Sub-picture signaling in video coding

Abstract

A method, apparatus, and system for signaling use of subpictures in coded video pictures are described. One example of a video processing method includes performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, and wherein the format rule specifies that a first syntax element that indicates whether a picture of the video can be partitioned is conditionally included in a picture parameter set (PPS) of the bitstream based on values of a second syntax element and a third syntax element, wherein the second syntax element indicates whether identifiers of subpictures are signaled in the PPS, and the third syntax element indicates a number of subpictures in the PPS.

Description

[0001] Cross-references to related applications

[0002] Pursuant to the applicable Patent Act and / or the Paris Convention, this application promptly claims priority and interest in U.S. Provisional Patent Application No. 62 / 954,364, filed December 27, 2019. For all legal purposes, the entire disclosure of the aforementioned application is incorporated herein by reference as a part of this application disclosure. Technical Field

[0003] This application relates to image and video encoding and decoding. Background Technology

[0004] Digital video accounts for the largest share of 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 is expected to continue to grow. Summary of the Invention

[0005] This document discloses methods, devices, and systems for sub-picture signaling used by video encoders and decoders for video encoding and decoding, respectively.

[0006] In one example aspect, a video processing method is disclosed. The method includes: performing a conversion between a video comprising images and a bitstream of the video, wherein the number of sub-images in the images is signaled as a field in a sequence parameter set (SPS) of the bitstream, the bit width of the field being based on a value of the number of sub-images, and wherein the field is a left-bit-first unsigned integer Exp-Golomb encoding / decoding syntax element.

[0007] In another example, a video processing method is disclosed. The method includes: performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, and wherein the format rule specifies that a first syntax element indicating whether pictures of the video can be segmented is conditionally included in a picture parameter set (PPS) of the bitstream based on the values ​​of a second syntax element and a third syntax element, wherein the second syntax element indicates whether an identifier of a sub-picture is signaled in the PPS, and the third syntax element indicates the number of sub-pictures in the PPS.

[0008] In another example, a video processing method is disclosed. The method includes: performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, and wherein the format rule specifies that a first syntax element indicating whether a picture of the video can be segmented is included in a picture parameter set (PPS) of the bitstream, preceding a set of syntax elements in the PPS indicating identifiers of subpictures of the picture.

[0009] In another example, a video processing method is disclosed. The method includes: performing a conversion between a video region of a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies the value of a second syntax element based on whether information indicating a sub-picture is included in a sequence parameter set (SPS), wherein a first syntax element is conditionally included in the SPS, wherein the first syntax element indicates whether information indicating a sub-picture identifier is included in the parameter set of the bitstream.

[0010] In another example, a video processing method is disclosed. The method includes: performing a conversion between images of a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that the mapping between identifiers of one or more sub-images of the image and one or more sub-images is not included in the image header of the image, wherein the format rule further specifies that the identifiers of the one or more sub-images are derived based on syntax elements in the Picture Parameter Set (PPS) and Sequence Parameter Set (SPS) referenced by the image.

[0011] In another example, a video processing method is disclosed. The method includes: performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, and wherein the format rule specifies that when the value of a first syntax element indicates a mapping between an identifier of a sub-picture and one or more sub-pictures of a picture is explicitly signaled for one or more sub-pictures, the mapping is signaled in a Sequence Parameter Set (SPS) or a Picture Parameter Set (PPS).

[0012] In another example, a video processing method is disclosed. The method includes: performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, and wherein the format rule specifies that the length of the identifier for a signaling notification subpicture in a Sequence Parameter Set (SPS) is not based on the value of a syntax element indicating whether the signaling notification identifier is in the SPS.

[0013] In another example, a video processing method is disclosed. The method includes: performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, and wherein the format rule specifies the length of the signaling notification identifier in the PPS due to syntax elements indicating an identifier for explicitly signaling notification sub-pictures in a Picture Parameter Set (PPS).

[0014] In another example, a video processing method is disclosed. The method includes: performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that a first syntax element in the sequence parameter set (SPS) of the bitstream indicates the length of an identifier for a subpicture in the SPS, and wherein the signaling of the first syntax element is independent of the value of a second syntax element, the value of which indicates that the identifier for the subpicture is explicitly signaled in the SPS or picture parameter set (PPS).

[0015] In yet another example, a video encoder apparatus is disclosed. The video encoder includes a processor configured to implement the methods described above.

[0016] In yet another example, a video decoder apparatus is disclosed. The video decoder includes components configured to implement the methods described above.

[0017] In yet another example, a computer-readable medium is disclosed on which code is stored. The code implements one of the methods described herein in the form of processor-executable code.

[0018] This document describes these and other features. Attached Figure Description

[0019] Figure 1 An example of segmenting an image using a luminance codec tree unit (CTU) is shown.

[0020] Figure 2 Another example of image segmentation using luminance CTU is shown.

[0021] Figure 3 An example of image segmentation is shown.

[0022] Figure 4 Another example of image segmentation is shown.

[0023] Figure 5 This is a block diagram of an example video processing system that can implement the disclosed technology.

[0024] Figure 6 This is a block diagram of an example hardware platform used for video processing.

[0025] Figure 7 This is a block diagram illustrating a video encoding / decoding system according to some embodiments of the present disclosure.

[0026] Figure 8 This is a block diagram illustrating an encoder according to some embodiments of the present disclosure.

[0027] Figure 9 This is a block diagram illustrating a decoder according to some embodiments of the present disclosure.

[0028] Figure 10-12 A flowchart of an example method for video processing is shown. Detailed Implementation

[0029] In this document, chapter headings are used for ease of understanding and do not limit the applicability of the techniques and embodiments disclosed in each chapter to that chapter. Furthermore, the use of H.266 terminology in some descriptions is merely for ease of understanding and not to limit the scope of the disclosed techniques. Therefore, the techniques described herein are also applicable to other video codec protocols and designs.

[0030] 1. Overview

[0031] This article relates to video codec technology. Specifically, it concerns signaling for subpictures, slices, and stripes. These concepts can be applied individually or in various combinations to any video codec standard or non-standard video codec that supports multi-layer video codecs, such as the Multi-Functional Video Codec (VVC) currently under development.

[0032] 2. Abbreviation

[0033] APS Adaptive Parameter Set

[0034] AU Access Unit

[0035] AUD access unit separator

[0036] AVC Advanced Video Encoding and Decoding

[0037] CLVS codec layer video sequence

[0038] CPB image buffer

[0039] CRA Clears Random Access

[0040] CTU encoding / decoding tree unit

[0041] CVS encoded video sequence

[0042] DPB decode image buffer

[0043] DPS Decoding Parameter Set

[0044] EOB bitstream ends

[0045] EOS sequence ends

[0046] GDR Progressive Decoding Refresh

[0047] HEVC High-Efficiency Video Encoding and Decoding

[0048] HRD Virtual Reference Decoder

[0049] IDR instant decoding refresh

[0050] JEM Joint Exploration Model

[0051] MCTS Motion Restraint Piece Set

[0052] NAL Network Abstraction Layer

[0053] OLS Output Layer Set

[0054] PH image header

[0055] PPS Image Parameter Set

[0056] PTL configuration files, hierarchies, and levels

[0057] PU image unit

[0058] RBSP raw byte sequence payload

[0059] SEI Supplemental Enhancement Information

[0060] SPS sequence parameter set

[0061] SVC Scalable Video Codec

[0062] VCL video codec layer

[0063] VPS Video Parameter Set

[0064] VTM VVC Test Model

[0065] VUI Video Availability Information

[0066] VVC Multifunctional Video Encoding and Decoding

[0067] 3. Preliminary Discussion

[0068] Video codec standards have primarily evolved through the development of known ITU-T and ISO / IEC standards. ITU-T developed H.261 and H.263, while ISO / IEC developed MPEG-1 and MPEG-4 video. The two organizations jointly developed the H.262 / MPEG-2 video standard, the H.264 / MPEG-4 Advanced Video Codec (AVC) standard, and the H.265 / HEVC standard. Since H.262, video codec standards have been based on a hybrid video codec architecture, employing temporal prediction plus transform coding. To explore future video codec 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 applied them to reference software called the Joint Exploration Model (JEM). JVET meetings are held quarterly, and the goal of the new codec standard is to reduce the bitrate by 50% compared to HEVC. The new video codec standard was officially named Versatile Video Coding (VVC) at the JVET meeting in April 2018, at which time the first version of the VVC Test Model (VTM) was released. With ongoing efforts to standardize VVC, new codec technologies have been adopted into the VVC standard at each JVET meeting. The VVC working draft and test model VTM are updated after each meeting. The current goal of the VVC project is Technical Completion (FDIS) at the July 2020 meeting.

[0069] 3.1. Image Segmentation Schemes in HEVC

[0070] HEVC includes four different image segmentation schemes: regular striping, non-independent striping, slice, and wavefront parallel processing (WPP), which can be applied to maximum transmission unit (MTU) size matching, parallel processing, and reduction of end-to-end latency.

[0071] Regular slices are similar to those in H.264 / AVC. Each regular slice is encapsulated in its own NAL unit, and intra-frame prediction (intra-sample prediction, motion information prediction, and encoding / decoding mode prediction) and entropy coding dependencies across slice boundaries are disabled. Therefore, regular slices can be reconstructed independently of other regular slices within the same image (although interdependencies may still exist due to loop filtering operations).

[0072] Regular striping is the only tool available for parallelization, and it is available in almost the same form in H.264 / AVC. Parallelization based on regular striping requires minimal inter-processor or inter-core communication (except for inter-processor or inter-core data sharing for motion compensation when decoding predictive encoded images, which is typically much heavier than inter-processor or inter-core data sharing due to intra-frame image prediction). However, for the same reason, using regular striping can incur significant encoding / decoding overhead due to the bit cost of the stripe header and the lack of prediction across stripe boundaries. Furthermore, due to the intra-image independence of regular striping and the fact that each regular stripe is encapsulated in its own NAL, regular striping (compared to other tools mentioned below) can also serve as a key mechanism for bitstream segmentation to match MTU size requirements. In many cases, the goals of parallelization and MTU size matching are contradictory in terms of stripe layout requirements within the image. The implementation of such situations led to the development of the parallelization tools mentioned below.

[0073] Non-independent striping has a short stripe header and allows partitioning of the bitstream at tree block boundaries without disrupting any intra-picture predictions. Essentially, non-independent striping divides a regular stripe into multiple NAL units, reducing end-to-end latency by allowing a portion of the regular stripe to be sent before the entire regular stripe's encoding is complete.

[0074] In WPP, images are segmented into single-row codec blocks (CTBs). Entropy decoding and prediction are allowed to use data from CTBs in other segments. Parallel processing is possible through parallel decoding of CTB rows, where the decoding of a CTB row is delayed by two CTBs to ensure that data associated with CTBs above and to the right of the main CTB is available before the main CTB being decoded. Using this staggered start (which looks like a wavefront when represented graphically), as many processors / cores as images containing CTB rows can be parallelized. Because intra-image prediction between adjacent tree block rows within an image is allowed, the inter-processor / inter-core communication required to implement intra-image prediction can be substantial. WPP segmentation does not result in additional NAL units compared to segmentation without WPP application, therefore WPP is not a tool for MTU size matching. However, if MTU size matching is required, regular striping can be used with WPP, but with some encoding / decoding overhead.

[0075] A slice is defined by the horizontal and vertical boundaries that divide an image into slice columns and slice rows. Slice columns extend from the top to the bottom of the image. Similarly, slice rows extend from the left to the right of the image. The number of slices in an image can be simply obtained by multiplying the number of slice columns by the number of slice rows.

[0076] Before decoding the top-left CTB of the next slice in the order of slice raster scans of an image, the scan order of the CTBs is changed to the local scan order within the slice (according to the order of the slice's CTB raster scans). Similar to regular stripes, slices break the intra-image prediction dependency and entropy decoding dependency. However, they do not need to be contained in separate NAL units (the same as WPP in this respect); therefore, slices cannot be used for MTU size matching. Each slice can be processed by one processor / core, and in the case of a stripe spanning multiple slices, the inter-processor / inter-core communication required between processing units decoding intra-image predictions of adjacent slices is limited to transmitting the shared stripe header and loop filtering associated with reconstructed samples and metadata sharing. When a stripe contains more than one slice or WPP segment, the entry point byte offset of each slice or WPP segment in the stripe, except for the first one, is signaled in the stripe header.

[0077] For simplicity, restrictions are specified in HEVC for the application of four different image segmentation schemes. For most profiles specified in HEVC, a given codec video sequence cannot contain both slices and wavefronts simultaneously. For each strip and slice, one or both of the following conditions must be met: 1) All codec blocks in a strip belong to the same slice; 2) All codec blocks in a slice belong to the same strip. Finally, a wavefront segment contains exactly one CTB line, and when using WPP, if a strip begins within a CTB line, then that strip must end within the same CTB line.

[0078] The most recent revision of HEVC is specified in the JCT-VC output document JCTVC-AC1005, edited by J. Boyce, A. Ramasubramonian, R. Skupin, G. J. Sullivan, A. Tourapis, and Y.-K. Wang. "HEVC Additional Supplemental Enhancement Information (Draft 4)" was released on October 24, 2017 at http: / / phenix.intevry.fr / jct / doc_end_user / documents- / 29_Macau / wg11 / JCTVC-AC1005-v2.zip. Including this revision, HEVC specifies three SEI messages related to MCT: the i.e., the domain MCTS SEI message, the MCTS extracted information set SEI message, and the MCTS extracted information nested SEI message.

[0079] The temporal MCTS SEI message indicates the presence of an MCTS in the bitstream and signals this to the MCTS. For each MCTS, motion vectors are restricted to pointing to full-sample locations within the MCTS and fractional-sample locations that require interpolation only from full-sample locations within the MCTS. Motion vector candidates predicted from temporal motion vectors from blocks outside the MCTS are not allowed. This allows each MCTS to decode independently even when no slices are not included in the MCTS.

[0080] The MCTS Extraction Information Set (SEI) message provides supplementary information that can be used for MCTS sub-bitstream extraction (specified as part of the semantics of the SEI message) to generate a bitstream conforming to the MCTS set. This information consists of multiple extraction information sets, each defining multiple MCTS sets and containing RBSP bytes for replacing the VPS, SPS, and PPS to be used during the MCTS sub-bitstream extraction process. When extracting the sub-bitstream according to the MCTS sub-bitstream extraction process, the parameter sets (VPS, SPS, and PPS) need to be rewritten or replaced, and the slice header needs to be slightly updated because one or all of the slice address-related syntax elements (including first_slice_segment_in_pic_flag and slice_segment_address) typically need to have different values.

[0081] 3.2. Image Segmentation in VVC

[0082] In VVC, an image is divided into one or more slice rows and one or more slice columns. A slice is a sequence of CTUs that covers a rectangular area of ​​the image. The CTUs in a slice are scanned within that slice in raster scan order.

[0083] A stripe consists of an integer number of complete slices or an integer number of consecutive complete CTU lines within an image.

[0084] Two stripe modes are supported: raster scan stripe mode and rectangular stripe mode. In raster scan stripe mode, a stripe contains a complete sequence of stripes in a raster scan of the image. In rectangular stripe mode, a stripe contains multiple complete slices of a rectangular region that together form the image, or multiple consecutive complete CTU rows of a slice of a rectangular region that together form the image. Stripes within a rectangular stripe are scanned in the raster scan sequence within the rectangular region corresponding to that stripe.

[0085] A sub-image contains one or more stripes that collectively cover a rectangular area of ​​the image.

[0086] Figure 1 An example of raster scan strip segmentation of an image is shown, where the image is divided into 12 slices and 3 raster scan strips.

[0087] Figure 2 An example of rectangular strip segmentation of an image is shown, where the image is divided into 24 slices (6 slice columns and 4 slice rows) and 9 rectangular slices.

[0088] Figure 3 An example of an image divided into slices and rectangular strips is shown, where the image is divided into 4 slices (2 slice columns and 2 slice rows) and 4 rectangular strips.

[0089] Figure 4 An example of sub-image segmentation of an image is shown, where the image is segmented into 18 slices: 12 slices on the left, each covered by a strip with 4x4 CTUs, and 6 slices on the right, each covered by two vertically stacked strips with 2x2 CTUs, resulting in a total of 24 strips and 24 sub-images of different dimensions (each strip is a sub-image).

[0090] 3.3. Signaling for VVC neutron images, slices, and strips

[0091] In the latest VVC draft text, sub-image information is signaled in the SPS. This sub-image information includes sub-image layout (i.e., the number of sub-images per image, and the position and size of each image) and other sequence-level sub-image information. The order of sub-images signaled in the SPS defines the sub-image index. For example, a list of sub-image IDs for each sub-image can be explicitly signaled in the SPS or PPS.

[0092] In VVC, slices are conceptually the same as those in HEVC, that is, each image is divided into slice columns and slice rows, but PPS has a different syntax for signaling notification slices.

[0093] In VVC, the stripe pattern is also signaled in PPS. When the stripe pattern is rectangular stripe pattern, the stripe layout for each image (i.e., the number of stripes per image and the position and size of each stripe) is signaled in PPS. The order of the rectangular stripes within the image signaled in PPS defines the image-level stripe index. The sub-image-level stripe index is defined as the order of the stripes within the sub-image in ascending order of its image-level stripe index. The position and size of the rectangular stripes are sent / exported based on the sub-image position and size signaled in SPS (when each sub-image contains only one stripe), or based on the slice position and size signaled in PPS (when a sub-image may contain multiple stripes). When the stripe pattern is raster scan stripe pattern, similar to HEVC, the stripe layout within the image is signaled in detail within the stripe itself.

[0094] The SPS, PPS, and strip headers and semantics in the latest VVC draft text most relevant to this invention are as follows.

[0095] 7.3.2.3 Sequence Parameter Set (RBSP) Syntax

[0096]

[0097]

[0098] 7.4.3.3 Sequence Parameter Set (RBSP) Semantics ...

[0100] A value of 1 indicates that the subpics_present_flag exists in the SPS RBSP syntax. A value of 0 indicates that the subpics_present_flag does not exist in the SPS RBSP syntax.

[0101] Note 2 – When the bitstream is the result of a sub-bitstream extraction process and contains only a subset of subpics of the input bitstream of the sub-bitstream extraction process, it may be necessary to set the value of subpics_present_flag in the RBSP of the SPS to equal 1.

[0102] Increment by 1 to specify the number of subpics. sps_num_subpics_minus1 should be in the range of 0 to 254. If it does not exist, the value of sps_num_subpics_minus1 is inferred to be equal to 0.

[0103] [i] Specifies the horizontal position of the top-left corner (CTU) of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil(Log2(pic_width_max_in_luma_samples / CtbSizeY)) bits. If it does not exist, the value of subpic_ctu_top_left_x[i] is assumed to be equal to 0.

[0104] [i] Specifies the vertical position of the top-left corner CTU of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil(Log2(pic_height_max_in_luma_samples / CtbSizeY)) bits. If it does not exist, the value of subpic_ctu_top_left_y[i] is inferred to be equal to 0.

[0105] [i] Increment 1 to specify the width of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil(Log2(pic_width_max_in_luma_samples / CtbSizeY)) bits. If it does not exist, the value of subpic_width_minus1[i] is inferred to be equal to Ceil(pic_width_max_in_luma_samples / CtbSizeY)-1.

[0106] [i] Increment 1 to specify the height of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil(Log2(pic_height_max_in_luma_samples / CtbSizeY)) bits. If it does not exist, the value of subpic_height_minus1[i] is inferred to be equal to Ceil(pic_height_max_in_luma_samples / CtbSizeY)-1.

[0107] [i] equal to 1 indicates that the i-th sub-image of each encoded / decoded image in CLVS is treated as an image during the decoding process excluding the loop filtering operation. subpic_treatment_as_pic_flag[i] equal to 0 indicates that the i-th sub-image of each encoded / decoded image in CLVS is not treated as an image during the decoding process excluding the loop filtering operation. If it does not exist, then the value of subpic_treatment_as_pic_flag[i] is inferred to be 0.

[0108] [i] equal to 1 specifies that loop filtering can be performed across the boundary of the i-th subpic in each codec image in CLVS. loop_filter_across_subpic_enabled_flag[i] equal to 0 specifies that loop filtering cannot be performed across the boundary of the i-th subpic in each codec image in CLVS. If it does not exist, the value of loop_filter_across_subpic_enabled_pic_flag[i] is inferred to be equal to 1.

[0109] The following constraints apply to bitstream consistency requirements:

[0110] For any two subpics, subpicA and subpicB, when the subpic index of subpicA is less than the subpic index of subpicB, any NAL unit of the codec stripe of subpicA should be decoded before any NAL unit of the codec stripe of subpicB.

[0111] The shape of the sub-images should be such that, when each sub-image is decoded, its entire left boundary and entire top boundary are composed of the image boundary or the boundary of the previously decoded sub-images.

[0112] A value of 1 indicates that a subpic ID mapping exists in SPS. A value of 0 for sps_subpic_id_present_flag indicates that a subpic ID mapping does not exist in SPS.

[0113] A value of 1 indicates that the subpic ID mapping is signaled in SPS. A value of 0 indicates that the subpic ID mapping is not signaled in SPS. When it does not exist, the value of sps_subpic_id_signalling_present_flag is inferred to be 0.

[0114] The addition of 1 specifies the number of bits used to represent the syntax element sps_subpic_id[i]. The value of sps_subpic_id_len_minus1 should be in the range of 0 to 15, inclusive.

[0115] [i] Specifies the subpick ID of the i-th subpick. The length of the sps_subpic_id[i] syntax element is sps_subpic_id_len_minus1+1 bits. When it does not exist, and when sps_subpic_id_present_flag is equal to 0, the value of sps_subpic_id[i] is inferred to be equal to i, where i is in the range from 0 to sps_num_subpics_minus1, inclusive. ...

[0117] 7.3.2.4 Image Parameter Set RBSP Syntax

[0118]

[0119]

[0120] 7.4.3.4 Image Parameter Set RBSP Semantics ...

[0122] A value of 1 indicates that the subpic ID mapping is signaled in PPS. A value of 0 indicates that the subpic ID mapping is not signaled in PPS. When sps_subpic_id_present_flag is 0 or sps_subpic_id_signalling_present_flag is 1, pps_subpic_id_signalling_present_flag should be 0.

[0123] Add 1 to specify the number of sub-images in the reference PPS encoding / decoding image.

[0124] The value of pps_num_subpic_minus1 should be equal to sps_num_subpics_minus1, which is a requirement for bitstream consistency.

[0125] Adding 1 specifies the number of bits used to represent the syntax element pps_subpic_id[i]. The value of pps_subpic_id_len_minus1 should be in the range of 0 to 15, inclusive.

[0126] The value of pps_subpic_id_len_minus1, which is referenced by the encoded and decoded images in CLVS, should be the same for all PPSs; this is a requirement for bitstream consistency.

[0127] [i] Specifies the subpicture ID of the i-th subpicture. The length of the pps_subpic_id[i] syntax element is pps_subpic_id_len_minus1+1 bits.

[0128] A value of 1 specifies that image partitioning should not be applied to every image referencing PPS. A value of 0 for no_pic_partition_flag specifies that every image referencing PPS can be partitioned into multiple slices or strips.

[0129] For all PPS referenced by the encoded and decoded images within CLVS, the value of no_pic_partition_flag should be the same, which is a requirement for bitstream consistency.

[0130] When the value of sps_num_subpics_minus1+1 is greater than 1, the value of no_pic_partition_flag cannot be equal to 1, which is a requirement for bitstream consistency.

[0131] The 5 plus 5 specifies the luma codec tree block size for each CTU. pps_log2_ctu_size_minus5 should be equal to sps_log2_ctu_size_minus5.

[0132] Adding 1 specifies the number of explicitly provided tile column widths. The value of num_exp_tile_columns_minus1 should be in the range of 0 to PicWidthInCtbsY-1, inclusive. When no_pic_partition_flag equals 1, the value of num_exp_tile_columns_minus1 is inferred to be 0.

[0133] Adding 1 specifies the number of explicitly provided tile row heights. The value of num_exp_tile_rows_minus1 should be in the range of 0 to PicHeightInCtbsY-1, inclusive. When no_pic_partition_flag equals 1, the value of num_exp_tile_columns_minus1 is inferred to be 0.

[0134] [i] +1 specifies the width of the i-th tile column in CTB units, where i is in the range of 0 to num_exp_tile_columns_minus1-1, inclusive. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to deduce the width of tile columns whose index is greater than or equal to num_exp_tile_columns_minus1, as described in Clause 6.5.1. If it does not exist, the value of tile_column_width_minus1[0] is deduced to be equal to PicWidthInCtbsY-1.

[0135] [i] +1 specifies the height of the i-th slice row in CTB units, where i is in the range of 0 to num_exp_tile_rows_minus1-1, inclusive. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to deduce the height of slice rows whose index is greater than or equal to num_exp_tile_rows_minus1, as described in Clause 6.5.1. If it does not exist, the value of tile_row_height_minus1[0] is deduced to be equal to PicHeightInCtbsY-1.

[0136] A value of 0 indicates that the slices within each slice are arranged in raster scan order, and slice information is not signaled in the PPS. A value of 1 indicates that the slices within each slice cover a rectangular area of ​​the image, and slice information is signaled in the PPS. If this value does not exist, it is assumed that rect_slice_flag is equal to 1. When subpics_present_flag is equal to 1, the value of rect_slice_flag should be equal to 1.

[0137] A value of 1 indicates that each subpick consists of one and only one rectangular stripe. A value of 0 for `single_slice_per_subpic_flag` indicates that each subpick may contain one or more rectangular stripes. When `subpics_present_flag` is 0, `single_slice_per_subpic_flag` should be 0. When `single_slice_per_subpic_flag` is 1, it is inferred that `num_slices_in_pic_minus1` equals `sps_num_subpics_minus1`.

[0138] Adding 1 specifies the number of rectangular strips referencing the PPS in each image. The value of num_slices_in_pic_minus1 should be in the range of 0 to MaxSlicesPerPicture-1, inclusive, where MaxSlicesPerPicture is specified in Appendix A. When no_pic_partition_flag equals 1, it is inferred that the value of num_slices_in_pic_minus1 is equal to 0.

[0139] A value of 0 indicates that the tile_idx_delta value does not exist in the PPS, and all rectangular stripes in the image referencing the PPS are specified in raster order according to the procedure defined in Clause 6.5.1. A tile_idx_delta_present_flag value of 1 indicates that the tile_idx_delta value may exist in the PPS, and all rectangular stripes in the image referencing the PPS are specified in the order indicated by the tile_idx_delta value.

[0140] [i] Incrementing by 1 specifies the width of the i-th rectangular strip in units of slice columns. The value of slice_width_in_tiles_minus1[i] should be in the range of 0 to NumTileColumns-1, inclusive. If it does not exist, the value of slice_width_in_tiles_minus1[i] will be inferred as specified in Section 6.5.1.

[0141] [i] Incrementing by 1 specifies the height of the i-th rectangular strip, in units of slice rows. The value of slice_height_in_tiles_minus1[i] should be in the range of 0 to NumTileRows-1, inclusive. If it does not exist, the value of slice_height_in_tiles_minus1[i] will be inferred as specified in Section 6.5.1.

[0142] [i] Incrementing by 1 specifies the number of slices in the current slice, applicable when the i-th slice contains a subset of CTU rows from a single slice. The value of num_slices_in_tile_minus1[i] should be in the range of 0 to RowHeight[tileY]-1, inclusive, where tileY is the slice row index containing the i-th slice. If it does not exist, it is inferred that the value of num_slices_in_tile_minus1[i] is equal to 0.

[0143] [i] Increment 1 to specify the height of the i-th rectangular strip in units of CTU rows, applicable when the i-th strip contains a subset of CTU rows from a single slice. The value of slice_height_in_ctu_minus1[i] should be in the range of 0 to RowHeight[tileY]-1, inclusive, where tileY is the slice row index containing the i-th strip.

[0144] [i] Specifies the slice index difference between the i-th and (i+1)-th rectangular stripes. The value of tile_idx_delta[i] should be in the range of –NumTilesInPic+1 to NumTilesInPic-1, inclusive. If it does not exist, the value of tile_idx_delta[i] is inferred to be equal to 0. In all other cases, the value of tile_idx_delta[i] should not be equal to 0.

[0145] A value of 1 indicates that loop filtering can be performed across tile boundaries in the reference PPS image. A value of 0 for `loop_filter_across_tiles_enabled_flag` indicates that loop filtering is not performed across tile boundaries in the reference PPS image. Loop filtering operations include deblocking filtering, sample adaptive offset filtering, and adaptive loop filtering. If this flag is not present, the value of `loop_filter_across_tiles_enabled_flag` is inferred to be 1.

[0146] A value of 1 indicates that loop filtering can be performed across slice boundaries in the reference PPS image. A value of 0 for `loop_filter_across_slice_enabled_flag` indicates that loop filtering is not performed across slice boundaries in the reference PPS image. Loop filtering operations include deblocking filtering, sample adaptive offset filtering, and adaptive loop filtering. If this flag is not present, the value of `loop_filter_across_slices_enabled_flag` is inferred to be 0.

[0147] 7.3.7.1 General Strip Header Syntax

[0148]

[0149]

[0150] 7.4.8.1 General Strip Header Semantics ...

[0152] Specifies the subpick identifier containing the slice. If slice_subpic_id exists, the value of variable SubPicIdx is deduced such that SubpicIdList[SubPicIdx] equals slice_subpic_id. Otherwise (if slice_subpic_id does not exist), variable SubPicIdx is deduced to be 0. The length of slice_subpic_id, in bits, is deduced as follows:

[0153] —If sps_subpic_id_signalling_present_flag equals 1, the length of slice_subpic_id is equal to sps_subpic_id_len_minus1+1.

[0154] —Otherwise, if ph_subpic_id_signalling_present_flag equals 1, then the length of slice_subpic_id is equal to ph_subpic_id_len_minus1+1.

[0155] —Otherwise, if pps_subpic_id_signalling_present_flag equals 1, then the length of slice_subpic_id is equal to pps_subpic_id_len_minus1+1.

[0156] —Otherwise, the length of slice_subpic_id is equal to Ceil(Log2(sps_num_subpics_minus1+1)).

[0157] Specifies the slice address. If it does not exist, the value of slice_address is inferred to be 0.

[0158] If rect_slice_flag equals 0, then the following applies:

[0159] —The stripe address is the raster scan chip index.

[0160] The length of the slice_address is Ceil(Log2(NumTilesInPic)) bits.

[0161] The value of `--slice_address` should be in the range of 0 to `NumTilesInPic-1`, including the end value.

[0162] Otherwise (rect_slice_flag equals 1), the following applies:

[0163] —The stripe address is the stripe index within the SubPicIdx sub-image.

[0164] The length of `--slice_address` is `Ceil(Log2(NumSlicesInSubpic[SubPicIdx]))` bits.

[0165] The value of `--slice_address` should be in the range of 0 to `NumSlicesInSubpic[SubPicIdx]-1`, inclusive.

[0166] The following constraints apply to bitstream consistency requirements:

[0167] —If rect_slice_flag is equal to 0 or subpics_present_flag is equal to 0, then the value of slice_address should not be equal to the value of slice_address of any other codec strip NAL unit of the same codec image.

[0168] —Otherwise, the slice_subpic_id and slice_address pair should not be equal to the slice_subpic_id and slice_address pair of any other codec strip NAL unit of the same codec picture.

[0169] —When rect_slice_flag equals 0, the slices of the image should be sorted in ascending order of their slice_address values.

[0170] —The shape of the image strip should be such that, when each CTU is being decoded, its entire left and entire top boundaries should consist of the image boundary or the boundaries of the previously decoded CTU.

[0171] Add 1 (if present) to specify the number of slices in the strip. The value of num_tiles_in_slice_minus1 should be in the range of 0 to NumTilesInPic-1, inclusive.

[0172] The variable NumCtuInCurrSlice specifies the number of CTUs in the current slice, and the list CtbAddrInCurrSlice[i] specifies the raster scan address of the i-th CTU within the slice, where i ranges from 0 to NumCtuInCurrSlice-1, inclusive, as derived below:

[0173]

[0174]

[0175] The variables SubPicLeftBoundaryPos, SubPicTopBoundaryPos, SubPicRightBoundaryPos, and SubPicBotBoundaryPos are derived as follows:

[0176] if(subpic_treated_as_pic_flag[SubPicIdx]){

[0177] SubPicLeftBoundaryPos=

[0178] subpic_ctu_top_left_x[SubPicIdx]*CtbSizeY

[0179] SubPicRightBoundaryPos=

[0180] Min(pic_width_max_in_luma_samples-1,

[0181] (subpic_ctu_top_left_x[SubPicIdx]+subpic_width_minus1[SubPicIdx]+1)*CtbSizeY-1)

[0182] SubPicTopBoundaryPos=

[0183] subpic_ctu_top_left_y[SubPicIdx]*CtbSizeY (116)

[0184] SubPicBotBoundaryPos=Min(pic_height_max_in_luma_samples-1,

[0185] (subpic_ctu_top_left_y[SubPicIdx]+subpic_height_minus1[SubPicIdx]+1)*CtbSizeY-1)

[0186] } ...

[0188] 4. Examples of technical problems solved by the solution presented in this paper

[0189] The existing design for signaling sub-images, slices, and stripes in VVC has the following problems:

[0190] 1) The encoding and decoding of sps_num_subpics_minus1 is u(8), which means that each image is not allowed to have more than 256 subpics. However, in some applications, the maximum number of subpics per image may need to be greater than 256.

[0191] 2) Allowing subpics_present_flag to be 0 and sps_subpic_id_present_flag to be 1. However, this makes no sense because subpics_present_flag being 0 means that CLVS has no information about the subpics at all.

[0192] 3) For each sub-picture, the list of sub-picture IDs can be signaled in the Picture Header (PH). However, when the list of sub-picture IDs is signaled in the PH, and when a subset of sub-pictures is extracted from the bitstream, all PHs will need to be changed. This is undesirable.

[0193] 4) Currently, when a subpic ID is indicated for explicit signaling notification, the subpic ID can be signaled without being notified anywhere by setting `sps_subpic_id_present_flag` to 1 (or by changing the syntax element name to `subpic_ids_explicitly_signalled_flag`). This is problematic because when a subpic ID is indicated for explicit signaling notification, the subpic ID needs to be explicitly signaled in either the SPS or PPS.

[0194] 5) When there is no explicit signaling notification for the subpick ID, the slice_subpic_id header syntax element still requires signaling notification as long as subpics_present_flag equals 1, including when sps_num_subpics_minus1 equals 0. However, the length of slice_subpic_id is currently specified as Ceil(Log2(sps_num_subpics_minus1+1)) bits, and 0 bits when sps_num_subpics_minus1 equals 0. This is problematic because the length of any existing syntax element cannot be 0 bits.

[0195] 6) The sub-image layout, including the number, size, and position of sub-images, remains constant throughout CLVS. Even if the sub-image ID is not explicitly signaled in SPS or PPS, the sub-image ID length still needs to be signaled for the sub-image ID syntax element in the strip header.

[0196] 7) Whenever `rect_slice_flag` equals 1, the syntax element `slice_address` is signaled in the slice header and specifies the slice index within the subpicture containing the slice, including when the number of slices within the subpicture (i.e., `NumSlicesInSubpic[SubPicIdx]`) equals 1. However, currently, when `rect_slice_flag` equals 1, the length of `slice_address` is specified as Ceil(Log2(NumSlicesInSubpic[SubPicIdx])) bits, and when `NumSlicesInSubpic[SubPicIdx]` equals 1, the length of `slice_address` is 0 bits. This is problematic because the length of any existing syntax element cannot be 0 bits.

[0197] 8) There is redundancy between the syntax elements no_pic_partition_flag and pps_num_subpics_minus1, although the latest VVC text has the following constraint: when sps_num_subpics_minus1 is greater than 0, the value of no_pic_partition_flag should be equal to 1.

[0198] 5. Example Implementations and Solutions

[0199] To address the aforementioned and other problems, methods outlined below are disclosed. This invention should be considered as an example of interpreting general concepts and should not be interpreted narrowly. Furthermore, these inventions can be applied individually or in any combination.

[0200] 1) To solve the first problem, the encoding and decoding of sps_num_subpics_minus1 was changed from u(8) to ue(v), so that each image can have more than 256 sub-images.

[0201] a. In addition, the value of sps_num_subpics_minus1 is limited to the range of 0 to Ceil(pic_width_max_in_luma_samples÷CtbSizeY)*Ceil(pic_height_max_in_luma_samples÷CtbSizeY)-1.

[0202] b. In addition, the number of sub-images per image is further limited in the definition of the level.

[0203] 2) To solve the second problem, the condition of the signaling notification syntax element sps_subpic_id_present_flag is set to "if(subpics_present_flag)", that is, when subpics_present_flag is equal to 0, no signaling notification is given to the sps_subpic_id_present_flag syntax element, and if it does not exist, it is inferred that the value of sps_subpic_id_present_flag is equal to 0.

[0204] a. Alternatively, when subpics_present_flag equals 0, the syntax element sps_subpic_id_present_flag is still signaled, but when subpics_present_flag equals 0, the value must be equal to 0.

[0205] b. In addition, the names of the syntax elements subpics_present_flag and sps_subpic_id_present_flag are changed to subpic_info_present_flag and subpic_ids_explicitly_signalled_flag, respectively.

[0206] 3) To solve the third problem, the signaling for subpick IDs in the PH syntax is removed. Therefore, for i in the range of 0 to sps_num_subpics_minus1 (inclusive), the list SubpicIdList[i] is derived as follows:

[0207] for(i=0;i<=sps_num_subpics_minus1;i++)

[0208] if(subpic_ids_explicitly_signalled_flag)

[0209] SubpicIdList[i]=subpic_ids_in_pps_flag? pps_subpic_id[i]:sps_subpic_id[i]

[0210] else

[0211] SubpicIdList[i] = i

[0212] 4) To address the fourth issue, when a sub-picture is instructed to be explicitly signaled, the sub-picture ID is signaled in the SPS or PPS.

[0213] a. This can be achieved by adding the following constraint: If `subpic_ids_explicitly_signalled_flag` is 0 or `subpic_ids_in_sps_flag` is 1, then `subpic_ids_in_pps_flag` should be 0. Otherwise (if `subpic_ids_explicitly_signalled_flag` is 1 or `subpic_ids_in_sps_flag` is 0), `subpic_ids_in_pps_flag` should be 1.

[0214] 5) To address issues 5 and 6, regardless of the value of the SPS flag `sps_subpic_id_present_flag` (or renamed to `subpic_ids_explicitly_signalled_flag`), the length of the subpic ID is signaled in the SPS, even though the length can also be signaled in the PPS to avoid resolving the PPS dependency on the SPS. In this case, the length also specifies the length of the subpic ID in the slice header, even if the subpic ID is not explicitly signaled in either the SPS or PPS. Therefore, when present, the length of `slice_subpic_id` is also specified by the length of the subpic ID signaled in the SPS.

[0215] 6) Alternatively, to address issues 5 and 6, add a flag to the SPS syntax with a value of 1 to specify the presence of a subpic ID length in the SPS syntax. The presence of this flag is independent of the value of the flag indicating whether the subpic ID is explicitly signaled in SPS or PPS. When `subpic_ids_explicitly_signalled_flag` equals 0, the flag can be either 1 or 0, but when `subpic_ids_explicitly_signalled_flag` equals 1, the flag must be 1. When this flag is 0, i.e., the subpic length does not exist, the length of `slice_subpic_id` is specified as `Max(Ceil(Log2(sps_num_subpics_minus1+1)), 1) bits` (instead of `Ceil(Log2(sps_num_subpics_minus1+1)) bits` in the latest VVC draft text).

[0216] a. Alternatively, this flag exists only if subpic_ids_explicitly_signalled_flag equals 0, and if subpic_ids_explicitly_signalled_flag equals 1, the value of this flag is inferred to be 1.

[0217] 7) To solve the seventh problem, when rect_slice_flag equals 1, specify the length of slice_address as Max(Ceil(Log2(NumSlicesInSubpic[SubPicIdx])), 1) bits.

[0218] a. Alternatively, when rect_slice_flag equals 0, the length of slice_address is specified as Max(Ceil(Log2(NumTilesInPic)), 1) bits instead of Ceil(Log2(NumTilesInPic)) bits.

[0219] 8) To solve the eighth problem, set the condition for signaling no_pic_partition_flag to "if(subpic_ids_in_pps_flag&&pps_num_subpics-_minus1>0)" and add the following inference: if it does not exist, infer that the value of no_pic_partition_flag is equal to 1.

[0220] a. Alternatively, move the subpico ID syntax (all four syntax elements) after the slice and strip syntax in PPS, for example, immediately before the syntax element entropy_coding_sync_enabled_flag, and then set the condition of the signaling notification pps_num_subpics_minus1 to "if(no_pic_partition_flag)".

[0221] 6. Example

[0222] The following are some example embodiments of all the invention sections other than the eight summarized in Section 5 above, which can be applied to the VVC specification. The modified text is based on the latest VVC text in JVET-P2001-v14. The most relevant parts that have been added or modified are listed below. Underlined, bold, and italic text The most relevant deleted parts are highlighted in bold double brackets; for example, [[a]] indicates that "a" has been deleted. Other changes are editable and therefore not highlighted.

[0223] 6.1. First Embodiment

[0224] 7.3.2.3 Sequence Parameter Set (RBSP) Syntax

[0225]

[0226]

[0227] 7.4.3.3 Sequence Parameter Set (RBSP) Semantics ...

[0229]

[0230] Note 2 – When the bitstream is the result of a sub-bitstream extraction process and contains only a subset of the sub-images of the input bitstream of the sub-bitstream extraction process, it may be necessary to include it in SPS. The value is set to 1.

[0231] Add 1 to specify the number of sub-images.

[0232]

[0233] When it does not exist, the value of sps_num_subpics_minus1 is inferred to be equal to 0.

[0234] [i] Specifies the top-left CTU position of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil(Log2(pic_width_max_in_luma_samples / CtbSizeY)) bits. If it does not exist, the value of subpic_ctu_top_left_x[i] is inferred to be equal to 0.

[0235] [i] Specifies the vertical position of the top-left corner CTU of the i-th subgraph in units of CtbSizeY. The length of the syntax element is Ceil(Log2(pic_height_max_in_luma_samples / CtbSizeY)) bits. If it does not exist, the value of subpic_ctu_top_left_y[i] is inferred to be equal to 0.

[0236] [i] plus 1 specifies the width of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil(Log2(pic_width_max_in_luma_samples / CtbSizeY)) bits. If it does not exist, the value of subpic_width_minus1[i] is inferred to be equal to Ceil(pic_width_max_in_luma_samples / CtbSizeY)-1.

[0237] [i] plus 1 specifies the height of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil(Log2(pic_height_max_in_luma_samples / CtbSizeY)) bits. If it does not exist, the value of subpic_height_minus1[i] is inferred to be equal to Ceil(pic_height_max_in_luma_samples / CtbSizeY)-1.

[0238] [i] equal to 1 indicates that the i-th sub-picture of each encoded / decoded image in CLVS is treated as an image during the decoding process excluding loop filtering operations. subpic_treatment_as_pic_flag[i] equal to 0 specifies that the i-th sub-picture of each encoded / decoded image in CLVS is not treated as an image during the decoding process excluding loop filtering operations. If it does not exist, the value of subpic_treatment_as_pic_flag[i] is inferred to be 0.

[0239] [i] equal to 1 indicates that loop filtering can be performed across the boundary of the i-th subpic in each codec image in CLVS. loop_filter_across_subpic_enabled_flag[i] equal to 0 indicates that loop filtering cannot be performed across the boundary of the i-th subpic in each codec image in CLVS. If it does not exist, the value of loop_filter_across_subpic_enabled_pic_flag[i] is inferred to be equal to 1.

[0240] The following constraints apply to bitstream consistency requirements:

[0241] —For any two subpics, subpicA and subpicB, when the subpic index of subpicA is less than the subpic index of subpicB, any codec strip NAL unit of subpicA should be decoded in priority over any codec strip NAL unit of subpicB.

[0242] —The shape of the sub-images should be such that, when each sub-image is decoded, its entire left boundary and entire top boundary are composed of the image boundary or the boundary of the previously decoded sub-images.

[0243]

[0244]

[0245] sps_subpic_id[i] specifies the subpick ID of the i-th subpick. The length of the sps_subpic_id[i] syntax element is sps_subpic_id_len_minus1+1 bits. ...

[0247] 7.3.2.4 Image Parameter Set RBSP Syntax

[0248]

[0249]

[0250] 7.4.3.4 Image Parameter Set RBSP Semantics...

[0251]

[0252] It should be equal to sps_num_subpics_minus1.

[0253] It should be equal to sps_subpic_id_len_minus1.

[0254] [i] Specifies the subpicture ID of the i-th subpicture. The length of the pps_subpic_id[i] syntax element is pps_subpic_id_len_minus1+1 bits.

[0255]

[0256] The requirement for bitstream consistency is that for any i and j in the range from 0 to sps_num_subpics_minus1 (inclusive), when i is less than j, SubpicIdList[i] should be less than SubpicIdList[j]. ...

[0258] A value of 0 indicates that slices within each slice are arranged in raster scan order, and slice information is not signaled in the PPS. A value of 1 indicates that the slices within each slice cover a rectangular area of ​​the image, and slice information is signaled in the PPS. If this value does not exist, it is inferred that rect_slice_flag is equal to 1. When the value is 1, the value of rect_slice_flag should be equal to 1.

[0259] A value of 1 specifies that each subpicture consists of one and only one rectangular stripe. A value of 0 for `single_slice_per_subpic_flag` specifies that each subpicture may contain one or more rectangular stripes. When it equals 0, single_slice_per_subpic_flag should be equal to 0. When single_slice_per_subpic_flag equals 1, it is inferred that num_slices_in_pic_minus1 equals sps_num_subpics_minus1. ...

[0261] 7.3.7.1 General Strip Header Syntax

[0262]

[0263] 7.4.8.1 General Strip Header Semantics ...

[0265] Specify the sub-image ID that contains the stripe.

[0266] If it does not exist, then the value of slice_subpic_id is inferred to be 0.

[0267] The variable SubPicIdx is derived to make SubpicIdList[SubPicIdx] equal to the value of slice_subpic_id.

[0268] Specifies the slice address. If it does not exist, the value of slice_address is assumed to be 0.

[0269] If rect_slice_flag equals 0, then the following applies:

[0270] —The stripe address is the raster scan chip index.

[0271] The length of the slice_address is Ceil(Log2(NumTilesInPic)) bits.

[0272] The value of `--slice_address` should be in the range of 0 to `NumTilesInPic-1`, including the end value.

[0273] Otherwise (rect_slice_flag equals 1), the following applies:

[0274] —A stripe address is a sub-image level stripe index.

[0275] The length of —slice_address is Bit.

[0276] The value of `--slice_address` should be in the range of 0 to `NumSlicesInSubpic[SubPicIdx]-1`, inclusive.

[0277] The following constraints apply to bitstream consistency requirements:

[0278] —If rect_slice_flag equals 0 or The value of slice_address should not be equal to 0, and should not be equal to the value of slice_address of any other codec slice NAL unit of the same codec image.

[0279] —Otherwise, the slice_subpic_id and slice_address pair should not be equal to the slice_subpic_id and slice_address pair of any other codec strip NAL unit of the same codec picture.

[0280] —When rect_slice_flag equals 0, the slices of the image should be sorted in ascending order of their slice_address values.

[0281] —The shape of the image strip should be such that, when each CTU is being decoded, its entire left boundary and its entire top boundary should consist of an image boundary or the boundaries of the previously decoded (multiple) CTUs. ...

[0283] Figure 5 A block diagram of an example video processing system 500 that can implement various technologies of this disclosure is shown. Various implementations may include some or all of the components of system 500. System 500 may include an input 502 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 in a compressed or encoded format. Input 502 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.

[0284] System 500 may include an encoding / decoding component 504, which may implement various encoding / decoding or coding methods described in this disclosure. Encoding / decoding component 504 may reduce the average bit rate of the video from input 502 to the output of encoding / decoding component 504 to produce an encoded / decoded representation of the video. Therefore, encoding / decoding techniques are sometimes referred to as video compression or video transcoding techniques. The output of encoding / decoding component 504 may be stored or transmitted via a communication connection as indicated by component 506. The stored or communicated bitstream (or encoded / decoded) representation of the video received at input 502 may be used by component 508 to generate pixel values ​​or displayable video to be sent to display interface 510. The process of generating a user-viewable video from the bitstream representation is sometimes referred to as video decompression. Furthermore, although some video processing operations are referred to as “encoding / decoding” operations or tools, it should be understood that encoding tools or operations are used at the encoder, and corresponding decoding tools or operations that reverse the encoded result will be performed by the decoder.

[0285] Examples of peripheral bus interfaces or display interfaces may include Universal Serial Bus (USB), High Definition Multimedia Interface (HDMI), or DisplayPort. Examples of storage interfaces include SATA (Serial Advanced Technology Accessory), PCI, IDE, etc. The techniques described in this disclosure can be implemented in a variety of electronic devices, such as mobile phones, laptops, smartphones, or other devices capable of performing digital data processing and / or video display.

[0286] Figure 6 This is a block diagram of a video processing apparatus 600. Apparatus 600 can be used to implement one or more methods described in this disclosure. Apparatus 600 can be located in a smartphone, tablet, computer, Internet of Things (IoT) receiver, etc. Apparatus 600 may include one or more processors 602, one or more memories 604, and video processing hardware 606. Processor 602 can be configured to implement one or more methods described in this disclosure. Memory 604 can be used to store data and code for implementing the methods and techniques described in this disclosure. Video processing hardware 606 can be used in hardware circuitry to implement some of the techniques described in this disclosure. In some embodiments, hardware 606 may be partially or wholly located in processor 602, such as a graphics processor.

[0287] Figure 7 This is a block diagram illustrating an example video codec system 100 that can utilize the technology disclosed herein.

[0288] like Figure 7As shown, the video encoding / decoding system 100 may include a source device 110 and a target device 120. The source device 110 can generate encoded video data and may be referred to as a video encoding device. The target device 120 can decode the encoded video data generated by the source device 110 and may be referred to as a video decoding device.

[0289] The source device 110 may include a video source 112, a video encoder 114, and an input / output (I / O) interface 116.

[0290] Video source 112 may include, for example, 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 for generating video data, or a combination of these sources. Video data may include one or more images. Video encoder 114 encodes the video data from video source 112 to generate a bitstream. The bitstream may include bit sequences forming a codec representation of the video data. The bitstream may include codec images and associated data. A codec image is a codec representation of an image. Associated data may include sequence parameter sets, image parameter sets, and other syntax structures. I / O interface 116 may include a modulator / demodulator (modem) and / or a transmitter. Encoded video data may be transmitted directly to target device 120 via network 130a through I / O interface 116. Encoded video data may also be stored on storage medium / server 130b for access by target device 120.

[0291] The target device 120 may include an I / O interface 126, a video decoder 124, and a display device 122.

[0292] I / O interface 126 may include a receiver and / or a modem. I / O interface 126 may acquire encoded video data from source device 110 or storage medium / server 130b. Video decoder 124 may decode the encoded video data. Display device 122 may display the decoded video data to a user. Display device 122 may be integrated with target device 120, or may be external to target device 120, which is configured to interface with an external display device.

[0293] The video encoder 114 and the video decoder 124 can operate according to video compression standards, such as the High Efficiency Video Coding (HEVC) standard, the Multi-Function Video Coding (VVM) standard, and other current and / or other standards.

[0294] Figure 8 This is a block diagram illustrating an example of a video encoder 200. The video encoder 200 can be... Figure 7 The video encoder 114 in the system 100 described herein.

[0295] The video encoder 200 can be configured to perform any or all of the technologies disclosed herein. Figure 8 In the example shown, the video encoder 200 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of the video encoder 200. In some examples, the processor can be configured to perform any or all of the techniques described in this disclosure.

[0296] 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, 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.

[0297] 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 can perform prediction in IBC mode, where at least one reference picture is the picture containing the current video block.

[0298] Furthermore, some components, such as the motion estimation unit 204 and the motion compensation unit 205, can be highly integrated, but for descriptive purposes... Figure 8 The examples are shown separately.

[0299] The segmentation unit 201 can segment an image into one or more video blocks. The video encoder 200 and the video decoder 300 can support various video block sizes.

[0300] The mode selection unit 203 can select one of the encoding / decoding modes (intra-frame or inter-frame) based, for example, on the error result, and provide the resulting intra-frame or inter-frame codec block to the residual generation unit 207 to generate residual block data, and the reconstruction unit 212 reconstructs the codec block for use as a reference picture. In some examples, the mode selection unit 203 can select a combination of intra-frame and inter-frame prediction (CIIP) modes, where the prediction is based on the inter-frame prediction signal and the intra-frame prediction signal. In the case of inter-frame prediction, the mode selection unit 203 can also select the resolution of the motion vector for the block (e.g., sub-pixel or integer pixel precision).

[0301] To perform inter-frame prediction on the current video block, 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. Motion compensation unit 205 can determine the predicted video block for the current video block based on motion information and decoded samples from images other than those associated with the current video block from buffer 213.

[0302] The motion estimation unit 204 and the motion compensation unit 205 can perform different operations on the current video block, for example, depending on whether the current video block is in an I-band, P-band, or B-band.

[0303] In some examples, motion estimation unit 204 can perform unidirectional prediction on the current video block, and motion estimation unit 204 can search for reference images in reference video block search list 0 or 1 for the current video block. Motion estimation unit 204 can then generate a reference index indicating that the reference image in list 0 or list 1 contains the reference video block, and a motion vector indicating the spatial displacement between the current video block and the reference video block. Motion estimation unit 204 can output the reference index, prediction direction indicator, and motion vector as motion information for the current video block. 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.

[0304] In other examples, motion estimation unit 204 can perform bidirectional prediction on the current video block. Motion estimation unit 204 can search for reference images in reference video block list 0 and reference video block list 1. Motion estimation unit 204 can then generate reference indices indicating the reference images in lists 0 and 1, containing reference video blocks and motion vectors indicating the spatial displacement between the reference video blocks and the current video block. Motion estimation unit 204 can output the reference index and motion vector of the current video block as motion information for the current video block. Motion compensation unit 205 can generate a predicted video block for the current video block based on the reference video blocks indicated by the motion information of the current video block.

[0305] In some examples, the motion estimation unit 204 can output a complete set of motion information for the decoder to use in the decoding process.

[0306] In some examples, motion estimation unit 204 may not output the complete set of motion information for the current video. Instead, motion estimation unit 204 may signal the motion information of the current video block to 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 neighboring video blocks.

[0307] In one example, the motion estimation unit 204 may instruct the video decoder 300 in the syntax structure associated with the current video block to indicate that the current video block has the same motion information as another video block.

[0308] In another example, motion estimation unit 204 can identify another video block and motion vector difference (MVD) within the syntax structure associated with the current video block. The motion vector difference represents the difference between the motion vector of the current video block and the motion vector of the indicated video block. Video decoder 300 can use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0309] As described above, the video encoder 200 can predictively signal motion vectors. Two examples of predictive signaling techniques that can be implemented by the video encoder 200 include Advanced Motion Vector Prediction (AMVP) and merge mode signaling.

[0310] Intra-prediction unit 206 can perform intra-prediction on the current video block. When intra-prediction unit 206 performs intra-prediction on the current video block, it can generate prediction data for the current video block based on decoded samples from other video blocks in the same frame. The prediction data for the current video block may include the predicted video block and various syntax elements.

[0311] The residual generation unit 207 can generate residual data for the current video block by subtracting (e.g., indicated by a negative sign) the predicted video block of the current video block from the current video block. The residual data for the current video block can include residual video blocks corresponding to different sample components of the samples in the current video block.

[0312] In other examples, for the current video block, such as in skip mode, there may not be residual data for the current video block, and the residual generation unit 207 may not perform the subtraction operation.

[0313] The transform processing unit 208 can generate one or more transform coefficient video blocks of the current video block by applying one or more transforms to the residual video blocks associated with the current video block.

[0314] After the transform processing unit 208 generates a transform coefficient video block associated with the current video block, the quantization unit 209 can 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.

[0315] Inverse quantization unit 210 and inverse transform unit 211 can apply inverse quantization and inverse transform to the transform coefficient video block, respectively, to reconstruct the residual video block from the transform coefficient video block. Reconstruction unit 212 can add the reconstructed residual video block to the corresponding sample points of one or more predicted video blocks generated by prediction unit 202 to produce a reconstructed video block associated with the current block stored in buffer 213.

[0316] After the video block is reconstructed by the reconstruction unit 212, a loop filtering operation can be performed to reduce video block artifacts in the video block.

[0317] Entropy encoding unit 214 can receive data from other functional components of video encoder 200. When entropy encoding unit 214 receives data, it can perform one or more entropy encoding operations to generate entropy encoded data and output a bit stream including the entropy encoded data.

[0318] Figure 9 This is a block diagram illustrating an example of a video decoder 300, which can be... Figure 7 The video decoder 114 in the system 100 shown.

[0319] The video decoder 300 can be configured to perform any or all of the technologies disclosed herein. Figure 8 In the example shown, the video decoder 300 includes multiple functional components. The techniques described in this disclosure can be shared among the 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 this disclosure.

[0320] In such Figure 9 The example shown includes an entropy decoding unit 301, a motion compensation unit 302, an intra-frame prediction unit 303, an inverse quantization unit 304, an inverse transform unit 305, a reconstruction unit 306, and a buffer 307. In some examples, the video decoder 300 can perform functions typically associated with the video encoder 200. Figure 8 The encoding channel is the opposite of the decoding channel described.

[0321] The entropy decoding unit 301 can obtain the encoded bitstream. The encoded bitstream may include entropy-coded video data (e.g., encoded video data blocks). The entropy decoding unit 301 can decode the entropy-coded video data, and based on the entropy-decoded video data, the motion compensation unit 302 can determine motion information including motion vectors, motion vector precision, reference image list index, and other motion information. For example, the motion compensation unit 302 can determine such information by executing AMVP and merge modes.

[0322] The motion compensation unit 302 can generate motion compensation blocks, possibly performing interpolation based on an interpolation filter. Identifiers for the interpolation filter at sub-pixel precision can be included in the syntax elements.

[0323] The motion compensation unit 302 can use the interpolation filter used by the video encoder 20 during the encoding of the video block to calculate the interpolated values ​​of the sub-integer pixels of the reference block. The motion compensation unit 302 can determine the interpolation filter used by the video encoder 200 based on the received syntax information and use the interpolation filter to generate the prediction block.

[0324] The motion compensation unit 302 can use some syntax information to determine the size of the blocks used to encode the frames and / or stripes of the encoded video sequence, segmentation information describing how each macroblock of the image of the encoded video sequence is segmented, mode indicating how each partition is encoded, one or more reference frames (and a list of reference frames) for each inter-frame coded block, and other information for decoding the encoded video sequence.

[0325] Intra-prediction unit 303 can use, for example, an intra-prediction mode received in the bitstream to form prediction blocks from spatially adjacent blocks. Inverse quantization unit 303 performs inverse quantization, i.e., dequantization, on the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 301. Inverse transform unit 303 applies an inverse transform.

[0326] The reconstruction unit 306 can add the residual block to the corresponding predicted block generated by the motion compensation unit 202 or the intra-frame prediction unit 303 to form a decoded block. If necessary, a deblocking filter can also be applied to filter the decoded block to remove block artifacts. The decoded video block is then stored in a buffer 307, which provides a reference block for subsequent motion compensation / intra-frame prediction and also generates the decoded video for presentation on the display device.

[0327] Figure 10-12 Example methods for implementing the above technical solutions are shown, for example, Figure 5-9 The example shown.

[0328] Figure 10 A flowchart of an example method 1000 for video processing is shown. Method 1000 includes, in operation 1010, performing a conversion between a video including images and a bitstream of the video, wherein the number of sub-images in the images is signaled as a field in the Sequence Parameter Set (SPS) of the bitstream, the bit width of the field is based on the value of the number of sub-images, and the field is a left-bit-first unsigned integer 0th-order exponentiation Golomb (Exp-Golomb) codec syntax element.

[0329] Figure 11A flowchart of an example method 1100 for video processing is shown. Method 1100 includes performing a conversion between a video and a bitstream of the video, the bitstream conforming to a format rule specifying that a first syntax element indicating whether a picture of the video can be segmented is conditionally included in a picture parameter set (PPS) of the bitstream based on the values ​​of a second syntax element and a third syntax element, wherein the second syntax element indicates whether the identifier of the subpicture is signaled in the PPS, and the third syntax element indicates the number of subpictures in the PPS.

[0330] Figure 12 A flowchart of an example method 1200 for video processing is shown. Method 1200 includes performing a conversion between a video and a bitstream of the video at operation 1210. The bitstream conforms to a format rule that specifies that a first syntax element indicating whether a picture of the video can be segmented is included in the picture parameter set (PPS) of the bitstream, preceding the set of syntax elements in the PPS that indicate the identifiers of the subpictures of the picture.

[0331] The following is a list of preferred solutions for some embodiments.

[0332] A1. A video processing method comprising: performing a conversion between a video including images and a bitstream of the video, wherein the number of sub-images in the images is signaled as a field in a sequence parameter set (SPS) of the bitstream, the bit width of the field being based on a value of the number of sub-images, wherein the field is a left-bit-first unsigned integer 0th-order exponent Golomb (Exp-Golomb) codec syntax element.

[0333] A2. Following the method of solution A1, the values ​​of the fields are restricted to a range from zero to a maximum value, which is based on the maximum width and maximum height of the image in units of luminance samples.

[0334] A3. According to the method of solution A2, the maximum value is equal to the integer number of suitable codec tree blocks within the image.

[0335] A4. The approach of solution A1, where the number of sub-images is limited based on the encoding / decoding level associated with the bitstream.

[0336] A5. A video processing method comprising performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that a first syntax element indicating whether a picture of the video can be segmented is conditionally included in a picture parameter set (PPS) of the bitstream based on the values ​​of a second syntax element and a third syntax element, wherein the second syntax element indicates whether an identifier of a subpicture is signaled in the PPS, and the third syntax element indicates the number of subpictures in the PPS.

[0337] A6. According to the method of solution A5, the first syntax element is no_pic_partition_flag, the second syntax element is subpic_ids_in_pps_flag, and the third syntax element is pps_num_subpics_minus1.

[0338] A7. According to the method of solution A5 or A6, the first syntax element is excluded from the PPS and is inferred to indicate that no image segmentation is applied to each image in the reference PPS.

[0339] A8. According to the method of solution A5 or A6, the first syntax element is not signaled in the PPS and the first syntax element is inferred to be equal to one.

[0340] A9. According to the method of solution A5 or A6, the second syntax element is signaled after one or more slice and / or strip syntax elements in the PPS.

[0341] A10. A video processing method comprising performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that a first syntax element indicating whether a picture of the video can be segmented is included in a picture parameter set (PPS) of the bitstream, preceding a set of syntax elements in the PPS indicating identifiers of subpictures of the picture.

[0342] A11. According to the method of solution A10, the second syntax element indicating the number of sub-pictures is conditionally included in the syntax element set based on the value of the first syntax element.

[0343] A12. The method according to any one of solutions A1 to A11, wherein the conversion includes decoding video from the bitstream.

[0344] A13. The method according to any one of solutions A1 to A11, wherein the conversion includes encoding the video into a bitstream.

[0345] A14. A method for storing a bitstream representing a video into a computer-readable recording medium, comprising generating a bitstream from the video according to one or more of solutions A1 to A11; and writing the bitstream into the computer-readable recording medium.

[0346] A15. A video processing apparatus, including a processor configured to perform a method according to any one or more of solutions A1 to A14.

[0347] A16. A computer-readable medium having instructions stored thereon, which, when executed, cause a processor to perform one or more of the methods of solutions A1 to A14.

[0348] A17. A computer-readable medium storing a bit stream generated according to any one or more of schemes A1 to A14.

[0349] A18. A video processing apparatus for storing bit streams, wherein the video processing apparatus is configured to perform one or more of the methods of schemes A1 to A14.

[0350] The following is another list of preferred solutions for some of the embodiments.

[0351] B1. A video processing method comprising performing a conversion between a video region of a video and a bitstream of the video, wherein the bitstream conforms to a format rule specifying a value of a second syntax element based on whether information of a subpicture is included in a sequence parameter set (SPS), wherein a first syntax element is conditionally included in the SPS, wherein the first syntax element indicates whether information of a subpicture identifier is included in the parameter set of the bitstream.

[0352] B2. According to the method of solution B1, the format rule further specifies that the value of the second syntax element is 0, the value of the second syntax element being 0 indicates that the information of the sub-picture is omitted in the SPS, and thus each video region associated with the SPS is not divided into multiple sub-pictures, and based on the value of the second syntax element being 0, the first syntax element is omitted in the SPS.

[0353] B3. According to the method of solution B1 or B2, where the first syntax element is subpic_ids_explicitly_signalled_flag and the second syntax element is subpic_info_present_flag.

[0354] B4. According to the method of solution B1 or B3, where the formatting rule also specifies that if the value of the first syntax element is 0, the first syntax element with a value of 0 is included in the SPS.

[0355] B5. According to any one of solutions B1 to B4, where the video region is a video image.

[0356] B6. A video processing method comprising performing a conversion between a video image and a video bitstream, wherein the bitstream conforms to a format rule specifying that the mapping between the identifiers of one or more sub-images of the image and the one or more sub-images is not included in the image header of the image, wherein the format rule further specifies that the identifiers of the one or more sub-images are derived based on syntax elements in the Picture Parameter Set (PPS) and Sequence Parameter Set (SPS) referenced by the image.

[0357] B7. According to the method of solution B6, the flag in SPS takes a first value to indicate that the identifier of one or more sub-images is derived based on the syntax elements in PPS, or takes a second value to indicate that the identifier of one or more sub-images is derived based on the syntax elements in SPS.

[0358] B8. According to the method in solution B7, the flag corresponds to the subpic_ids_in_pps_flag field, with a first value of 1 and a second value of 0.

[0359] B9. According to the method in solution B6, the identifier (denoted as SubpicIdList[i]) is obtained as follows:

[0360] for(i=0;i<=sps_num_subpics_minus1;i++)

[0361] if(subpic_ids_explicitly_signalled_flag)

[0362] SubpicIdList[i]=subpic_ids_in_pps_flag? pps_subpic_id[i]:sps_subpic_id[i]

[0363] else

[0364] SubpicIdList[i] = i.

[0365] B10. A video processing method comprising performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that when the value of a first syntax element indicating a mapping between an identifier of a subpicture and one or more subpictures of a picture is explicitly signaled for one or more subpictures, the mapping is signaled in a Sequence Parameter Set (SPS) or a Picture Parameter Set (PPS).

[0366] B11. According to the method of solution B10, where the first syntax element is subpic_ids_explicitly_signalled_flag.

[0367] B12. According to the method of solution B11, the signaling notification identifier in SPS is based on the value of the second syntax element (represented as subpic_ids_in_sps_flag), and the signaling notification identifier in PPS is based on the value of the third syntax element (represented as subpic_ids_in_pps_flag).

[0368] B13. According to the method of solution B12, where subpic_ids_in_pps_flag equals 0 because subpic_ids_explicitly_signalled_flag is 0 or subpic_ids_in_sps_flag is 1.

[0369] B14. According to the approach of solution B13, where subpic_ids_in_pps_flag equals 0, it indicates that the signaling notification identifier is not in the PPS.

[0370] B15. According to the method of solution B12, where subpic_ids_in_pps_flag equals 1 because subpic_ids_explicitly_signalled_flag is 1 and subpic_ids_in_sps_flag is 0.

[0371] B16. According to the method of solution B15, where subpic_ids_in_pps_flag equal to 1 indicates that the identifier of each subpic in one or more subpics is explicitly signaled in the PPS.

[0372] B17. The method according to any one of solutions B1 to B15, wherein the conversion includes decoding video from the bitstream.

[0373] B18. The method according to any one of solutions B1 to B15, wherein the conversion includes encoding the video into a bitstream.

[0374] B19. A method for storing a bitstream representing a video into a computer-readable recording medium, comprising generating a bitstream from a video according to one or more of solutions B1 to B15; and writing the bitstream into the computer-readable recording medium.

[0375] B20. A video processing apparatus, including a processor configured to perform a method of any one or more of solutions B1 to B19.

[0376] B21. A computer-readable medium having instructions stored thereon, wherein the instructions, when executed, cause a processor to perform one or more of schemes B1 to B19.

[0377] B22. A computer-readable medium storing a bit stream generated according to any one or more of schemes B1 to B19.

[0378] B23. A video processing apparatus for storing bitstreams, wherein the video processing apparatus is configured to perform a method of any one or more of solutions B1 to B19.

[0379] The following is another list of preferred solutions for some embodiments.

[0380] C1. A video processing method comprising performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that the length of an identifier for a signaling notification subpicture in a Sequence Parameter Set (SPS) is not based on the value of a syntax element indicating whether the signaling notification identifier is in the SPS.

[0381] C2. A video processing method comprising performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies the length of the signaling notification identifier in the PPS due to syntax elements indicating an identifier for explicitly signaling notification of a sub-picture in a Picture Parameter Set (PPS).

[0382] C3. According to the method of solution C1 or C2, where the length also corresponds to the length of the sub-image identifier in the strip header.

[0383] C4. According to any one of solutions C1 through C3, where the syntax element is subpic_ids_explicitly_signalled_flag.

[0384] C5. According to the method of solution C3 or C4, where the signaling notification identifier is not in SPS and not in PPS.

[0385] C6. According to the method of solution C5, the length of the sub-picture identifier corresponds to the length of the sub-picture identifier notified in the signaling in SPS.

[0386] C7. A video processing method comprising performing a conversion between a video and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that a first syntax element of signaling notification in a sequence parameter set (SPS) of the bitstream indicates the length of an identifier for a subpicture in the SPS, wherein the signaling of the first syntax element is independent of the value of a second syntax element, the value of the second syntax element indicating that the identifier for the subpicture is explicitly signaled in the SPS or picture parameter set (PPS).

[0387] C8. According to the approach in solution C7, the second syntax element is subpic_ids_explicitly_signalled_flag.

[0388] C9. According to the method of solution C7 or C8, wherein the second syntax element equal to 1 indicates a set of signaling notification identifiers for each sub-picture in SPS or PPS, wherein each sub-picture corresponds to one identifier, and wherein the second syntax element equal to 0 indicates that the signaling notification identifier is not explicitly specified in SPS or PPS.

[0389] C10. According to the method of solution C7 or C8, where the value of the first syntax element is 0 or 1 because the value of the second syntax element is 0.

[0390] C11. According to the method of solution C7 or C8, where the value of the first syntax element is 1 because the value of the second syntax element is 1.

[0391] C12. According to the method of solution C7 or C8, where the value of the second syntax element is 0.

[0392] C13. The method according to any one of solutions C1 to C12, wherein the conversion includes decoding video from the bitstream.

[0393] C14. The method according to any one of solutions C1 to C12, wherein the conversion includes encoding the video into a bitstream.

[0394] C15. A method for storing a bitstream representing a video into a computer-readable recording medium, comprising generating a bitstream from a video according to one or more of schemes C1 to C12; and writing the bitstream into the computer-readable recording medium.

[0395] C16. A video processing apparatus, including a processor configured to perform one or more of schemes C1 to C15.

[0396] C17. A computer-readable medium having instructions stored thereon, which, when executed, cause a processor to perform one or more of the methods of solutions C1 to C15.

[0397] C18. A computer-readable medium storing a bit stream generated according to any one or more of schemes C1 to C15.

[0398] C19. A video processing apparatus for storing bit streams, wherein the video processing apparatus is configured to perform a method of any one or more of schemes C1 to C15.

[0399] The following is another list of preferred solutions for some of the embodiments.

[0400] P1. A video processing method comprising performing a conversion between images of a video and a codec representation of the video, wherein the number of sub-images in the images is included as a field in the codec representation, the bit width of the field depending on the value of the number of sub-images.

[0401] P2. Following the method of solution P1, where the field represents the number of sub-images using codewords.

[0402] P3. According to the method of solution P2, where the codewords include Columbus codewords.

[0403] P4. According to any of the solutions P1 to P3, the value of the number of sub-images is restricted to an integer number less than or equal to the number of suitable codec tree blocks within the image.

[0404] P5. According to the method of any one of the solutions P1 to P4, where the field depends on the codec level associated with the codec representation.

[0405] P6. A video processing method comprising 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 since the video region does not contain any sub-pictures, a syntax element indicating a sub-picture identifier is omitted.

[0406] P7. According to the method in solution P6, the codec representation includes a field with a value of 0, which indicates that the video region does not include any sub-pictures.

[0407] P8. A video processing method comprising performing a conversion between a video region of a video and a coded / decoded representation of the video, wherein the coded representation conforms to a format rule, wherein the format rule specifies that identifiers of sub-pictures in the video region are omitted at the header level of the video region in the coded / decoded representation.

[0408] P9. According to the method in solution P8, where encoding and decoding represent the digital identification of sub-pictures based on the order in which they are listed in the video region header.

[0409] P10. A video processing method, comprising 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 the length of identifiers of sub-pictures in the video region and / or the identifiers of sub-pictures at a sequence parameter set level or a picture parameter set level.

[0410] P11. According to the method in solution P10, where length is included in the image parameter set level.

[0411] P12. A video processing 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 the codec representation at the video sequence level includes a field indicating whether a sub-picture identifier length field is included in the codec representation at the video sequence level.

[0412] P13. According to the method in solution P12, where the format rule specifies that another field in the codec representation indicates the length identifier of the video region included in the codec representation, the field is set to 1.

[0413] P14. The method of any of the above schemes, wherein the video region includes sub-images of the video.

[0414] P15. The method of any of the above schemes, wherein the conversion includes parsing and decoding the codec representation to generate video.

[0415] P16. The method of any of the above schemes, wherein the conversion includes encoding the video to generate a codec representation.

[0416] P17. A video decoding apparatus, including a processor configured to perform one or more of schemes P1 to P16.

[0417] P18. A video encoding apparatus, including a processor configured to perform one or more of schemes P1 to P16.

[0418] P19. A computer program product having computer code stored thereon, wherein when the code is executed, a method for the processor to execute any one of schemes P1 to P16.

[0419] The disclosures and other solutions, examples, embodiments, modules, and functional operations described in this application can be implemented in digital electronic circuits, or computer software, firmware, or hardware, including the structures disclosed herein and their structural equivalents, or combinations thereof. The disclosures and other embodiments herein can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a tangible and non-volatile computer-readable medium for execution by a data processing apparatus or for controlling the operation of the data processing apparatus. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a storage device, a material composition affecting machine-readable propagated signals, or one or more of these. The terms "data processing unit" or "data processing apparatus" include all means, devices, and machines for processing data, including, for example, programmable processors, computers, or multiprocessors or computer groups. In addition to hardware, the apparatus may also include code that creates an execution environment for a computer program, such as code constituting processor firmware, a protocol stack, a database management system, an operating system, or a combination thereof. The propagated signals are artificially generated signals, such as machine-generated electrical, optical, or electromagnetic signals, which are generated to encode information for transmission to a suitable receiver device.

[0420] Computer programs (also known as programs, software, software applications, scripts, or code) can be written in any programming language (including compiled or interpreted languages) and can be deployed in any form, including as standalone programs or as 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 holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to that program, or in multiple coordinating files (e.g., a file storing one or more modules, subroutines, or portions of code). Computer programs can be deployed and executed on one or more computers located at a single site or distributed across multiple sites interconnected by a communication network.

[0421] The processing and logic flows described in this specification can be executed by one or more programmable processors that execute one or more computer programs to perform functions by manipulating input data and generating outputs. The processing and logic flows can also be executed by special-purpose logic circuitry, and the device can be implemented as special-purpose logic circuitry, such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit).

[0422] For example, processors suitable for executing computer programs include general-purpose and special-purpose microprocessors, as well as one or more of any type of digital computer. Typically, the processor receives instructions and data from read-only memory or random access memory, or both. The basic components of a computer are a processor that executes instructions and one or more storage devices that store the instructions and data. Typically, a computer will also include one or more mass storage devices for storing data, such as magnetic disks, magneto-optical disks, or optical disks, or receive data from or transfer data to one or more mass storage devices via operative coupling, or both. However, a computer does not necessarily 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 hard disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and memory may be supplemented by or incorporated into special-purpose logic circuitry.

[0423] While this patent document contains numerous details, it should not be construed as limiting the scope of any invention or claim, but rather as a description of features of specific embodiments of a particular invention. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various functions described in the context of a single embodiment may also be implemented individually in multiple embodiments, or in any suitable sub-combination. Furthermore, although the foregoing features may be described as functioning in certain combinations, or even initially claimed to be so, in certain circumstances, one or more features from a combination of claims may be removed from the combination, and a combination of claims may refer to a sub-combination or a variation of a sub-combination.

[0424] Similarly, although the operations are described in a specific order in the accompanying drawings, this should not be construed as requiring the specific order or sequence shown to perform such operations, or all the described operations, in order to obtain the desired result. Furthermore, the separation of various system components in the embodiments described in this patent document should not be construed as requiring such separation in all embodiments.

[0425] Only some implementations and examples are described; other implementations, enhancements, and variations can be made based on the content described and illustrated in this patent document.

Claims

1. A video processing method, comprising: Perform conversion between a video containing multiple images and the bitstream of that video. Specifically, the Sequence Parameter Set (SPS) of the bitstream conditionally signals a field indicating the number of sub-pictures in each frame of the video sequence, the bit width of which is based on the value of the number of sub-pictures. Wherein, the field is a left-bit-first unsigned integer 0th-order exponent Golomb encoding syntax element, and Specifically, when the flag indicates that sub-image information exists for the video sequence, the field is signaled in the SPS.

2. The method according to claim 1, wherein, The field is sps_num_subpics_minus1. When no signaling is given to the field, it is inferred that the value of the field is equal to 0.

3. The method according to claim 1, wherein, A first syntax element indicating whether each picture in the reference picture parameter set (PPS) can be segmented is included in the PPS of the bitstream, preceding the set of syntax elements in the PPS that indicate the subpicture identifiers of the pictures.

4. The method according to claim 3, wherein, A second syntax element, indicating the number of sub-images in each image of the reference PPS, is conditionally included in the PPS based on the value of the first syntax element.

5. The method according to claim 4, wherein, In response to the value of the first syntax element indicating that image segmentation should not be applied to each image of the reference PPS, the second syntax element is omitted.

6. The method according to claim 4, wherein, Bitstream consistency requires that the value of the second syntax element be equal to the field.

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

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

9. The method of claim 1, wherein the value of the field is limited to a range from zero to a maximum value, the maximum value being based on the maximum width of the image in units of luminance samples and the maximum height of the image in units of luminance samples.

10. The method according to claim 9, wherein the maximum value is equal to the integer number of suitable codec tree blocks within the image.

11. The method of claim 1, wherein the number of sub-images is limited based on the encoding / decoding level associated with the bitstream.

12. The method according to claim 1, in, The bitstream conforms to the format rules, and The format rule specifies that a first syntax element is conditionally included in the Picture Parameter Set (PPS) of the bitstream based on the values ​​of a second syntax element and a third syntax element. The first syntax element indicates whether the pictures of the video can be segmented, the second syntax element indicates whether the identifier of the sub-picture is signaled in the PPS, and the third syntax element indicates the number of sub-pictures in the PPS.

13. The method according to claim 12, wherein, The first syntax element is no_pic_partition_flag, the second syntax element is subpic_ids_in_pps_flag, and the third syntax element is pps_num_subpics_minus1.

14. The method according to claim 12, wherein, The first syntax element is excluded from the PPS and is inferred to indicate that no image segmentation is applied to each image referencing the PPS.

15. The method according to claim 12, wherein, The first syntax element is not signaled in the PPS and is inferred to be equal to one.

16. The method according to claim 12, wherein, The second syntax element is signaled after one or more slice and / or strip syntax elements in the PPS.

17. The method according to claim 1, in, The bitstream conforms to the format rules, and The format rule specifies that a first syntax element indicating whether the images of the video can be segmented is included in the Picture Parameter Set (PPS) of the bitstream, preceding the set of syntax elements in the PPS that indicate the identifiers of the sub-images of the image.

18. The method according to claim 17, wherein, A second syntax element indicating the number of sub-images is conditionally included in the set of syntax elements based on the value of the first syntax element.

19. An apparatus for processing video data, the apparatus comprising a processor and a non-transitory memory having instructions thereon, wherein, When the instruction is executed by the processor, the processor: Perform conversion between a video containing multiple images and the bitstream of that video. Specifically, the Sequence Parameter Set (SPS) of the bitstream conditionally signals a field indicating the number of sub-pictures in each frame of the video sequence, the bit width of which is based on the value of the number of sub-pictures. Wherein, the field is a left-bit-first unsigned integer 0th-order exponent Golomb encoding syntax element, and Specifically, when the flag indicates that sub-image information exists for the video sequence, the field is signaled in the SPS.

20. The apparatus according to claim 19, wherein, The field is sps_num_subpics_minus1. When no signaling is given to the field, it is inferred that the value of the field is equal to 0.

21. The apparatus according to claim 19, wherein, A second syntax element, indicating the number of sub-images in each image of a reference image parameter set (PPS), is conditionally included in the PPS based on the value of a first syntax element, which indicates whether each sub-image of the PPS is segmented.

22. The apparatus according to claim 21, wherein, Bitstream consistency requires that the value of the second syntax element be equal to the field.

23. A non-transitory computer-readable storage medium storing instructions that cause a processor to: Perform conversion between a video containing multiple images and the bitstream of that video. in, The Sequence Parameter Set (SPS) of the bitstream conditionally signals a field indicating the number of sub-pictures in each frame of the video sequence, the bit width of which is based on the value of the number of sub-pictures. Wherein, the field is a left-bit-first unsigned integer 0th-order exponent Golomb encoding syntax element, and Specifically, when the flag indicates that sub-image information exists for the video sequence, the field is signaled in the SPS.

24. The non-transitory computer-readable storage medium according to claim 23, in, The field is sps_num_subpics_minus1. When no signaling is given to the field, it is inferred that the value of the field is equal to 0.

25. The non-transitory computer-readable storage medium according to claim 24, wherein, A second syntax element, indicating the number of sub-images in each image of a reference image parameter set (PPS), is conditionally included in the PPS based on the value of a first syntax element, which indicates whether each sub-image of the PPS is segmented. Bitstream consistency requires that the value of the second syntax element be equal to the field.

26. A non-transitory computer-readable recording medium storing computer-readable instructions and a bitstream of video, the computer-readable instructions causing the processor, when executed by a processor, to: Generate the bitstream of the video, wherein the video includes multiple images. in, The Sequence Parameter Set (SPS) of the bitstream conditionally signals a field indicating the number of sub-pictures in each frame of the video sequence, the bit width of which is based on the value of the number of sub-pictures. Wherein, the field is a left-bit-first unsigned integer 0th-order exponent Golomb encoding syntax element, and Specifically, when the flag indicates that sub-image information exists for the video sequence, the field is signaled in the SPS.

27. The non-transitory computer-readable recording medium according to claim 26 in, The field is sps_num_subpics_minus1. When no signaling is given to the field, it is inferred that the value of the field is equal to 0.

28. The non-transitory computer-readable recording medium according to claim 26, wherein, A second syntax element, indicating the number of sub-images in each image of a reference image parameter set (PPS), is conditionally included in the PPS based on the value of a first syntax element, which indicates whether each sub-image of the PPS is segmented. Bitstream consistency requires that the value of the second syntax element be equal to the field.

29. A method for storing a video bitstream, comprising: Perform the method as described in any one of claims 1-6 to generate a bitstream of a video comprising multiple images; as well as The bitstream is stored in a non-transitory computer-readable recording medium. Specifically, the Sequence Parameter Set (SPS) of the bitstream conditionally signals a field indicating the number of sub-pictures in each frame of the video sequence, the bit width of which is based on the value of the number of sub-pictures. Wherein, the field is a left-bit-first unsigned integer 0th-order exponent Golomb encoding syntax element, and Specifically, when the flag indicates that sub-image information exists for the video sequence, the field is signaled in the SPS.

30. A method for storing a bitstream representing video into a computer-readable recording medium, comprising: The method according to any one of claims 9-18 generates a bitstream from video; as well as The bit stream is written into the computer-readable recording medium.

31. A video processing apparatus comprising a processor configured to perform the method of any one of claims 9-18.

32. A computer-readable medium having instructions stored thereon, wherein, When executed, the instructions cause the processor to perform the method according to any one of claims 9-18.

33. A computer-readable medium storing computer-readable instructions and a bitstream of video, wherein the computer-readable instructions, when executed by a processor, cause the processor to perform the method according to any one of claims 9-18 to generate the bitstream.

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