for identifying any one or more of a video parameter set (VPS), an SPS, and a picture parameter set (PPS). In some embodiments of method 700, rules provide for including a field in the APS indicating an SPS associated with the APS, wherein a value of the field is in a range from 0 to 15 (inclusive), and wherein the value of the field is the same in all APSs referenced by one or more video pictures in a codec layer video sequence (CLVS). In some embodiments of method 700, rules provide for including a second syntax element in the APS based on a value of a first syntax element indicating whether the APS includes a syntax element related to chroma components, and wherein the second syntax element specifies whether the value of the scaling list is the same as the value of the reference scaling list. In some embodiments of method 700, rules provide for deriving an implicit relationship between the APS and any one or more of the video parameter set (VPS), the SPS, and the picture parameter set (PPS).

[1237] In some embodiments of method 700, a rule provides that when an APS is referenced by a header of a video unit, and when a video unit depends on any one or more of a VPS, an SPS, and a PPS, the APS is implicitly associated with any one or more of the VPS, the SPS, and the PPS. In some embodiments of method 700, the header of the video unit includes a picture header or a slice header. In some embodiments of method 700, a rule provides that flat quantization including a scaling list is applied to chroma video blocks of the video, regardless of whether a user-defined scaling list is applied to luma video blocks of the video. In some embodiments of method 700, a rule provides that a bitstream that excludes explicit scaling lists for chroma video blocks of the video does not depend on a bitstream that includes explicit scaling lists for luma video blocks of the video. In some embodiments of method 700, a rule provides that one or more syntax elements in the SPS include a flag to indicate whether an explicit scaling list is used for a particular video unit. In some embodiments of method 700, the particular video unit includes a video block coded with a low-frequency inseparable transform.

[1238] In some embodiments of method 700, rules specify whether the first syntax element is included in the APS independently of the value of a flag indicating whether scaling lists are present in the APS. In some embodiments of method 700, rules specify that whether explicit scaling lists or default scaling lists are used for different color components of the video is separately indicated or controlled in the APS. In some embodiments of method 700, rules specify that at least one syntax element be added to an SPS, a picture parameter set (PPS), a picture header (PH), or a slice header (SH) to specify whether explicit scaling lists are enabled for the luma component of the video and / or the chroma components of the video. In some embodiments of method 700, rules specify that one or more syntax elements in the SPS include a flag indicating whether flat quantization or explicit scaling lists are used for the luma transform coefficients of the video. In some embodiments of method 700, rules specify that one or more syntax elements added to the SPS indicate whether flat quantization and explicit scaling lists are used for chroma-U and / or chroma-V transform coefficients. In some embodiments of method 700, rules specify that when the value of the flag indicating whether scaling lists are present in the APS is equal to 1, the first syntax element is equal to 0. In some embodiments of the method 700 , the rules further provide that when the video pictures of the video are in 4:0:0 chroma format, N sets of scaling matrices are indicated in the APS.

[1239] In some embodiments of the method 700, the rules further provide that when the video pictures of the video are in a 4:4:4 chroma format and when the individual color plane flags indicate that the three color components of the 4:4:4 chroma format are encoded and decoded separately, M sets of scaling matrices are indicated in the APS. In some embodiments of the method 700, the rules provide that when the individual color plane flags indicate that the three color components of the 4:4:4 chroma format are encoded and decoded separately and M sets of scaling matrices are indicated in the APS: (1) each of the luma, chroma-U, and chroma-V transform coefficients is treated as a luma-Y channel, and (2) the luma, chroma-U, and chroma-V transform coefficients have the same scaling matrix identifier. In some embodiments of the method 700, the rules provide that when the individual color plane flag indicates that the three color components of the 4:4:4 chroma format are to be encoded separately and M sets of scaling matrices are indicated in the APS: (1) a first scaling matrix identifier for deriving luma transform coefficients for the luma component, (2) a second scaling matrix identifier for deriving chroma-U transform coefficients for the chroma-U component, and (3) a third scaling matrix identifier for deriving chroma-V transform coefficients for the chroma-V component. In some embodiments of the method 700, the rules provide that when the value of the flag indicating whether a scaling list is present in the APS is equal to 0, the first syntax element is equal to 1. In some embodiments of the method 700, the rules further provide that whether chroma transform coefficients are allowed to use explicit scaling lists is based on the value of the flag.

[1240] In some embodiments of the method 700, the rules provide that when the value of the flag is equal to 0, explicit scaling lists are not allowed to be used for chroma transform coefficients, regardless of the value of the syntax element indicating whether scaling lists are enabled for the SPS, picture header (PH), and slice header (SH). In some embodiments of the method 700, the rules provide that when the value of the flag is equal to 1, explicit scaling lists are allowed to be used for chroma transform coefficients. In some embodiments of the method 700, the rules further provide that when a video picture of the video has a 4:2:0 chroma format, a 4:2:2 chroma format, and / or a 4:4:4 chroma format, and when the value of the individual color plane flag is 0, N sets of scaling matrices are indicated in the APS.

[1241] In some embodiments of method 700, the rules further provide that when the first syntax element is greater than 0, and when N sets of scaling matrices are indicated in the APS, the scaling matrices for the chroma-U and / or chroma-V transform coefficients are derived from the N sets of scaling matrices indicated in the APS for the luma transform coefficients. In some embodiments of method 700, the rules further provide that when the first syntax element is greater than 0, and when N sets of scaling matrices are indicated in the APS, the chroma-U and / or chroma-V transform coefficients are not allowed to use explicit scaling lists, and the chroma-U and / or chroma-V transform coefficients are allowed to use flat quantization with default scaling factors. In some embodiments of method 700, the rules provide that the first value of the first syntax element does not depend on the value of a flag indicating whether a scaling list is present in the APS. In some embodiments of method 700, the rules provide that when the value of the flag indicating whether a scaling list is present in the APS is equal to 1, the first value of the first syntax element need not be 0.

[1242] In some embodiments of method 700, rules specify whether a value of a flag indicating whether a scaling list is present in an APS is based on a first value of a first syntax element, and wherein the rules further specify that the first value of the first syntax element is derived from one or more values derived from one or more syntax elements in a picture header (PH) and / or a slice header (SH). In some embodiments of method 700, when the first value of the first syntax element is 0, the value of the flag indicating whether a scaling list is present in an APS is 0, and wherein when the value of the first syntax element is 1, the value of the flag indicating whether a scaling list is present in an APS is 1. In some embodiments of method 700, when the first value of the first syntax element is 0, the value of the flag indicating whether a scali...

Claims

1. A method for processing video data, comprising: performing conversion between a video comprising a block and a bitstream of said video according to a rule, The rule specifies whether to include a first syntax element in the slice header SH, the first syntax element indicating whether to disable the transform skip TS based residual codec syntax structure for the residual samples of the transform skip TS block of the slice, and wherein the rule specifies that whether to include the first syntax element in the SH is based on a second syntax element in a sequence parameter set SPS, the second syntax element indicating whether TS mode is enabled for a block referencing the SPS; The rule specifies that when the first general constraint information syntax element is equal to 1, the adaptive loop filter ALF operation on the chrominance component of the video region is disabled, the cross-component adaptive loop filter CC-ALF operation on the video region is disabled, and the ALF operation on the luminance component of the video region is allowed, and The first general constraint information syntax element being equal to 1 specifies that there are no one or more APS NAL units including adaptive loop filter data, and the first general constraint information syntax element is no_aps_constraint_flag.

2. The method according to claim 1, wherein The rule provides that, in response to the second syntax element being equal to a second value, the first syntax element is equal to a first value, wherein the first value of the first syntax element is 0 and the second value of the second syntax element is 0.

3. The method according to claim 2, wherein: The first syntax element being equal to 1 specifies that a conventional residual codec syntax structure is used for the residual samples of the TS block.

4. The method according to claim 2, wherein: The first syntax element being equal to 0 specifies that the TS-based residual codec syntax structure is used for the residual samples of the TS block.

5. The method according to claim 1, wherein For the block, when a third syntax element associated with the block is equal to 0 or when the first syntax element is equal to 1, a normal residual codec syntax structure is used for the residual samples of the block, wherein the third syntax element equal to 0 indicates that transformation is allowed to be applied to the block.

6. The method according to claim 1, wherein For the block, when a third syntax element associated with the block is equal to 1 and the first syntax element is equal to 0, the TS-based residual codec syntax structure is used for the residual samples of the block, wherein the third syntax element is equal to 1 indicating that transform skipping is applied to the block.

7. The method according to claim 1, wherein Performing the conversion includes encoding the video into the bitstream.

8. The method according to claim 1, wherein Performing the conversion includes decoding the video from the bitstream.

9. An apparatus for processing video data, comprising a processor and a non-transitory memory with instructions thereon, wherein: The instructions, when executed by the processor, cause the processor to: performing conversion between a video comprising a block and a bitstream of said video according to a rule, The rule specifies whether to include a first syntax element in the slice header SH, the first syntax element indicating whether to disable the transform skip TS based residual codec syntax structure for the residual samples of the transform skip TS block of the slice, and wherein the rule specifies that whether to include the first syntax element in the SH is based on a second syntax element in a sequence parameter set SPS, the second syntax element indicating whether TS mode is enabled for a block referencing the SPS; The rule specifies that when the first general constraint information syntax element is equal to 1, the adaptive loop filter ALF operation on the chrominance component of the video region is disabled, the cross-component adaptive loop filter CC-ALF operation on the video region is disabled, and the ALF operation on the luminance component of the video region is allowed, and The first general constraint information syntax element being equal to 1 specifies that there are no one or more APS NAL units including adaptive loop filter data, and the first general constraint information syntax element is no_aps_constraint_flag.

10. The device according to claim 9, wherein the rule providing that, in response to the second syntax element being equal to a second value, the first syntax element is equal to a first value, wherein the first value of the first syntax element is 0 and the second value of the second syntax element is 0; wherein the first syntax element being equal to 1 specifies that a conventional residual codec syntax structure is used for the residual samples of the TS block; and The first syntax element being equal to 0 specifies that the TS-based residual coding syntax structure is used for the residual samples of the TS block.

11. The device according to claim 9, wherein For the block, when a third syntax element associated with the block is equal to 0 or when the first syntax element is equal to 1, a normal residual codec syntax structure is used for the residual samples of the block, wherein the third syntax element equal to 0 indicates that transformation is allowed to be applied to the block.

12. The device according to claim 9, wherein For the block, when a third syntax element associated with the block is equal to 1 and the first syntax element is equal to 0, the TS-based residual codec syntax structure is used for the residual samples of the block, wherein the third syntax element is equal to 1 indicating that transform skipping is applied to the block.

13. A non-transitory computer-readable storage medium storing instructions that cause a processor to: performing conversion between a video comprising a block and a bitstream of said video according to a rule, in, The rule specifies whether to include a first syntax element in the slice header SH, the first syntax element indicating whether to disable the transform skip TS based residual codec syntax structure for the residual samples of the transform skip TS blocks of the slice, and wherein the rule specifies that whether to include the first syntax element in the SH is based on a second syntax element in a sequence parameter set SPS, the second syntax element indicating whether TS mode is enabled for a block referencing the SPS; The rule specifies that when the first general constraint information syntax element is equal to 1, the adaptive loop filter ALF operation on the chrominance component of the video region is disabled, the cross-component adaptive loop filter CC-ALF operation on the video region is disabled, and the ALF operation on the luminance component of the video region is allowed, and The first general constraint information syntax element being equal to 1 specifies that there are no one or more APS NAL units including adaptive loop filter data, and the first general constraint information syntax element is no_aps_constraint_flag.

14. The non-transitory computer-readable storage medium of claim 13, wherein: the rule providing that, in response to the second syntax element being equal to a second value, the first syntax element is equal to a first value, wherein the first value of the first syntax element is 0 and the second value of the second syntax element is 0; wherein the first syntax element being equal to 1 specifies that a conventional residual codec syntax structure is used for the residual samples of the TS block; and The first syntax element being equal to 0 specifies that the TS-based residual coding syntax structure is used for the residual samples of the TS block.

15. The non-transitory computer-readable storage medium of claim 13, wherein: For the block, when a third syntax element associated with the block is equal to 0 or when the first syntax element is equal to 1, a normal residual codec syntax structure is used for the residual samples of the block, wherein the third syntax element equal to 0 indicates that transformation is allowed to be applied to the block.

16. The non-transitory computer-readable storage medium of claim 13, wherein: For the block, when a third syntax element associated with the block is equal to 1 and the first syntax element is equal to 0, the TS-based residual codec syntax structure is used for the residual samples of the block, wherein the third syntax element is equal to 1 indicating that transform skipping is applied to the block.

17. A non-transitory computer-readable recording medium storing a bit stream of a video generated by a method performed by a video processing apparatus, wherein: The method comprises: generating said bitstream for said video comprising blocks according to a rule, The rule specifies whether to include a first syntax element in the slice header SH, the first syntax element indicating whether to disable the transform skip TS based residual codec syntax structure for the residual samples of the transform skip TS block of the slice, and wherein the rule specifies that whether to include the first syntax element in the SH is based on a second syntax element in a sequence parameter set SPS, the second syntax element indicating whether TS mode is enabled for a block referencing the SPS; The rule specifies that when the first general constraint information syntax element is equal to 1, the adaptive loop filter ALF operation on the chrominance component of the video region is disabled, the cross-component adaptive loop filter CC-ALF operation on the video region is disabled, and the ALF operation on the luminance component of the video region is allowed, and The first general constraint information syntax element being equal to 1 specifies that there are no one or more APS NAL units including adaptive loop filter data, and the first general constraint information syntax element is no_aps_constraint_flag.

18. The non-transitory computer-readable recording medium according to claim 17, wherein the rule providing that, in response to the second syntax element being equal to a second value, the first syntax element is equal to a first value, wherein the first value of the first syntax element is 0 and the second value of the second syntax element is 0; wherein the first syntax element being equal to 1 specifies that a conventional residual codec syntax structure is used for the residual samples of the TS block; and The first syntax element being equal to 0 specifies that the TS-based residual coding syntax structure is used for the residual samples of the TS block.

19. The non-transitory computer-readable recording medium according to claim 17, wherein For the block, when a third syntax element associated with the block is equal to 0 or when the first syntax element is equal to 1, a normal residual codec syntax structure is used for the residual samples of the block, wherein the third syntax element equal to 0 indicates that transformation is allowed to be applied to the block.

20. The non-transitory computer-readable recording medium according to claim 17, wherein For the block, when a third syntax element associated with the block is equal to 1 and the first syntax element is equal to 0, the TS-based residual codec syntax structure is used for the residual samples of the block, wherein the third syntax element is equal to 1 indicating that transform skipping is applied to the block.

21. A method for storing a video bitstream, comprising: generating said bitstream for said video comprising blocks according to a rule, and storing the bitstream in a non-transitory computer-readable storage medium, The rule specifies whether to include a first syntax element in the slice header SH, the first syntax element indicating whether to disable the transform skip TS based residual codec syntax structure for the residual samples of the transform skip TS block of the slice, and wherein the rule specifies that whether to include the first syntax element in the SH is based on a second syntax element in a sequence parameter set SPS, the second syntax element indicating whether TS mode is enabled for a block referencing the SPS; The rule specifies that when the first general constraint information syntax element is equal to 1, the adaptive loop filter ALF operation on the chrominance component of the video region is disabled, the cross-component adaptive loop filter CC-ALF operation on the video region is disabled, and the ALF operation on the luminance component of the video region is allowed, and The first general constraint information syntax element being equal to 1 specifies that there are no one or more APS NAL units including adaptive loop filter data, and the first general constraint information syntax element is no_aps_constraint_flag.

Images