Signaling of syntax elements for reference picture indication

Abstract

A video processing method is provided, comprising: performing conversion between a video including one or more pictures and a bitstream of the video, each picture including at least one slice, wherein the bitstream complies with a format rule, wherein the format rule specifies a first field including a presence indicating a second field, the second field identifying a maximum index of a reference picture used to encode and decode the slice based on a condition; wherein the condition can be expressed as a logical expression "A&(B||C)", wherein: A indicates that a first flag indicating whether reference picture list information is included in a picture header syntax structure is equal to 1, or a network abstraction layer (NAL) unit type is not equal to an instantaneous decoding refresh (IDR) type, or a second flag indicating whether reference picture list information may exist in a slice header of a slice with an IDR NAL unit type is equal to 1, B indicates that the slice type is equal to P or B, and the number of reference entries in reference picture list 0 is greater than 1, C indicates that the slice type is equal to B, and the number of reference entries in reference picture list 1 is greater than 1, and wherein "&" is a logical "AND" operation, and "||" is a logical "OR" operation.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is filed in accordance with the patent laws and / or rules applicable under the Paris Convention to timely claim the priority and benefits of PCT application PCT / CN2020 / 077331 filed on February 29, 2020. The entire disclosure of the above application is incorporated by reference as part of the disclosure of this application for all purposes prescribed by law. Technical Field

[0003] This patent document refers 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. Bandwidth demand for digital video usage is expected to continue to grow as the number of connected user devices capable of receiving and displaying video increases. 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 a conversion between a video having one or more pictures and a codec representation of the video, wherein each of the one or more pictures includes exactly one slice; wherein the codec representation complies with a format rule; wherein the format rule specifies that the picture parameter set flag is excluded from the codec representation because the picture has exactly one slice.

[0007] In another example aspect, another video processing method is disclosed. The method includes performing conversion between a video slice 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 first field including a first field indicating the presence of a second field, the second field identifying a maximum index of a reference picture used to encode and decode the slice based on a condition; wherein the condition can be expressed as a logical expression "A&(B||C)", wherein: A indicates "rpl_info_in_ph_flag=1, or NAL unit type is not equal to IDR, or sps_idr_rpl_present_flag is equal to 1", and "B" indicates "slice_type is equal to P or B, and the number of reference entries in reference picture list 0 is greater than 1", and "C" indicates "slice_type is equal to B, and the number of reference entries in reference picture list 1 is greater than 1", and "&" is a logical "and" operation, and "||" is a logical "or" operation.

[0008] 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, wherein the codec representation conforms to a format rule, wherein the format rule specifies conditions controlling use of a syntax element indicating a picture order count of a long-term reference picture for conversion of the video region.

[0009] 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, wherein the codec representation conforms to a format rule, wherein the format rule specifies that a reference picture related syntax structure is included if and only if a variable X is equal to a specific value, wherein X depends on a slice type of the video region.

[0010] In another example aspect, another video processing method is disclosed. The method includes performing conversion between a video including one or more pictures and a bitstream of the video; wherein the bitstream complies with a format rule; wherein the format rule specifies that in response to whether each picture of the reference picture parameter set includes a single slice, one or more syntax elements indicating codec information are selectively included in a picture parameter set of the bitstream.

[0011] In another example aspect, another video processing method is disclosed. The method includes performing conversion between a video including a plurality of pictures and a bitstream of the video, each picture including at least one slice, wherein the bitstream conforms to a format rule; wherein the format rule specifies that a first flag in the bitstream indicates whether a picture header syntax structure of the picture is included in a slice header of a slice of the picture; and wherein the format rule provides that in response to any one of six flags in a picture parameter set associated with the picture being equal to 1, the first flag is equal to 0.

[0012] In another example aspect, another video processing method is disclosed. The method includes performing conversion between a video including one or more pictures and a bitstream of the video, each picture including at least one slice, wherein the bitstream conforms to a format rule, wherein the format rule specifies a first field including a presence of a second field, the second field identifying a maximum index of a reference picture for encoding and decoding the slice based on a condition; wherein the condition can be expressed as a logical expression "A&(B||C)", wherein: A indicates that a first flag indicating whether reference picture list information is included in a picture header syntax structure is equal to 1, or a network abstraction layer (NAL) unit type is not equal to an instantaneous decoding refresh (IDR) type, or a second flag indicating whether reference picture list information may be present in a slice header of a slice with an IDR NAL unit type is equal to 1, B indicates that the slice type is equal to P or B, and the number of reference entries in reference picture list 0 is greater than 1, C indicates that the slice type is equal to B, and the number of reference entries in reference picture list 1 is greater than 1, and wherein "&" is a logical "and" operation, and "||" is a logical "or" operation.

[0013] In another example aspect, another video processing method is disclosed. The method includes performing conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, and wherein the format rule specifies conditions controlling whether or how one or more syntax elements related to a picture order count of a long-term reference picture are included in a reference picture list syntax structure in the bitstream.

[0014] In another example aspect, another video processing method is disclosed. The method includes performing conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether syntax elements related to reference pictures in a reference picture list are included in a reference picture list syntax structure.

[0015] In yet another example aspect, a video codec apparatus is disclosed. The video codec includes a processor configured to implement the above method.

[0016] In yet another example aspect, a video decoder apparatus is disclosed. The video decoder includes a processor configured to implement the above method.

[0017] In yet another example aspect, a bitstream generated according to the methods described herein is disclosed.The bitstream may be stored on a computer-readable storage medium.

[0018] In yet another exemplary aspect, a computer readable medium having code stored thereon is disclosed. The code is in the form of processor executable code embodying one of the methods described herein.

[0019] These and other features are described in this document. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a block diagram of an example video processing system.

[0021] Figure 2 A block diagram of a video processing device.

[0022] Figure 3 A flow chart of an example method for video processing.

[0023] Figure 4 is a block diagram illustrating a video encoding and decoding system according to some embodiments of the present disclosure.

[0024] Figure 5 is a block diagram illustrating an encoder according to some embodiments of the present disclosure.

[0025] Figure 6 is a block diagram illustrating a decoder according to some embodiments of the present disclosure.

[0026] Figures 7A to 7D is a flow chart of an example method of video processing. DETAILED DESCRIPTION

[0027] 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. In addition, the use of H.266 terminology in some descriptions is only for ease of understanding and is not intended to limit the scope of the disclosed technology. Therefore, the techniques described herein are also applicable to other video codec protocols and designs.

[0028] 1. Preliminary Discussion

[0029] This document is about video codec technology. Specifically, it is about the design of PPS, PH, SH syntax in video codec. 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 codec, such as the Versatile Video Codec (VVC) under development.

[0030] 2. Abbreviations

[0031] APS Adaptive Parameter Set

[0032] AU Access Unit

[0033] AUD Access Unit Delimiter

[0034] AVC Advanced Video Codec

[0035] CLVS Codec Layer Video Sequence

[0036] CPB Codec Picture Buffer

[0037] CRA Clean Random Access

[0038] CTU Codec Tree Unit

[0039] CVS codec video sequence

[0040] DPB Decoded Picture Buffer

[0041] DPS Decoding Parameter Set

[0042] EOB End of bitstream

[0043] EOS sequence ends

[0044] GDR Gradual Decode Refresh

[0045] HEVC High Efficiency Video Codec

[0046] HRD Hypothesized Reference Decoder

[0047] IDR Instantaneous Decode Refresh

[0048] JEM Joint Exploration Model

[0049] LTRP Long Term Reference Picture

[0050] MCTS Motion Constraint Episodes

[0051] NAL Network Abstraction Layer

[0052] OLS output layer set

[0053] PH Image Header

[0054] PPS Picture Parameter Set

[0055] PTL Profiles, Tiers, Levels

[0056] PU Picture Unit

[0057] RBSP Raw Byte Sequence Payload

[0058] SEI Supplemental Enhancement Information

[0059] SH Strip Header

[0060] SPS Sequence Parameter Set

[0061] STRP Short-term reference picture

[0062] SVC Scalable Video Codec

[0063] VCL video codec layer

[0064] VPS Video Parameter Set

[0065] VTM VVC test model

[0066] VUI Video Availability Information

[0067] VVC Multi-functional Video Codec

[0068] 3. Introduction to video processing

[0069] 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 are based on a hybrid video codec structure, which utilizes temporal prediction plus transform codec. In order 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 simultaneously every quarter, and the goal of the new codec standard is to reduce the bit rate 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. With the continuous efforts of VVC standardization, new codec technologies are adopted into the VVC standard at each JVET meeting. The working draft of VVC and the test model VTM are updated after each meeting. The VVC project now aims to be technically completed (FDIS) at the meeting in July 2020.

[0070] 3.1.PPS Syntax and Semantics

[0071] In the latest VVC draft text, the PPS syntax and semantics are as follows:

[0072]

[0073]

[0074]

[0075]

[0076] 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.

[0077] All PPS NAL units within a PU with a specific value of pps_pic_parameter_set_id shall have the same content.

[0078] 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).

[0079] Regardless of the nuh_layer_id value, PPS NAL units share the same value space of pps_pic_parameter_set_id.

[0080] Let ppsLayerId be the value of numh_layer_id of a particular PPS NAL unit, and vclLayerId be the value of numh_layer_id of a particular VCL NAL unit. A particular VCL NAL unit shall not refer to a particular PPS NAL unit unless a layer with ppsLayerId less than or equal to vclLayerId and nuh_layer_id equal to ppsLayerId is contained in at least one OLS that includes a layer with nuh_layer_id equal to vclLayerId.

[0081] 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 shall be in the range of 0 to 15 (inclusive). The value of pps_seq_parameter_set_id shall be the same in all pps referenced by a codec picture in CLVS.

[0082] 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.

[0083] 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.

[0084] For each slice with nal_unit_type value nalUnitTypeA in the range IDR_W_RADL to CRA_NUT (inclusive) in picture picA that also contains one or more slices with 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:

[0085] - The slice shall belong to the sub-picture subpicA for which the value of subpic_treated_as_pic_flag[i] is equal to 1.

[0086] - A slice shall not belong to a sub-picture of picA that contains VCL NAL units whose nal_unit_type is not equal to nalUnitTypeA.

[0087] - 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.

[0088] - 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 should include any picture that precedes picA in decoding order in the active entry.

[0089] NOTE 1 – mixed_nalu_types_in_pic_flag equal to 1 indicates that the picture referencing the PPS contains slices with different NAL unit types, for example, a codec picture originating from a sub-picture bitstream merging operation, and the encoder must ensure matching bitstream structures and further alignment of parameters of the original bitstreams. 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.

[0090] 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.

[0091] 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.

[0092] pic_height_in_luma_samples specifies the height of each decoded picture that references the PPS, in units of luma samples. 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.

[0093] 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.

[0094] The derivation of the variables PicWidthInCtbsY, PicHeightInCtbsY, PicSizeInCtbsY, PicWidthInMinCbsY, PicHeightInMinCbsY, PicSizeInMinCbsY, PicSizeInSamplesY, PicWidthInSamplesC, and PicHeightInSamplesC is as follows:

[0095] PicWidthInCtbsY = Ceil(pic_width_in_luma_samples ÷ CtbSizeY) (69)

[0096] PicHeightInCtbsY = Ceil(pic_height_in_luma_samples ÷ CtbSizeY) (70)

[0097] PicSizeInCtbsY = PicWidthInCtbsY * PicHeightInCtbsY (71)

[0098] PicWidthInMinCbsY = pic_width_in_luma_samples / MinCbSizeY (72)

[0099] PicHeightInMinCbsY = pic_height_in_luma_samples / MinCbSizeY (73)

[0100] PicSizeInMinCbsY = PicWidthInMinCbsY * PicHeightInMinCbsY (74)

[0101] PicSizeInSamplesY = pic_width_in_luma_samples * pic_height_in_luma_samples (75)

[0102] PicWidthInSamplesC = pic_width_in_luma_samples / SubWidthC (76)

[0103] PicHeightInSamplesC = pic_height_in_luma_samples / SubHeightC (77)

[0104] 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.

[0105] 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 the 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.

[0106] The consistent 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.

[0107] 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.

[0108] 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.

[0109] NOTE 2 – The consistency crop window offset parameter applies only to output. All internal decoding processes are applied to the uncropped picture size.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] scaling_win_left_offset, scaling_win_right_offset, scaling_win_top_offset, and scaling_win_bottom_offset specify offsets to the picture size that are applied to the scaling calculation. 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.

[0114] 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.

[0115] The variables PicOutputWidthL and PicOutputHeightL are derived as follows:

[0116] PicOutputWidthL=pic_width_in_luma_samples- (78)

[0117] SubWidthC*(scaling_win_right_offset+scaling_win_left_offset)

[0118] PicOutputHeightL=

[0119] pic_height_in_luma_samples- (79)

[0120] SubWidthC*(scaling_win_bottom_offset+scaling_win_top_offset)

[0121] Assume that refPicOutputWidthL and refPicOutputHeightL are the PicOutputWidthL and PicOutputHeightL of the reference picture of the current picture that refers to this PPS. The requirement for bitstream conformance is that all of the following conditions are met:

[0122] –PicOutputWidthL*2 should be greater than or equal to refPicWidthInLumaSamples.

[0123] –PicOutputHeightL*2 should be greater than or equal to refPicHeightInLumaSamples.

[0124] –PicOutputWidthL should be less than or equal to refPicWidthInLumaSamples*8.

[0125] –PicOutputHeightL should be less than or equal to refPicHeightInLumaSamples*8.

[0126] –PicOutputWidthL*pic_width_max_in_luma_samples shall be greater than or equal to refPicOutputWidthL*(pic_width_in_luma_samples-Max(8,MinCbSizeY)).

[0127] –PicOutputHeightL*pic_height_max_in_luma_samples shall be greater than or equal to refPicOutputHeightL*(pic_height_in_luma_samples-Max(8,MinCbSizeY)).

[0128] output_flag_present_flag equal to 1 indicates that the pic_output_flag syntax element is present in the slice header referencing the PPS. output_flag_present_flag equal to 0 indicates that the pic_output_flag syntax element is not present in the slice header referencing the PPS.

[0129] subpic_id_mapping_in_pps_flag equal to 1 specifies that sub-picture ID mapping is signaled in PPS. subpic_id_mapping_in_pps_flag equal to 0 specifies that sub-picture ID mapping is not signaled in PPS. If subpic_id_mapping_explicitly_signalled_flag is 0 or subpic_id_mapping_in_sps_flag is equal to 1, then the value of subpic_id_mapping_in_pps_flag shall be equal to 0. Otherwise (subpic_id_mapping_explicitly_signalled_flag is equal to 1 and subpic_id_mapping_in_sps_flag is equal to 0), the value of subpic_id_mapping_in_pps_flag shall be equal to 1.

[0130] pps_num_subpics_minus1 shall be equal to sps_num_subpics_minus1.

[0131] pps_subpic_id_len_minus1 shall be equal to sps_subpic_id_len_minus1.

[0132] 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.

[0133] For each value of i in the range of 0 to sps_num_subpics_minus1 (inclusive), the variable SubpicIdVal[i] is derived as follows:

[0134]

[0135] The requirement for bitstream conformance is that the following two constraints apply:

[0136] --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].

[0137] --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 a specific value in the range of IDR_W_RADL to CRA_NUT (inclusive).

[0138] 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.

[0139] A bitstream conformance requirement is that the value of no_pic_partition_flag should be the same for all PPSs referenced by a coded picture within a CLVS.

[0140] It is a bitstream conformance requirement 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.

[0141] pps_log2_ctu_size_minus5 plus 5 specifies the luma codec tree block size for each CTU. pps_log2_ctu_size_minus5 shall be equal to sps_log2_ctu_size_minus5.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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 with 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.

[0146] 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.

[0147] 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.

[0148] num_slices_in_pic_minus1 plus 1 specifies the number of rectangular slices in each picture that references 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.

[0149] tile_idx_delta_present_flag equal to 0 specifies that tile_idx_delta values ​​are not present in the PPS and that 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 that 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.

[0150] 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).

[0151] When slice_width_in_tiles_minus1[i] is not present, the following applies:

[0152] --If NumTileColumns is equal to 1, the value of slice_width_in_tiles_minus1[i] is inferred to be equal to 0.

[0153] -- Otherwise, the value of slice_width_in_tiles_minus1[i] is inferred as specified in clause 6.5.1.

[0154] 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).

[0155] When slice_height_in_tiles_minus1[i] is not present, the following applies:

[0156] --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.

[0157] --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].

[0158] num_exp_slices_in_tile[i] specifies the number of explicitly provided strip heights in the current strip containing multiple rectangular strips. The value of num_exp_slices_in_tile[i] should be in the range of 0 to RowHeight[tileY]–1 (inclusive), where tileY is the index of the strip 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.

[0159] exp_slice_height_in_ctus_minus1[j] plus 1 specifies the height of the j-th rectangular slice in the current slice in CTU rows. The value of exp_slice_height_in_ctus_minus1[j] shall be in the range of 0 to RowHeight[tileY]–1 (inclusive), where tileY is the slice row index of the current slice.

[0160] 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:

[0161]

[0162] tile_idx_delta[i] specifies the difference between the tile index of the first tile in the i-th rectangular strip and the tile index of the first tile in the (i+1)-th rectangular strip. 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] num_ref_idx_default_active_minus1[i] increments by 1 and, when equal to 0, specifies the inferred value of the variable NumRefIdxActive[0] for P 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.

[0167] 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 in the slice header of the pictures 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 in the slice header of the pictures referencing the PPS.

[0168] 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 init_qp_minus26 is modified at the picture level, or at the slice level when a non-zero value of slice_qp_delta is decoded. The value of init_qp_minus26 should be in the range of -(26+QpBdOffset) to +37 (inclusive).

[0169] 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.

[0170] 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.

[0171] pps_cb_qp_offset and pps_cr_qp_offset are respectively specified for deriving Qp′ Cb and Qp′ Cr The brightness quantization parameter Qp′ Y The values ​​of pps_cb_qp_offset and pps_cr_qp_offset shall be in the range -12 to +12 (inclusive). When ChromaArrayType is equal to 0, pps_cb_qp_offset and pps_cr_qp_offset are not used during decoding and the decoder shall 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.

[0172] 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.

[0173] pps_joint_cbcr_qp_offset_value specifies the value used to derive Qp′ CbCr The brightness 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 does not exist and is inferred to be equal to 0.

[0174] 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.

[0175] 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, indicating that the PPS and 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 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.

[0176] 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).

[0177] cb_qp_offset_list[i], cr_qp_offset_list[i] and joint_cbcr_qp_offset_list[i] specify Qp′ respectively. Cb , Qp′ Cr and Qp′ CbCr The offset 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.

[0178] pps_weighted_pred_flag equal to 0 specifies that weighted prediction is not applied to P slices that reference a PPS. pps_weighted_pred_flag equal to 1 specifies that weighted prediction is applied to P slices that reference a PPS. When sps_weighted_pred_flag is equal to 0, the value of pps_weighted_pred_flag shall be equal to 0.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] pps_beta_offset_div2 and pps_tc_offset_div2 specify the default deblocking parameter offsets for β and tC (divided by 2) that are applied to the luma components of slices that reference the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the picture header or slice header of slices that reference 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.

[0184] pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 specify the default deblocking parameter offsets for β and tC (divided by 2) that are applied to the Cb component of slices that reference the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the picture header or slice header of slices that reference the PPS. The values ​​of pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 should 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.

[0185] pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 specify the default deblocking parameter offsets for β and tC (divided by 2) that 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.

[0186] 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 a PPS that does 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 a PPS that does not contain the PH syntax structure.

[0187] dbf_info_in_ph_flag equal to 1 specifies that the deblocking filter information is present in the PH syntax structure and not in the slice headers referencing a PPS that does not contain the PH syntax structure. dbf_info_in_ph_flag equal to 0 specifies that the deblocking filter information is not present in the PH syntax structure and may be present in the slice headers referencing a PPS that does not contain the PH syntax structure. When not present, the value of dbf_info_in_ph_flag is inferred to be equal to 0.

[0188] sao_info_in_ph_flag equal to 1 specifies that the SAO filter information is present in the PH syntax structure and not in slice headers referencing a PPS that does not contain a 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 a PPS that does not contain a PH syntax structure.

[0189] 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 the 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 the PH syntax structure.

[0190] wp_info_in_ph_flag equal to 1 specifies that weighted prediction information may be present in the PH syntax structure and not in slice headers referencing a PPS that does 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 a PPS that does not contain a PH syntax structure. When not present, the value of wp_info_in_ph_flag is inferred to be equal to 0.

[0191] qp_delta_info_in_ph_flag equal to 1 specifies that QP delta information is present in the PH syntax structure and not in slice headers referencing a PPS that does 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 a PPS that does not contain a PH syntax structure.

[0192] pps_ref_wraparound_enabled_flag equal to 1 specifies that horizontal wraparound motion compensation is applied in inter prediction. pps_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, 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.

[0193] pps_ref_wraparound_offset plus (CtbSizeY / MinCbSizeY)+2 specifies the offset used to calculate the horizontal wrapping 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.

[0194] The variable PpsRefWraparoundOffset is set equal to pps_ref_wraparound_offset+(CtbSizeY / MinCbSizeY)+2.

[0195] 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. picture_header_extension_present_flag shall be equal to 0 in bitstreams conforming to this version of this specification.

[0196] 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.

[0197] 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.

[0198] pps_extension_data_flag 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 pps_extension_data_flag syntax elements.

[0199] PH Syntax and Semantics

[0200] In the latest VVC draft text, the PH syntax and semantics are as follows:

[0201]

[0202] The PH RBSP contains the PH syntax structure, namely picture_header_structure().

[0203]

[0204]

[0205]

[0206]

[0207]

[0208] The PH syntax structure contains information common to all slices of the coded picture associated with the PH syntax structure.

[0209] gdr_or_irap_pic_flag equal to 1 specifies that the current picture is a GDR or IRAP picture. gdr_or_irap_pic_flag equal to 0 specifies that the current picture may or may not be a GDR or IRAP picture.

[0210] 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.

[0211] 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 there may or may not be one or more codec slices with slice_type equal to 0 or 1 in the picture.

[0212] 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.

[0213] NOTE 1 – For bitstreams that should undergo sub-picture based bitstream merging without requiring changes to PH NAL units, the codec shall set the values ​​of ph_inter_slice_allowed_flag and ph_intra_slice_allowed_flag equal to 1.

[0214] 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.

[0215] 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).

[0216] The bitstream conformance requirement is that the value of TemporalId of the 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.

[0217] 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.

[0218] 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.

[0219] 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 in CLVS that follows the current GDR picture in decoding order, whose PicOrderCntVal is equal to the PicOrderCntVal of the current GDR picture plus the value of recovery_poc_cnt, then the picture picA is called the recovery point picture. Otherwise, the first picture in the 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 be before the current GDR picture. The value of recovery_poc_cnt should be in the range of 0 to MaxPicOrderCntLsb–1 (including the end value).

[0220] When the current picture is a GDR picture, the variable RpPicOrderCntVal is derived as follows:

[0221] RpPicOrderCntVal=PicOrderCntVal+recovery_poc_cnt (82)

[0222] 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 preceding the associated GDR picture in decoding order (if any).

[0223] 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.

[0224] 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.

[0225] 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.

[0226] 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.

[0227] ph_num_alf_aps_ids_luma specifies the number of ALF APSs referenced by the slice associated with the PH.

[0228] 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.

[0229] 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].

[0230] 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.

[0231] ph_alf_chroma_idc equal to 0 specifies that the adaptive loop filter is not applied to the Cb and Cr color components. 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 and Cr color components. When ph_alf_chroma_idc is not present, it is inferred to be equal to 0.

[0232] ph_alf_aps_id_chroma specifies the adaptation_parameter_set_id of the ALF APS to which the chroma components of the slice associated with the PH refer.

[0233] 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.

[0234] 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.

[0235] ph_cc_alf_cb_enabled_flag equal to 1 specifies that the cross-component filter of the Cb color component is enabled for all slices associated with the PH and may be applied to the Cb color components in the slices. ph_cc_alf_cb_enabled_flag equal to 0 specifies that the cross-component filter of 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.

[0236] 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.

[0237] 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.

[0238] 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.

[0239] 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.

[0240] 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.

[0241] 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.

[0242] 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.

[0243] ph_lmcs_enabled_flag equal to 1 specifies that luma mapping with chroma scaling is enabled for all slices associated with 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 PH, and when not present, the value of ph_lmcs_enabled_flag is inferred to be equal to 0.

[0244] 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.

[0245] ph_chroma_residual_scale_flag equal to 1 specifies that chroma residual scaling is enabled for all slices associated with 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 PH. When ph_chroma_residual_scale_flag is not present, it is inferred to be equal to 0.

[0246] 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.

[0247] 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.

[0248] ph_virtual_boundaries_present_flag equal to 1 specifies that information about virtual boundaries is signaled in PH. ph_virtual_boundaries_present_flag equal to 0 specifies that information about virtual boundaries is not signaled in PH. When one or more virtual boundaries are signaled in PH, loop filtering operations are disabled on 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.

[0249] 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.

[0250] The variable VirtualBoundariesPresentFlag is exported as follows:

[0251]

[0252] ph_num_ver_virtual_boundaries specifies the number of ph_virtual_boundaries_pos_x[i] syntax elements present in the PH. When ph_num_ver_virtual_boundaries is not present, it is inferred to be equal to 0.

[0253] The variable NumVerVirtualBoundaries is exported as follows:

[0254]

[0255] 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.

[0256] 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:

[0257] for(i=0;i <NumVerVirtualBoundaries;i++)VirtualBoundariesPosX[i]=(sps_virtual_boundaries_present_flag?sps_virtual_boundaries_pos_x[i]:ph_virtual_boundaries_pos_x[i])*8 (85)

[0258] The distance between any two vertical virtual boundaries should be greater than or equal to CtbSizeY luminance samples.

[0259] ph_num_hor_virtual_boundaries specifies the number of ph_virtual_boundaries_pos_y[i] syntax elements present in the PH. When ph_num_hor_virtual_boundaries is not present, it is inferred to be equal to 0.

[0260] The parameter NumHorVirtualBoundaries is derived as follows:

[0261]

[0262]

[0263] 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 zero.

[0264] 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.

[0265] 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:

[0266] for(i=0;i <NumHorVirtualBoundaries;i++)VirtualBoundariesPosY[i]=(sps_virtual_boundaries_present_flag?sps_virtual_boundaries_pos_y[i]:ph_virtual_boundaries_pos_y[i])*8 (87)

[0267] The distance between any two horizontal virtual boundaries should be greater than or equal to CtbSizeY luminance samples.

[0268] 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.

[0269] partition_constraints_override_flag equal to 1 specifies that the partition constraints parameters are present in the PH. partition_constraints_override_flag equal to 0 specifies that the partition constraints parameters are not present in the PH. When not present, the value of partition_constraints_override_flag is inferred to be equal to 0.

[0270] 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 luma leaf blocks resulting from quadtree partitioning of the CTU and the base 2 logarithm of the minimum decoded block size of luma samples of luma CUs in slices with slice_type equal to 2(I) 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.

[0271] ph_max_mtt_hierarchy_depth_intra_slice_luma specifies the maximum hierarchical depth of codec units resulting from multi-type tree partitioning of quadtree leaves 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.

[0272] ph_log2_diff_max_bt_min_qt_intra_slice_luma specifies the difference between the base 2 logarithm of the maximum size (width or height) in 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) in 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) 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.

[0273] ph_log2_diff_max_tt_min_qt_intra_slice_luma specified

[0274] The difference between the base 2 logarithm of the maximum size (width or height) in the luma samples of a luma coding block that may be partitioned using ternary partitioning and the base 2 logarithm of the minimum size (width or height) in the luma samples of luma leaf blocks resulting from quadtree partitioning of a CTU 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_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.

[0275] 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 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.

[0276] ph_max_mtt_hierarchy_depth_intra_slice_chroma specifies the maximum hierarchy depth of 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) 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.

[0277] ph_log2_diff_max_bt_min_qt_intra_slice_chroma specified

[0278] The difference between the base 2 logarithm of the maximum size (width or height) in the luma samples of a chroma codec block that may be partitioned using binary partitioning, and the base 2 logarithm of the minimum size (width or height) in 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.

[0279] ph_log2_diff_max_tt_min_qt_intra_slice_chroma specifies the difference between the base 2 logarithm of the maximum size (width or height) in 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) in 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.

[0280] 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.

[0281] When not present, the value of ph_cu_qp_delta_subdiv_intra_slice is inferred to be equal to 0.

[0282] ph_cu_chroma_qp_offset_subdiv_intra_slice specifies the maximum cbSubdiv value of the codec unit in the intra slices that transmit 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.

[0283] When not present, the value of ph_cu_chroma_qp_offset_subdiv_intra_slice is inferred to be equal to 0.

[0284] 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 quadtree partitioning of the CTU and the base 2 logarithm of the minimum luma codec block size in 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.

[0285] 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.

[0286] ph_log2_diff_max_bt_min_qt_inter_slice specifies the difference between the base 2 logarithm of the maximum size (width or height) in 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) in the luma samples of luma leaf blocks resulting from quadtree partitioning of CTUs in slices with slice_type equal to 0 (B) or 1 (P) associated with PH. The value of ph_log2_diff_max_bt_min_qt_inter_slice should 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.

[0287] ph_log2_diff_max_tt_min_qt_inter_slice specifies the difference between the base 2 logarithm of the maximum size (width or height) in 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) in the luma samples of luma leaf blocks resulting from quadtree partitioning of CTUs in slices with slice_type equal to 0 (B) or 1 (P) associated with PH. The value of ph_log2_diff_max_tt_min_qt_inter_slice should 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.

[0288] ph_cu_qp_delta_subdiv_inter_slice specifies the maximum cbSubdiv value of the codec unit that transmits 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.

[0289] When not present, the value of ph_cu_qp_delta_subdiv_inter_slice is inferred to be equal to 0.

[0290] 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.

[0291] When not present, the value of ph_cu_chroma_qp_offset_subdiv_inter_slice is inferred to be equal to 0.

[0292] ph_temporal_mvp_enabled_flag specifies whether the temporal motion vector predictor can be used for inter prediction of the 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 should be equal to 0 when no reference picture in the DPB has the same spatial resolution as the current picture.

[0293] The maximum number of sub-block-based merging MVP candidates, MaxNumSubblockMergeCand, is derived as follows:

[0294]

[0295] The value of MaxNumSubblockMergeCand should be in the range of 0 to 5 (inclusive).

[0296] 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.

[0297] ph_collocated_ref_idx specifies the reference index of the collocated picture used for temporal motion vector prediction.

[0298] When ph_collocated_from_l0_flag is equal to 1, ph_collocated_ref_idx refers to the 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).

[0299] 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).

[0300] When not present, the value of ph_collocated_ref_idx is inferred to be equal to 0.

[0301] 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.

[0302] ph_fpel_mmvd_enabled_flag equal to 1 specifies that merge mode with motion vector differences uses integer sample precision in slices associated with 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 PH. When not present, the value of ph_fpel_mmvd_enabled_flag is inferred to be 0.

[0303] ph_disable_bdof_flag equal to 1 specifies that inter-frame bi-directional prediction based on bidirectional optical flow inter-frame prediction is disabled in the slices associated with the PH. ph_disable_bdof_flag equal to 0 specifies that inter-frame bi-directional prediction based on bidirectional optical flow inter-frame prediction may be enabled or not enabled in the slices associated with the PH.

[0304] When ph_disable_bdof_flag is not present, the following applies:

[0305] --If sps_bdof_enabled_flag is equal to 1, the value of ph_disable_bdof_flag is inferred to be equal to 0.

[0306] --Otherwise (sps_bdof_enabled_flag is equal to 0), the value of ph_disable_bdof_flag is inferred to be equal to 1.

[0307] ph_disable_dmvr_flag equal to 1 specifies that inter bi-prediction based on decoder motion vector refinement is disabled in slices associated with the PH. ph_disable_dmvr_flag equal to 0 specifies that inter bi-prediction based on decoder motion vector refinement may or may not be enabled in slices associated with the PH.

[0308] When ph_disable_dmvr_flag is not present, the following applies:

[0309] --If sps_dmvr_enabled_flag is equal to 1, the value of ph_disable_dmvr_flag is inferred to be equal to 0.

[0310] --Otherwise (sps_dmvr_enabled_flag is equal to 0), the value of ph_disable_dmvr_flag is inferred to be equal to 1.

[0311] ph_disable_prof_flag equal to 1 specifies that prediction refinement of optical flow is disabled in the 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 the slices associated with PH.

[0312] When ph_disable_prof_flag is not present, the following applies:

[0313] --If sps_affine_prof_enabled_flag is equal to 1, the value of ph_disable_prof_flag is inferred to be equal to 0.

[0314] --Otherwise (sps_affine_prof_enabled_flag is equal to 0), the value of ph_disable_prof_flag is inferred to be equal to 1.

[0315] 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.

[0316] 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 SliceQpY is derived as follows:

[0317] SliceQp Y=26+init_qp_minus26+ph_qp_delta (89)

[0318] SliceQp Y The value should be in the range of -QpBdOffset to +63 (inclusive).

[0319] ph_joint_cbcr_sign_flag specifies whether the co-located residual samples of the two chroma components have inverted 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 a 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 co-located 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 inverted sign of the co-located Cb (or Cr) residual sample.

[0320] 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.

[0321] 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.

[0322] ph_dep_quant_enabled_flag equal to 0 specifies that correlated quantization is disabled for the current picture. ph_dep_quant_enabled_flag equal to 1 specifies that correlated quantization is enabled for the current picture. When ph_dep_quant_enabled_flag is not present, it is inferred to be equal to 0.

[0323] 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.

[0324] 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.

[0325] 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.

[0326] ph_beta_offset_div2 and ph_tc_offset_div2 specify the deblocking parameter offsets for beta 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.

[0327] ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 specify the deblocking parameter offsets for beta 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.

[0328] 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 component of the slice associated with the PH. The values ​​of ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 should 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.

[0329] 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.

[0330] ph_extension_data_byte can have any value. Decoders conforming to this version of this specification should 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.

[0331] SH Syntax and Semantics

[0332] In the latest VVC draft text, the SH syntax and semantics are as follows:

[0333]

[0334]

[0335]

[0336]

[0337] The variable CuQpDeltaVal, which specifies the difference between the luma quantization parameter and its prediction for the codec unit containing cu_qp_delta_abs, is set equal to 0. The variable CuQpDeltaVal, which specifies the difference between the luma quantization parameter and its prediction for the codec unit containing cu_chroma_qp_offset_flag, is set equal to 0. 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.

[0338] 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.

[0339] A bitstream conformance requirement is that the value of picture_header_in_slice_header_flag shall be the same in all codec slices in CLVS.

[0340] When picture_header_in_slice_header_flag is equal to 1 for a codec slice, the bitstream conformance requirement is that there shall be no VCL NAL units with nal_unit_type equal to PH_NUT in the CLVS.

[0341] 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.

[0342] 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.

[0343] 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.

[0344] If rect_slice_flag is equal to 0, the following applies:

[0345] --The stripe address is the raster scan stripe index.

[0346] --slice_address has a length of Ceil(Log2(NumTilesInPic)) bits.

[0347] The value of --slice_address should be in the range of 0 to NumTilesInPic–1 (inclusive).

[0348] Otherwise (rect_slice_flag is equal to 1), the following applies:

[0349] --The strip address is the sub-picture level strip index of the strip.

[0350] --The length of slice_address is Ceil(Log2(NumSlicesInSubpic[CurrSubpicIdx])) bits.

[0351] --slice_address values ​​should be in the range of 0 to NumSlicesInSubpic[CurrSubpicIdx]–1 (inclusive).

[0352] The requirement for bitstream conformance is that the following constraints apply:

[0353] --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.

[0354] -- 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.

[0355] -- The shape of the slices of a picture shall be such that, when each CTU is decoded, its entire left and entire top borders shall consist of either the picture boundary or the boundaries of the previously decoded CTU(s).

[0356] 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.

[0357] 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.

[0358] 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:

[0359]

[0360]

[0361] The variables SubpicLeftBoundaryPos, SubpicTopBoundaryPos, SubpicRightBoundaryPos, and SubpicBotBoundaryPos are derived as follows:

[0362]

[0363] slice_type specifies the codec type of the slice according to Table 9.

[0364] Table 9 – Name associations with slice_type

[0365] slice_type slice_type name 0 B(B band) 1 P(P stripe) 2 I(I strip)

[0366] When not present, the value of slice_type is inferred to be equal to 2.

[0367] 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.

[0368] The variables MinQtLog2SizeY, MinQtLog2SizeC, MinQtSizeY, MinQtSizeC, MaxBtSizeY, MaxBtSizeC, MinBtSizeY, MaxTtSizeY, MaxTtSizeC, MinTtSizeY, MaxMttDepthY and MaxMttDepthC are derived as follows:

[0369] --If slice_type is equal to 2 (I), the following applies:

[0370] MinQtLog2SizeY=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_intra_slice_luma (119)

[0371] MinQtLog2SizeC=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_intra_slice_chroma (120)

[0372] MaxBtSizeY=1<<(MinQtLog2SizeY+ph_log2_diff_max_bt_min_qt_intra_slice_luma) (121)

[0373] MaxBtSizeC=1<<(MinQtLog2SizeC+ph_log2_diff_max_bt_min_qt_intra_slice_chroma) (122)

[0374] MaxTtSizeY = 1 << (MinQtLog2SizeY + ph_log2_diff_max_tt_min_qt_intra_slice_luma) (123)

[0375] MaxTtSizeC = 1 << (MinQtLog2SizeC + ph_log2_diff_max_tt_min_qt_intra_slice_chroma) (124)

[0376] MaxMttDepthY = ph_max_mtt_hierarchy_depth_intra_slice_luma (125)

[0377] MaxMttDepthC = ph_max_mtt_hierarchy_depth_intra_slice_chroma (126)

[0378] CuQpDeltaSubdiv = ph_cu_qp_delta_subdiv_intra_slice (127)

[0379] CuChromaQpOffsetSubdiv = ph_cu_chroma_qp_offset_subdiv_intra_slice(128)

[0380] -- Otherwise (slice_type equals 0 (B) or 1 (P)), the following applies:

[0381] MinQtLog2SizeY = MinCbLog2SizeY + ph_log2_diff_min_qt_min_cb_inter_slice(129)

[0382] MinQtLog2SizeC = MinCbLog2SizeY + ph_log2_diff_min_qt_min_cb_inter_slice(130)

[0383] MaxBtSizeY = 1 << (MinQtLog2SizeY + ph_log2_diff_max_bt_min_qt_inter_slice) (131)

[0384] MaxBtSizeC = 1 << (MinQtLog2SizeC + ph_log2_diff_max_bt_min_qt_inter_slice) (132)

[0385] MaxTtSizeY = 1 << (MinQtLog2SizeY + ph_log2_diff_max_tt_min_qt_inter_slice) (133)

[0386] MaxTtSizeC = 1 << (MinQtLog2SizeC + ph_log2_diff_max_tt_min_qt_inter_slice) (134)

[0387] MaxMttDepthY = ph_max_mtt_hierarchy_depth_inter_slice (135)

[0388] MaxMttDepthC = ph_max_mtt_hierarchy_depth_inter_slice (136)

[0389] CuQpDeltaSubdiv = ph_cu_qp_delta_subdiv_inter_slice (137)

[0390] CuChromaQpOffsetSubdiv = ph_cu_chroma_qp_offset_subdiv_inter_slice(138)

[0391] -- The following applies:

[0392] MinQtSizeY = 1 << MinQtLog2SizeY (139)

[0393] MinQtSizeC = 1 << MinQtLog2SizeC (140)

[0394] MinBtSizeY = 1 << MinCbLog2SizeY (141)

[0395] MinTtSizeY = 1 << MinCbLog2SizeY (142)

[0396] slice_alf_enabled_flag equal to 1 specifies that the adaptive loop filter is enabled and may 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.

[0397] slice_num_alf_aps_ids_luma specifies the number of ALFAPS 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.

[0398] slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALFAPS referenced by the luma component of the slice. The TemporalId of the APS NAL units 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 NAL units of the coded slice. 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].

[0399] 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].

[0400] 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 component. 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.

[0401] 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 the APS NAL unit 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 codec 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.

[0402] 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.

[0403] slice_cc_alf_cb_enabled_flag equal to 0 specifies that the cross-component filter is not applied to the Cb color component. slice_cc_alf_cb_enabled_flag equal to 1 indicates that the cross-component filter is 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.

[0404] slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id referenced by the Cb color component of the slice.

[0405] 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.

[0406] 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.

[0407] 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 may 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.

[0408] 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.

[0409] 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.

[0410] 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 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.

[0411] NOTE 1 – There is no dependency between the decoding processes of different color planes of a picture.

[0412] num_ref_idx_active_override_flag equal to 1 specifies that the syntax element num_ref_idx_active_minus1[0] is present in P 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.

[0413] 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.

[0414] 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.

[0415] 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.

[0416] The variable NumRefIdxActive[i] is derived as follows:

[0417]

[0418] 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 is available for decoding the slice.

[0419] When the current slice is a P slice, the value of NumRefIdxActive[0] should be greater than 0.

[0420] When the current slice is a B slice, NumRefIdxActive[0] and NumRefIdxActive[1] should both be greater than 0.

[0421] 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.

[0422] 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.

[0423] 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:

[0424] --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.

[0425] --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.

[0426] slice_collocated_ref_idx specifies the reference index of the collocated picture used for temporal motion vector prediction.

[0427] 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 shall be in the range of 0 to NumRefIdxActive[0]−1, inclusive.

[0428] 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).

[0429] When slice_collocated_ref_idx is not present, the following applies:

[0430] --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.

[0431] --Otherwise (rpl_info_in_ph_flag is equal to 0), the value of slice_collocated_ref_idx is inferred to be equal to 0.

[0432] 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.

[0433] The bitstream conformance requirement is 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 of the current picture, respectively, and RprConstraintsActive[slice_collocated_from_l0_flag? 0:1][slice_collocated_ref_idx] shall be equal to 0.

[0434] slice_qp_delta specifies the Qp used for the codec blocks in the slice. Y The initial value of until it is modified by the value of CuQpDeltaVal in the codec unit layer.

[0435] 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:

[0436] SliceQp Y =26+init_qp_minus26+slice_qp_delta (144)

[0437] SliceQp Y The value should be in the range of -QpBdOffset to +63 (inclusive).

[0438] When any of the following conditions is true:

[0439] --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.

[0440] --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.

[0441] The following applies:

[0442] --The value of NumRefIdxActive[0] shall be less than or equal to the value of NumWeightsL0.

[0443] – 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.

[0444] 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:

[0445] --The value of NumRefIdxActive[1] shall be less than or equal to the value of NumWeightsL1.

[0446] – 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.

[0447] slice_cb_qp_offset specifies the offset in determining Qp′ CbThe difference to be added to the value of pps_cb_qp_offset when quantizing the parameter value. The value of slice_cb_qp_offset shall be in the range -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 shall be in the range -12 to +12, inclusive.

[0448] slice_cr_qp_offset specifies the offset in determining 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 -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 -12 to +12, inclusive.

[0449] slice_join_cbcr_qp_offset specifies the offset in determining Qp′ 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.

[0450] 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.

[0451] slice_sao_luma_flag equal to 1 specifies that SAO is enabled for luma components in the current slice; slice_sao_luma_flag equal to 0 specifies that SAO is disabled for 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.

[0452] 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.

[0453] 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.

[0454] slice_deblocking_filter_disabled_flag equal to 1 specifies that the operation of the deblocking filter is not applied to the current slice. slice_deblocking_filter_disabled_flag equal to 0 specifies that the operation of the deblocking filter 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.

[0455] 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 components 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.

[0456] 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 should 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.

[0457] 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 should 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.

[0458] 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.

[0459] 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.

[0460] 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.

[0461] The variable NumEntryPoints specifies the number of entry points in the current strip and is derived as follows:

[0462]

[0463] 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).

[0464] 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:

[0465]

[0466] lastByte[k]=firstByte[k]+entry_point_offset_minus1[k] (147)

[0467] The last subset (where the subset index is equal to NumEntryPoints) consists of the remaining bytes of the encoded and decoded slice data.

[0468] 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.

[0469] 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.

[0470] When sps_entropy_coding_sync_enabled_flag is equal to 1, each subset k in the range of 0 to NumEntryPoints (including the end value) 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.

[0471] 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.

[0472] slice_header_extension_data_byte[i] can have any value. Decoders conforming to this version of this specification shall ignore the value of all slice_header_extension_data_byte[i] syntax elements. Its value does not affect the conformance of a decoder to the profile specified in this version of this specification.

[0473] 4. Examples of technical problems solved

[0474] The existing designs of PPS, PH and SH grammars have the following problems:

[0475] 1) According to the latest VVC draft text, for any picture in CLVS, if the PH syntax structure is included in the SH instead of the PH NAL unit, each picture in the CLVS has only one slice, and the PH syntax structure of each picture in the CLVS is included in the SH instead of the PH NAL unit. In this case, the signaling of the six PPS flags rpl_info_in_ph_flag, dbf_info_in_ph_flag, sao_info_in_ph_flag, alf_info_in_ph_flag, wp_info_in_ph_flag, and qp_delta_info_in_ph_flag in the PPS referenced by the picture in the CLVS is useless.

[0476] 2) According to the latest VVC draft text, when the condition "A&B||C" is met, the syntax element num_ref_idx_active_override_flag in the SH syntax is signaled, where "A" indicates "rpl_info_in_ph_flag is equal to 1, or the NAL unit type is not IDR, or sps_idr_rpl_present_flag is equal to 1", "B" indicates "slice_type is equal to P or B, and the number of reference entries in reference picture list 0 is greater than 1", and "C" indicates "slice_type is equal to B and the number of reference entries in reference picture list 1 is greater than 1". In this case, when rpl_info_in_ph_flag is equal to 0, the NAL unit type is IDR, and sps_idr_rpl_present_flag is equal to 0, but at the same time slice_type is equal to B, and the number of reference entries in list 1 is greater than 1, the parameters about num_ref_idx_active_minus1[0] and num_ref_idx_active_minus1[1] may still be overwritten and set to certain numbers; this may lead to unexpected decoder behavior, including decoder crashes.

[0477] 3) The syntax structure ref_pic_list_struct() may be included in the SPS and / or PH or SH. When ref_pic_list_struct() is included in the PH or SH and long_term_ref_pics_flag is equal to 1, the syntax element ltrp_in_header_flag[][] will be signaled in the ref_pic_list_struct() to indicate whether the picture order count value of the LTRP entry is signaled by the syntax element rpls_poc_lsb_lt[][][] in the ref_pic_list_struct() in the PH / SH or directly in the ref_pic_lists() in the PH or SH by the syntax element poc_lsb_lt[][] . However, in this case, the signaling of ltrp_in_header_flag in the ref_pic_list_struct() is meaningless because the LTRP POC information will be signaled in the picture header instead of in the SPS.

[0478] 4) The syntax structure ref_pic_lists() shall be included in either PH or SH. When ref_pic_lists() is included in SH, the reference picture information of both reference picture list 0 and reference picture list 1 is always signaled, even if slice_type is equal to P. In this case (when ref_pic_lists() is included in SH and slice_type = P), the signaling of the reference picture list 1 reference information (e.g., rpl_sps_flag[1], rpl_idx[1], poc_lsb_lt[1][j], delta_poc_msb_present_flag[1][j], delta_poc_msb_cycle_lt[1][j], where j is in the range of 0 to NumLtrpEntries[1][RplsIdx[1]-1 (inclusive)) in ref_pic_lists() for P slices becomes useless.

[0479] 5. Example Techniques and Embodiments

[0480] To solve the above problems and some other unmentioned problems, the methods summarized in the following list are disclosed. These items should be considered as examples to explain the general concept and should not be interpreted in a narrow way. In addition, these items can be used alone or in combination in any way.

[0481] 1. To address the first issue, whether the signaling indication of certain information should be present in the PH or SH (e.g., rpl_info_in_ph_flag, dbf_info_in_ph_flag, sao_info_in_ph_flag, alf_info_in_ph_flag, wp_info_in_ph_flag, and qp_delta_info_in_ph_flag in the PPS) and / or the presence of the picture header syntax structure in the slice header (e.g., picture_header_in_slice) may depend on the indication of whether there is only one slice per picture in the CLVS.

[0482] 1) When there is an indication that there is only one slice per picture in the CLVS, for a CLVS with only one slice per picture, no signaling is required regarding an indication of certain information present in the PH or SH (e.g., one or more of the 6 PPS flags), since in this case the PH is in the SH.

[0483] a. In one example, an indication of whether each picture that references the PPS has only one slice may be signaled in the PPS.

[0484] i. Alternatively, an indication of whether each picture that references the PPS has only one intra slice may be signaled in the PPS.

[0485] ii. Alternatively, an indicator may be signaled in the PPS to indicate whether each picture referencing the PPS has only one inter slice.

[0486] b. In one example, the indication may be a flag in the PPS, for example named pps_one_slice_per_picture_flag. Alternatively, or in addition, the flag equal to 1 specifies that each picture of the referenced PPS has only one slice, and the flag equal to 0 specifies that each picture of the referenced PPS has one or more slices.

[0487] i. Alternatively, the indication may not be signaled but inferred from the signaled slice partitioning information, such as the PPS syntax element num_slices_in_pic_minus1 being equal to 0 (signaled or inferred, in either case the value of rect_slice_flag will be equal to 1, since num_slices_in_pic_minus1 is not signaled when rect_slice_flag is equal to 0, and the value is not inferred either.) Therefore, when rect_slice_flag is equal to 1, pps_one_slice_per_picture_flag being equal to 1 is equivalent to num_slices_in_pic_minus1 being equal to 0. The disadvantage of this alternative approach is that it does not cover the case where rect_slice_flag is equal to 0, whereas the approach using pps_one_slice_per_picture_flag is applicable to both the cases where rect_slice_flag is equal to 0 and rect_slice_flag is equal to 1.

[0488] ii. In addition, in one example, when sps_num_subpics_minus1 is greater than 0, the value of pps_one_slice_per_picture_flag needs to be equal to 0.

[0489] iii. In addition, the flag may need to be the same for all PPSs referenced by a picture in a CLVS.

[0490] iv. In addition, when the value of one_slice_per_pic_constraint_flag is equal to 1, this flag can be required to be equal to 1.

[0491] v. In addition, the semantics of one_slice_per_pic_constraint_flag is updated by adding that one_slice_per_pic_constraint_flag equal to 1 also specifies that pps_one_slice_per_picture_flag should be equal to 1.

[0492] vi. When it is known from the PPS that there is only one sub-picture in each picture (for example, sps_num_subpics_minus1 is 0) and each sub-picture contains only one slice (in this case, it can be known that each picture contains only one slice), the signaling of this flag in the PPS can be skipped.

[0493] c. When the indication indicates that each picture contains only one slice (eg, pps_one_slice_per_picture_flag is equal to 1), the signaling of indications of certain information present in the PH or SH (eg, 6 PPS flags) may be skipped.

[0494] i. In addition, when pps_one_slice_per_picture_flag is equal to 1, the values ​​of the 6 flags are all inferred to be equal to 0.

[0495] Note that for at least some parameters, such as those related to RPL (such as co-located pictures and weighted prediction parameters), inferring them to be 0 is better (than inferring them to be equal to 1) because the number of active entries is known for their signaling, and knowing this can make the signaling more optimized.

[0496] 1. Alternatively, in addition, when pps_one_slice_per_picture_flag is equal to 1, the values ​​of the 6 flags are all inferred to be equal to 1.

[0497] 2. Alternatively, when pps_one_slice_per_picture_flag is equal to 1, additionally, the value of each of the 6 flags except wp_info_in_ph_flag is inferred to be equal to 1 or 0, regardless of how the other flags are inferred, and for wp_info_in_ph_flag, when rpl_info_in_ph_flag is equal to 0, the value is inferred to be equal to 0, and when rpl_info_in_ph_flag is equal to 1, the value is inferred to be 1 or 0, regardless of the values ​​of the other 4 of the 6 flags.

[0498] d. When the indication indicates that each picture contains only one slice (e.g., pps_one_slice_per_picture_flag is equal to 1), the signaling of picture_header_in_slice_header_flag in the SH syntax can be skipped, for example, by adjusting the syntax element to "if (!pps_one_slice_per_picture_flag)" and inferring the value of picture_header_in_slice_header_flag when pps_one_slice_per_picture_flag is equal to 1.

[0499] e. When pps_one_slice_per_picture_flag is equal to 1, the signaling of slice_address in the SH syntax can be skipped as follows (the added parts are italicized and underlined):

[0500]

[0501] And add the following inference:

[0502] f. When pps_one_slice_per_picture_flag is equal to 1, the signaling of num_tiles_in_slice_minus1 in the SH syntax can be skipped as follows:

[0503]

[0504] And add the following inference:

[0505] g. Instead of all the above, do not add the flag pps_one_slice_per_picture_flag, but when picture_header_in_slice_header_flag of any slice referencing the PPS is equal to 1, the values ​​of the six PPS flags are required to be equal to 0.

[0506] i. This is technically equivalent to the following constraint added to the semantics of picture_header_in_slice_header_flag (editorially better): when any of the six PPS flags is equal to 1, the value of picture_header_in_slice_header_flag shall be equal to 0.

[0507] h. Instead of all the above, do not add the flag pps_one_slice_per_pic_flag, but when one_slice_per_pic_constraint_flag is equal to 1, the values ​​of the six PPS flags need to be equal to 0.

[0508] i. Independently of any of the above, the following constraint may be added: when one_slice_per_pic_constraint_flag is equal to 1, the value of picture_header_in_slice_header_flag shall be equal to 1. Technically equivalently, the semantics of one_slice_per_pic_constraint_flag is updated by adding one_slice_per_pic_constraint_flag equal to 1, also specifying that picture_header_in_slice_header_flag shall be equal to 1 (for all slices in each OLS to which the PTL syntax structure containing this flag applies).

[0509] j. When pps_one_slice_per_picture_flag is equal to 1, the signaling of rect_slice_flag in the PPS syntax can be skipped as follows (the added parts are italicized and underlined):

[0510]

[0511] i. And add the following inference:

[0512] k. When pps_one_slice_per_picture_flag is equal to 1, the signaling of single_slice_per_subpic_flag in the PPS syntax can be skipped as follows (the additions are italicized and underlined):

[0513]

[0514] i. And add the following inference:

[0515] 1. When pps_one_slice_per_picture_flag is equal to 1, the signaling of loop_filter_cross_slices_enabled_flag in the PPS syntax can be skipped, for example, by adjusting the syntax element to "if(!pps_one_slice_per_picture_flag)" and inferring the value of loop_filter_cross_slices_enabled_flag when pps_one_slice_per_picture_flag is equal to 0.

[0516] m. In one example, an indication of whether each picture in the CLVS has only one slice may be signaled in the SPS associated with the CLVS.

[0517] n. In one example, an indication of whether there is only one slice per picture in the CLVS may be signaled in the SPS associated with the CLVS.

[0518] o. When it is indicated that each picture associated with the first PPS has only one slice, one or more syntax elements related to slice partitioning (such as rect_slice_flag, single_slice_per_subpic_flag, num_slices_in_pic_minus1, tile_idx_delta_present_flag, slice_width_in_tiles_minus1, slice_height_in_tiles_minus1, num_exp_slices_in_tile, exp_slice_height_in_ctus_minus1, tile_idx_delta, etc. in JVET-Q2001-vC) may not be signaled in the first PPS.

[0519] i. In one example, the indication is pps_one_slice_per_picture_flag, which is included in the PPS syntax before the slice signaling syntax, for example, just before rect_slice_flag.

[0520] 1. Additionally, in one example, when pps_one_slice_per_picture_flag is equal to 1 and rect_slice_flag is not signaled, its value is inferred to be equal to 1.

[0521] 2. Additionally, in one example, when pps_one_slice_per_picture_flag is equal to 1 and single_slice_per_subpic_flag is not signaled, its value is inferred to be equal to 1.

[0522] 3. Additionally, in one example, when pps_one_slice_per_picture_flag is equal to 1 and num_slices_in_pic_minus1 is not signaled, its value is inferred to be equal to 0.

[0523] p. When it is indicated that each picture associated with the first PPS has only one slice, one or more syntax elements related to slice partitioning (e.g., num_exp_tile_columns_minus1, num_exp_tile_rows_minus1, tile_column_width_minus1, tile_row_height_minus1 in JVET-Q2001-vC) may not be signaled in the first PPS.

[0524] i. In one example, the indication is pps_one_tile_per_picture_flag, which is included in the PPS syntax before the slice signaling syntax, for example, just before pps_log2_ctu_size_minus5 (but under the same syntax condition "if (!no_pic_partition_flag)").

[0525] 2. About the signaling of the syntax element num_ref_idx_active_override_flag in SH:

[0526] 1) To solve the second problem, the syntax element num_ref_idx_active_override_flag in SH can be signaled by the condition "A&(B||C)", where "A" indicates "rpl_info_in_ph_flag=1, or the NAL unit type is not equal to IDR, or sps_idr_rpl_present_flag is equal to 1", and "B" indicates "slice_type is equal to P or B, and the number of reference entries in reference picture list 0 is greater than 1", and "C" indicates "slice_type is equal to B, and the number of reference entries in reference picture list 1 is greater than 1".

[0527] a. In one example, the following syntax in PH:

[0528]

[0529] Change it to the following:

[0530]

[0531] 3. To solve the third problem, the following method for signaling the syntax elements ltrp_in_header_flag[listIdx][rplsIdx] and rpls_poc_lsb_lt[listIdx][rplsIdx][i] in the syntax structure ref_pic_list_struct() is disclosed:

[0532] 1) Whether to signal the syntax elements related to the value of the picture order count for long-term reference in the syntax structure ref_pic_list_struct() (e.g., ltrp_in_header_flag and / or rpls_poc_lsb_lt) may depend on whether the index of the reference picture list (e.g., rplsIdx) is less than the number of ref_pic_list_struct(listIdx, rplsIdx) syntaxes in the SPS (e.g., num_ref_pic_lists_in_sps[listIdx]), as in the second embodiment,

[0533] a. In one example, if the index of the reference picture list is equal to the number of ref_pic_list_struct(listIdx, rplsIdx) syntax in the SPS (i.e., rplsIdx is equal to num_ref_pic_lists_in_sps[listIdx]), then the syntax elements related to the value of the picture sequence count for long-term reference (e.g., ltrp_in_header_flag) may not be signaled, and the value of ltrp_in_header_flag is inferred to be equal to 1 or 0.

[0534] 2) Alternatively, whether syntax elements related to the value of the picture order count for long-term reference (e.g., ltrp_in_header_flag and / or rpls_poc_lsb_lt) are signaled in the syntax structure ref_pic_list_struct() may depend on whether the syntax structure ref_pic_list_struct() is included in the SPS, as in the second embodiment.

[0535] a. In one example, if the syntax structure ref_pic_list_struct() is not included in the SPS, the syntax elements related to the value of the picture sequence count for long-term reference (eg, ltrp_in_header_flag) may not be signaled, and the value of ltrp_in_header_flag is inferred to be equal to 1 or 0.

[0536] 3) Alternatively, instead of signaling ltrp_in_header_flag within ref_pic_list_struct(), signal it directly in the SPS, one for each ref_pic_list_struct() in the SPS, for example, as follows:

[0537]

[0538]

[0539]

[0540] And the ref_pic_list_struct(listIdx, rplsIdx) syntax changes as follows. Deleted text is marked with double brackets (for example, [[a]] means to delete the character "a"):

[0541]

[0542] 4) Alternatively, instead of signaling ltrp_in_header_flag in ref_pic_list_struct(), signal it directly in the SPS, one for list 0 and one for list 1, for example, as follows:

[0543]

[0544]

[0545] And the ref_pic_lists() sytnax is changed as follows:

[0546] if(ltrp_in_header_flag[i][[[RplsIdx[i]]]]) poc_lsb_lt[i][j] u(v)

[0547] And the ref_pic_list_struct(listIdx, rplsIdx) syntax changes as follows:

[0548]

[0549]

[0550] 5) Alternatively, instead of signaling ltrp_in_header_flag in ref_pic_list_struct(), signal directly in the SPS, only one, for example, as follows:

[0551]

[0552]

[0553] And the ref_pic_lists() sytnax is changed as follows:

[0554] if(ltrp_in_header_flag[[[i][RplsIdx[i]]]]) poc_lsb_lt[i][j] u(v)

[0555] And the ref_pic_list_struct(listIdx, rplsIdx) syntax changes as follows:

[0556]

[0557] 6) Alternatively, instead of signaling ltrp_in_header_flag and rpls_poc_lsb_lt within a ref_pic_list_struct(), they may be signaled directly in the SPS, one set per ref_pic_list_struct() in the SPS, for example, as in the second embodiment.

[0558] 7) Alternatively, instead of signaling ltrp_in_header_flag and rpls_poc_lsb_lt within ref_pic_list_struct(), they are signaled directly in the SPS, one set each for list 0 and list 1, for example, as in the second embodiment.

[0559] 8) Alternatively, instead of signaling ltrp_in_header_flag and rpls_poc_lsb_lt within ref_pic_list_struct(), they are signaled directly in the SPS, with only one set, for example, as in the second embodiment.

[0560] 4. Signaling of syntax elements related to reference pictures in reference picture list 1 in the syntax structure ref_pic_list():

[0561] 1) To address the fourth issue, whether syntax elements related to reference information of reference picture list 1 (e.g., rpl_sps_flag[1], rpl_idx[1], poc_lsb_lt[1][j], delta_poc_msb_present_flag[1][j], delta_poc_msb_cycle_lt[1][j], where j is in the range of 0 to NumLtrpEntries[1][RplsIdx[1]-1 (including the end values)) are signaled in the syntax structure ref_pic_list() may depend on a variable X (e.g., X=1 or 2 or depends on the slice type), as in the third embodiment.

[0562] 6. Examples

[0563]

[0564] First embodiment

[0565] This is an embodiment of items 1, 1.1, 1.1.a, 1.1.b, 1.1.b.iii, 1.1.b.iv, 1.1.c, 1.1.ci, 1.1.e, 1.1.f and 1.1.i summarized in Section 5 above.

[0566] 7.3.2.4 Picture parameter set RBSP syntax

[0567]

[0568] 7.4.3.4 Picture parameter set RBSP semantics ...

[0570]

[0571] 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 a PPS that does 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 a PPS that does not contain the PH syntax structure.

[0572] dbf_info_in_ph_flag equal to 1 specifies that the deblocking filter information is present in the PH syntax structure and not in the slice headers referencing a PPS that does not contain the PH syntax structure. dbf_info_in_ph_flag equal to 0 specifies that the deblocking filter information is not present in the PH syntax structure and may be present in the slice headers referencing a PPS that does not contain the PH syntax structure. When not present, the value of dbf_info_in_ph_flag is inferred to be equal to 0.

[0573] sao_info_in_ph_flag equal to 1 specifies that the SAO filter information is present in the PH syntax structure and not in slice headers referencing a PPS that does not contain a 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 a PPS that does not contain a PH syntax structure.

[0574] 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 the 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 the PH syntax structure.

[0575] wp_info_in_ph_flag equal to 1 specifies that weighted prediction information may be present in the PH syntax structure and not in slice headers referencing a PPS that does 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 a PPS that does not contain a PH syntax structure. When not present, the value of wp_info_in_ph_flag is inferred to be equal to 0.

[0576] qp_delta_info_in_ph_flag equal to 1 specifies that QP delta information is present in the PH syntax structure and not in slice headers referencing a PPS that does 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 a PPS that does not contain a PH syntax structure. ...

[0578] 7.3.7.1 General Strip Header Syntax

[0579]

[0580] 7.4.8.1 General Strip Header Semantics ...

[0582] 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.

[0583] A bitstream conformance requirement is that the value of picture_header_in_slice_header_flag shall be the same in all codec slices in CLVS.

[0584] When picture_header_in_slice_header_flag is equal to 1 for a codec slice, the bitstream conformance requirement is that there shall be no VCL NAL units with nal_unit_type equal to PH_NUT in the CLVS.

[0585] 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.

[0586]

[0587] 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.

[0588] 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. ]]

[0589] If rect_slice_flag is equal to 0, the following applies:

[0590] --The stripe address is the raster scan stripe index.

[0591] --slice_address has a length of Ceil(Log2(NumTilesInPic)) bits.

[0592] The value of --slice_address should be in the range of 0 to NumTilesInPic–1 (inclusive).

[0593] Otherwise (rect_slice_flag is equal to 1), the following applies:

[0594] --The strip address is the sub-picture level strip index of the strip.

[0595] --The length of slice_address is Ceil(Log2(NumSlicesInSubpic[CurrSubpicIdx])) bits.

[0596] --slice_address values ​​should be in the range of 0 to NumSlicesInSubpic[CurrSubpicIdx]–1 (inclusive).

[0597] The requirement for bitstream conformance is that the following constraints apply:

[0598] --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.

[0599] -- 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.

[0600] -- The shape of the slices of a picture shall be such that, when each CTU is decoded, its entire left and entire top borders shall consist of either the picture boundary or the boundaries of the previously decoded CTU(s).

[0601] 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.

[0602] num_tiles_in_slice_minus1 plus 1 [[, if present,]] specifies The number of tiles in a stripe. The value of num_tiles_in_slice_minus1 should be in the range of 0 to NumTilesInPic–1, inclusive. ...

[0604] 6.1. Second embodiment

[0605] This is an embodiment of items 3.1, 3.1a, 3.2, 3.2a, 3.6, 3.7 and 3.8 summarized in Section 5 above.

[0606] 6.1.1. Examples of Items 3.1 and 3.1a

[0607] In one example, ref_pic_list_struct(listIdx, rplsIdx) is changed as follows:

[0608]

[0609]

[0610] 6.1.2. Examples of Items 3.2 and 3.2a

[0611] Alternatively, ref_pic_list_struct(listIdx, rplsIdx) is changed as follows:

[0612]

[0613] ltrp_in_header_flag[listIdx][rplsIdx] equal to 0 specifies that the POC LSB of the LTRP entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure is present in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure. ltrp_in_header_flag[listidx][rplsIdx] equal to 1 specifies that the POC LSB of the LTRP entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure is not present in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure.

[0614] 6.1.3. Implementation of Item 3.6

[0615] Alternatively, seq_parameter_set_rbsp() and ref_pic_list_struct() can be changed as follows:

[0616]

[0617]

[0618] And the ref_pic_list_struct(listIdx, rplsIdx) syntax changes as follows:

[0619]

[0620]

[0621] [[ltrp_in_header_flag[listIdx][rplsIdx] equal to 0 specifies that the POC LSB of the LTRP entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure is present in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure. ltrp_in_header_flag[listidx][rplsIdx] equal to 1 specifies that the POC LSB of the LTRP entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure is not present in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure.

[0622] rpls_poc_lsb_lt[listIdx][rplsIdx][i] specifies the value of the picture order count modulo MaxPicOrderCntLsb of the picture referenced by the i-th entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure. The length of the rpls_poc_lsb_lt[listIdx][rplsIdx][i] syntax element is log2_max_pic_order_cnt_lsb_minus4+4 bits. ]]

[0623] 6.1.4. Implementation of Item 3.7

[0624] Alternatively, seq_parameter_set_rbsp() and ref_pic_list_struct() can be changed as follows:

[0625]

[0626]

[0627]

[0628] And the ref_pic_lists() syntax changes as follows:

[0629] if(ltrp_in_header_flag[i][[[RplsIdx[i]]]]) poc_lsb_lt[i][j] u(v)

[0630] And the ref_pic_list_struct(listIdx, rplsIdx) syntax changes as follows:

[0631]

[0632]

[0633] [[ltrp_in_header_flag[listIdx][rplsIdx] equal to 0 specifies that the POC LSB of the LTRP entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure is present in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure. ltrp_in_header_flag[listidx][rplsIdx] equal to 1 specifies that the POC LSB of the LTRP entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure is not present in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure.

[0634] rpls_poc_lsb_lt[listIdx][rplsIdx][i] specifies the value of the picture order count modulo MaxPicOrderCntLsb of the picture referenced by the i-th entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure. The length of the rpls_poc_lsb_lt[listIdx][rplsIdx][i] syntax element is log2_max_pic_order_cnt_lsb_minus4+4 bits. ]]

[0635] 6.1.5. Implementation of Item 3.8

[0636] Alternatively, seq_parameter_set_rbsp() and ref_pic_list_struct() can be changed as follows:

[0637]

[0638]

[0639]

[0640] And the ref_pic_lists() sytnax is changed as follows:

[0641] if(ltrp_in_header_flag[[[i][RplsIdx[i]]]]) poc_lsb_lt[i][j] u(v)

[0642] And the ref_pic_list_struct(listIdx, rplsIdx) syntax changes as follows:

[0643]

[0644] [[ltrp_in_header_flag[listIdx][rplsIdx] equal to 0 specifies that the POC LSB of the LTRP entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure is present in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure. ltrp_in_header_flag[listidx][rplsIdx] equal to 1 specifies that the POC LSB of the LTRP entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure is not present in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure.

[0645] rpls_poc_lsb_lt[listIdx][rplsIdx][i] specifies the value of the picture order count modulo MaxPicOrderCntLsb of the picture referenced by the i-th entry in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure. The length of the rpls_poc_lsb_lt[listIdx][rplsIdx][i] syntax element is log2_max_pic_order_cnt_lsb_minus4+4 bits. ]]

[0646] 6.2. Third embodiment

[0647] This is an embodiment of item 4.1 summarized in Section 5 above.

[0648] In one example, the syntax structures picture_header_structure(), slice_header(), and ref_pic_lists() are changed as follows:

[0649]

[0650]

[0651]

[0652]

[0653] Figure 1 1 is a block diagram of an example video processing system 1900 that may implement various techniques disclosed herein. Various implementations may include some or all of the components in 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).

[0654] System 1900 may include a codec component 1904 that can implement 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 generate 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 the connected communication, as represented by component 1906. The bitstream (or codec) representation of the storage or communication of the video received at input 1902 can be used by component 3108 to generate pixel values ​​or displayable video sent to display interface 1910. The process of generating user-visible video from the bitstream representation 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 codec tools or operations are used at the encoder, and corresponding decoding tools or operations of the results of the inverse codec will be performed by the decoder.

[0655] Examples of peripheral bus interfaces or display interfaces may include Universal Serial Bus (USB) or High Definition Multimedia Interface (HDMI) or Displayport, etc. Examples of storage interfaces include SATA (Serial Advanced Technology Attachment), PCI, IDE interfaces, etc. The technology described in this document may 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.

[0656] Figure 2 3600 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 smart phone, a tablet, a computer, an Internet of Things (IoT) receiver, etc. Device 3600 may include one or more processors 3602, one or more memories 3604, and video processing hardware 3606. (Multiple) processors 3602 can be configured to implement one or more methods described in this document. (Multiple) memories 3604 can be used to store data and code, which is used to implement the methods and techniques described herein. Video processing hardware 3606 can be used to implement some of the techniques described in this document in hardware circuits. In some embodiments, hardware 3606 can be partially or completely in processor 3602, such as a graphics processor.

[0657] Figure 4 is a block diagram illustrating an example video coding system 100 that may utilize the techniques of this disclosure.

[0658] like Figure 4As 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, which 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, which may be referred to as a video decoding device.

[0659] Source device 110 may include a video source 112 , a video encoder 114 , and an input / output (I / O) interface 116 .

[0660] 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 bit stream. The bit stream may include a sequence of bits that form a codec representation of the video data. The bit stream 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 directly sent to the destination device 120 via the I / O interface 116 through the network 130a. The encoded video data may also be stored on a storage medium / server 130b for access by the destination device 120.

[0661] Destination device 120 may include an I / O interface 126 , a video decoder 124 , and a display device 122 .

[0662] The I / O interface 126 may include a receiver and / or a modem. The I / O interface 126 may obtain the encoded video data from the source device 110 or the storage medium / server 130b. The video decoder 124 may decode the encoded video data. The display device 122 may display the decoded video data to a user. The display device 122 may be integrated with the destination device 120, or may be external to the destination device 120 configured to interface with an external display device.

[0663] 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.

[0664] Figure 5 is a block diagram illustrating an example of a video encoder 200, which may be Figure 4 1. The video encoder 114 in the system 100 is shown in FIG.

[0665] Video encoder 200 may be configured to perform any or all of the techniques of this disclosure. Figure 5 In the example of , video encoder 200 includes multiple functional components. The techniques described in this disclosure can be shared between 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.

[0666] 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.

[0667] 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 where the current video block is located.

[0668] 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.

[0669] 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.

[0670] The mode selection unit 203 may select one of the intra or inter coding modes, for example, 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 may select a combination of 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 may also select a resolution of motion vectors (e.g., sub-pixel or whole pixel accuracy) for blocks in the case of inter prediction.

[0671] To perform inter-frame prediction on the current video block, the motion estimation unit 204 may generate motion information of 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 (rather than a picture associated with the current video block).

[0672] Motion estimation unit 204 and 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.

[0673] In some examples, the motion estimation unit 204 may perform unidirectional prediction of the current video block, and the motion estimation unit 204 may search for a reference video block of the current video block in the reference picture of list 0 or list 1. The motion estimation unit 204 may then generate a reference index indicating a reference video block in the reference picture of list 0 or list 1 and a motion vector indicating a spatial displacement between the current video block and the reference video block. The motion estimation unit 204 may output the reference index, the prediction direction indicator, and the motion vector as motion information of the current video block. The motion compensation unit 205 may generate a predicted video block of the current block based on the reference video block indicated by the motion information of the current video block.

[0674] In other examples, the motion estimation unit 204 may perform bidirectional prediction of the current video block, and the motion estimation unit 204 may search for a reference video block of the current video block in the reference picture of list 0 and may also search for another reference video block of the current video block in the reference picture of list 1. The motion estimation unit 204 may then generate a reference index indicating a reference video block in the reference picture of list 0 or list 1 and a motion vector indicating a 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 of the current video block. The motion compensation unit 205 may generate a predicted video block of the current video block based on the reference video block indicated by the motion information of the current video block.

[0675] In some examples, motion estimation unit 204 may output the entire set of motion information for use in a decoding process by a decoder.

[0676] In some examples, motion estimation unit 204 may not output a full set of motion information for the current video. Instead, motion estimation unit 204 may signal the motion information of the current video block with reference to the motion information of another 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.

[0677] 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.

[0678] 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.

[0679] 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.

[0680] The intra prediction unit 206 may perform intra prediction on the current video block. When the intra prediction unit 206 performs intra prediction on the current video block, the intra prediction unit 206 may 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 may include a predicted video block and various syntax elements.

[0681] 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 samples in the current video block.

[0682] 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.

[0683] 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.

[0684] 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.

[0685] 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 the residual video block from the transform coefficient video block. The reconstruction unit 212 may add the reconstructed residual video block to the 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.

[0686] 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.

[0687] 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.

[0688] Figure 6 is a block diagram illustrating an example of a video decoder 300, which may be Figure 4 1. The video decoder 114 in the system 100 is shown in FIG.

[0689] Video decoder 300 may be configured to perform any or all of the techniques of this disclosure. Figure 6 In the example of , video decoder 300 includes multiple functional components. The techniques described in this disclosure can be shared between 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.

[0690] exist Figure 6 In the example of , 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 be performed with respect to the video encoder 200 ( Figure 5 ) is a decoding process that is the overall inverse of the encoding process described.

[0691] The entropy decoding unit 301 may retrieve a coded bitstream. The coded bitstream may include entropy coded video data (e.g., coded blocks of video data). The entropy decoding unit 301 may decode the entropy coded video, and based on the entropy decoded video data, the motion compensation unit 302 may determine motion information including motion vectors, motion vector precision, reference picture list index, and other motion information. The motion compensation unit 302 may determine such information, for example, by performing AMVP and merge modes.

[0692] 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 the syntax element.

[0693] The motion compensation unit 302 may calculate interpolated values ​​of a sub-integer number of pixels of the reference block using an 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.

[0694] The motion compensation unit 302 can use some syntax information to determine: the size of the blocks used to encode (multiple) frames and / or (multiple) slices of the coded video sequence, the partitioning information describing how each macroblock of the pictures of the coded video sequence is partitioned, the mode indicating how to encode each partition, one or more reference frames (and reference frame lists) for each inter-frame coding block, and other information for decoding the coded video sequence.

[0695] The intra prediction unit 303 may 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.

[0696] The reconstruction unit 306 may 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. As desired, a deblocking filter may 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.

[0697] A list of some preferred examples of embodiments is provided below.

[0698] The first set of items shows example implementations of the techniques discussed in the previous section (eg, item 1).

[0699] 1. A video processing method (eg, Figure 3 ), comprising: performing (302) a conversion between a video having one or more pictures and a codec representation of the video, wherein each of the one or more pictures includes exactly one slice; wherein the codec representation complies with a format rule; wherein the format rule specifies that a picture parameter set flag is excluded from the codec representation because the picture has exactly one slice.

[0700] 2. A method according to clause 1, wherein the format rule specifies whether an indication of each picture of a reference picture parameter set is signalled in a picture parameter set.

[0701] 3. A method according to clause 1, wherein the format rules further specify that an indication of the absence of a picture parameter set flag is omitted in the codec representation.

[0702] 4. The method of clause 1, wherein the format rule specifies that, for a picture having exactly one slice, the codec indicates skipping signaling of a flag indicating the presence of a picture header in a slice header.

[0703] The following items show example embodiments of the techniques discussed in the previous section (eg, Item 2).

[0704] 5. A method of video processing, comprising: performing conversion between a video slice of a video and a codec representation of the video, wherein the codec representation complies with a format rule, wherein the format rule specifies a first field including an indication of the presence of a second field, the second field identifying a maximum index of a reference picture used to encode and decode the video slice based on a condition; wherein the condition can be expressed as a logical expression "A&(B||C)", wherein A indicates "rpl_info_in_ph_flag=1, or NAL unit type is not equal to IDR, or sps_idr_rpl_present_flag is equal to 1", and "B" indicates "slice_type is equal to P or B, and the number of reference entries in reference picture list 0 is greater than 1", and "C" indicates "slice_type is equal to B, and the number of reference entries in reference picture list 1 is greater than 1", and "&" is a logical "and" operation, and "||" is a logical "or" operation.

[0705] The following items show example embodiments (eg, projects) of the techniques discussed in the previous section.

[0706] 6. A method of video processing, comprising: performing 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 conditions for controlling the use of a syntax element indicating a picture sequence count of a long-term reference picture used for conversion of the video region.

[0707] 7. A method according to clause 6, wherein the format rule specifies that the syntax element is included in the codec representation if and only if the index of the reference picture list is less than the number of reference picture list syntax structures included in the sequence parameter set.

[0708] 8. A method as described in clause 6, wherein the format rule specifies that the syntax element is included in the codec representation if and only if the reference picture list syntax structure is included in a sequence parameter set of the codec representation.

[0709] The following items show example embodiments of the techniques discussed in the previous section (eg, item 4).

[0710] 9. A method of video processing, comprising: performing 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 that a reference picture related syntax structure is included if and only if a variable X is equal to a specific value, wherein X depends on a slice type of the video region.

[0711] 10. The method of clause 9, wherein the specific value is equal to 1 or 2.

[0712] 11. A method according to any of the preceding clauses, wherein the video region comprises a video codec unit.

[0713] 12. A method according to any of the preceding clauses, wherein the video region comprises a video picture.

[0714] 13. A method as described in any of clauses 1 to 12, wherein converting includes encoding the video into a codec representation.

[0715] 14. A method according to any of clauses 1 to 12, wherein converting comprises decoding the codec representation to generate pixel values ​​of the video.

[0716] 15. A video decoding apparatus comprising a processor configured to implement the method of one or more of clauses 1 to 14.

[0717] 16. A video coding and decoding apparatus, comprising a processor configured to implement one or more of the methods described in clauses 1 to 14.

[0718] 17. A computer program product having computer code stored thereon, which code, when executed by a processor, causes the processor to implement the method of any of clauses 1 to 14.

[0719] 18. The methods, devices, or systems described in this document.

[0720] The second group of clauses describes certain features and aspects of the technology disclosed in the previous section (e.g., items 1.1.a to 1.1.f and 1.1.h to 1.1.p in the "Example Techniques and Implementations" section).

[0721] 1. A method for video processing (e.g., Fig. 7AThe method 710 shown in the figure comprises: performing 712 conversion between a video including one or more pictures and a bitstream of the video; wherein the bitstream complies with a format rule; wherein the format rule specifies that in response to whether each picture of the reference picture parameter set includes a single slice, one or more syntax elements indicating codec information are selectively included in the picture parameter set of the bitstream.

[0722] 2. A method according to clause 1, wherein one or more syntax elements include six flags, the six flags indicating whether certain codec syntax elements are included in a picture header syntax structure or directly in a slice header.

[0723] 3. A method as described in clause 2, wherein the six flags include a first flag, the first flag indicating whether the reference picture list information is included in a picture header syntax structure or directly in a slice header.

[0724] 4. A method according to clause 3, wherein the format rule further specifies that, in the absence of the first flag in the picture parameter set, the value of the first flag is inferred to be equal to 0.

[0725] 5. A method according to clauses 2 to 4, wherein the six flags include a second flag indicating whether the deblocking filter information is included in a picture header syntax structure or directly in a slice header.

[0726] 6. A method according to any of clause 5, wherein the format rule further specifies that in case the second flag is not present in the picture parameter set, the value of the second flag is inferred to be equal to 0.

[0727] 7. A method according to any of clauses 2 to 6, wherein the six flags include a third flag indicating whether the SAO filter information is included in a picture header syntax structure or directly in a slice header.

[0728] 8. A method according to any of clause 7, wherein the format rule further specifies that in case the third flag is not present in the picture parameter set, the value of the third flag is inferred to be equal to 0.

[0729] 9. A method according to any of clauses 2 to 8, wherein the six flags include a fourth flag indicating whether the adaptive loop filter information is included in a picture header syntax structure or directly in a slice header.

[0730] 10. A method according to any of clause 9, wherein the format rule further specifies that, in case the fourth flag is not present in the picture parameter set, the value of the fourth flag is inferred to be equal to 0.

[0731] 11. A method according to any of clauses 2 to 10, wherein the six flags include a fifth flag indicating whether the weighted prediction information is included in a picture header syntax structure or directly in a slice header.

[0732] 12. A method according to clause 11, wherein the format rule further specifies that in the absence of the fifth flag in the picture parameter set, the value of the fifth flag is inferred to be equal to 0.

[0733] 13. A method according to any of clauses 2 to 12, wherein the six flags include a sixth flag indicating whether the quantization parameter increment information is included in a picture header syntax structure or directly in a slice header.

[0734] 14. A method according to any of clause 13, wherein the format rule further specifies that in case the sixth flag is not present in the picture parameter set, the value of the sixth flag is inferred to be equal to 0.

[0735] 15. A method according to any of clauses 1 to 14, wherein the at least one flag comprises a seventh flag indicating whether loop filtering operations across slice boundaries are enabled for pictures of the reference picture parameter set.

[0736] 16. A method according to any of clause 15, wherein the format rule further specifies that in case the seventh flag is not present in the picture parameter set, the value of the seventh flag is inferred to be equal to 0.

[0737] 17. A method according to any of clauses 1 to 16, wherein the format rule further specifies that one or more syntax elements are omitted in case each picture indicating the reference picture parameter set comprises a single slice.

[0738] 18. A method as described in clause 17, wherein the format rule further specifies including an indication indicating whether each picture of the reference picture parameter set has only one slice in the picture parameter set.

[0739] 19. The method of clause 17, wherein the format rule further specifies including an indication indicating whether each picture of the reference picture parameter set has only one intra slice in the picture parameter set.

[0740] 20. The method of clause 17, wherein the format rule further specifies including an indication indicating whether each picture of the reference picture parameter set has only one inter slice in the picture parameter set.

[0741] 21. A method as described in clause 1, wherein the format rule further specifies an indication of whether each picture of the reference picture parameter set has only one slice, the one slice corresponding to a flag included in the picture parameter set.

[0742] 22. A method according to clause 21, wherein a flag with a value of 1 specifies that each picture of the reference picture parameter set has only one slice, and a flag with a value of 0 specifies that each picture of the reference picture parameter set has more than one slice.

[0743] 23. A method according to clause 21, wherein the format rule further specifies an omission indication and the indication is inferred from slice partitioning information included in the picture parameter set.

[0744] 24. A method according to clause 21, wherein the format rule further specifies that the indication is equal to 0 if another indication indicating whether there is only one sub-picture in each picture is greater than 0.

[0745] 25. The method of clause 21, wherein the format rule further specifies that the flag is the same for all picture parameter sets referenced by one or more pictures in the codec layer video sequence.

[0746] 26. A method according to clause 21, wherein the format rule further specifies that flag is equal to 1 if one_slice_per_pic_constraint_flag is equal to 1.

[0747] 27. A method according to clause 21, wherein the format rule further specifies semantics of updating one_slice_per_pic_constraint_flag by adding one_slice_per_pic_constraint_flag equal to 1 to specify flag equal to 1.

[0748] 28. A method according to clause 21, wherein the format rule further specifies that the flag is omitted if it is known from the picture parameter set that there is only one sub-picture in each picture and each sub-picture contains only one slice.

[0749] 29. A method according to clause 17, wherein the format rule further specifies that, in case each picture indicating the reference picture parameter set comprises a single slice, the value of the one or more syntax elements is inferred to be equal to 0 or 1.

[0750] 30. A method according to clause 17, wherein the one or more syntax elements include an eighth flag (wp_info_in_ph_flag), the eighth flag indicating whether weighted prediction information is included in a picture header syntax structure, and wherein the format rule further specifies that i) in the case where each picture indicating the reference picture parameter set includes a single slice, the value of each other syntax element except wp_info_in_ph_flag is inferred to be equal to 1 or 0, and ii) in the case where the value of a ninth flag (rpl_info_in_ph_flag) indicating whether reference picture list information is included in the picture header syntax structure is equal to 0, the value of wp_info_in_ph_flag is inferred to be equal to 0, and in the case where the value of rpl_info_in_ph_flag is equal to 1, the value of wp_info_in_ph_flag is inferred to be 1 or 0.

[0751] 31. A method according to clause 1, wherein the format rule further specifies that, in a case where each picture indicating a reference picture parameter set includes a single slice, in a case where each picture indicating a reference picture parameter set includes a single slice, a picture header in a slice header flag in a slice header syntax structure is omitted and the value of the picture header is inferred to be equal to 1.

[0752] 32. The method of clause 1, wherein the format rule further specifies that a slice address parameter is omitted in a slice header syntax structure in the case where each picture indicating the reference picture parameter set comprises a single slice.

[0753] 33. A method according to clause 32, wherein the format rule further specifies that the value of the slice address parameter is inferred to be equal to 0 if: i) each picture indicating the reference picture parameter set comprises a single slice, and ii) rect_slice_flag is equal to 0.

[0754] 34. A method as described in clause 1, wherein the format rule further specifies that in the case where each picture indicating the reference picture parameter set comprises a single slice, a parameter indicating the number of slices in the slice is omitted.

[0755] 35. A method according to clause 34, wherein the format rule further specifies that the value of the parameter is inferred to be equal to "NumTilesInPic-1" in the following cases: i) indicating that each picture of the reference picture parameter set includes a single slice, and ii) rect_slice_flag is equal to 0, NumTilesInPic indicates the number of tiles in the picture.

[0756] 36. A method according to clause 1, wherein the format rule further specifies that if one_slice_per_pic_constraint_flag is equal to 1, the value of one or more syntax elements is equal to 0.

[0757] 37. The method of clause 1, wherein the format rule further specifies that if one_slice_per_pic_constraint_flag is equal to 1, the value of the picture header in the slice header flags is equal to 1.

[0758] 38. A method as described in clause 1, wherein the format rules further specify that rect_slice_flag is omitted in the case where each picture indicating the reference picture parameter set comprises a single slice.

[0759] 39. A method according to clause 38, wherein the format rule further specifies that in case each picture indicating the reference picture parameter set comprises a single slice, the value of rect_slice_flag is inferred to be equal to 1.

[0760] 40. The method of clause 1, wherein the format rule further specifies that single_slice_per_subpic_flag is omitted in the case where each picture indicating the reference picture parameter set comprises a single slice.

[0761] 41. A method according to clause 40, wherein the format rule further specifies that in case each picture indicating the reference picture parameter set comprises a single slice, the value of single_slice_per_subpic_flag is inferred to be equal to 1.

[0762] 42. The method of clause 1, wherein the format rules further specify that loop_filter_cross_slices_enabled_flag is omitted in the case where each picture indicating the reference picture parameter set comprises a single slice.

[0763] 43. A method according to clause 42, wherein the format rule further specifies that in a case where each picture of the reference picture parameter set includes a single slice, a tenth flag in the bitstream is omitted, wherein the tenth flag specifies whether to enable cross-slice boundary loop filtering operations for the pictures of the reference picture parameter set.

[0764] 44. A method as described in clause 1, wherein the format rule further specifies including whether each picture of the reference picture parameter set is indicated to include a single slice in a sequence parameter set associated with the codec layer video sequence.

[0765] 45. The method of clause 1, wherein the format rule further specifies including an indication indicating whether each picture in the codec layer video sequence has only one slice in a sequence parameter set associated with the codec layer video sequence.

[0766] 46. ​​A method as described in clause 1, wherein the format rule further specifies that one or more slice partitioning-related syntax elements are omitted from the first picture parameter set if each picture associated with the first picture parameter set has only one slice.

[0767] 47. The method of clause 1, wherein the format rule further specifies that one or more slice partitioning-related syntax elements are omitted from the first picture parameter set if each picture associated with the first picture parameter set has only one slice.

[0768] 48. A method according to any of clauses 1 to 47, wherein converting comprises encoding the video into a bitstream.

[0769] 49. A method according to any of clauses 1 to 47, wherein converting comprises decoding the video from a bitstream.

[0770] 50. The method of clauses 1 to 47, wherein converting comprises generating a bitstream from the video; and the method further comprises: storing the bitstream in a non-transitory computer-readable recording medium.

[0771] 51. A video processing apparatus comprising a processor configured to implement the method of any one or more of clauses 1 to 50.

[0772] 52. A method of storing a bitstream of a video, comprising the method of any one of clauses 1 to 50, and further comprising storing the bitstream to a non-transitory computer-readable recording medium.

[0773] 53. A computer readable medium storing program code which, when executed, causes a processor to implement the method of any one or more of clauses 1 to 50.

[0774] 54. A computer readable medium storing a codec representation or a bitstream representation generated according to any of the above methods.

[0775] 55. A video processing apparatus for storing a bitstream representation, wherein the video processing apparatus is configured to implement the method of any one or more of clauses 1 to 50.

[0776] The third group of clauses describes certain features and aspects of the technology disclosed in the previous section (e.g., item 1.1.g in the "Example Techniques and Implementations" section).

[0777] 1. A method for video processing (e.g., Figure 7B The method 720 shown in the figure comprises: performing 722 conversion between a video comprising a plurality of pictures and a bitstream of the video, each picture comprising at least one slice, wherein the bitstream complies with a format rule; wherein the format rule specifies that a first flag in the bitstream indicates whether a picture header syntax structure of the picture is included in a slice header of a slice of the picture; and wherein the format rule provides that in response to any one of six flags in a picture parameter set associated with the picture being equal to 1, the first flag is equal to 0.

[0778] 2. A method as described in clause 1, wherein six flags indicate whether certain codec syntax elements are included in the picture header syntax structure or directly in the slice header.

[0779] 3. A method according to any of clauses 1 and 2, wherein the six flags include a second flag indicating whether the reference picture list information is included in a picture header syntax structure or directly in a slice header.

[0780] 4. A method according to any of clauses 1 to 3, wherein the six flags include a third flag indicating whether the deblocking filter information is included in a picture header syntax structure or directly in a slice header.

[0781] 5. A method according to any of clauses 1 to 4, wherein the six flags include a fourth flag indicating whether the SAO filter information is included in a picture header syntax structure or directly in a slice header.

[0782] 6. A method according to any of clauses 1 to 5, wherein the six flags include a fifth flag indicating whether the adaptive loop filter information is included in a picture header syntax structure or directly in a slice header.

[0783] 7. A method according to any of clauses 1 to 6, wherein the six flags include a sixth flag indicating whether the weighted prediction information is included in a picture header syntax structure or directly in a slice header.

[0784] 8. A method according to any of clauses 1 to 7, wherein the six flags include a seventh flag indicating whether the quantization parameter increment information is included in a picture header syntax structure or directly in a slice header.

[0785] 9. The method of any of clauses 1 to 8, wherein a first flag equal to 0 specifies that a picture header syntax structure is not present in a slice header.

[0786] 10. The method of any of clauses 1 to 9, wherein one of the six flags equal to 1 specifies that the associated information is included in a picture header syntax structure.

[0787] 11. A method according to any of clauses 1 to 10, wherein converting comprises encoding the video into a bitstream.

[0788] 12. A method according to any one of clauses 1 to 10, wherein converting comprises decoding the video from a bitstream.

[0789] 13. The method of clauses 1 to 10, wherein converting comprises generating a bitstream from the video, and the method further comprises storing the bitstream in a non-transitory computer-readable recording medium.

[0790] 14. A video processing apparatus comprising a processor configured to implement the method of any one or more of clauses 1 to 13.

[0791] 15. A method of storing a bitstream of a video, comprising the method of any one of clauses 1 to 13, and further comprising storing the bitstream to a non-transitory computer-readable recording medium.

[0792] 16. A computer readable medium storing program code which, when executed, causes a processor to implement the method of any one or more of clauses 1 to 13.

[0793] 17. A computer readable medium storing a bitstream generated according to any of the above methods.

[0794] 18. A video processing device for storing a bitstream, wherein the video processing device is configured to implement the method of any one or more of clauses 1 to 13.

[0795] The fourth group of items describes certain features and aspects of the technology disclosed in the previous section (e.g., item 2 in the "Example Techniques and Implementations" section).

[0796] 1. A method for video processing (e.g., Figure 7C The method 730 shown in the figure comprises: performing 732 conversion between a video including one or more pictures and a bitstream of the video, each picture including at least one slice, wherein the bitstream conforms to a format rule, wherein the format rule specifies a first field including an indication of the presence of a second field, the second field identifying a maximum index of a reference picture for encoding and decoding the slice based on a condition; wherein the condition can be expressed as a logical expression "A&(B||C)", wherein:

[0797] A indicates that a first flag indicating whether reference picture list information is included in a picture header syntax structure is equal to 1, or a network abstraction layer (NAL) unit type is not equal to an instantaneous decoding refresh (IDR) type, or a second flag indicating whether reference picture list information may be present in a slice header of a slice with an IDR NAL unit type is equal to 1,

[0798] B indicates that the slice type is equal to P or B, and the number of reference entries in reference picture list 0 is greater than 1,

[0799] C indicates that the slice type is equal to B, and the number of reference entries in reference picture list 1 is greater than 1, and

[0800] The “&” is a logical “AND” operation, and the “||” is a logical “OR” operation.

[0801] 2. A method as described in clause 1, wherein the first flag corresponds to rpl_info_in_ph_flag.

[0802] 3. A method according to clause 1, wherein a first flag equal to 1 specifies that the reference picture list information is present in the picture header syntax structure and not in the slice header, and a first flag equal to 0 specifies that the reference picture list information is not present in the picture header syntax structure and the reference picture list information has the opportunity to be directly present in the slice header.

[0803] 4. A method as described in clause 1, wherein the second flag corresponds to sps_idr_rpl_present_flag.

[0804] 5. A method as described in clause 1, wherein the first field corresponds to num_ref_idx_active_override_flag.

[0805] 6. A method as described in clause 1, wherein the second field corresponds to num_ref_idx_active_minus1.

[0806] 7. A method according to any of clauses 1 to 6, wherein converting comprises encoding the video into a bitstream.

[0807] 8. A method according to any of clauses 1 to 6, wherein converting comprises decoding the video from a bitstream.

[0808] 9. The method of any one of clauses 1 to 6, wherein converting comprises generating a bitstream from the video; and the method further comprises: storing the bitstream in a non-transitory computer-readable recording medium.

[0809] 10. A video processing apparatus comprising a processor configured to implement the method of any one or more of clauses 1 to 9.

[0810] 11. A method of storing a bitstream of a video, comprising the method of any one of clauses 1 to 9, and further comprising storing the bitstream to a non-transitory computer-readable recording medium.

[0811] 12. A computer readable medium storing program code which, when executed, causes a processor to implement the method of any one or more of clauses 1 to 9.

[0812] 13. A computer readable medium storing a bitstream generated according to any of the above methods.

[0813] The fifth group of items describes certain features and aspects of the technology disclosed in the previous section (e.g., items 2 and 3 in the "Example Techniques and Implementations" section).

[0814] 1. A method for video processing (e.g., Fig.7D The method 740 shown includes: performing conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, and wherein the format rule specifies conditions that control whether or how one or more syntax elements related to a picture order count of a long-term reference picture are included in a reference picture list syntax structure in the bitstream.

[0815] 2. A method according to clause 1, wherein the format rule further specifies that in response to the index of the reference picture list being less than the number of reference picture list syntax structures included in the sequence parameter set, one or more syntax elements are included in the reference picture list syntax structure.

[0816] 3. A method according to clause 2, wherein the format rule further specifies whether a flag indicating whether one or more syntax elements are included in the reference picture list syntax structure is included in the reference picture list syntax structure.

[0817] 4. A method as described in clause 3, wherein the flag corresponds to ltrp_in_header_flag.

[0818] 5. A method according to clause 4, wherein the format rule further specifies that when the index of the reference picture list is equal to the number of reference picture list syntax structures in the sequence parameter set, ltrp_in_header_flag is omitted from being included in the reference picture list syntax structure.

[0819] 6. A method as described in clause 5, wherein the format rule further specifies that when the index of the reference picture list is equal to the number of reference picture list syntax structures in the sequence parameter set, the value of ltrp_in_header_flag is inferred to be equal to 1.

[0820] 7. A method as described in clause 1, wherein the format rule further specifies that one or more syntax elements are included in the reference picture list syntax structure in response to whether the reference picture list syntax structure is included in a sequence parameter set of the bitstream.

[0821] 8. A method according to clause 1, wherein the format rule further specifies that one or more syntax elements are omitted in the reference picture list syntax structure, and one or more syntax elements are included for each of the reference picture list syntax structure and the further reference picture list syntax structure.

[0822] 9. A method as described in clause 1, wherein the format rule further specifies that one or more syntax elements are omitted in the reference picture list syntax structure and one or more syntax elements are included for each reference of the picture list.

[0823] 10. A method as described in clause 1, wherein the format rule further specifies that one or more syntax elements are omitted in a reference picture list syntax structure and one or more syntax elements are included for the reference picture list syntax structure and another reference picture list syntax structure.

[0824] 11. A method of video processing (e.g., Fig.7D The method 740 shown includes: performing 742 conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies whether syntax elements associated with a reference picture in a reference picture list are included in a reference picture list syntax structure.

[0825] 12. A method according to clause 11, wherein the reference picture list is reference picture list 1.

[0826] 13. The method of clause 11, wherein the format rule depends on whether a variable X is equal to a certain value, wherein X depends on a slice type of the video region.

[0827] 14. The method according to clause 11, wherein the specific value is equal to 1 or 2.

[0828] 15. A method according to any of the preceding clauses, wherein the syntax element comprises a flag indicating the presence of a reference picture list in a sequence parameter set.

[0829] 16. A method according to any of the preceding clauses, wherein the syntax element indicates an index to a reference picture list.

[0830] 17. A method according to any of the preceding clauses, wherein the syntax element indicates the value of the least significant bit of the picture order count of the long-term reference picture.

[0831] 18. A method according to any of the preceding clauses, wherein the syntax element indicates whether the difference between the most significant bits of the picture order counts of the current picture and the long-term reference picture is included in the bitstream.

[0832] 19. A method according to any of the preceding clauses, wherein the syntax element indicates whether the difference between the most significant bits of the picture order counts of the current picture and the long-term reference picture is included in the bitstream.

[0833] 20. A method according to any of clauses 1 to 19, wherein converting comprises encoding the video into a bitstream.

[0834] 21. A method according to any of clauses 1 to 19, wherein converting comprises decoding the video from a bitstream.

[0835] 22. The method of clauses 1 to 19, wherein converting comprises generating a bitstream from the video; and the method further comprises: storing the bitstream in a non-transitory computer-readable recording medium.

[0836] 23. A video processing apparatus comprising a processor configured to implement the method of any one or more of clauses 1 to 22.

[0837] 24. A method of storing a bitstream of a video, comprising the method of any one of clauses 1 to 22, and further comprising storing the bitstream to a non-transitory computer-readable recording medium.

[0838] 25. A computer readable medium storing program code which, when executed, causes a processor to implement the method of any one or more of clauses 1 to 22.

[0839] 26. A computer readable medium storing a bitstream generated according to any of the above methods.

[0840] 27. A video processing device for storing a bitstream, wherein the video processing device is configured to implement the method of any one or more of clauses 1 to 22.

[0841] In this document, the term "video processing" may refer to video encoding, video decoding, video compression, or video decompression. For example, during the conversion from a pixel representation of a video to a corresponding bitstream representation, a video compression algorithm may be applied, and vice versa. As defined by the syntax, the bitstream representation of the current video block may correspond to bits that are co-located or scattered at different positions within the bitstream, for example. For example, a macroblock may be encoded based on the error residual values ​​of the transform and the codec and also using bits in the header and other fields in the bitstream. In addition, during the conversion, the decoder may parse the bitstream based on this determination, knowing that some fields may or may not be present, as described in the above solution. Similarly, the encoder may determine whether to include or not include certain syntax fields, and generate the codec representation accordingly by including or excluding the syntax fields from the codec representation.

[0842] The disclosure and other schemes, examples, embodiments, modules and functional operations described in this document may be implemented in digital electronic circuits or in computer software, firmware or hardware, containing the structures disclosed in this document and the equivalents of their structures, or a combination of one or more of them. The disclosed and other embodiments may be implemented as one or more computer program products encoded on a computer-readable medium, such as one or more computer program instruction modules, for execution by a data processing device or for controlling the operation of a data processing device. The computer-readable medium may be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composite that affects a machine-readable propagable signal, or a combination of one or more thereof. The term "data processing device" encompasses all devices, equipment and machines for processing data, including, for example, a programmable processor, a computer or multiple processors or computers. In addition to hardware, the device may also include code that creates an execution environment for the computer program in question, for example, code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagation signal is an artificially generated signal, for example, a machine-generated electrical, optical or electromagnetic signal, which is generated to encode information for transmission to a suitable receiver device.

[0843] A computer program (also referred to as a program, software, software application, script or code) can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including stand-alone programs or modules, components, subroutines or other units suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that stores other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple collaborative files (e.g., files storing one or more modules, subroutines or code portions). A computer program can be deployed to execute on one computer or on multiple computers, which are located at one site or distributed across multiple sites and interconnected by a communication network.

[0844] The processes and logic flows described in this document may be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows may also be performed by special purpose logic circuits (e.g., field programmable gate arrays (FPGAs) or application specific integrated circuits (ASICs)), and the apparatus may be implemented as special purpose logic circuits (e.g., FPGAs or ASICs).

[0845] Processors suitable for the execution of computer programs include, for example, both general-purpose and special-purpose microprocessors, and any one or more processors of any type of digital computer. Typically, the processor will receive instructions and data from a read-only memory or a random access memory or both. The basic elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Typically, a computer will also include one or more mass storage devices (such as magnetic, magneto-optical disks or optical disks) for storing data, or be operably coupled to receive data from a mass storage device (such as magnetic, magneto-optical disks or optical disks) or transfer data to a mass storage device (such as magnetic, magneto-optical disks or optical disks), or both. However, a computer does not have to have such devices. Computer-readable media suitable for storing computer program instructions and data contain all forms of non-volatile memory, media and memory devices, including, for example, semiconductor memory devices (such as EPROM, EEPROM and flash memory devices); disks (such as internal hard disks or removable disks); magneto-optical disks; and CD ROM and DVD-ROM disks. The processor and memory can be supplemented by special-purpose logic circuits, or incorporated in special-purpose logic circuits.

[0846] Although this patent document contains many details, these details should not be interpreted as limitations on any subject matter or the scope of protection that can be claimed, but as descriptions of features of specific embodiments specified in specific technologies. In this patent document, certain features described in the context of separate embodiments may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments, respectively, or in various suitable sub-combinations. In addition, although features may be described as working in certain combinations and even initially required in the same manner as described above, one or more features from the claimed combination may be removed from the combination in some cases, and the claimed combination may be directed to a sub-combination or a variation of the sub-combination.

[0847] Similarly, although operations are depicted in a particular order in the drawings, this should not be understood as requiring that such operations be performed in the particular order shown or in the sequential order shown, or that all illustrated operations be performed, in order to achieve the desired results. Furthermore, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

[0848] Only a few implementations and examples are described, and other implementations, enhancements, and variations may be made based on what is described and illustrated in this patent document.

Claims

1. A video processing method, comprising: performing conversion between a video comprising one or more pictures and a bitstream of the video, wherein each of the pictures comprises at least one slice, wherein the bit stream complies with the format rules, The format rule specifies that a first field indicating the presence of a second field is included based on a condition, the second field indicating a maximum index of a reference picture used for encoding and decoding a slice; The condition can be expressed as a logical expression "A&(B||C)", where: A indicates that the first flag is equal to 1 or the network abstraction layer NAL unit type is not equal to the instantaneous decoding refresh IDR type or the second flag is equal to 1, the first flag indicating whether the reference picture list information is included in the picture header syntax structure, and the second flag indicating whether the reference picture list information may be present in the slice header of the slice with the IDR NAL unit type, B indicates that the slice type is equal to P or B, and the number of reference entries in reference picture list 0 is greater than 1, C indicates that the slice type is equal to B, and the number of reference entries in reference picture list 1 is greater than 1, and Among them, "&" is a logical "AND" operation, and "||" is a logical "OR" operation. The format rule further specifies that, in response to whether each picture of the reference picture parameter set includes a single slice, one or more syntax elements indicating coding information are selectively included in the picture parameter set of the bitstream, The one or more syntax elements include six flags, the six flags include the first flag, and the six flags indicate whether the corresponding codec syntax elements are included in the picture header syntax structure or directly included in the slice header, wherein the codec syntax elements corresponding to the six flags include reference picture list information, deblocking filter information, sample adaptive offset filter information, adaptive loop filter information, weighted prediction information and quantization parameter increment information.

2. The method according to claim 1, wherein: The first flag corresponds to rpl_info_in_ph_flag.

3. The method according to claim 1, wherein: A first flag equal to 1 specifies that the reference picture list information is present in the picture header syntax structure and not in the slice header, and a first flag equal to 0 specifies that the reference picture list information is not present in the picture header syntax structure and the reference picture list information has a chance to be present directly in the slice header.

4. The method according to claim 1, wherein: The second flag corresponds to sps_idr_rpl_present_flag.

5. The method according to claim 1, wherein: The first field corresponds to num_ref_idx_active_override_flag.

6. The method according to claim 1, wherein: The second field corresponds to num_ref_idx_active_minus1.

7. The method according to any one of claims 1 to 6, wherein: The converting includes encoding the video into the bitstream.

8. The method according to any one of claims 1 to 6, wherein: The converting includes decoding the video from the bitstream.

9. The method according to any one of claims 1 to 6, wherein: The converting comprises generating the bitstream from the video; and the method further comprises: The bit stream is stored in a non-transitory computer-readable recording medium. 10 . A video processing device, comprising a processor configured to implement the method according to claim 1 .

11. A method of storing a bit stream of a video, comprising the method of any one of claims 1 to 9, and further comprising storing the bit stream to a non-transitory computer-readable recording medium.

12. A computer readable medium storing program code, which, when executed, causes a processor to implement the method of any one of claims 1 to 9.

13. A computer-readable medium storing a bit stream generated by the method according to any one of claims 1 to 9.

14. A video processing device for storing a bit stream, wherein: The video processing device is configured to implement the method according to any one of claims 1 to 9.

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