Consistency Window Parameters in Video Coding and Decoding

Abstract

Methods and apparatuses for video processing are described. Video processing may include video encoding, video decoding, or video transcoding. An example video processing method includes performing a conversion between a video and a bitstream of the video including pictures in a video unit according to format rules. The format rules specify that, in response to the width of a picture being equal to the maximum allowable picture width in the video unit and the height of the picture being equal to the maximum allowable picture height in the video unit, a consistency window flag in a picture parameter set corresponding to the picture is set to a value of 0.

Description

[0001] Cross - Reference to Related Applications

[0002] This application is the national phase of International Patent Application No. PCT / CN2021 / 024675, filed on March 29, 2021, and claims the priority and benefit of U.S. Provisional Patent Application No. 63 / 002,064, filed on March 30, 2020. The entire disclosure of all the foregoing patent applications is hereby incorporated by reference. Technical Field

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

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

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

[0006] In one example aspect, a video processing method is disclosed. The method includes performing a conversion between a video including one or more pictures each including one or more strips and a bitstream of the video, where the bitstream conforms to format rules; where the format rules specify whether or how the strip type of the strips in one or more strips is indicated in the bitstream depending on a condition, where the condition is based on a common constraint flag, a network abstraction layer unit type, or whether the strip is in the first picture of an access unit.

[0007] In another example aspect, a video processing method is disclosed. The method includes performing a conversion between a video including a picture including multiple strips and a bitstream of the video, where the bitstream conforms to format rules that specify the applicability of adaptive loop filtering for all strips in the picture controlled by a flag in the picture header.

[0008] In another example aspect, a video processing method is disclosed. The method includes performing a conversion between a video including one or more pictures each including one or more strips and a bitstream of the video according to format rules, where the format rules specify the repetition time of a parameter set associated with the video.

[0009] In another example aspect, a video processing method is disclosed. The method includes performing a conversion between a video including pictures in a video unit and a bitstream of the video according to format rules, where the format rules specify that in response to the width of a picture being equal to the maximum allowed picture width in the video unit and the height of the picture being equal to the maximum allowed picture height in the video unit, a consistency window flag in a picture parameter set corresponding to the picture is set to a value of 0.

[0010] In another example aspect, a video processing method is disclosed. The method includes performing a conversion between a video including one or more pictures each including one or more strips and a codec representation of the video, where the codec representation complies with format rules that specify conditions for fields in the codec representation to control constraints on strip types or whether a strip type is included in the codec representation, and the field includes a general constraint flag, a network abstraction layer unit type, or whether the video strip is in the first video picture of an access unit.

[0011] In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video including one or more pictures each including one or more strips and a codec representation of the video, where the codec representation complies with format rules that specify disabling adaptive loop filtering for all strips in a video picture based on the value of a flag in a picture header of the video picture.

[0012] In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video including one or more pictures each including one or more strips and a codec representation of the video, where the codec representation complies with format rules that specify setting a consistency window flag to a disabled mode when the height and width of the current picture are equal to the maximum height and maximum width in the video.

[0013] In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a video including one or more pictures each including one or more strips and a codec representation of the video, where the codec representation complies with format rules that specify a repeat time of a parameter set.

[0014] In yet another example aspect, a video encoder device is disclosed. The video encoder includes a processor configured to implement the above method.

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

[0016] In yet another example aspect, a computer-readable medium storing code is disclosed. The code embodies one of the methods described herein in the form of processor-executable code.

[0017] These and other features will be described in this document. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a block diagram of an example video processing system.

[0019] Figure 2 is a block diagram of a video processing apparatus.

[0020] Figure 3 is a flowchart of an example method of video processing.

[0021] Figure 4 is a block diagram showing a video codec system according to some embodiments of the present disclosure.

[0022] Figure 5 is a block diagram showing an encoder according to some embodiments of the present disclosure.

[0023] Figure 6 is a block diagram showing a decoder according to some embodiments of the present disclosure.

[0024] Figure 7 shows an example of an adaptive loop filter (ALF) filter shape (chrominance: 5×5 rhombus, luminance: 7×7 rhombus).

[0025] Figure 8 shows an example of ALF and CC-ALF diagrams.

[0026] Figures 9 - 11 is a flowchart of an example method of video processing. DETAILED DESCRIPTION

[0027] In this document, chapter headings are used for ease of understanding, and the applicability of the technologies and embodiments disclosed in each chapter is not limited to that chapter only. In addition, in some descriptions, H.266 technical terms are used merely for ease of understanding and not to limit the scope of the disclosed technologies. Therefore, the technologies described herein are also applicable to other video codec protocols and designs.

[0028] 1. INTRODUCTION

[0029] This document relates to video codec technology. Specifically, it relates to improvements to signaling of slice types, ALF and consistency windows, and repetition of some non-VCL NAL units (including VPS, SPS, PPS, APS, and DCI NAL units). 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 coding, such as the multi-functional video coding (VVC) being developed.

[0030] 2. ABBREVIATIONS

[0031] ALF Adaptive Loop Filter

[0032] APS Adaptive Parameter Set

[0033] AU Access Unit

[0034] AUD Access Unit Delimiter

[0035] AVC Advanced Video Coding

[0036] CLVS Coding Layer Video Sequence

[0037] CPB Coding Picture Buffer

[0038] CRA Completely Random Access

[0039] CTU Coding Tree Unit

[0040] CVS Coding Video Sequence

[0041] DCI Decoding Capability Information

[0042] DPB Decoding Picture Buffer

[0043] DU Decoding Unit

[0044] EOB End of Bitstream

[0045] EOS End of Sequence

[0046] GDR Gradual Decoding Refresh

[0047] HEVC High Efficiency Video Coding

[0048] HRD Hypothetical Reference Decoder

[0049] IDR Instantaneous Decoding Refresh

[0050] JEM Joint Exploration Model

[0051] LMCS Luminance Mapping and Chrominance Scaling

[0052] MCTS Motion Constrained Tile Set

[0053] NAL Network Abstraction Layer

[0054] OLS Output Layer Set

[0055] PH Picture Header

[0056] PPS Picture Parameter Set

[0057] PTL Profile, Tier and Level

[0058] PU Picture Unit

[0059] RADL Random Access Decodable Leading (picture)

[0060] RAP Random Access Point

[0061] RASL Random Access Skipped Leading (picture)

[0062] RBSP Raw Byte Sequence Payload

[0063] RPL Reference Picture List

[0064] SAO Sample Adaptive Offset

[0065] SEI Supplemental Enhancement Information

[0066] SPS Sequence Parameter Set

[0067] STSA Stepwise Temporal Sub-layer Access

[0068] SVC Scalable Video Coding

[0069] VCL Video Coding Layer

[0070] VPS Video Parameter Set

[0071] VTM VVC Test Model

[0072] VUI Video Usability Information

[0073] VVC Versatile Video Coding

[0074] 3. Preliminary Discussion

[0075] Video coding standards have evolved mainly through the development of well-known ITU-T and ISO / IEC standards. ITU-T developed H.261 and H.263, ISO / IEC developed MPEG-1 and MPEG-4 Visual, and the two organizations jointly developed the H.262 / MPEG-2 video, H.264 / MPEG-4 Advanced Video Coding (AVC), and H.265 / HEVC [1] standards. Since H.262, video coding standards have been based on a hybrid video coding structure, in which temporal prediction plus transform coding is employed. To explore future video coding technologies beyond HEVC, VCEG and MPEG jointly established the Joint Video Exploration Team (JVET) in 2015. Since then, JVET has adopted many new methods and incorporated them into a reference software called the Joint Exploration Model (JEM) [2]. JVET meetings are held quarterly simultaneously, and the goal of the new coding standard is to reduce the bit rate by 50% compared to HEVC. The new video coding 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. Due to the continuous efforts on VVC standardization, new coding technologies have been incorporated 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.

[0076] 3.1. Parameter Sets

[0077] AVC, HEVC, and VVC specify parameter sets. The types of parameter sets include SPS, PPS, APS, and VPS. SPS and PPS are supported in all of AVC, HEVC, and VVC. VPS was introduced starting from HEVC and is included in HEVC and VVC. APS is not included in AVC or HEVC but is included in the latest VVC draft text.

[0078] SPS is designed to carry sequence-level header information, and PPS is designed to carry picture-level header information that does not change frequently. With SPS and PPS, information that does not change frequently does not need to be repeated for each sequence or picture, thus avoiding redundant signaling of this information. In addition, the use of SPS and PPS enables out-of-band transmission of important header information, thus not only avoiding the need for redundant transmission but also improving fault tolerance.

[0079] A VPS is introduced to carry sequence level header information common to all layers in a multi-layer bitstream.

[0080] An APS is introduced to carry picture level or slice level information that requires a significant number of bits to encode and decode, can be shared by multiple pictures, and can have a significant number of different variations in the sequence.

[0081] 3.2. Slice Headers and Picture Headers in VVC

[0082] Similar to HEVC, the slice header in VVC conveys information about a specific slice. This includes slice address, slice type, slice QP, least significant bit (LSB) of the picture order count (POC), RPS and RPL information, weighted prediction parameters, loop filter parameters, entry offsets for slices and WPP, etc.

[0083] VVC introduces a picture header (PH) that contains header parameters for a specific picture. Each picture must have one or only one PH. The PH basically carries those parameters that would be in the slice header if the PH were not introduced, but each parameter has the same value for all slices of the picture. These include IRAP / GDR picture indication, inter / intra slice allow flag, POC LSB and optionally POC MSB, information about RPL, deblocking, SAO, ALF, QP delta, and weighted prediction, coding block partition information, virtual boundary, collocated picture information, etc. It often occurs that each picture in an entire picture sequence contains only one slice. To allow for each picture not to have at least two NAL units in this case, the PH syntax structure is allowed to be included in the PH NAL unit or the slice header.

[0084] In VVC, information about collocated pictures for temporal motion vector prediction is signaled in the picture header or slice header.

[0085] 3.3. Picture Resolution Change within a Sequence

[0086] In AVC and HEVC, the spatial resolution of a picture cannot change unless a new sequence with a new SPS starts with an IRAP picture. VVC enables picture resolution change within a sequence at positions where no IRAP picture is encoded, and the IRAP picture is always intra-coded. This feature is sometimes referred to as reference picture resampling (RPR) because it requires resampling of reference pictures used for inter prediction when the reference picture has a different resolution from the current picture being decoded.

[0087] The scaling ratio is limited to be greater than or equal to 1 / 2 (2x downsampling from the reference picture to the current picture) and less than or equal to 8 (8x upsampling). Three sets of resampling filters with different frequency cut-offs are specified to handle various scaling ratios between the reference picture and the current picture. The three sets of resampling filters are applied to scaling ratios in the ranges from 1 / 2 to 1 / 1.75, from 1 / 1.75 to 1 / 1.25, and from 1 / 1.25 to 8, respectively. Each set of resampling filters has 16 phases for luminance and 32 phases for chrominance, the same as in the case of the motion compensation interpolation filter. In fact, the normal MC interpolation process is a special case of the resampling process, where the scaling ratio ranges from 1 / 1.25 to 8. The horizontal and vertical scaling ratios are derived based on the picture width and height and the left, right, top, and bottom scaling offsets specified for the reference picture and the current picture.

[0088] Other aspects in which the VVC design supporting this feature differs from HEVC include: i) The picture resolution and the corresponding consistency window are signaled in the PPS rather than in the SPS, where the maximum picture resolution is signaled. ii) For a single-layer bitstream, each picture storage (the slot in the DPB for storing a decoded picture) occupies the buffer size required to store a decoded picture with the maximum picture resolution.

[0089] 3.4. Adaptive Loop Filter (ALF)

[0090] Two diamond filter shapes (as Figure 7 shown) are used for the block-based ALF. The 7×7 diamond is applied to the luminance component, and the 5×5 diamond is applied to the chrominance component. One of up to 25 filters is selected for each 4×4 block based on the local gradient direction and activity. Each 4×4 block in the picture is classified according to the directionality and activity. Before filtering each 4×4 block, a simple geometric transformation, such as rotation or diagonal and vertical flipping, can be applied to the filter coefficients based on the gradient value calculated for that block. This is equivalent to applying these transformations to the samples in the filter support region. The idea is to make different blocks more similar by aligning the directionality of the different blocks to which the ALF is applied. The block-based classification is not applied to the chrominance component.

[0091] The ALF filter parameters are signaled in the Adaptive Parameter Set (APS). In one APS, up to 25 sets of luminance filter coefficients and clipping value indices, as well as up to 8 sets of chrominance filter coefficients and clipping value indices, can be signaled. To reduce the bit overhead, the filter coefficients of different classifications of the luminance component can be merged. In the picture or slice header, up to 7 APS IDs can be signaled to specify the luminance filter set for the current picture or slice. The filtering process is further controlled at the CTB level. The luminance CTB can select a filter set among 16 fixed filter sets and the filter set signaled in the APS. For the chrominance component, the APS ID is signaled in the picture or slice header to indicate the chrominance filter set for the current picture or slice. At the CTB level, if there are more than one chrominance filter sets in the APS, the filter index is signaled for each chrominance CTB. When ALF is enabled for a CTB, for each sample within the CTB, a diamond filter with the signaled weights is performed, where a clipping operation is applied to clip the difference between neighboring samples and the current sample. The clipping operation introduces non-linearity to make the ALF more efficient by reducing the influence of neighboring sample values that are too different from the current sample value.

[0092] The Cross-Component Adaptive Loop Filter (CC-ALF) can further enhance each chrominance component on top of the previously described ALF. The goal of CC-ALF is to use the luminance sample values to refine each chrominance component. This is achieved by applying a diamond high-pass linear filter and then using the output of this filtering operation for chrominance refinement. Figure 8 A system-level diagram of the CC-ALF process for other loop filters is provided. As Figure 8 shown, CC-ALF uses the same input as the luminance ALF to avoid additional steps in the overall loop filtering process.

[0093] 4. Technical problems solved by the disclosed solution

[0094] The existing designs in the latest VVC text (in JVET-Q2001-vE / v15) have the following problems:

[0095] 1) The value of slice_type is constrained as follows:

[0096] When nal_unit_type is in the range from IDR_W_RADL to CRA_NUT (including IDR_W_RADL and CRA_NUT) and vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1, slice_type shall be equal to 2.

[0097] However, under the following two conditions, the value of slice_type must also be equal to 2: i) when intra_only_constraint_flag is equal to 1; and ii) when the NAL unit type is an IRAP NAL unit type and the current picture is the first picture in the current AU.

[0098] 2) The semantics of ph_alf_enabled_flag defined as follows are ambiguous.

[0099] ph_alf_enabled_flag being equal to 1 specifies that the adaptive loop filter is enabled for all slices associated with PH, and this adaptive loop filter can be applied to the Y, Cb, or Cr color components in the slice. ph_alf_enabled_flag being equal to 0 specifies that the adaptive loop filter can be disabled for one or more or all slices associated with PH. When absent, ph_alf_enabled_flag is inferred to be equal to 0.

[0100] 3) The consistency window parameters are always signaled in the PPS, including when the picture width and height are the same as the maximum picture width and height signaled in the SPS referenced by the PPS. On the other hand, the consistency window parameters for pictures with the maximum picture width and height are also signaled in the SPS. The signaling of the consistency window parameters for pictures with the maximum picture width and height in the PPS is redundant.

[0101] 4) The repetition of most SEI messages is limited to at most 4 times within a PU or DU. Repetition of PH, AUD, EOS, and EOBNAL units is not allowed. The number of repetitions required to allow padding data NAL units to repeat (e.g., to achieve a constant bit rate) is allowed. However, there is no limit on the number of repetitions for other non-VCL NAL units (i.e., VPS, SPS, PPS, APS, and DCI NAL units).

[0102] 5. List of technical solutions

[0103] To solve the above problems and other problems, the methods summarized below are disclosed. The present invention should be considered as an example for explaining general concepts and should not be interpreted in a narrow way. In addition, these inventions can be applied alone or combined in any way.

[0104] 1) To solve Problem 1, the constraints on slice_type and / or the signaling of slice_type can depend on conditions related to the general constraint flag / NAL unit type / whether the current picture is the first picture in the current AU.

[0105] a. In one example, the conditions can include:

[0106] i. When intra_only_constraint_flag is equal to 1.

[0107] ii. When the NAL unit type is an IRAP NAL unit type and the current picture is the first picture in the current AU.

[0108] iii. When an indication (e.g., an SPS flag) informs that only intra slices are allowed in the picture (or the CLVS containing the current picture, or any other picture set containing the current picture).

[0109] b. The constraint on the slice_type value can be updated such that additionally, when one or all of the above two conditions are true, the value of slice_type is also required to be equal to 2.

[0110] c. Alternatively, when one or all of the above two conditions are true, the signaling of slice_type can be skipped and inferred as an I slice (i.e., slice_type is 2).

[0111] d. Additionally, when the NAL unit type is an IRAP NAL unit type and the current layer is an independent layer, the signaling of slice_type can also be skipped and inferred as an I slice.

[0112] 2) To solve Problem 2, ph_alf_enabled_flag can be specified to be equal to 0 to disable ALF for all slices of the current picture.

[0113] 3) To solve Problem 3, it can be required that when the picture width and height are the maximum picture width and height, the value of pps_conformance_window_flag should be equal to 0.

[0114] a. Additionally, it can be specified that if the picture width and height are the maximum picture width and height, the value of the PPS conformance window syntax element is inferred to be the same as the value signaled in the SPS, otherwise, it is inferred to be equal to 0.

[0115] 4) To solve Problem 4, one or more of the following constraints can be specified to provide some limitations on the repeat times of VPS, SPS, PPS, APS, and DCI NAL units without affecting functions such as random access:

[0116] For VPS

[0117] a. When a VPS NAL unit with a specific value of vps_video_parameter_set_id exists in the CVS, the VPS NAL unit shall exist in the first AU of the CVS, may exist in any AU with at least one VCL NAL unit having a nal_unit_type within the range of IDR_W_RADL to GDR_NUT (including IDR_W_RADL and GDR_NUT), and shall not exist in any other AU.

[0118] i. Alternatively, the above "IDR_W_RADL to GDR_NUT" is changed to "IDR_W_RADL to RSV_IRAP_12".

[0119] b. The number of VPS NAL units with a specific value of vps_video_parameter_set_id in a PU shall not be greater than 1.

[0120] For SPS

[0121] c. Let the associated AU set of the CLVS be the set of AUs starting from the AU containing the first Picture picture of the CLVS in decoding order to the AU containing the last picture of the CLVS in decoding order (including these two AUs).

[0122] d. When an SPS NAL unit with a specific value of sps_seq_parameter_set_id exists in the associated AuSet of the CLVS of the reference SPS, the SPS NAL unit shall exist in the first AU of the associatedAuSet, and may exist in any AU of the associatedAuSet with at least one VCL NAL unit having a nal_unit_type within the range of IDR_W_RADL to GDR_NUT (including IDR_W_RADL and GDR_NUT), and shall not exist in any other AU.

[0123] i. Alternatively, when an SPS NAL unit with a specific value of sps_seq_parameter_set_id exists in the CLVS, it shall exist in the first PU of the CLVS, and may exist in any PU with at least one coded slice NAL unit having a nal_unit_type within the range of IDR_W_RADL to GDR_NUT (including IDR_W_RADL and GDR_NUT), and shall not exist in any other PU.

[0124] ii. Alternatively, in item 4.d or 4.d.i, change "IDR_W_RADL to GDR_NUT" to "IDR_W_RADL to RSV_IRAP_12".

[0125] e. The number of SPS NAL units with a specific value of sps_seq_parameter_set_id in the PU shall not be greater than 1.

[0126] For PPS

[0127] f. The number of PPS NAL units with a specific value of pps_pic_parameter_set_id in the PU shall not be greater than 1.

[0128] For APS

[0129] g. The number of APS NAL units with a specific value of adaptation_parameter_set_id and a specific value of aps_params_type in the PU shall not be greater than 1.

[0130] i. Alternatively, the number of APS NAL units with a specific value of adaptation_parameter_set_id and a specific value of aps_params_type in the DU shall not be greater than 1.

[0131] For DCI

[0132] h. When DCI the NAL unit exists in the bitstream, it shall exist in the first CVS of the bitstream.

[0133] i. When the DCI NAL unit exists in the CVS, it shall exist in the first AU of the CVS, may exist in any AU with at least one VCL NAL unit having a nal_unit_type within the range of IDR_W_RADL to GDR_NUT (including IDR_W_RADL and GDR_NUT), and shall not exist in any other AU.

[0134] j. The number of DCI NAL units in the PU shall not be greater than 1.

[0135] 6. Example embodiments

[0136] The following are some example embodiments of some aspects of the present invention summarized above in Section 5, which can be applied to the VVC specification. The changed text is based on the latest VVC text in JVET-Q2001-vE / v15. The most relevant parts that have been added or modified are highlighted in bold italics, and some of the deleted parts are highlighted in bold with double brackets. There are some other changes that are editorial in nature or not part of the present invention and thus not highlighted.

[0137] 6.1. First Embodiment

[0138] This embodiment is for Item 1.

[0139] The following constraints:

[0140] When nal_unit_type is in the range from IDR_W_RADL to CRA_NUT (including IDR_W_RADL and CRA_NUT) and vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1, slice_type shall be equal to 2.

[0141] It is changed as follows:

[0142] When intra_only_constraint_flag is equal to 1 or when both of the following two conditions are true, the value of slice_type shall be equal to 2:

[0143] - The value of nal_unit_type is in the range from IDR_W_RADL to CRA_NUT (including IDR_W_RADL and CRA_NUT).

[0144] - The value of vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1 or the current picture is the first picture in the current AU.

[0145] 6.2. Second Embodiment

[0146] This embodiment is for Item 2.

[0147] It is proposed that the semantics of ph_alf_enabled_flag be updated as follows:

[0148] ph_alf_enabled_flag being equal to 0 specifies that [[adaptive loop filter]] can be disabled for [[one, or more, or]] all strips associated with PH.

[0149] 6.3. Third Embodiment

[0150] This embodiment is directed to Item 3.

[0151] 7.4.3.4 Picture Parameter Set RBSP Semantics ...

[0152] A pps_conformance_window_flag equal to 1 specifies [indicates] that the conformance cropping window offset parameter follows in the PPS. A pps_conformance_window_flag equal to 0 specifies [indicates] that the conformance cropping window offset parameter does not exist in the PPS. 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 value of pps_conformance_window_flag shall be equal to 0.

[0153] pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset specify samples of the picture output from the decoding process in the CLVS, according to the rectangular region specified in the picture coordinates for output.

[0154] When pps_conformance_window_flag is equal to 0, the following applies:

[0155] - If 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 values of pps_conf_win_left_offset, pps_conf_win_right_offset, pps_conf_win_top_offset, and pps_conf_win_bottom_offset are respectively inferred to be equal to sps_conf_win_left_offset, sps_conf_win_right_offset, sps_conf_win_top_offset, and sps_conf_win_bottom_offset.

[0156] - Otherwise, 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.

[0157] The consistency cropping window contains luma samples, where the horizontal picture coordinates range from SubWidthC * pps_conf_win_left_offset to pic_width_in_luma_samples - (SubWidthC * pps_conf_win_right_offset + 1) (including SubWidthC * pps_conf_win_left_offset and pic_width_in_luma_samples - (SubWidthC * pps_conf_win_right_offset + 1)), and the vertical picture coordinates range from SubHeightC * pps_conf_win_top_offset to pic_height_in_luma_samples - (SubHeightC * pps_conf_win_bottom_offset + 1) (including SubHeightC * pps_conf_win_top_offset and pic_height_in_luma_samples - (SubHeightC * pps_conf_win_bottom_offset + 1)).

[0158] The value of SubWidthC * (pps_conf_win_left_offset + pps_conf_win_right_offset) shall be less than pic_width_in_luma_samples, and the value of SubHeightC * (pps_conf_win_top_offset + pps_conf_win_bottom_offset) shall be less than pic_height_in_luma_samples.

[0159] When ChromaArrayType is not equal to 0, the corresponding specified samples of the two chroma arrays are the samples with picture coordinates (x / SubWidthC, y / SubHeightC), where (x, y) are the picture coordinates of the specified luma sample.

[0160] Note 2 – The output application consistency clipping window offset parameter is the only one applied. All internal decoding processes are applied to the unclipped picture size.

[0161] Let ppsA and ppsB be any two PPSs that refer to the same SPS. The requirement for bitstream consistency 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.

[0162] 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 requirement for bitstream consistency 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.

[0163] Figure 1 is a block diagram showing an example video processing system 1900 in which various techniques disclosed herein may be implemented. Various embodiments may include some or all components of system 1900. System 1900 may include an input 1902 for receiving video content. The video content may be received in a raw or uncompressed format, such as 8- or 10-bit multi-component pixel values, or may be 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 Network (PON), etc., and wireless interfaces such as Wi-Fi or cellular interfaces.

[0164] System 1900 may include a codec component 1904 that may implement various codec or encoding methods described in this document. The codec component 1904 may reduce the average bit rate of the video from input 1902 to the output of the codec component 1904 to produce a coded representation of the video. Codec techniques are thus sometimes referred to as video compression or video transcoding techniques. The output of the codec component 1904 may be stored or transmitted via a communication connection as represented by component 1906. The stored or communicated bitstream (or coded) representation of the video received at input 1902 may be used by component 1908 to generate pixel values or a displayable video for transmission to the display interface 1910. The process of generating a user-visible video from the bitstream representation is sometimes referred to as video decompression. Additionally, while certain video processing operations are referred to as "codec" operations or tools, it will be understood that the codec tools or operations are used at the encoder and the corresponding decoding tools or operations that reverse the codec results will be performed by the decoder.

[0165] Examples of a peripheral bus interface or a display interface may include Universal Serial Bus (USB), or High-Definition Multimedia Interface (HDMI), or Displayport, etc. Examples of a storage interface include SATA (Serial Advanced Technology Attachment), PCI, IDE interface, etc. The techniques described in this document may be embodied in various electronic devices, such as mobile phones, laptops, smartphones, or other devices capable of performing digital data processing and / or video display.

[0166] Figure 2 is a block diagram of a video processing apparatus 3600. The apparatus 3600 may be used to implement one or more methods described herein. The apparatus 3600 may be embodied in a smartphone, a tablet computer, a computer, an Internet of Things (IoT) receiver, etc. The apparatus 3600 may include one or more processors 3602, one or more memories 3604, and video processing hardware 3606. The (multiple) processors 3602 may be configured to implement one or more methods described in this document. The memory (multiple memories) 3604 may be used to store data and code for implementing the methods and techniques described herein. The video processing hardware 3606 may be used to implement some of the techniques described in this document in hardware circuitry.

[0167] Figure 4 is a block diagram showing an example video codec system 100 that may utilize the techniques of the present disclosure.

[0168] As Figure 4As shown, the video encoding and decoding system 100 may include a source device 110 and a destination device 120. The source device 110 generates encoded video data, where the source device 110 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, where the destination device 120 may be referred to as a video decoding device.

[0169] The source device 110 may include a video source 112, a video encoder 114, and an input / output (I / O) interface 116.

[0170] The video source 112 may include sources such as a video capture device, an interface for receiving video data from a video content provider, and / or a computer graphics system for generating video data, or a combination of these sources. The video data may include one or more pictures. The video encoder 114 encodes the video data from the video source 112 to generate a bitstream. The bitstream may include a sequence of bits forming an encoded representation of the video data. The bitstream may include encoded pictures and associated data. An encoded picture is an encoded representation of a picture. The associated data may include a sequence parameter set, a picture parameter set, and other syntax structures. The I / O interface 116 may include 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 over a network 130a. The encoded video data may also be stored on a storage medium / server 130b for access by the destination device 120.

[0171] The destination device 120 may include an I / O interface 126, a video decoder 124, and a display device 122.

[0172] 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.

[0173] The video encoder 114 and the video decoder 124 may operate according to a video compression standard, such as the High Efficiency Video Coding (HEVC) standard, the Versatile Video Coding (VVC) standard, and other current and / or additional standards.

[0174] Figure 5 is a block diagram showing an example of a video encoder 200, which may be Figure 4 the video encoder 114 in the system 100 shown.

[0175] Video encoder 200 may be configured to perform any or all of the techniques of the present disclosure. In Figure 5 the example, video encoder 200 includes a plurality of functional components. The techniques described in the present disclosure may be shared among various components of video encoder 200. In some examples, a processor may be configured to perform any or all of the techniques described in the present disclosure.

[0176] The functional components of video encoder 200 may include a splitting 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 prediction unit 206), a residual generation unit 207, a transformation unit 208, a quantization unit 209, an inverse quantization unit 210, an inverse transformation unit 211, a reconstruction unit 212, a buffer 213, and an entropy encoding unit 214.

[0177] In other examples, video encoder 200 may include more, fewer, or different functional components. In an example, prediction unit 202 may include an intra block copy (IBC) unit. The IBC unit may perform prediction in the IBC mode, where at least one reference picture is the picture in which the current video block is located.

[0178] In addition, some components such as motion estimation unit 204 and motion compensation unit 205 may be highly integrated, but are shown separately in the Figure 5 example for purposes of explanation.

[0179] Splitting unit 201 may split a picture into one or more video blocks. Video encoder 200 and video decoder 300 may support various video block sizes.

[0180] Mode selection unit 203 may select one of the encoding / decoding modes (e.g., intra or inter) based on error results, and provide the resulting intra-encoded / decoded block or inter-encoded / decoded block to residual generation unit 207 to generate residual block data, and to reconstruction unit 212 to reconstruct the encoded block for use as a reference picture. In some examples, mode selection unit 203 may select a combination of intra and inter prediction modes (CIIP), where the prediction is based on an inter prediction signal and an intra prediction signal. In the case of inter prediction, mode selection unit 203 may also select the resolution of the motion vector of the block (e.g., sub-pixel or integer pixel accuracy).

[0181] To perform inter - frame prediction on a current video block, the motion estimation unit 204 can generate motion information for the current video block by comparing one or more reference frames from buffer 213 with the current video block. The motion compensation unit 205 can determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from buffer 213 other than the picture associated with the current video block.

[0182] The motion estimation unit 204 and the motion compensation unit 205 can perform different operations on the current video block, e.g., depending on whether the current video block is in an I - slice, a P - slice, or a B - slice.

[0183] In some examples, the motion estimation unit 204 can perform uni - directional prediction on the current video block, and the motion estimation unit 204 can search for a reference picture in list 0 or list 1 of the reference video block list for the current video block. The motion estimation unit 204 can then generate a reference index indicating the reference picture in list 0 or list 1, which includes the reference video block and a motion vector indicating the spatial displacement between the current video block and the reference video block. The motion estimation unit 204 can output the reference index, a prediction direction indicator, and the motion vector as the motion information for the current video block. The motion compensation unit 205 can generate a predicted video block for the current block based on the reference video block indicated by the motion information of the current video block.

[0184] In other examples, the motion estimation unit 204 can perform bi - directional prediction on the current video block. The motion estimation unit 204 can search for a reference video block of the current video block in the reference pictures in list 0 and can also search for another reference video block of the current video block in list 1. The motion estimation unit 204 can then generate a reference index that indicates the reference pictures in list 0 and list 1 that include the reference video block and a motion vector indicating the spatial displacement between the reference video block and the current video block. The motion estimation unit 204 can output the reference index and the motion vector of the current video block as the motion information for the current video block. The motion compensation unit 205 can generate a predicted video block for the current video block based on the reference video block indicated by the motion information of the current video block.

[0185] In some examples, the motion estimation unit 204 can output a complete set of motion information for the decoder's decoding process.

[0186] In some examples, the motion estimation unit 204 may not output a complete set of motion information for the current video. Instead, the motion estimation unit 204 can signal the motion information of the current video block by referring to the motion information of another video block. For example, the motion estimation unit 204 can determine that the motion information of the current video block is similar enough to the motion information of a neighboring video block.

[0187] In one example, the motion estimation unit 204 may indicate a value in a syntax structure associated with the current video block, and this value indicates to the video decoder 300 that the current video block has the same motion information as another video block.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] The residual generation unit 207 may generate residual data for the current video block by subtracting (e.g., indicated by a minus sign) the (multiple) predicted video blocks of the current video block from the current video block. The residual data for the current video block may include residual video blocks corresponding to different sample components of the samples in the current video block.

[0192] In other examples, such as in the skip mode, there may be no residual data for the current video block, and the residual generation unit 207 may not perform the subtraction operation.

[0193] The 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.

[0194] After the transform processing unit 208 generates the transform coefficient video block associated with the current video block, the 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.

[0195] The inverse quantization unit 210 and the inverse transform unit 211 can respectively apply inverse quantization and inverse transform to the transformed coefficient video block to reconstruct the residual video block from the transformed coefficient video block. The reconstruction unit 212 can add the reconstructed residual video block to the corresponding samples of one or more predicted 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.

[0196] After the reconstruction unit 212 reconstructs the video block, a loop filtering operation can be performed to reduce the block effect in the video block.

[0197] The entropy encoding unit 214 can receive data from other functional components of the video encoder 200. When the entropy encoding unit 214 receives the data, the entropy encoding unit 214 can perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream including the entropy encoded data.

[0198] Figure 6 is a block diagram showing an example of the video decoder 300, and the video decoder 300 can be Figure 4 the video decoder 114 in the system 100 shown.

[0199] The video decoder 300 can be configured to perform any or all of the techniques of the present disclosure. In Figure 6 the example, the video decoder 300 includes multiple functional components. The techniques described in the present disclosure can be shared among various components of the video decoder 300. In some examples, the processor can be configured to perform any or all of the techniques described in the present disclosure.

[0200] In Figure 6 the example, the video decoder 300 includes an entropy decoding unit 301, a motion compensation unit 302, an intra prediction unit 303, an inverse quantization unit 304, an inverse transform unit 305, a reconstruction unit 306, and a buffer 307. In some examples, the video decoder 300 can perform a decoding process that is generally opposite to the encoding process described for the video encoder 200 ( Figure 5 ).

[0201] The entropy decoding unit 301 can retrieve the encoded bitstream. The encoded bitstream can include entropy encoded video data (e.g., encoded blocks of video data). The entropy decoding unit 301 can decode the entropy encoded video data, and from the entropy decoded video data, the motion compensation unit 302 can determine motion information including a motion vector, motion vector precision, reference picture list index, and other motion information. The motion compensation unit 302 can determine such information, for example, by performing AMVP and Merge modes.

[0202] The motion compensation unit 302 may generate motion-compensated blocks and may perform interpolation based on an interpolation filter. An identifier of the interpolation filter to be used with sub-pixel precision may be included in a syntax element.

[0203] The motion compensation unit 302 may compute an interpolation of sub-integer pixels of a reference block using an interpolation filter such as that used by the video encoder 200 during encoding of a video block. The motion compensation unit 302 may determine the interpolation filter used by the video encoder 200 according to received syntax information and may use that interpolation filter to generate a prediction block.

[0204] The motion compensation unit 302 may use some syntax information to determine the size of the blocks used to encode the (multiple) frames and / or (multiple) slices of an encoded video sequence, the partitioning information that describes how each macroblock of a picture of the encoded video sequence is partitioned, the mode indicating how each partition is encoded, one or more reference frames (and reference frame lists) for each inter-coded block, and other information for decoding the encoded video sequence.

[0205] The intra prediction unit 303 may form a prediction block from spatially adjacent blocks using, for example, an intra prediction mode received in the bitstream. The inverse quantization unit 303 inverse quantizes the quantized video block coefficients provided in the bitstream and decoded by the entropy decoding unit 301, i.e., dequantizes. The inverse transform unit 303 applies an inverse transform.

[0206] The reconstruction unit 306 may add a residual block to the corresponding prediction block generated by the motion compensation unit 202 or the intra prediction unit 303 to form a decoded block. If desired, a deblocking filter may also be applied to the decoded block to remove blocking artifacts. The decoded video block is then stored in the buffer 307 to provide a reference block for subsequent motion compensation / intra prediction and also to produce decoded video for presentation on a display device.

[0207] Next, a list of preferred solutions for some embodiments is provided.

[0208] The following solutions illustrate example embodiments of the techniques discussed in the previous section (e.g., item 1).

[0209] 1. A video processing method (e.g., Figure 3The method shown in (3000) includes performing a conversion between a video including one or more pictures each including one or more strips and an encoded / decoded representation of the video, where the encoded / decoded representation complies with formatting rules that specify conditions for fields in the encoded / decoded representation to control constraints on strip types or whether a strip type is included in the encoded / decoded representation, and where the field includes a general constraint flag, a network abstraction layer unit type, or whether the video strip is in the first video picture of an access unit.

[0210] 2. The method according to Solution 1, wherein the formatting rules specify that the condition is that an intra-only constraint has been enabled for the video strip.

[0211] The following solutions show example embodiments of the techniques discussed in the previous section (e.g., item 2).

[0212] 3. A video processing method, including: performing a conversion between a video including one or more pictures each including one or more strips and an encoded / decoded representation of the video, where the encoded / decoded representation complies with formatting rules that specify disabling adaptive loop filtering for all strips in a video picture based on the value of a flag in the picture header of the video picture.

[0213] The following solutions show example embodiments of the techniques discussed in the previous section (e.g., item 3).

[0214] 4. A video processing method, including: performing a conversion between a video including one or more pictures each including one or more strips and an encoded / decoded representation of the video, where the encoded / decoded representation complies with formatting rules that specify setting a consistency window flag to a disabled mode when the height and width of the current picture are equal to the maximum height and maximum width in the video.

[0215] The following solutions show example embodiments of the techniques discussed in the previous section (e.g., item 4).

[0216] 5. A video processing method, including: performing a conversion between a video including one or more pictures each including one or more strips and an encoded / decoded representation of the video, where the encoded / decoded representation complies with formatting rules that specify the repeat time of a parameter set.

[0217] 6. The method according to Solution 5, wherein the parameter set is a video parameter set or a sequence parameter set or a picture parameter set of an adaptive parameter set.

[0218] 7. The method according to Solution 5, wherein the parameter set is a decoding capability information network abstraction layer unit (DCINAL).

[0219] 8. The method according to solution 6, wherein the parameter set is a video parameter set, and wherein the formatting rule specifies that, in the case where the video parameter set includes a specific value of the identifier field, the video parameter set is included in the first access unit of the coded video representation.

[0220] 9. The method according to solution 8, wherein the formatting rule further specifies that the video parameter set having a specific value of the identifier field is included if and only if another access unit has a network abstraction layer type within a range between two pre-specified values.

[0221] 10. The method according to solution 6, wherein the parameter set is a sequence parameter set, and wherein the formatting rule specifies that the coded representation is organized as one or more access units of one or more coded layers of a video sequence, and wherein the formatting rule specifies that the network abstraction layer including the sequence parameter set having a specific identifier value is included in the first access unit of the set of access units of the reference sequence parameter set.

[0222] 11. The method according to solution 7, wherein the formatting rule specifies that, in the case where the DCI NAL is included in the coded representation of the video, the DCI NAL is included in the first coded video sequence of the video.

[0223] 12. The method according to solution 7 or 11, wherein the formatting rule further specifies that the number of DCI NAL units in a prediction unit is limited to one.

[0224] 13. The method according to any one of solutions 1 to 12, wherein the transformation includes encoding the video into a coded representation.

[0225] 14. The method according to any one of solutions 1 to 12, wherein the transformation includes decoding the coded representation to generate pixel values of the video.

[0226] 15. A video decoding apparatus, comprising a processor configured to implement the method according to one or more of solutions 1 to 14.

[0227] 16. A video encoding apparatus, comprising a processor configured to implement the method according to one or more of solutions 1 to 14.

[0228] 17. A computer program product storing computer code, which when executed by a processor causes the processor to implement the method according to any one of solutions 1 to 14.

[0229] 18. A method, apparatus or system described in this document.

[0230] The following list provides a second set of preferred solutions implemented through some embodiments.

[0231] The following solutions illustrate example embodiments of the techniques discussed in the previous section (e.g., item 1).

[0232] 1. A video processing method (e.g., Figure 3 the method 3000 depicted in), comprising: performing a conversion (3002) between a video including one or more pictures each including one or more slices and a bitstream of the video, wherein the bitstream conforms to format rules; wherein the format rules specify whether or how the slice type of a slice in one or more slices is indicated in the bitstream depending on a condition, and wherein the condition is based on at least one of the following: a general constraint flag, a network abstraction layer unit type, or whether the slice is in the first picture of an access unit.

[0233] 2. The method according to solution 1, wherein the condition includes or corresponds to the general constraint flag indicating an intra-only constraint on the slice.

[0234] 3. The method according to solution 1, wherein the condition includes or corresponds to the slice being in the first picture of an access unit and the network abstraction layer unit type having a specific type, and wherein the specific type indicates an intra random access point type.

[0235] 4. The method according to solution 1, wherein the condition includes or corresponds to the bitstream indicating that only intra slices are permitted in a set of pictures including the picture.

[0236] 5. The method according to solution 4, wherein the set of pictures corresponds to the picture.

[0237] 6. The method according to solution 4, wherein the set of pictures corresponds to a coded layer video sequence (CLVS) including the picture.

[0238] 7. The method according to any one of solutions 1-6, wherein the format rules specify that in response to (a) the general constraint flag or the network abstraction layer unit type satisfying the condition, or (b) the slice being in the first picture of an access unit, a slice type value 2 is indicated in the bitstream.

[0239] 8. The method according to solution 1, wherein the format rules specify that the slice type has a value 2, and in response to (a) the general constraint flag or the network abstraction layer unit type satisfying the condition, or (b) the slice being in the first picture of an access unit, the indication of the slice type is omitted from the bitstream.

[0240] 9. The method according to Solution 1, wherein the format rule specifies that the slice type has a value of 2, and the indication of the slice type is omitted from the bitstream in response to (a) the network abstraction layer unit type being an intra random access point type, and (b) the layer to which the picture containing the slice belongs being an independently decodable layer.

[0241] The following solutions illustrate additional examples of example embodiments of the techniques discussed in the previous section (e.g., items 2 and 4).

[0242] 1. A video processing method (e.g., Figure 9 the method 900 depicted in), comprising: performing a conversion (902) between a video including a picture containing a plurality of slices and a bitstream of the video, wherein the bitstream complies with a format rule that specifies the applicability of adaptive loop filtering for all slices in the picture header.

[0243] 2. The method according to Solution 1, wherein a value of 0 for the flag indicates that adaptive loop filtering is disabled for all slices in the picture.

[0244] 3. The method according to Solution 1, wherein a value of 1 for the flag indicates that adaptive loop filtering is enabled for all slices in the picture.

[0245] 4. A video processing method (e.g., Figure 10 the method 1000 depicted in), comprising: performing a conversion (1002) between a video including one or more pictures containing one or more slices and a bitstream of the video according to a format rule, wherein the format rule specifies the repeat time of a parameter set associated with the video.

[0246] 5. The method according to Solution 4, wherein the parameter set is a video parameter set (VPS).

[0247] 6. The method according to Solution 5, wherein the format rule specifies that in response to a VPS network abstraction layer (NAL) unit of a coded video sequence (CVS) containing a VPS with a specific identifier value, the VPS NAL unit is included in the first access unit (AU) of the CVS, and is selectively included in another AU based on the value of another VPS NAL unit in another AU of the CVS, and is excluded from the remaining AUs of the CVS.

[0248] 7. The method according to Solution 6, wherein the value of another VPS NAL unit in another AU is in the range from IDR_W_RADL to GDR_NUT.

[0249] 8. The method according to solution 6, wherein the value of another VPS NAL unit in another AU is in the range from IDR_W_RADL to RSV_IRAP_12.

[0250] 9. The method according to any one of solutions 5 - 8, wherein the formatting rule further specifies that no more than one VPS NAL unit with a given identifier value is included in a picture unit (PU) in the bitstream.

[0251] 10. The method according to solution 4, wherein the parameter set is a sequence parameter set (SPS).

[0252] 11. The method according to solution 10, wherein the coded layer video sequence (CLVS) in the bitstream includes an associated set of access units (AUs), and the associated set of AUs includes the AUs starting from the first AU of the first picture of the CLVS in decoding order and ending with the last AU of the last picture of the CLVS in decoding order.

[0253] 12. The method according to solution 11, wherein the formatting rule specifies that in response to the SPS network abstraction layer (NAL) unit containing an SPS with a specific identifier value, the SPS NAL unit is included in the first AU of the associated set of AUs, and is selectively included in another AU based on the value of another SPS NAL unit in another AU of the associated set, and is excluded from the remaining AUs of the CVS.

[0254] 13. The method according to solution 11, wherein the formatting rule specifies that in response to the coded layer video sequence (CVLS) containing an SPS with a specific identifier value in the first picture unit (PU) of the CVLS, the SPS NAL unit is selectively included in another PU based on the value of the slice NAL unit in another PU of the CVLS, and is excluded from the remaining PUs of the CVLS.

[0255] 14. The method according to solution 12, wherein the value of another SPS NAL unit in another AU is in the range from IDR_W_RADL to GDR_NUT.

[0256] 15. The method according to solution 13, wherein the value of the slice NAL unit in another PU is in the range from IDR_W_RADL to GDR_NUT.

[0257] 16. The method according to solution 12, wherein the value of another SPS NAL unit in another AU is in the range from IDR_W_RADL to RSV_IRAP_12.

[0258] 17. The method according to solution 13, wherein the value of the strip NAL unit in another PU is in the range from IDR_W_RADL to RSV_IRAP_12.

[0259] 18. The method according to any one of solutions 11-17, wherein the formatting rule further specifies that no more than one SPS NAL unit with a given identifier value is included in a picture unit (PU) in the bitstream.

[0260] 19. The method according to solution 4, wherein the parameter set is a picture parameter set (PPS), and wherein the formatting rule further specifies that no more than one PPS network abstraction layer (NAL) unit with a given identifier value is included in a picture unit (PU) in the bitstream.

[0261] 20. The method according to solution 4, wherein the parameter set is an adaptive parameter set (APS).

[0262] 21. The method according to solution 20, wherein the formatting rule further specifies that no more than one APS network abstraction layer (NAL) unit with a given identifier value and a specific value of the parameter type is included in a picture unit (PU) in the bitstream.

[0263] 22. The method according to solution 20, wherein the formatting rule further specifies that no more than one APS network abstraction layer (NAL) unit with a given identifier value and a specific value of the parameter type is included in a decoding unit (DU) in the bitstream.

[0264] 23. The method according to solution 4, wherein the parameter set is a decoding capability information network abstraction layer unit (DCI NAL).

[0265] 24. The method according to solution 23, wherein the formatting rule specifies that when present, the DCI NAL unit is not allowed to be included in a coded video sequence (CVS) in the bitstream that is not the first CVS in the bitstream.

[0266] 25. The method according to solution 23, wherein the formatting rule specifies that in response to a coded video sequence (CVS) including a DCI NAL unit, the DCI NAL unit is in the first access unit (AU) of the CVS and is selectively present in another AU based on whether the other AU includes a video coding layer (VCL) NAL unit with a specific NAL unit identifier value, and is excluded from the remaining AUs of the CVS.

[0267] 26. The method according to solution 21, wherein the specific identifier value is in the range from IDR_W_RADL to GDR_NUT.

[0268] 27. The method according to any one of solutions 23 - 26, wherein the formatting rule specifies that a picture unit (PU) includes at most one DCI NAL unit.

[0269] The following solutions show additional examples of preferred embodiments of the techniques discussed in the previous section (e.g., item 3).

[0270] 1. A video processing method (e.g., Figure 11 the method 1100 depicted in), comprising: performing a conversion (1102) between a video including pictures in a video unit and a bitstream of the video according to formatting rules, wherein the formatting rules specify that in response to the width of a picture being equal to the maximum allowable picture width in the video unit and the height of the picture being equal to the maximum allowable picture height in the video unit, the consistency window flag in the picture parameter set corresponding to the picture is set to a value of 0.

[0271] 2. The method according to solution 1, wherein the maximum allowable picture width and the maximum allowable picture height are indicated in the sequence parameter set referenced by the video unit.

[0272] 3. The method according to solution 2, wherein the formatting rules specify that in response to the width of a picture being equal to the maximum allowable picture width in the video unit and the height of the picture being equal to the maximum allowable picture height in the video unit, the consistency window syntax element is excluded from the picture parameter set and is inferred to have the same value as indicated in the sequence parameter set.

[0273] 4. The method according to solution 2, wherein the formatting rules specify that in response to the width of a picture not being equal to the maximum allowable picture width in the video unit or the height of the picture not being equal to the maximum allowable picture height in the video unit, the consistency window syntax element is inferred to have a value of 0.

[0274] In the solutions listed above, the conversion includes encoding the video into a bitstream.

[0275] In the solutions listed above, the conversion includes generating a video from the bitstream.

[0276] In some embodiments, a video decoding device may include a processor configured to implement the method according to one or more of the above solutions.

[0277] In some embodiments, a video encoding device including a processor may be configured to implement the method according to one or more of the above solutions.

[0278] In some embodiments, a computer-readable medium may store thereon code that, when executed by a processor, causes the processor to implement the method according to any one of the above solutions.

[0279] In some embodiments, a method of video processing includes generating a bitstream according to the method according to any one or more of the above solutions and storing the bitstream on a computer-readable medium.

[0280] In some embodiments, a computer-readable medium may store thereon a bitstream that is generated from a video according to the method according to any one or more of the above solutions.

[0281] 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 the pixel representation of a video to the 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, for example, correspond to bits juxtaposed or scattered in different places within the bitstream. For example, a macroblock may be encoded according to the transformed and decoded error residual values and also using bits in the headers 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 solutions. Similarly, the encoder may determine to include or not include a particular syntax field and generate the encoded representation accordingly by including the syntax field or excluding the syntax field from the encoded representation.

[0282] The disclosed and other solutions, examples, embodiments, modules, and functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware (including the structures disclosed in this document and their structural equivalents), or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer-readable medium for execution by, or to control the operation of, a data processing apparatus. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a combination of substances affecting a machine-readable propagated signal, or a combination of one or more of them. The term "data processing apparatus" encompasses all apparatus, devices, and machines for processing data, including, by way of example, a programmable processor, a computer, or multiple processors or computers. In addition to hardware, the apparatus can also include code that creates an execution environment for the computer programs being discussed, e.g., 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 propagated signal is an artificially generated signal that is generated to encode information for transmission to a suitable receiver apparatus, e.g., a machine-generated electrical, optical, or electromagnetic signal.

[0283] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language (including compiled or interpreted languages), and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. The program can be stored as part of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program being discussed, or in multiple coordinated files (e.g., files that store one or more modules, subroutines, or portions of code). A computer program can be deployed to execute on one computer or on multiple computers distributed across one site or multiple sites and interconnected by a communication network.

[0284] The processes and logical flows described in this document can 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 logical flows can also be performed by special-purpose logic circuitry, and the apparatus can also be implemented as special-purpose logic circuitry, e.g., an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0285] Processors suitable for executing computer programs include, for example, any one or more processors of general and special purpose microprocessors, as well as any type of digital computer. Generally, a 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 executing instructions and one or more memory devices for storing the instructions and data. Generally, a computer will also include one or more mass storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks) for storing data, or be operatively coupled to receive data from or transfer data to or both from and to such one or more mass storage devices. However, a computer need not have such devices. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, including, for example, semiconductor memory devices such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as internal hard disks or removable disks; magneto-optical disks; and CD ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[0286] Although this patent document contains many details, these details should not be construed as limitations on any subject or the scope that may be claimed, but rather as descriptions of features specific to particular embodiments of a particular technology. Certain features described in the context of separate embodiments in this patent document may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. Additionally, although features may be described as acting in certain combinations and even initially claimed as such, in some cases one or more features from a claimed combination may be excluded from the combination, and the claimed combination may be directed to a sub-combination or variations of a sub-combination.

[0287] Similarly, although operations are depicted in the drawings in a particular order, this should not be understood to require that such operations be performed in the particular order shown or in sequential order, or that all shown operations be performed to achieve a desired result. Additionally, the separation of various system components in the embodiments described in this patent document should not be understood to be required in all embodiments.

[0288] Only some embodiments and examples have been described, and other embodiments, enhancements, and variations may be made based on what is described and shown in this patent document.

Claims

1. A video processing method, comprising: performing a conversion between a video including pictures and a bitstream of the video according to format rules, wherein the format rules specify that, in response to the width of the picture being equal to the maximum allowed picture width and the height of the picture being equal to the maximum allowed picture height, a consistency window flag in a picture parameter set corresponding to the picture is set to a value of 0; wherein the maximum allowed picture width and the maximum allowed picture height are indicated in a referenced sequence parameter set; wherein the format rules specify: in response to (a) the consistency window flag having a value of 0, and (b) the width of the picture being equal to the maximum allowed picture width and the height of the picture being equal to the maximum allowed picture height, a consistency window syntax element indicating a consistency cropping window offset parameter is excluded from the picture parameter set and is inferred to have the same value as that indicated in the sequence parameter set; or in response to (c) the consistency window flag having a value of 0, and (d) the width of the picture not being equal to the maximum allowed picture width or the height of the picture not being equal to the maximum allowed picture height, a consistency window syntax element indicating the consistency cropping window offset parameter is inferred to have a value of 0.

2. The method according to claim 1, wherein the consistency window flag being equal to a value of 0 indicates that the consistency cropping window offset parameter does not exist in the picture parameter set.

3. The method according to claim 1, wherein the conversion includes decoding the video from the bitstream.

4. The method according to claim 1, wherein the conversion includes encoding the video into the bitstream.

5. An apparatus for processing video data, comprising a processor and a non-transitory memory having instructions thereon, wherein when the instructions are executed by the processor, the processor is caused to: perform a conversion between a video including pictures and a bitstream of the video according to format rules, wherein the format rules specify that, in response to the width of the picture being equal to the maximum allowed picture width and the height of the picture being equal to the maximum allowed picture height, a consistency window flag in a picture parameter set corresponding to the picture is set to a value of 0; wherein the maximum allowed picture width and the maximum allowed picture height are indicated in a referenced sequence parameter set; wherein the format rules specify: in response to (a) the consistency window flag having a value of 0, and (b) the width of the picture being equal to the maximum allowed picture width and the height of the picture being equal to the maximum allowed picture height, a consistency window syntax element indicating a consistency cropping window offset parameter is excluded from the picture parameter set and is inferred to have the same value as that indicated in the sequence parameter set; or in response to (c) the consistency window flag having a value of 0, and (d) the width of the picture not being equal to the maximum allowed picture width or the height of the picture not being equal to the maximum allowed picture height, a consistency window syntax element indicating the consistency cropping window offset parameter is inferred to have a value of 0.

6. The apparatus according to claim 5, wherein, the consistency window flag being equal to a value of 0 indicates that the consistency cropping window offset parameter does not exist in the picture parameter set.

7. A non - transitory computer - readable storage medium storing instructions that cause a processor to: perform a conversion between a video including pictures and a bitstream of the video according to format rules, wherein, the format rules specify that in response to the width of the picture being equal to the maximum allowable picture width and the height of the picture being equal to the maximum allowable picture height, the consistency window flag in the picture parameter set corresponding to the picture is set to a value of 0; wherein the maximum allowable picture width and the maximum allowable picture height are indicated in the referenced sequence parameter set; wherein the format rules specify: in response to (a) the consistency window flag having a value of 0, and (b) the width of the picture being equal to the maximum allowable picture width and the height of the picture being equal to the maximum allowable picture height, the consistency window syntax element indicating the consistency cropping window offset parameter is excluded from the picture parameter set and is inferred to have the same value as that indicated in the sequence parameter set; or in response to (c) the consistency window flag having a value of 0, and (d) the width of the picture not being equal to the maximum allowable picture width or the height of the picture not being equal to the maximum allowable picture height, the consistency window syntax element indicating the consistency cropping window offset parameter is inferred to have a value of 0.

8. The non - transitory computer - readable storage medium according to claim 7, wherein, the consistency window flag being equal to a value of 0 indicates that the consistency cropping window offset parameter does not exist in the picture parameter set.

9. A non - transitory computer - readable recording medium storing a bitstream of a video, the bitstream of the video being generated by a method executed by a video processing apparatus, wherein the method comprises: generating the bitstream of the video including pictures according to format rules, wherein the format rules specify that in response to the width of the picture being equal to the maximum allowable picture width and the height of the picture being equal to the maximum allowable picture height, the consistency window flag in the picture parameter set corresponding to the picture is set to a value of 0; wherein the maximum allowable picture width and the maximum allowable picture height are indicated in the referenced sequence parameter set; wherein the format rules specify: in response to (a) the consistency window flag having a value of 0, and (b) the width of the picture being equal to the maximum allowable picture width and the height of the picture being equal to the maximum allowable picture height, the consistency window syntax element indicating the consistency cropping window offset parameter is excluded from the picture parameter set and is inferred to have the same value as that indicated in the sequence parameter set; or In response to (c) the consistency window flag having a value of 0, and (d) the width of the picture not being equal to the maximum allowed picture width or the height of the picture not being equal to the maximum allowed picture height, the consistency window syntax element indicating the consistency cropping window offset parameter is inferred to have a value of 0.

10. The non-transitory computer-readable recording medium according to claim 9, wherein, the consistency window flag being equal to 0 value indicates that the consistency cropping window offset parameter does not exist in the picture parameter set.

11. A method for storing a bitstream of a video, comprising: generating the bitstream of the video including the picture according to format rules, storing the bitstream on a non-transitory computer-readable recording medium, wherein the format rules specify that in response to the width of the picture being equal to the maximum allowed picture width and the height of the picture being equal to the maximum allowed picture height, the consistency window flag in the picture parameter set corresponding to the picture is set to a value of 0; wherein the maximum allowed picture width and the maximum allowed picture height are indicated in the referenced sequence parameter set; wherein the format rules specify: in response to (a) the consistency window flag having a value of 0, and (b) the width of the picture being equal to the maximum allowed picture width and the height of the picture being equal to the maximum allowed picture height, the consistency window syntax element indicating the consistency cropping window offset parameter is excluded from the picture parameter set and is inferred to have the same value as that indicated in the sequence parameter set; or in response to (c) the consistency window flag having a value of 0, and (d) the width of the picture not being equal to the maximum allowed picture width or the height of the picture not being equal to the maximum allowed picture height, the consistency window syntax element indicating the consistency cropping window offset parameter is inferred to have a value of 0.

12. A video decoding device, comprising a processor configured to implement the method according to any one of claims 1 to 3 and 11.

13. A video encoding device, comprising a processor configured to implement the method according to any one of claims 1 to 2, 4 and 11.

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