WO2021110170A1 - Mise à jour de tables hmvp - Google Patents

Mise à jour de tables hmvp Download PDF

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Publication number
WO2021110170A1
WO2021110170A1 PCT/CN2020/134287 CN2020134287W WO2021110170A1 WO 2021110170 A1 WO2021110170 A1 WO 2021110170A1 CN 2020134287 W CN2020134287 W CN 2020134287W WO 2021110170 A1 WO2021110170 A1 WO 2021110170A1
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candidate
video
hmvp
motion
conversion
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PCT/CN2020/134287
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Li Zhang
Kai Zhang
Hongbin Liu
Yue Wang
Siwei Ma
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Beijing Bytedance Network Technology Co., Ltd.
Bytedance Inc.
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Priority to CN202080084219.8A priority Critical patent/CN114747218A/zh
Publication of WO2021110170A1 publication Critical patent/WO2021110170A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/103—Selection of coding mode or of prediction mode
    • H04N19/105—Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H04N19/513—Processing of motion vectors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H04N19/513—Processing of motion vectors
    • H04N19/517—Processing of motion vectors by encoding
    • H04N19/52—Processing of motion vectors by encoding by predictive encoding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H04N19/577—Motion compensation with bidirectional frame interpolation, i.e. using B-pictures

Definitions

  • This patent document relates to image and video coding and decoding.
  • Digital video accounts for the largest bandwidth use on the internet and other digital communication networks. As the number of connected user devices capable of receiving and displaying video increases, it is expected that the bandwidth demand for digital video usage will continue to grow.
  • the present document discloses techniques that can be used by video encoders and decoders to perform cross-component adaptive loop filtering during video encoding or decoding.
  • a method of video processing is disclosed.
  • a method of video processing includes performing a conversion between a video block of a video and a bitstream representation of the video; and selectively updating a table of motion candidates used for another video block by removing a Kth entry of the table, wherein K is a positive integer based on a rule.
  • a method of video processing includes performing a conversion between a video block of a video and a bitstream representation of the video; and updating, selectively based on a rule, a table of motion candidates used for another video block by adding a new candidate by removing an existing candidate in the table, wherein the rule depends on a characteristic of the existing candidate.
  • a method of video processing includes performing a conversion between a video block of a video and a bitstream representation of the video; and updating, selectively based on a rule, a table of motion candidates used for another video block by adding a new candidate based on the conversion at a Kth position from 0th position in the table, wherein K is dependent on a rule.
  • a method of video processing includes performing a conversion between a video block of a video processing unit of a video and a bitstream representation of the video; and updating, selectively based on a rule, a table of motion candidates used for another video block, wherein the rule depends on the video processing unit.
  • a method of video processing includes maintaining a history-based motion vector prediction (HMVP) table which comprises at least one motion candidate; performing a conversion between a current video block of a video and a bitstream representation of the video; and updating the table by removing a Kth entry in the table and adding a motion candidate into the HMVP table, wherein K is a positive integer and is determined based on a predetermined rule and the motion candidate added into the HMVP table is derived from motion information derived during the conversion.
  • HMVP history-based motion vector prediction
  • a method of video processing includes maintaining a history-based motion vector prediction (HMVP) table which comprises at least one motion candidate; performing a conversion between a current video block of a video and a bitstream representation of the video; and updating the table with a motion candidate based on position of a redundant candidate in the HMVP table, wherein the motion candidate is derived from motion information derived during the conversion and the redundant candidate is identical to or similar to the motion candidate.
  • HMVP history-based motion vector prediction
  • a method of video processing includes maintaining a history-based motion vector prediction (HMVP) table which comprises at least one motion candidate; performing a conversion between a current video block of a video and a bitstream representation of the video; and updating the table by adding a motion candidate to a Kth entry in the HMVP table, wherein the motion candidate added into the HMVP table is derived from motion information derived during the conversion and K is a positive integer and is determined based on a predetermined rule.
  • HMVP history-based motion vector prediction
  • a method of video processing includes maintaining a history-based motion vector prediction (HMVP) table which comprises at least one motion candidate; performing a conversion between video processing units of video blocks of a video and a bitstream representation of the video; and updating the HMVP table based on one or more rules associated with the video processing units, wherein the rules change from one video processing unit to another video processing unit.
  • HMVP history-based motion vector prediction
  • a video encoder apparatus comprising a processor configured to implement above-described methods.
  • a video encoder apparatus comprising a processor configured to implement above-described methods.
  • a computer readable medium having code stored thereon is disclose.
  • the code embodies one of the methods described herein in the form of processor-executable code.
  • FIG. 1 shows a typical HEVC video encoder (with decoder modeling elements shaded in light gray) .
  • FIG. 2 shows examples of video block partitions.
  • FIG. 3 shows examples of allowed prediction blocks for an MxM coding unit or video block.
  • FIGS. 4A-4B shows a splitting pattern
  • FIGS. 5A-5B shows a splitting pattern example using quadtree binary tree.
  • FIG. 6 (a) to (e) show various block partitioning patterns.
  • FIG. 7 shows a derivation process for merge candidates list construction.
  • FIG. 8 shows example positions of spatial merge candidates.
  • FIG. 9 shows candidate pairs considered for redundancy check of spatial merge candidates.
  • FIG. 10A-10B show positions for the second PU of N ⁇ 2N and 2N ⁇ N partitions.
  • FIG. 11 is an illustration of motion vector scaling for temporal merge candidate.
  • FIG. 12 shows candidate positions for temporal merge candidate, C0 and C1, in the col-located picture.
  • FIG. 13 shows an example of combined bi-predictive merge candidate.
  • FIG. 14 shows derivation process for motion vector prediction candidates.
  • FIG. 15 is an illustration of motion vector scaling for spatial motion vector candidate.
  • FIG. 16 shows an example coding flow of history based motion vector prediction (HMVP) .
  • HMVP history based motion vector prediction
  • FIG. 17 shows a modified merge list construction process.
  • FIGS. 18A-18B show redundancy-removal based HMVP updating method (with one redundancy motion candidate removed) .
  • FIGS. 19A-19B show examples of redundancy-removal based HMVP updating method (with one redundancy motion candidate removed) .
  • FIG. 20 shows CU and PU partitioning example.
  • FIG. 21 shows an example of a current block and its neighboring blocks used in AVS3.
  • FIGS. 22A-22D depict examples of redundancy-removal based HMVP updating method (with table size set to L) .
  • FIGS. 23A-23F depict examples if HMVP table updating processes.
  • FIG. 24 is a block diagram of an example video processing system in which disclosed techniques may be implemented.
  • FIG. 25 is a block diagram of an example hardware platform used for video processing.
  • FIG. 26 is a flowchart for an example method of video processing.
  • FIG. 27 is a flowchart for an example method of video processing.
  • FIG. 28 is a flowchart for an example method of video processing.
  • FIG. 29 is a flowchart for an example method of video processing.
  • FIG. 30 is a flowchart for an example method of video processing.
  • This patent document is related to video coding technologies. Specifically, it is related to motion vector coding in image/video coding. It may be applied to the existing video coding standard like HEVC, or the standard (Versatile Video Coding) , third generation of the Chinese Audio and Video coding Standard (AVS3) to be finalized. It may be also applicable to future video coding standards or video codec.
  • Video coding standards have evolved primarily through the development of the well-known ITU-T and ISO/IEC standards.
  • the ITU-T produced H. 261 and H. 263, ISO/IEC produced MPEG-1 and MPEG-4 Visual, and the two organizations jointly produced the H. 262/MPEG-2 Video and H. 264/MPEG-4 Advanced Video Coding (AVC) and H. 265/HEVC standards.
  • AVC H. 264/MPEG-4 Advanced Video Coding
  • H. 265/HEVC High Efficiency Video Coding
  • the video coding standards are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized.
  • An example of a typical HEVC encoder framework is depicted in FIG. 1.
  • the core of the coding layer in previous standards was the macroblock, containing a 16 ⁇ 16 block of luma samples and, in the usual case of 4: 2: 0 color sampling, two corresponding 8 ⁇ 8 blocks of chroma samples.
  • An intra-coded block uses spatial prediction to exploit spatial correlation among pixels.
  • Two partitions are defined: 16x16 and 4x4.
  • An inter-coded block uses temporal prediction, instead of spatial prediction, by estimating motion among pictures.
  • Motion can be estimated independently for either 16x16 macroblock or any of its sub-macroblock partitions: 16x8, 8x16, 8x8, 8x4, 4x8, 4x4 (see Fig. 2) . Only one motion vector (MV) per sub-macroblock partition is allowed.
  • a CTU is split into CUs by using a quadtree structure denoted as coding tree to adapt to various local characteristics.
  • the decision whether to code a picture area using inter-picture (temporal) or intra-picture (spatial) prediction is made at the CU level.
  • Each CU can be further split into one, two or four PUs according to the PU splitting type. Inside one PU, the same prediction process is applied and the relevant information is transmitted to the decoder on a PU basis.
  • a CU can be partitioned into transform units (TUs) according to another quadtree structure similar to the coding tree for the CU.
  • TUs transform units
  • Coding tree units and coding tree block (CTB) structure The analogous structure in HEVC is the coding tree unit (CTU) , which has a size selected by the encoder and can be larger than a traditional macroblock.
  • the CTU consists of a luma CTB and the corresponding chroma CTBs and syntax elements.
  • HEVC then supports a partitioning of the CTBs into smaller blocks using a tree structure and quadtree-like signaling.
  • Coding units and coding blocks (CBs)
  • the quadtree syntax of the CTU specifies the size and positions of its luma and chroma CBs. The root of the quadtree is associated with the CTU. Hence, the size of the luma CTB is the largest supported size for a luma CB.
  • the splitting of a CTU into luma and chroma CBs is signaled jointly.
  • a CTB may contain only one CU or may be split to form multiple CUs, and each CU has an associated partitioning into prediction units (PUs) and a tree of transform units (TUs) .
  • PUs prediction units
  • TUs tree of transform units
  • Prediction units and prediction blocks The decision whether to code a picture area using inter picture or intra picture prediction is made at the CU level.
  • a PU partitioning structure has its root at the CU level.
  • the luma and chroma CBs can then be further split in size and predicted from luma and chroma prediction blocks (PBs) .
  • HEVC supports variable PB sizes from 64 ⁇ 64 down to 4 ⁇ 4 samples.
  • Fig. 3 shows examples of allowed PBs for a MxM CU.
  • the prediction residual is coded using block transforms.
  • a TU tree structure has its root at the CU level.
  • the luma CB residual may be identical to the luma transform block (TB) or may be further split into smaller luma TBs. The same applies to the chroma TBs.
  • Integer basis functions similar to those of a discrete cosine transform (DCT) are defined for the square TB sizes 4 ⁇ 4, 8 ⁇ 8, 16 ⁇ 16, and 32 ⁇ 32.
  • DCT discrete cosine transform
  • an integer transform derived from a form of discrete sine transform (DST) is alternatively specified.
  • a CB can be recursively partitioned into transform blocks (TBs) .
  • the partitioning is signaled by a residual quadtree. Only square CB and TB partitioning is specified, where a block can be recursively split into quadrants, as illustrated in FIGS. 4A-4B.
  • a flag signals whether it is split into four blocks of size M/2 ⁇ M/2. If further splitting is possible, as signaled by a maximum depth of the residual quadtree indicated in the SPS, each quadrant is assigned a flag that indicates whether it is split into four quadrants.
  • the leaf node blocks resulting from the residual quadtree are the transform blocks that are further processed by transform coding.
  • the encoder indicates the maximum and minimum luma TB sizes that it will use. Splitting is implicit when the CB size is larger than the maximum TB size. Not splitting is implicit when splitting would result in aluma TB size smaller than the indicated minimum.
  • the chroma TB size is half the luma TB size in each dimension, except when the luma TB size is 4 ⁇ 4, in which case a single 4 ⁇ 4 chroma TB is used for the region covered by four 4 ⁇ 4 luma TBs.
  • intra-picture-predicted CUs the decoded samples of the nearest-neighboring TBs (within or outside the CB) are used as reference data for intra picture prediction.
  • the HEVC design allows a TB to span across multiple PBs for inter-picture predicted CUs to maximize the potential coding efficiency benefits of the quadtree-structured TB partitioning.
  • a CTB is divided according to a quad-tree structure, the nodes of which are coding units.
  • the plurality of nodes in a quad-tree structure includes leaf nodes and non-leaf nodes.
  • the leaf nodes have no child nodes in the tree structure (i.e., the leaf nodes are not further split) .
  • The, non-leaf nodes include a root node of the tree structure.
  • the root node corresponds to an initial video block of the video data (e.g., a CTB) .
  • the respective non-root node corresponds to a video block that is a sub-block of a video block corresponding to a parent node in the tree structure of the respective non-root node.
  • Each respective non-leaf node of the plurality of non-leaf nodes has one or more child nodes in the tree structure.
  • JVET Joint Video Exploration Team
  • the QTBT structure removes the concepts of multiple partition types, i.e. it removes the separation of the CU, PU and TU concepts, and supports more flexibility for CU partition shapes.
  • a CU can have either a square or rectangular shape.
  • a coding tree unit (CTU) is first partitioned by a quadtree structure.
  • the quadtree leaf nodes are further partitioned by a binary tree structure.
  • the binary tree leaf nodes are called coding units (CUs) , and that segmentation is used for prediction and transform processing without any further partitioning.
  • a CU sometimes consists of coding blocks (CBs) of different colour components, e.g. one CU contains one luma CB and two chroma CBs in the case of P and B slices of the 4: 2: 0 chroma format and sometimes consists of a CB of a single component, e.g., one CU contains only one luma CB or just two chroma CBs in the case of I slices.
  • CBs coding blocks
  • - CTU size the root node size of a quadtree, the same concept as in HEVC.
  • MaxBTSize the maximally allowed binary tree root node size.
  • the CTU size is set as 128 ⁇ 128 luma samples with two corresponding 64 ⁇ 64 blocks of chroma samples
  • the MinQTSize is set as 16 ⁇ 16
  • the MaxBTSize is set as 64 ⁇ 64
  • the MinBTSize (for both width and height) is set as 4 ⁇ 4
  • the MaxBTDepth is set as 4.
  • the quadtree partitioning is applied to the CTU first to generate quadtree leaf nodes.
  • the quadtree leaf nodes may have a size from 16 ⁇ 16 (i.e., the MinQTSize) to 128 ⁇ 128 (i.e., the CTU size) .
  • the quadtree leaf node is also the root node for the binary tree and it has the binary tree depth as 0.
  • MaxBTDepth i.e., 4
  • no further splitting is considered.
  • MinBTSize i.e., 4
  • no further horizontal splitting is considered.
  • the binary tree node has height equal to MinBTSize
  • no further vertical splitting is considered.
  • the leaf nodes of the binary tree are further processed by prediction and transform processing without any further partitioning. In the JEM, the maximum CTU size is 256 ⁇ 256 luma samples.
  • FIG. 5A illustrates an example of block partitioning by using QTBT
  • FIG. 5B illustrates the corresponding tree representation.
  • the solid lines indicate quadtree splitting and dotted lines indicate binary tree splitting.
  • each splitting (i.e., non-leaf) node of the binary tree one flag is signalled to indicate which splitting type (i.e., horizontal or vertical) is used, where 0 indicates horizontal splitting and 1 indicates vertical splitting.
  • the quadtree splitting there is no need to indicate the splitting type since quadtree splitting always splits a block both horizontally and vertically to produce 4 sub-blocks with an equal size.
  • the QTBT scheme supports the ability for the luma and chroma to have a separate QTBT structure.
  • the luma and chroma CTBs in one CTU share the same QTBT structure.
  • the luma CTB is partitioned into CUs by a QTBT structure
  • the chroma CTBs are partitioned into chroma CUs by another QTBT structure. This means that a CU in an I slice consists of a coding block of the luma component or coding blocks of two chroma components, and a CU in a P or B slice consists of coding blocks of all three colour components.
  • inter prediction for small blocks is restricted to reduce the memory access of motion compensation, such that bi-prediction is not supported for 4 ⁇ 8 and 8 ⁇ 4 blocks, and inter prediction is not supported for 4 ⁇ 4 blocks.
  • these restrictions are removed.
  • TT ternary tree
  • FIG. 6 (a) quad-tree partitioning 6 (b) vertical binary-tree partitioning 6 (c) horizontal binary-tree partitioning 6 (d) vertical center-side ternary-tree partitioning 6 (e) horizontal center-side ternary-tree partitioning.
  • a CTU is firstly partitioned by region tree (RT) .
  • a RT leaf may be further split with prediction tree (PT) .
  • a PT leaf may also be further split with PT until max PT depth is reached.
  • a PT leaf is the basic coding unit. It is still called CU for convenience.
  • a CU cannot be further split.
  • Prediction and transform are both applied on CU in the same way as JEM.
  • the whole partition structure is named ‘multiple-type-tree’ .
  • Each inter-predicted PU has motion parameters for one or two reference picture lists.
  • Motion parameters include a motion vector and a reference picture index. Usage of one of the two reference picture lists may also be signalled using inter_pred_idc.
  • Motion vectors may be explicitly coded as deltas relative to predictors, such a coding mode is called AMVP mode.
  • a merge mode is specified whereby the motion parameters for the current PU are obtained from neighbouring PUs, including spatial and temporal candidates.
  • the merge mode can be applied to any inter-predicted PU, not only for skip mode.
  • the alternative to merge mode is the explicit transmission of motion parameters, where motion vector, corresponding reference picture index for each reference picture list and reference picture list usage are signalled explicitly per each PU.
  • the PU When signalling indicates that one of the two reference picture lists is to be used, the PU is produced from one block of samples. This is referred to as ‘uni-prediction’ . Uni-prediction is available both for P-slices and B-slices.
  • Bi-prediction When signalling indicates that both of the reference picture lists are to be used, the PU is produced from two blocks of samples. This is referred to as ‘bi-prediction’ . Bi-prediction is available for B-slices only.
  • Step 1.2 Redundancy check for spatial candidates
  • a maximum of four merge candidates are selected among candidates that are located in five different positions.
  • a maximum of one merge candidate is selected among two candidates. Since constant number of candidates for each PU is assumed at decoder, additional candidates are generated when the number of candidates does not reach to maximum number of merge candidate (MaxNumMergeCand) which is signalled in slice header. Since the number of candidates is constant, index of best merge candidate is encoded using truncated unary binarization (TU) . If the size of CU is equal to 8, all the PUs of the current CU share a single merge candidate list, which is identical to the merge candidate list of the 2N ⁇ 2N prediction unit.
  • TU truncated unary binarization
  • a maximum of four merge candidates are selected among candidates located in the positions depicted in FIG. 8.
  • the order of derivation is A 1 , B 1 , B 0 , A 0 and B 2 .
  • Position B 2 is considered only when any PU of position A 1 , B 1 , B 0 , A 0 is not available (e.g. because it belongs to another slice or tile) or is intra coded.
  • candidate at position A 1 is added, the addition of the remaining candidates is subject to a redundancy check which ensures that candidates with same motion information are excluded from the list so that coding efficiency is improved.
  • a redundancy check To reduce computational complexity, not all possible candidate pairs are considered in the mentioned redundancy check. Instead only the pairs linked with an arrow in FIG.
  • FIGS. 10A-10B depict the second PU for the case of N ⁇ 2N and 2N ⁇ N, respectively.
  • candidate at position A1 is not considered for list construction. In fact, by adding this candidate will lead to two prediction units having the same motion information, which is redundant to just have one PU in a coding unit.
  • position B 1 is not considered when the current PU is partitioned as 2N ⁇ N.
  • a scaled motion vector is derived based on co-located PU belonging to the picture which has the smallest POC difference with current picture within the given reference picture list.
  • the reference picture list to be used for derivation of the co-located PU is explicitly signalled in the slice header.
  • the scaled motion vector for temporal merge candidate is obtained as illustrated by the dotted line in 13, which is scaled from the motion vector of the co-located PU using the POC distances, tb and rd, where tb is defined to be the POC difference between the reference picture of the current picture and the current picture and td is defined to be the POC difference between the reference picture of the co-located picture and the co-located picture.
  • the reference picture index of temporal merge candidate is set equal to zero.
  • a practical realization of the scaling process is described in the HEVC specification. For a B-slice, two motion vectors, one is for reference picture list 0 and the other is for reference picture list 1, are obtained and combined to make the bi-predictive merge candidate.
  • FIG. 11 is an illustration of motion vector scaling for temporal merge candidate.
  • the position for the temporal candidate is selected between candidates C 0 and C 1 , as depicted in FIG. 12. If PU at position C 0 is not available, is intra coded, or is outside of the current CTU, position C 1 is used. Otherwise, position C 0 is used in the derivation of the temporal merge candidate.
  • merge candidates there are two additional types of merge candidates: combined bi-predictive merge candidate and zero merge candidate.
  • Combined bi-predictive merge candidates are generated by utilizing spatio-temporal merge candidates.
  • Combined bi-predictive merge candidate is used for B-Slice only.
  • the combined bi-predictive candidates are generated by combining the first reference picture list motion parameters of an initial candidate with the second reference picture list motion parameters of another. If these two tuples provide different motion hypotheses, they will form a new bi-predictive candidate. As an example, FIG.
  • Zero motion candidates are inserted to fill the remaining entries in the merge candidates list and therefore hit the MaxNumMergeCand capacity. These candidates have zero spatial displacement and a reference picture index which starts from zero and increases every time a new zero motion candidate is added to the list. The number of reference frames used by these candidates is one and two for uni and bi-directional prediction, respectively. Finally, no redundancy check is performed on these candidates.
  • HEVC defines the motion estimation region (MER) whose size is signalled in the picture parameter set using the “log2_parallel_merge_level_minus2” syntax element. When a MER is defined, merge candidates falling in the same region are marked as unavailable and therefore not considered in the list construction.
  • log2_parallel_merge_level_minus2 plus 2 specifies the value of the variable Log2ParMrgLevel, which is used in the derivation process for luma motion vectors for merge mode as specified in clause 8.5.3.2.2 and the derivation process for spatial merging candidates as specified in clause 8.5.3.2.3.
  • the value of log2_parallel_merge_level_minus2 shall be in the range of 0 to CtbLog2SizeY-2, inclusive.
  • Log2ParMrgLevel is derived as follows:
  • Log2ParMrgLevel log2_parallel_merge_level_minus2 + 2
  • Log2ParMrgLevel indicates the built-in capability of parallel derivation of the merging candidate lists. For example, when Log2ParMrgLevel is equal to 6, the merging candidate lists for all the prediction units (PUs) and coding units (CUs) contained in a 64x64 block can be derived in parallel.
  • PUs prediction units
  • CUs coding units
  • Motion vector prediction exploits spatio-temporal correlation of motion vector with neighbouring PUs, which is used for explicit transmission of motion parameters. It constructs a motion vector candidate list by firstly checking availability of left, above temporally neighbouring PU positions, removing redundant candidates and adding zero vector to make the candidate list to be constant length. Then, the encoder can select the best predictor from the candidate list and transmit the corresponding index indicating the chosen candidate. Similarly with merge index signalling, the index of the best motion vector candidate is encoded using truncated unary. The maximum value to be encoded in this case is 2 (see FIG. 14) . In the following sections, details about derivation process of motion vector prediction candidate are provided.
  • FIG. 14 summarizes derivation process for motion vector prediction candidate.
  • motion vector candidate two types are considered: spatial motion vector candidate and temporal motion vector candidate.
  • spatial motion vector candidate derivation two motion vector candidates are eventually derived based on motion vectors of each PU located in five different positions as depicted in FIG. 8.
  • one motion vector candidate is selected from two candidates, which are derived based on two different co-located positions. After the first list of spatio-temporal candidates is made, duplicated motion vector candidates in the list are removed. If the number of potential candidates is larger than two, motion vector candidates whose reference picture index within the associated reference picture list is larger than 1 are removed from the list. If the number of spatio-temporal motion vector candidates is smaller than two, additional zero motion vector candidates is added to the list.
  • a maximum of two candidates are considered among five potential candidates, which are derived from PUs located in positions as depicted in FIG. 8, those positions being the same as those of motion merge.
  • the order of derivation for the left side of the current PU is defined as A 0 , A 1 , and scaled A 0 , scaled A 1 .
  • the order of derivation for the above side of the current PU is defined as B 0 , B 1 , B 2 , scaled B 0 , scaled B 1 , scaled B 2 .
  • the no-spatial-scaling cases are checked first followed by the spatial scaling. Spatial scaling is considered when the POC is different between the reference picture of the neighbouring PU and that of the current PU regardless of reference picture list. If all PUs of left candidates are not available or are intra coded, scaling for the above motion vector is allowed to help parallel derivation of left and above MV candidates. Otherwise, spatial scaling is not allowed for the above motion vector.
  • the motion vector of the neighbouring PU is scaled in a similar manner as for temporal scaling, as depicted as FIG. 15.
  • the main difference is that the reference picture list and index of current PU is given as input; the actual scaling process is the same as that of temporal scaling.
  • AMVP mode For the AMVP mode, four parts may be signalled in the bitstream, i.e., prediction direction, reference index, MVD and mv predictor candidate index (highlighted in the syntax table below) . While for the merge mode, only a merge index may need to be signalled.
  • five_minus_max_num_merge_cand specifies the maximum number of merging MVP candidates supported in the slice subtracted from 5.
  • the maximum number of merging MVP candidates, MaxNumMergeCand is derived as follows:
  • MaxNumMergeCand 5-five_minus_max_num_merge_cand (2-1)
  • MaxNumMergeCand shall be in the range of 1 to 5, inclusive.
  • merge_flag [x0] [y0] specifies whether the inter prediction parameters for the current prediction unit are inferred from a neighbouring inter-predicted partition.
  • the array indices x0, y0 specify the location (x0, y0) of the top-left luma sample of the considered prediction block relative to the top-left luma sample of the picture.
  • merge_flag [x0] [y0] is inferred to be equal to 0.
  • merge_idx [x0] [y0] specifies the merging candidate index of the merging candidate list where x0, y0 specify the location (x0, y0) of the top-left luma sample of the considered prediction block relative to the top-left luma sample of the picture.
  • VVC the translational motion and affine motion are handled in different ways.
  • the enhanced AMVP and Merge design are employed.
  • HMVP history-based motion vector prediction
  • LUT-based motion vector prediction techniques using one or more tables (e.g., look up tables) with at least one motion candidate stored to predict motion information of a block can be implemented in various embodiments to provide video coding with higher coding efficiencies.
  • a look up table is an example of a table which can be used to include motion candidates to predict motion information of a block and other implementations are also possible.
  • Each LUT can include one or more motion candidates, each associated with corresponding motion information.
  • Motion information of a motion candidate can include partial or all of the prediction direction, reference indices/pictures, motion vectors, LIC flags, affine flags, Motion Vector Derivation (MVD) precisions, and/or MVD values.
  • Motion information may further include block position information to indicate from which the motion information is coming.
  • the LUT-based motion vector prediction based on the disclosed technology which may enhance both existing and future video coding standards, is elucidated in the following examples described for various implementations. Because the LUTs allow the encoding/decoding process to be performed based on historical data (e.g., the blocks that have been processed) , the LUT-based motion vector prediction can also be referred to as History-based Motion Vector Prediction (HMVP) method. In the LUT-based motion vector prediction method, one or multiple tables with motion information from previously coded blocks are maintained during the encoding/decoding process. These motion candidates stored in the LUTs are named HMVP candidates.
  • HMVP candidates are named HMVP candidates.
  • the associated motion information in LUTs may be added to the motion candidate lists (e.g., merge/AMVP candidate lists) , and after encoding/decoding one block, LUTs may be updated.
  • the updated LUTs are then used to code the subsequent blocks. That is, the updating of motion candidates in the LUTs are based on the encoding/decoding order of blocks.
  • HMVP the previously coded motion information is stored.
  • the motion information of a previously coded block is defined as an HMVP candidate.
  • Multiple HMVP candidates are stored in a table, named as the HMVP table, and this table is maintained during the encoding/decoding process on-the-fly.
  • the HMVP table is emptied when starting coding/decoding a new tile/LCU row/a slice.
  • non-TPM non-triangular prediction mode
  • Step 1 Derivation of temporal merge candidates (TMVP, temporal motion vector prediction)
  • HMVP candidates could be used in both AMVP and merge candidate list construction processes.
  • FIG. 17 depicts the modified merge candidate list construction process (highlighted in blue) .
  • HMVP candidates stored in the HMVP table could be utilized to fill in the merge candidate list.
  • the HMVP candidates in the table are inserted in a descending order of indices. The last entry in the table is firstly added to the list, while the first entry is added in the end. Similarly, redundancy removal is applied on the HMVP candidates. Once the total number of available merge candidates reaches the maximal number of merge candidates allowed to be signaled, the merge candidate list construction process is terminated.
  • HMVP table contains up to 5 motion candidates and each of them is unique.
  • a candidate is only added to the list if the corresponding candidate used for redundancy check has not the same motion information.
  • Such comparison process is called pruning process.
  • the pruning process among the spatial candidates is dependent on the usage of TPM for current block.
  • the HEVC pruning process i.e., five pruning for the spatial merge candidates is utilized.
  • the HMVP table is updated. Motion information of current block may be firstly pruned to all available HMVP candidates in the HMVP table.
  • a counter is assigned to the HMVP table which records number of available HMVP candidates in the table. It is initialized to be 0 if a HMVP table is reset.
  • the first case and last two cases are further depicted in the FIGS. 18A-18B and FIGS. 19A-19B, respectively.
  • FIG. 18A shows the case when redundant candidate found, and the LUT is full before adding a new motion candidate.
  • FIG. 18B shows the case when redundant candidate found, and the LUT is not full before adding a new motion candidate.
  • FIGS. 18A-18B show redundancy-removal based HMVP updating method (with one redundancy motion candidate removed) .
  • FIG. 19A Redundant candidate NOT found, and the LUT is full before adding a new motion candidate
  • FIG. 19B Redundant candidate NOT found, and the LUT is NOT full before adding a new motion candidate.
  • the MVP candidate hMvpCand consists of the luma motion vectors mvL0 and mvL1, the reference indices refldxL0 and refldxL1, the prediction list utilization flags predFlagL0 and predFlagL1, the bi-prediction weight index bcwldx, and the half sample interpolation filter index hpellfldx.
  • the candidate list HmvpCandList is modified using the candidate hMvpCand by the following ordered steps:
  • variable identicalCandExist is set equal to FALSE and the variable removeldx is set equal to 0.
  • the candidate list HmvpCandList is updated as follows:
  • HmvpCandList [i -1] is set equal to HmvpCandList [i] .
  • HmvpCandList [NumHmvpCand -1] is set equal to hMvpCand.
  • HmvpCandList [NumHmvpCand++] is set equal to hMvpCand.
  • HMVP is introduced to the AMVP list without pruning.
  • the AMVP and Merge list is shared, that is, the same construction process is utilized.
  • HMVP candidates in the IBC HMVP table and zero block vectors (BVs) are added to the candidate list.
  • two spatial IBC candidates, HMVP candidates, and zero BVs are added in order with partial pruning.
  • the IBC HMVP table is updated accordingly, in a similar way for the updating process of HMVP table used for inter mode.
  • the candidate list HmvplbcCandList is modified by the following ordered steps:
  • variable identicalCandExist is set equal to FALSE and the variable removeldx is set equal to 0.
  • the candidate list HmvplbcCandList is updated as follows:
  • HmvplbcCandList [i -1] is set equal to HmvplbcCandList [i] .
  • HmvplbcCandList [NumHmvplbcCand -1] is set equal to bvL.
  • HmvplbcCandList [NumHmvplbcCand ++] is set equal to bvL.
  • AVS2 Similar to HEVC, AVS2 also adopts the concept of CU, PU and TU-based coding/prediction/transform structure.
  • LCUs largest coding units
  • One LCU can be a single CU or can be split into four smaller CUs with a quad-tree partition structure; a CU can be recursively split until it reaches the smallest CU size limit, as shown in FIG. 20.
  • the leaf node CUs can be further split into PUs.
  • PU is the basic unit for intra-and inter prediction and allows multiple different shapes to encoder irregular image patterns, as shown in FIG. 20.
  • a P frame is a forward-predicted frame using a single reference picture
  • a B frame is a bipredicted frame that consists of forward, backward, bi-prediction, and symmetric prediction, using two reference frames.
  • symmetric prediction is defined as a special bi-prediction mode, wherein only one forward motion vector (MV) is coded and the backward MV is derived from the forward MV based on the picture-order-counter (POC) distances.
  • the symmetry mode could efficiently represent the linear motion model of an object.
  • the SKIP mode s motion information of the current block is derived from previously decoded blocks and no residual information is encoded. Similar to SKIP mode, DIRECT mode has no motion information to transmit while prediction residuals and mode information are transmitted.
  • a priority-based motion information derivation method is designed which takes block’s motion model (prediction direction) into consideration. A higher priority is assigned to the motion information of neighbor blocks with the same motion model as current block.
  • the motion information derivation process can be divided into three steps performed in order.
  • Motion model-matched search As shown in FIG. 21, an initial process of finding neighbor blocks with the same motion model as current block at positions F, G, C, A, B, D is conducted in that order. Once the first block sharing the same motion model with current block is found, the motion information of that block is assigned to current block.
  • N fw For bi-direction DIRECT/SKIP mode, count how many spatial neighbors are coded with forward-direction, denoted by N fw and how many spatial neighbors are coded with backward-direction, denoted by N bw . If N fw and N bw are both equal to or larger than 1, the combination of the first forward and the first backward prediction blocks’ motion information is assigned to current block.
  • the searching order is the same as the 1st step, i.e., from positions F, G, C, A, B, and D.
  • N bi - count how many spatial neighbors are coded with bi-direction
  • the motion information of neighbor bi-direction predicted blocks’ motion information of the last block in scanning order of F, G, C, A, B and D (which is equal to the first block in the scanning order of D, B, A, C, G and F) is assigned to current block.
  • N bi if N bi is smaller than 2) if N bw is equal to or larger than 1 wherein N bw denotes how many spatial neighbors are coded with backward-direction, the backward motion vector (denoted by MvE1) of the first backward prediction blocks’ motion information is assigned to current block and the forward motion vector MvE0 is set equal to Clip3 (-32768, 32767, -MvE1) .
  • the searching order is the same as the 1st step, i.e., from positions F, G, C, A, B, and D.
  • N fw denotes how many spatial neighbors are coded with forward-direction
  • the forward motion vector (denoted by MvE0) of the first forward prediction blocks’ motion information is assigned to current block and the backward motion vector MvE1 is set equal to Clip3 (-32768, 32767, -MvE0) .
  • the searching order is the same as the 1st step, i.e., from positions F, G, C, A, B, and D.
  • N bi For backward DIRECT/SKIP mode, count how many spatial neighbors are coded with bi-direction, denoted by N bi . the backward motion information of the last neighbor bi-direction predicted block is assigned to current block.
  • the searching order is the same as the 1st step, i.e., from positions F, G, C, A, B, and D.
  • N bi For forward DIRECT/SKIP mode, count how many spatial neighbors are coded with bi-direction, denoted by N bi . the forward motion information of the last neighbor bi-direction predicted block is assigned to current block.
  • the searching order is the same as the 1st step, i.e., from positions F, G, C, A, B, and D.
  • step 3 Default MVs construction: this step is invoked only when both step 1) and step 2) fail to find available motion vectors.
  • step 3 Default MVs construction:
  • the backward motion vector is set to be a zero MV, i.e., (0, 0)
  • the forward motion vector is set to be a zero MV, i.e., (0, 0) .
  • the HMVP candidate index in a merge/amvp list is dynamically changed due to pruning among spatial/temporal candidates, in AVS3, the HMVP candidates are fixed to be from the index equal to 4 to 11 for B slices, and 2 to 9 for P slices.
  • the updating process is same as that in VVC.
  • the HMVP table is a table to store candidates wherein a candidate is not limited to a motion candidate (e.g., with the prediction direction, reference indices/pictures, motion vectors, LIC flag, affine flag, MVD precision, MVD values, block position information, block vectors (BVs) for IBC coded blocks) , it could also be a intra mode candidate or others.
  • a motion candidate e.g., with the prediction direction, reference indices/pictures, motion vectors, LIC flag, affine flag, MVD precision, MVD values, block position information, block vectors (BVs) for IBC coded blocks
  • BVs block vectors
  • HMVP table size is denoted by L, and each of candidate in the table is associated with an index, in the range of [0, L-1] .
  • HMVP table updating processing instead of removing the firstly (the earliest) added candidate (e.g. maybe with candidate index set to 0) in a HMVP table, it is proposed to remove the K-th entry in the HMVP table (i.e., the HMVP candidate with index equal to K) wherein K is a non-zero integer value.
  • K is pre-defined, e.g., it is set to 1.
  • K is dependent on the HMVP table size, i.e., maximum number of candidates to be stored in the HMVP table.
  • K is dependent on how the HMVP table is utilized.
  • K when updating the HMVP tables used for inter-coded blocks, K may be set to K0, and when updating the HMVP tables used for IBC-coded blocks, K may be set to K1 wherein K0 is unequal to K1.
  • K when updating the HMVP tables used for intra-coded blocks, K may be set equal to K2.
  • K2 maybe unequal to K1 or/and K0.
  • K is dependent on the coded information, such as block dimension, block position, how many times the table has been updated, the parity of times the table has been updated.
  • K may be signaled in a bitstream, such as in sequence/video/picture/slice/tile/subpicture/brick/other video processing unit-level.
  • K may be signaled in SPS/PPS/Picture header/slice header/VPS/DPS.
  • a variable may be further assigned, such as, to indicate the frequency of the candidate.
  • K may be adaptively changed on-the-fly.
  • K may be set to a first value for a first video region and set to a second value for a second video region, wherein the first and second values are different.
  • the first or the second value may be equal to 0.
  • the above method may be applied under certain conditions.
  • HMVP table when updating a HMVP table with a new candidate, if the table is full, and there is no redundant candidate in the HMVP table (i.e., a candidate in the HMVP table is identical to or similar to the new candidate) , then the K-th entry in the HMVP table is removed.
  • a redundant candidate in the HMVP table i.e., a candidate in the HMVP table is identical to or similar to the new candidate
  • the redundant one is associated with index equal to 0
  • How to update an HMVP table with a new candidate may depend on where the redundant (or similar) candidate is in the table (e.g., the index of the redundant candidate) .
  • the redundant candidate may be firstly modified and stored in the HMVP table.
  • the motion vectors/BVs associated with the redundant candidate may be modified by adding one or multiple offsets or being scaled.
  • the modified redundant candidate may be associated with the same index, i.e., N.
  • K is smaller or equal to T, wherein T is the number of candidates already in the table.
  • How to add a new candidate may depend on the index of the redundant HMVP candidate in the HMVP table.
  • K is pre-defined, e.g., 1.
  • K is dependent on the HMVP table size, i.e., maximum number of candidates to be stored in the HMVP table.
  • K is dependent on how the HMVP table is utilized.
  • K when updating the HMVP tables used for inter-coded blocks, K may be set to K0, and when updating the HMVP tables used for IBC-coded blocks, K may be set to K1 wherein K0 is unequal to K1.
  • K when updating the HMVP tables used for intra-coded blocks, K may be set equal to K2.
  • K2 maybe unequal to K1 or/and K0.
  • K is dependent on the coded information, such as block dimension, block position, how many times the table has been updated, the parity of times the table has been updated.
  • K may be signaled in a bitstream, such as in sequence/video/picture/slice/tile/subpicture/brick/other video processing unit-level.
  • K may be signaled in SPS/PPS/Picture header/slice header/VPS/DPS.
  • a variable may be further assigned, such as, to indicate the frequency of the candidate.
  • K may be adaptively changed on-the-fly.
  • K may be set to a first value for a first video region and set to a second value for a second video region, wherein the first and second values are different.
  • the first or the second value may be equal to 0.
  • K may be dependent on the pruning results, e.g., whether there is one identical or similar one in the HMVP table before being updated.
  • HMVP tables may be changed from one video processing unit to another video processing unit.
  • a for a first rule, pruning is applied, and for a second rule, non-pruning is applied.
  • partial pruning is applied (i.e., compare the new candidate to be added with partial of existing ones in the table)
  • full pruning is applied (i.e., compare the new candidate to be added with all of existing ones in the table) .
  • HMVP table it may depend on how the HMVP table is going to be used, e.g., for blocks with which prediction mode the HMVP table is utilized.
  • the coded information may include the coded mode information.
  • the above method or the existing method may be applied, and when updating the HMVP tables used for IBC-coded blocks, the FIFO rule may be applied.
  • the coded information may include the coded mode information.
  • the above method when updating the HMVP tables used for inter-coded blocks, the above method may be applied, and when updating the HMVP tables used for IBC-coded blocks, the existing method may be applied.
  • the HMVP table updating process is modified for the case when the table is full, and no redundant candidate is found among the existing candidates in the HMVP table.
  • FIG. 22A shows the case of: Redundant candidate found, and the LUT is full before adding a new motion candidate.
  • FIG. 22B shows the case of: Redundant candidate found, and the LUT is not full before adding a new motion candidate.
  • FIG. 22C shows the case of: Redundant candidate NOT found, and the LUT is full before adding a new motion candidate.
  • FIG. 22D shows the case of: Redundant candidate NOT found, and the LUT is NOT full before adding a new motion candidate.
  • pls refer to FIG. 23E.
  • pls refer to FIG. 23C.
  • pls refer to FIG. 23D.
  • FIG. 23A shows the case of: Redundant candidate (with index unequal to 0) found, and the LUT is full before adding a new motion candidate.
  • FIG. 23B shows the case of: Redundant candidate (with index unequal to 0) found, and the LUT is not full before adding a new motion candidate.
  • FIG. 23C shows the case of: Redundant candidate (with index equal to 0) found, and the LUT is full before adding a new motion candidate.
  • FIG. 23D shows the case of: Redundant candidate (with index equal to 0) found, and the LUT is not full before adding a new motion candidate.
  • FIG. 23E shows the case of: Redundant candidate NOT found, and the LUT is full before adding a new motion candidate.
  • FIG. 23F shows the case of: Redundant candidate NOT found, and the LUT is NOT full before adding a new motion candidate.
  • the deleted text is marked with and the newly added is highlighted.
  • the candidate list HmvplbcCandList is modified by the following ordered steps:
  • variable identicalCandExist is set equal to FALSE and the variable removeldx is set equal to 0.
  • the candidate list HmvplbcCandList is updated as follows:
  • HmvplbcCandList [i - 1] is set equal to HmvplbcCandList [i] .
  • HmvplbcCandList [NumHmvplbcCand - 1] is set equal to bvL.
  • HmvplbcCandList [NumHmvplbcCand ++] is set equal to bvL.
  • the MVP candidate hMvpCand consists of the luma motion vectors mvL0 and mvL1, the reference indices refIdxL0 and refIdxL1, the prediction list utilization flags predFlagL0 and predFlagL1, the bi-prediction weight index bcwIdx, and the half sample interpolation filter index hpelIfIdx.
  • the candidate list HmvpCandList is modified using the candidate hMvpCand by the following ordered steps:
  • variable identicalCandExist is set equal to FALSE and the variable removeIdx is set equal to 0.
  • the candidate list HmvpCandList is updated as follows:
  • HmvpCandList [i-1] is set equal to HmvpCandList [i] .
  • HmvpCandList [NumHmvpCand -1] is set equal to hMvpCand.
  • HmvpCandList [NumHmvpCand++] is set equal to hMvpCand.
  • FIG. 24 is a block diagram showing an example video processing system 1900 in which various techniques disclosed herein may be implemented.
  • the system 1900 may include input 1902 for receiving video content.
  • the video content may be received in a raw or uncompressed format, e.g., 8 or 10 bit multi-component pixel values, or may be in a compressed or encoded format.
  • the input 1902 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interface include wired interfaces such as Ethernet, passive optical network (PON) , etc. and wireless interfaces such as Wi-Fi or cellular interfaces.
  • PON passive optical network
  • the system 1900 may include a coding component 1904 that may implement the various coding or encoding methods described in the present document.
  • the coding component 1904 may reduce the average bitrate of video from the input 1902 to the output of the coding component 1904 to produce a coded representation of the video.
  • the coding techniques are therefore sometimes called video compression or video transcoding techniques.
  • the output of the coding component 1904 may be either stored, or transmitted via a communication connected, as represented by the component 1906.
  • the stored or communicated bitstream (or coded) representation of the video received at the input 1902 may be used by the component 1908 for generating pixel values or displayable video that is sent to a display interface 1910.
  • the process of generating user-viewable video from the bitstream representation is sometimes called video decompression.
  • certain video processing operations are referred to as “coding” operations or tools, it will be appreciated that the coding tools or operations are used at an encoder and corresponding decoding tools or operations that reverse the results of the coding will be performed by
  • peripheral bus interface or a display interface may include universal serial bus (USB) or high definition multimedia interface (HDMI) or Displayport, and so on.
  • storage interfaces include SATA (serial advanced technology attachment) , PCI, IDE interface, and the like.
  • FIG. 25 is a block diagram of a video processing apparatus 3600.
  • the apparatus 3600 may be used to implement one or more of the methods described herein.
  • the apparatus 3600 may be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on.
  • the apparatus 3600 may include one or more processors 3602, one or more memories 3604 and video processing hardware 3606.
  • the processor (s) 3602 may be configured to implement one or more methods described in the present document.
  • the memory (memories) 3604 may be used for storing data and code used for implementing the methods and techniques described herein.
  • the video processing hardware 3606 may be used to implement, in hardware circuitry, some techniques described in the present document.
  • a method of video processing (e.g., method 2600 depicted in FIG. 26) , comprising: performing (2602) a conversion between a video block of a video and a bitstream representation of the video; and selectively updating (2604) a table of motion candidates used for another video block by removing a Kth entry of the table, wherein K is a positive integer based on a rule.
  • the rule specifies conditions under which the updating is done and conditions under which the updating is not performed (e.g., when there is no new candidate to be added) .
  • a method of video processing comprising: performing a conversion between a video block of a video and a bitstream representation of the video; and updating, selectively based on a rule, a table of motion candidates used for another video block by adding a new candidate by removing an existing candidate in the table, wherein the rule depends on a characteristic of the existing candidate.
  • a method of video processing comprising: performing a conversion between a video block of a video and a bitstream representation of the video; and updating, selectively based on a rule, a table of motion candidates used for another video block by adding a new candidate based on the conversion at a Kth position from 0th position in the table, wherein K is dependent on a rule.
  • a method of video processing comprising: performing a conversion between a video block of a video processing unit of a video and a bitstream representation of the video; and updating, selectively based on a rule, a table of motion candidates used for another video block, wherein the rule depends on the video processing unit.
  • a video decoding apparatus comprising a processor configured to implement a method recited in one or more of solutions 1 to 18.
  • a video encoding apparatus comprising a processor configured to implement a method recited in one or more of solutions 1 to 18.
  • a computer program product having computer code stored thereon, the code, when executed by a processor, causes the processor to implement a method recited in any of solutions 1 to 18.
  • FIG. 27 shows a flowchart of an example method for video processing.
  • the method includes maintaining (2702) a history-based motion vector prediction (HMVP) table which comprises at least one motion candidate; performing (2704) a conversion between a current video block of a video and a bitstream representation of the video; and updating (2706) the table by removing a Kth entry in the table and adding a motion candidate into the HMVP table, wherein K is a positive integer and is determined based on a predetermined rule and the motion candidate added into the HMVP table is derived from motion information derived during the conversion.
  • HMVP history-based motion vector prediction
  • the performing a conversion is at least in part based on the HMVP table.
  • the predetermined rule specifies that K is pre-defined.
  • K is set to 1.
  • the predetermined rule specifies that K is dependent on a size of the HMVP table.
  • the predetermined rule specifies that K is dependent on one or more characteristics of the conversion of the video blocks.
  • K when the HMVP table is used for inter-coded blocks, K is set to K0, and when the HMVP table is used for IBC-coded blocks, K is set to K1, wherein K0 is unequal to K1.
  • K is set equal to K2, wherein K2 is unequal to K1 or/and K0.
  • the predetermined rule specifies that K is dependent on at least one of coded information associated with the current video block, how many times the table has been updated and the parity of times that the table has been updated, wherein the coded information including at least one of block dimension and block position.
  • K is signaled in a bitstream in at least one of sequence level, video level, picture level, slice level, tile level, subpicture level, brick level or other video processing unit level.
  • a variable is assigned to indicate a frequency of the candidate associated with the entry, wherein the predetermined rule specifies that K is determined according to the variable.
  • the predetermined rule specifies that K is adaptively changed on-the-fly.
  • K is set to a first value for a first video region and set to a second value for a second video region, wherein the first and second values are different.
  • the first value or the second value is equal to 0.
  • the updating is applied under certain conditions.
  • the K-th entry in the table is removed, wherein the redundant candidate is identical to or similar to the new candidate.
  • the K-th entry in the table is removed, wherein the redundant candidate is identical to or similar to the new candidate.
  • FIG. 28 shows a flowchart of an example method for video processing.
  • the method includes maintaining (2802) a history-based motion vector prediction (HMVP) table which comprises at least one motion candidate; performing (2804) a conversion between a current video block of a video and a bitstream representation of the video; and updating (2806) the table with a motion candidate based on position of a redundant candidate in the HMVP table, wherein the motion candidate is derived from motion information derived during the conversion and the redundant candidate is identical to or similar to the motion candidate.
  • HMVP history-based motion vector prediction
  • the performing a conversion is at least in part based on the HMVP table.
  • the redundant candidate is associated with an index equal to N in the HMVP table, the redundant candidate is firstly modified and stored in the table, N being an integer.
  • N 0 or L-1, wherein L is a size of the HMVP table.
  • motion vectors or block vectors associated with the redundant candidate are modified by adding one or multiple offsets or being scaled.
  • the modified redundant candidate in the updated HMVP table, is associated with the same index N.
  • FIG. 29 shows a flowchart of an example method for video processing.
  • the method includes maintaining (2902) a history-based motion vector prediction (HMVP) table which comprises at least one motion candidate; performing (2904) a conversion between a current video block of a video and a bitstream representation of the video; and updating (2906) the table by adding a motion candidate to a Kth entry in the HMVP table, wherein the motion candidate added into the HMVP table is derived from motion information derived during the conversion and K is a positive integer and is determined based on a predetermined rule.
  • HMVP history-based motion vector prediction
  • the performing a conversion is at least in part based on the HMVP table.
  • the predetermined rule specifies that K is smaller or equal to T, wherein T is the number of candidates already in the HMVP table.
  • how to add the motion candidate depends on an index of a redundant candidate in the HVMP table, wherein the redundant candidate is identical to or similar to the motion candidate.
  • the predetermined rule specifies that K is pre-defined.
  • K is set to 1.
  • the motion candidate is added as a candidate with index set to (L-2) , wherein L is a size of the HMVP table.
  • the predetermined rule specifies that K is dependent on a size of the HMVP table.
  • the predetermined rule specifies that K is dependent on one or more characteristics of the conversion of the video blocks.
  • K when the HMVP table is used for inter-coded blocks, K is set to K0, and when the HMVP table is used for IBC-coded blocks, K is set to K1, wherein K0 is unequal to K1.
  • K is set equal to K2, wherein K2 is unequal to K1 or/and K0.
  • the predetermined rule specifies that K is dependent on at least one of coded information associated with the current video block, how many times the table has been updated and the parity of times that the table has been updated, wherein the coded information including at least one of block dimension and block position.
  • K is signaled in a bitstream in at least one of sequence level, video level, picture level, slice level, tile level, subpicture level, brick level or other video processing unit level.
  • a variable is assigned to indicate a frequency of the candidate associated with the entry, wherein the predetermined rule specifies that K is determined according to the variable.
  • the predetermined rule specifies that K is adaptively changed on-the-fly.
  • K is set to a first value for a first video region and set to a second value for a second video region, wherein the first and second values are different.
  • the first value or the second value is equal to 0.
  • the predetermined rule specifies that K is dependent on pruning results indicating whether there is one identical or similar candidate in the HMVP table before being updated.
  • FIG. 30 shows a flowchart of an example method for video processing.
  • the method includes maintaining (3002) a history-based motion vector prediction (HMVP) table which comprises at least one motion candidate; performing (3004) a conversion between a current video block of a video and a bitstream representation of the video; and updating (3006) the HMVP table based on one or more rules associated with the video processing units, wherein the rules change from one video processing unit to another video processing unit.
  • HMVP history-based motion vector prediction
  • the performing a conversion is at least in part based on the HMVP table.
  • pruning is applied, and for a second rule, non-pruning is applied.
  • partial pruning is applied, and for a second rule, full pruning is applied.
  • the rules are determined dependent on one or more characteristics of the conversion of the video processing unit.
  • the one or more characteristics include a prediction mode of the processing unit.
  • the rules are determined based on coded mode information of the video processing unit.
  • the rules change from one video processing unit to another video processing unit or the rules specify adaptive order according to pruning results.
  • the rules are FIFO rule.
  • the updating is dependent of coded information associated with the video blocks.
  • the coded information includes coded mode information.
  • the conversion generates the video blocks of video from the bitstream representation.
  • the conversion generates the bitstream representation from the video blocks of video.
  • video processing may refer to video encoding, video decoding, video compression or video decompression.
  • video compression algorithms may be applied during conversion from pixel representation of a video to a corresponding bitstream representation or vice versa.
  • the bitstream representation of a current video block may, for example, correspond to bits that are either co-located or spread in different places within the bitstream, as is defined by the syntax.
  • a macroblock may be encoded in terms of transformed and coded error residual values and also using bits in headers and other fields in the bitstream.
  • the disclosed and other solutions, examples, embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them.
  • the disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus.
  • the computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them.
  • data processing apparatus encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers.
  • the apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.
  • a propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.
  • a computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.
  • a computer program does not necessarily correspond to a file in a file system.
  • 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 the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code) .
  • a computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
  • the processes and logic flows described in this document can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output.
  • the processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit) .
  • processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer.
  • a processor will receive instructions and data from a read only memory or a random-access memory or both.
  • the essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data.
  • a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
  • mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
  • a computer need not have such devices.
  • Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks.
  • semiconductor memory devices e.g., EPROM, EEPROM, and flash memory devices
  • magnetic disks e.g., internal hard disks or removable disks
  • magneto optical disks e.g., CD ROM and DVD-ROM disks.
  • the processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

Est décrite ici la mise à jour de tables de prédiction de vecteur de mouvement basée sur l'historique. Le procédé de traitement vidéo donné à titre d'exemple consiste à tenir à jour une table de prédiction de vecteur de mouvement basée sur l'historique (HMVP) qui comprend au moins un candidat de mouvement ; à mettre en oeuvre une conversion entre un bloc vidéo actuel d'une vidéo et une représentation de trains de bits de la vidéo ; et à mettre à jour la table en retirant une Kième entrée de la table et en ajoutant un candidat de mouvement dans la table HMVP, K étant un nombre entier positif et étant déterminé sur la base d'une règle prédéfinie, et le candidat de mouvement ajouté à la table HMVP étant dérivé d'informations de mouvement dérivées pendant la conversion.
PCT/CN2020/134287 2019-12-06 2020-12-07 Mise à jour de tables hmvp WO2021110170A1 (fr)

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