WO2021013119A1 - Détermination de mode pour codage en mode palette - Google Patents

Détermination de mode pour codage en mode palette Download PDF

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Publication number
WO2021013119A1
WO2021013119A1 PCT/CN2020/102968 CN2020102968W WO2021013119A1 WO 2021013119 A1 WO2021013119 A1 WO 2021013119A1 CN 2020102968 W CN2020102968 W CN 2020102968W WO 2021013119 A1 WO2021013119 A1 WO 2021013119A1
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Prior art keywords
block
mode
palette
video
coded
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PCT/CN2020/102968
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English (en)
Inventor
Weijia Zhu
Li Zhang
Jizheng Xu
Kai Zhang
Hongbin Liu
Yue Wang
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Beijing Bytedance Network Technology Co., Ltd.
Bytedance Inc.
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Application filed by Beijing Bytedance Network Technology Co., Ltd., Bytedance Inc. filed Critical Beijing Bytedance Network Technology Co., Ltd.
Priority to CN202311388776.0A priority Critical patent/CN117221536A/zh
Priority to CN202080052803.5A priority patent/CN114145013B/zh
Publication of WO2021013119A1 publication Critical patent/WO2021013119A1/fr
Priority to US17/580,314 priority patent/US11677935B2/en
Priority to US18/334,120 priority patent/US20230328234A1/en

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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
    • H04N19/102—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
    • H04N19/124—Quantisation
    • 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
    • H04N19/11—Selection of coding mode or of prediction mode among a plurality of spatial predictive coding modes
    • 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
    • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards
    • 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
    • H04N19/129—Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO]

Definitions

  • This document is related to video and image coding technologies.
  • 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 disclosed techniques may be used by video or image decoder or encoder embodiments for in which palette mode coding is used.
  • a method of video processing includes performing a conversion between a block of a video region of a video and a bitstream representation of the video.
  • the bitstream representation is processed according to a first format rule that specifies whether a first indication of usage of a palette mode is signaled for the block and a second format rule that specifies a position of the first indication relative to a second indication of usage of a prediction mode for the block.
  • a method of video processing includes determining, for a conversion between a block of a video region in a video and a bitstream representation of the video, a prediction mode based on one or more allowed prediction modes that include at least a palette mode of the block. An indication of usage of the palette mode is determined according to the prediction mode. The method also includes performing the conversion based on the one or more allowed prediction modes.
  • a method of video processing includes performing a conversion between a block of a video and a bitstream representation of the video.
  • the bitstream representation is processed according to a format rule that specifies a first indication of usage of a palette mode and a second indication of usage of an intra block copy (IBC) mode are signaled dependent of each other.
  • IBC intra block copy
  • a method of video processing includes determining, for a conversion between a block of a video and a bitstream representation of the video, a presence of an indication of usage of a palette mode in the bitstream representation based on a dimension of the block; and performing the conversion based on the determining.
  • a method of video processing includes determining, for a conversion between a block of a video and a bitstream representation of the video, a presence of an indication of usage of an intra block copy (IBC) mode in the bitstream representation based on a dimension of the block; and performing the conversion based on the determining.
  • IBC intra block copy
  • a method of video processing includes determining, for a conversion between a block of a video and a bitstream representation of the video, whether a palette mode is allowed for the block based on a second indication of a video region containing the block; and performing the conversion based on the determining.
  • a method of video processing includes determining, for a conversion between a block of a video and a bitstream representation of the video, whether an intra block copy (IBC) mode is allowed for the block based on a second indication of a video region containing the block; and performing the conversion based on the determining.
  • IBC intra block copy
  • a method of video processing includes determining, for a conversion between a block of a video and a bitstream representation of the video, a first bit depth of a first sample associated with a palette entry in a palette mode. The first bit depth is different from a second bit depth associated with the block. The method also includes performing the conversion based on the determining.
  • a method of video processing includes determining, for a conversion between a current block of a video and a bitstream representation of the video, that a neighboring block of the current block that is coded in a palette mode is processed as an intra-coded block having a default mode during a construction of a list of most probable modes (MPM) candidates of the current block in case the neighboring block is located above or left of the current block.
  • the method also includes performing the conversion based on the determining.
  • a method of video processing includes determining, for a block of a video that is coded in a bitstream representation of the video as a palette mode coded block, a parameter for deblocking filtering according to a rule. The method also includes performing a conversion between the block and the bitstream representation of the video using the parameter for deblocking filtering.
  • a method of video processing includes determining, for a conversion between a current block of a video and a bitstream representation of the video, that a neighboring block of the current block that is coded in a palette mode is processed as a non-intra coded block during a construction of a list of most probable modes (MPM) candidates of the current block.
  • the method also includes performing the conversion based on the determining.
  • a method of video processing includes determining, for a block of a video, a quantization parameter associated with the block, coding the block of the video into a bitstream representation of the video as a palette coded block in part based on a modified value of the quantization parameter, and signaling coded information related to the quantization parameter in the bitstream representation.
  • a method of video processing includes deriving a quantization parameter based on a bitstream representation of a video and decoding a palette coded block in part based on a modified quantization parameter determined by modifying the quantization parameter.
  • a method of video processing includes determining, for a block of a video that is coded in a bitstream representation of the video as a palette coded block, a representation of an escape sample of the block in the bitstream representation regardless of whether a bypass mode is enabled for the block.
  • the method also includes performing a conversion between the block and the bitstream representation based on the determining.
  • a method of video processing includes determining, for a block of a video that is coded in a bitstream representation of the video as a palette coded block, a first quantization process.
  • the first quantization process is different from a second quantization process applicable to a non-palette mode coded block.
  • the method also includes performing a conversion between the block and the bitstream representation based on the determining.
  • a method of video processing includes determining that palette mode is to be used for processing a transform unit, a coding block, or a region, usage of palette mode being coded separately from a prediction mode, and performing further processing of the transform unit, the coding block, or the region using the palette mode.
  • a method of video processing includes determining, for a current video block, that a sample associated with one palette entry of a palette mode has a first bit depth that is different from a second bit depth associated with the current video block, and performing, based on at least the one palette entry, further processing of the current video block.
  • another method of video processing includes performing a conversion between a current video block of a picture of a video and a bitstream representation of the video in which information about whether or not an intra block copy mode is used in the conversion is signaled in the bitstream representation or derived based on a coding condition of the current video block; wherein the intra block copy mode comprises coding the current video block from another video block in the picture.
  • another method of video processing includes determining whether or not a deblocking filter is to be applied during a conversion of a current video block of a picture of video, wherein the current video block is coded using a palette mode coding in which the current video block is represented using representative sample values that are fewer than total pixels of the current video block and performing the conversion such that the deblocking filter is applied in case the determining is that the deblocking filter is to be applied.
  • another method of video processing includes determining a quantization or an inverse quantization process for use during a conversion between a current video block of a picture of a video and a bitstream representation of the video, wherein the current video block is coded using a palette mode coding in which the current video block is represented using representative sample values that are fewer than total pixels of the current video block and performing the conversion based on the determining the quantization or the inverse quantization process.
  • another method of video processing includes determining, for a conversion between a current video block of a video comprising multiple video blocks and a bitstream representation of the video, that the current video block is a palette-coded block; based on the determining, performing a list construction process of most probable mode by considering the current video block to be an intra coded block, and performing the conversion based on a result of the list construction process; wherein the palette-coded block is coded or decoded using a palette or representation sample values.
  • another method of video processing includes determining, for a conversion between a current video block of a video comprising multiple video blocks and a bitstream representation of the video, that the current video block is a palette-coded block; based on the determining, performing a list construction process of most probable mode by considering the current video block to be a non-intra coded block, and performing the conversion based on a result of the list construction process; wherein the palette-coded block is coded or decoded using a palette or representation sample values.
  • another method of video processing includes determining, for a conversion between a current video block of a video comprising multiple video blocks and a bitstream representation of the video, that the current video block is a palette-coded block; based on the determining, performing a list construction process by considering the current video block to be an unavailable block, and performing the conversion based on a result of the list construction process; wherein the palette-coded block is coded or decoded using a palette or representation sample values.
  • another method of video processing includes determining, during a conversion between a current video block and a bitstream representation of the current video block, that the current video block is a palette coded block, determining, based on the current video block being the palette coded block, a range of context coded bins used for the conversion; and performing the conversion based on the range of context coded bins.
  • the above-described method may be implemented by a video encoder apparatus that comprises a processor.
  • these methods may be embodied in the form of processor-executable instructions and stored on a computer-readable program medium.
  • FIG. 1 shows an example of intra block copy.
  • FIG. 2 shows an example of a block coded in palette mode.
  • FIG. 3 shows an example of use of a palette predictor to signal palette entries.
  • FIG. 4 shows an example of horizontal and vertical traverse scans.
  • FIG. 5 shows an example of coding of palette indices.
  • FIG. 6 is a block diagram of an example of a video processing apparatus.
  • FIG. 7 shows a block diagram of an example implementation of a video encoder.
  • FIG. 8 is a flowchart for an example of a video processing method.
  • FIG. 9 shows an example of pixels involved in filter on/off decision and strong/weak filter selection.
  • FIG. 10 shows an example of binarization of four modes.
  • FIG. 11 shows an example of binarization of four modes.
  • FIG. 12 shows examples of 67 intra mode prediction directions.
  • FIG. 13 shows examples of neighboring video blocks.
  • FIG. 14 shows examples of ALF filter shapes (chroma: 5 ⁇ 5 diamond, luma: 7 ⁇ 7 diamond) .
  • FIG. 15 (a) shows an examples of subsampled Laplacian calculation for vertical gradient.
  • FIG. 15 (b) shows an examples of subsampled Laplacian calculation for horizontal gradient.
  • FIG. 15 (c) shows an examples of subsampled Laplacian calculation for diagonal gradient.
  • FIG. 15 (d) shows an examples of subsampled Laplacian calculation for diagonal gradient.
  • FIG. 16 shows an examples of modified block classification at virtual boundaries.
  • FIG. 17 shows an examples of modified ALF filtering for luma component at virtual boundaries.
  • FIG. 18 shows an example of four 1-D 3-pixel patterns for the pixel classification in EO.
  • FIG. 19 shows an example of four bands are grouped together and represented by its starting band position.
  • FIG. 20 shows an example of top and left neighboring blocks used in CIIP weight derivation.
  • FIG. 21 shows an example of luma mapping with chroma scaling architecture.
  • FIG. 22 shows an example of scanning order for a 4x4 block.
  • FIG. 23 shows another example of scanning order for a 4x4 block.
  • FIG. 24 is a block diagram showing an example video processing system 2400 in which various techniques disclosed herein may be implemented.
  • FIG. 25 is a flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 26 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 27 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 28 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 29 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 30 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 31 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 32 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 33 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 34 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 35 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 36A is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 36B is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 37 is another flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 38 is yet another flowchart representation of another method for video processing in accordance with the present technology.
  • the present document provides various techniques that can be used by a decoder of image or video bitstreams to improve the quality of decompressed or decoded digital video or images.
  • video is used herein to include both a sequence of pictures (traditionally called video) and individual images.
  • a video encoder may also implement these techniques during the process of encoding in order to reconstruct decoded frames used for further encoding.
  • Section headings are used in the present document for ease of understanding and do not limit the embodiments and techniques to the corresponding sections. As such, embodiments from one section can be combined with embodiments from other sections.
  • This document is related to video coding technologies. Specifically, it is related to palette coding with employing base colors based representation in video coding. It may be applied to the existing video coding standard like HEVC, or the standard (Versatile Video Coding) 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.
  • Joint Video Exploration Team JVET was founded by VCEG and MPEG jointly in 2015.
  • JVET Joint Exploration Model
  • Fig. 7 is a block diagram of an example implementation of a video encoder.
  • Fig 7 shows that the encoder implementation has a feedback path built in in which the video encoder also performs video decoding functionality (reconstructing compressed representation of video data for use in encoding of next video data) .
  • Intra block copy (IBC) , a.k.a. current picture referencing, has been adopted in HEVC Screen Content Coding extensions (HEVC-SCC) and the current VVC test model (VTM-4.0) .
  • IBC extends the concept of motion compensation from inter-frame coding to intra-frame coding. As demonstrated in FIG. 1, the current block is predicted by a reference block in the same picture when IBC is applied. The samples in the reference block must have been already reconstructed before the current block is coded or decoded.
  • IBC is not so efficient for most camera-captured sequences, it shows significant coding gains for screen content. The reason is that there are lots of repeating patterns, such as icons and text characters in a screen content picture.
  • an inter-coded coding unit can apply IBC if it chooses the current picture as its reference picture.
  • the MV is renamed as block vector (BV) in this case, and a BV always has an integer-pixel precision.
  • BV block vector
  • the current picture is marked as a “long-term” reference picture in the Decoded Picture Buffer (DPB) .
  • DPB Decoded Picture Buffer
  • the prediction can be generated by copying the reference block.
  • the residual can be got by subtracting the reference pixels from the original signals.
  • transform and quantization can be applied as in other coding modes.
  • the luma motion vector mvLX shall obey the following constraints:
  • the whole reference block should be with the current coding tree unit (CTU) and does not overlap with the current block. Thus, there is no need to pad the reference or prediction block.
  • the IBC flag is coded as a prediction mode of the current CU. Thus, there are totally three prediction modes, MODE_INTRA, MODE_INTER and MODE_IBC for each CU.
  • IBC merge mode an index pointing to an entry in the IBC merge candidates list is parsed from the bitstream.
  • the construction of the IBC merge list can be summarized according to the following sequence of steps:
  • Step 1 Derivation of spatial candidates
  • Position B2 is considered only when any Prediction Unit (PU) of position A1, B1, B0, A0 is not available (e.g. because it belongs to another slice or tile) or is not coded with IBC mode.
  • PU Prediction Unit
  • not all possible candidate pairs are considered in the mentioned redundancy check. Instead only the pairs linked with an arrow in depicted in the figures are considered and a candidate is only added to the list if the corresponding candidate used for redundancy check has not the same motion information.
  • IBC candidates from HMVP table may be inserted. Redundancy check are performed when inserting the HMVP candidates.
  • pairwise average candidates are inserted into the IBC merge list.
  • the merge candidate When a reference block identified by a merge candidate is outside of the picture, or overlaps with the current block, or outside of the reconstructed area, or outside of the valid area restricted by some constrains, the merge candidate is called invalid merge candidate.
  • invalid merge candidates may be inserted into the IBC merge list.
  • IBC AMVP mode an AMVP index point to an entry in the IBC AMVP list is parsed from the bitstream.
  • the construction of the IBC AMVP list can be summarized according to the following sequence of steps:
  • Step 1 Derivation of spatial candidates
  • IBC candidates from HMVP table may be inserted.
  • palette mode The basic idea behind a palette mode is that the samples in the CU are represented by a small set of representative color values. This set is referred to as the palette. It is also possible to indicate a sample that is outside the palette by signaling an escape symbol followed by (possibly quantized) component values. This is illustrated in FIG. 2.
  • a palette predictor For coding of the palette entries, a palette predictor is maintained. The maximum size of the palette as well as the palette predictor is signaled in the Sequence Parameter Set (SPS) .
  • SPS Sequence Parameter Set
  • a palette_predictor_initializer_present_flag is introduced in the PPS. When this flag is 1, entries for initializing the palette predictor are signaled in the bitstream.
  • the palette predictor is initialized at the beginning of each CTU row, each slice and each tile.
  • the palette predictor is reset to 0 or initialized using the palette predictor intializer entries signaled in the PPS.
  • a palette predictor initializer of size 0 was enabled to allow explicit disabling of the palette predictor initialization at the PPS level.
  • a reuse flag is signaled to indicate whether it is part of the current palette. This is illustrated in FIG. 3.
  • the reuse flags are sent using run-length coding of zeros. After this, the number of new palette entries are signaled using exponential Golomb code of order 0. Finally, the component values for the new palette entries are signaled.
  • the palette indices are coded using horizontal and vertical traverse scans as shown in FIG. 4.
  • the scan order is explicitly signaled in the bitstream using the palette_transpose_flag. For the rest of the subsection it is assumed that the scan is horizontal.
  • the palette indices are coded using two main palette sample modes: 'INDEX' and 'COPY_ABOVE' .
  • the escape symbol is also signaled as an 'INDEX' mode and assigned an index equal to the maximum palette size.
  • the mode is signaled using a flag except for the top row or when the previous mode was 'COPY_ABOVE' .
  • the palette index of the sample in the row above is copied.
  • the palette index is explicitly signaled.
  • a run value is signaled which specifies the number of subsequent samples that are also coded using the same mode.
  • escape component values are signaled for each escape symbol.
  • the coding of palette indices is illustrated in FIG. 5.
  • This syntax order is accomplished as follows. First the number of index values for the CU is signaled. This is followed by signaling of the actual index values for the entire CU using truncated binary coding. Both the number of indices as well as the the index values are coded in bypass mode. This groups the index-related bypass bins together. Then the palette sample mode (if necessary) and run are signaled in an interleaved manner. Finally, the component escape values corresponding to the escape samples for the entire CU are grouped together and coded in bypass mode.
  • last_run_type_flag An additional syntax element, last_run_type_flag, is signaled after signaling the index values. This syntax element, in conjunction with the number of indices, eliminates the need to signal the run value corresponding to the last run in the block.
  • each palette entry consists of 3 components.
  • the chroma samples are associated with luma sample indices that are divisible by 2. After reconstructing the palette indices for the CU, if a sample has only a single component associated with it, only the first component of the palette entry is used. The only difference in signaling is for the escape component values. For each escape sample, the number of escape component values signaled may be different depending on the number of components associated with that sample.
  • the dual tree coding structure is used on coding the intra slices, so the luma component and two chroma components may have different palette and palette indices.
  • the two chroma component shares same palette and palette indices.
  • pN M denotes the left-side N-th sample in the M-th row relative to the vertical edge or the top-side N-th sample in the M-th column relative to the horizontal edge
  • qN M denotes the right-side N-th sample in the M-th row relative to the vertical edge or the bottom-side N-th sample in the M-th column relative to the horizontal edge.
  • An example of pN M and qN M is depicted in FIG. 9.
  • p N denotes the left-side N-th sample in a row relative to the vertical edge or the top-side N-th sample in a column relative to the horizontal edge
  • q N denotes the right-side N-th sample in a row relative to the vertical edge or the bottom-side N-th sample in a column relative to the horizontal edge.
  • Filter on/off decision is done for four lines as a unit.
  • FIG. 9 illustrates the pixels involving in filter on/off decision.
  • the 6 pixels in the two red boxes for the first four lines are used to determine filter on/off for 4 lines.
  • the 6 pixels in two red boxes for the second 4 lines are used to determine filter on/off for the second four lines.
  • the vertical edges in a picture are filtered first. Then the horizontal edges in a picture are filtered with samples modified by the vertical edge filtering process as input.
  • the vertical and horizontal edges in the CTBs of each CTU are processed separately on a coding unit basis.
  • the vertical edges of the coding blocks in a coding unit are filtered starting with the edge on the left-hand side of the coding blocks proceeding through the edges towards the right-hand side of the coding blocks in their geometrical order.
  • the horizontal edges of the coding blocks in a coding unit are filtered starting with the edge on the top of the coding blocks proceeding through the edges towards the bottom of the coding blocks in their geometrical order.
  • Filtering is applied to 8x8 block boundaries. In addition, it must be a transform block boundary or a coding subblock boundary (e.g., due to usage of Affine motion prediction, ATMVP) . For those which are not such boundaries, filter is disabled.
  • bS [xD i ] [yD j ] is set equal to 1.
  • the coding subblock containing the sample p 0 and the coding subblock containing the sample q 0 are both coded in IBC prediction mode, and the absolute difference between the horizontal or vertical component of the motion vectors used in the prediction of the two coding subblocks is greater than or equal to 4 in units of quarter luma samples.
  • One motion vector is used to predict the coding subblock containing the sample p 0 and one motion vector is used to predict the coding subblock containing the sample q 0 , and the absolute difference between the horizontal or vertical component of the motion vectors used is greater than or equal to 4 in units of quarter luma samples.
  • the absolute difference between the horizontal or vertical component of list 0 motion vectors used in the prediction of the two coding subblocks is greater than or equal to 4 in quarter luma samples, or the absolute difference between the horizontal or vertical component of the list 1 motion vectors used in the prediction of the two coding subblocks is greater than or equal to 4 in units of quarter luma samples.
  • the absolute difference between the horizontal or vertical component of list 0 motion vector used in the prediction of the coding subblock containing the sample p 0 and the list 1 motion vector used in the prediction of the coding subblock containing the sample q 0 is greater than or equal to 4 in units of quarter luma samples, or the absolute difference between the horizontal or vertical component of the list 1 motion vector used in the prediction of the coding subblock containing the sample p 0 and list 0 motion vector used in the prediction of the coding subblock containing the sample q 0 is greater than or equal to 4 in units of quarter luma samples.
  • variable bS [xD i ] [yD j ] is set equal to 0.
  • Table 2-1 and 2-2 summarize the BS calculation rules.
  • Wider-stronger luma filter is filters are used only if all of the Condition1, Condition2 and Condition 3 are TRUE.
  • the condition 1 is the “large block condition” . This condition detects whether the samples at P-side and Q-side belong to large blocks, which are represented by the variable bSidePisLargeBlk and bSideQisLargeBlk respectively.
  • the bSidePisLargeBlk and bSideQisLargeBlk are defined as follows.
  • condition 1 Based on bSidePisLargeBlk and bSideQisLargeBlk, the condition 1 is defined as follows.
  • Condition1 and Condition2 are valid, whether any of the blocks uses sub-blocks is further checked:
  • condition 3 the large block strong filter condition
  • dpq is derived as in HEVC.
  • StrongFilterCondition (dpq is less than ( ⁇ >> 2) , sp 3 + sq 3 is less than (3* ⁇ >> 5) , and Abs (p 0 -q 0 ) is less than (5*t C + 1) >> 1) ? TRUE: FALSE.
  • Bilinear filter is used when samples at either one side of a boundary belong to a large block.
  • the bilinear filter is listed below.
  • tcPD i and tcPD j term is a position dependent clipping described in Section 2.3.6 and g j , f i , Middle s, t , P s and Q s are given in Table 2-3:
  • the chroma strong filters are used on both sides of the block boundary.
  • the chroma filter is selected when both sides of the chroma edge are greater than or equal to 8 (chroma position) , and the following decision with three conditions are satisfied: the first one is for decision of boundary strength as well as large block.
  • the proposed filter can be applied when the block width or height which orthogonally crosses the block edge is equal to or larger than 8 in chroma sample domain.
  • the second and third one is basically the same as for HEVC luma deblocking decision, which are on/off decision and strong filter decision, respectively.
  • boundary strength (bS) is modified for chroma filtering as shown in Table 2-2.
  • the conditions in Table 2-2 are checked sequentially. If a condition is satisfied, then the remaining conditions with lower priorities are skipped.
  • Chroma deblocking is performed when bS is equal to 2, or bS is equal to 1 when a large block boundary is detected.
  • the second and third condition is basically the same as HEVC luma strong filter decision as follows.
  • d is then derived as in HEVC luma deblocking.
  • the second condition will be TRUE when d is less than ⁇ .
  • the proposed chroma filter performs deblocking on a 4x4 chroma sample grid.
  • the position dependent clipping tcPD is applied to the output samples of the luma filtering process involving strong and long filters that are modifying 7, 5 and 3 samples at the boundary. Assuming quantization error distribution, it is proposed to increase clipping value for samples which are expected to have higher quantization noise, thus expected to have higher deviation of the reconstructed sample value from the true sample value.
  • position dependent threshold table is selected from two tables (i.e., Tc7 and Tc3 tabulated below) that are provided to decoder as a side information:
  • Tc7 ⁇ 6, 5, 4, 3, 2, 1, 1 ⁇ ;
  • Tc3 ⁇ 6, 4, 2 ⁇ ;
  • position dependent threshold For the P or Q boundaries being filtered with a short symmetrical filter, position dependent threshold of lower magnitude is applied:
  • Tc3 ⁇ 3, 2, 1 ⁇ ;
  • filtered p’ i and q’ i sample values are clipped according to tcP and tcQ clipping values:
  • p’ i and q’ i are filtered sample values
  • p” i and q” j are output sample value after the clipping
  • tcP i tcP i are clipping thresholds that are derived from the VVC tc parameter and tcPD and tcQD.
  • the function Clip3 is a clipping function as it is specified in VVC.
  • the long filters is restricted to modify at most 5 samples on a side that uses sub-block deblocking (AFFINE or ATMVP or DMVR) as shown in the luma control for long filters. Additionally, the sub-block deblocking is adjusted such that that sub-block boundaries on an 8x8 grid that are close to a CU or an implicit TU boundary is restricted to modify at most two samples on each side.
  • AFFINE or ATMVP or DMVR sub-block deblocking
  • edge equal to 0 corresponds to CU boundary
  • edge equal to 2 or equal to orthogonalLength-2 corresponds to sub-block boundary 8 samples from a CU boundary etc.
  • implicit TU is true if implicit split of TU is used.
  • VTM5 the number of directional intra modes in VTM5 is extended from 33, as used in HEVC, to 65.
  • the new directional modes not in HEVC are depicted as red dotted arrows in FIG. 12, and the planar and DC modes remain the same.
  • These denser directional intra prediction modes apply for all block sizes and for both luma and chroma intra predictions.
  • VTM5 In VTM5, several conventional angular intra prediction modes are adaptively replaced with wide-angle intra prediction modes for the non-square blocks. Wide angle intra prediction is described in Section 3.3.1.2.
  • every intra-coded block has a square shape and the length of each of its side is a power of 2. Thus, no division operations are required to generate an intra-predictor using DC mode.
  • blocks can have a rectangular shape that necessitates the use of a division operation per block in the general case. To avoid division operations for DC prediction, only the longer side is used to compute the average for non-square blocks.
  • MPM most probable mode
  • a unified 6-MPM list is used for intra blocks irrespective of whether MRL and ISP coding tools are applied or not.
  • the MPM list is constructed based on intra modes of the left and above neighboring block. Suppose the mode of the left block is denoted as Left and the mode of the above block is denoted as Above, the unified MPM list is constructed as follows (The left and above blocks are shown in FIG. 13.
  • MPM list ⁇ ⁇ Planar, Left, Above, DC, Max -1, Max +1 ⁇
  • MPM list ⁇ ⁇ Planar, Left, Above, DC, Max -2, Max +2 ⁇
  • the first bin of the mpm index codeword is CABAC context coded. In total three contexts are used, corresponding to whether the current intra block is MRL enabled, ISP enabled, or a normal intra block.
  • TBC Truncated Binary Code
  • Chroma mode coding For chroma intra mode coding, a total of 8 intra modes are allowed for chroma intra mode coding. Those modes include five traditional intra modes and three cross-component linear model modes (CCLM, LM_A, and LM_L) . Chroma mode signalling and derivation process are shown in Table 2-4. Chroma mode coding directly depends on the intra prediction mode of the corresponding luma block. Since separate block partitioning structure for luma and chroma components is enabled in I slices, one chroma block may correspond to multiple luma blocks. Therefore, for Chroma DM mode, the intra prediction mode of the corresponding luma block covering the center position of the current chroma block is directly inherited.
  • QR-BDPCM quantized residual block differential pulse-code modulation
  • the prediction directions used in QR-BDPCM can be vertical and horizontal prediction modes.
  • the intra prediction is done on the entire block by sample copying in prediction direction (horizontal or vertical prediction) similar to intra prediction.
  • the residual is quantized and the delta between the quantized residual and its predictor (horizontal or vertical) quantized value is coded. This can be described by the following: For a block of size M (rows) ⁇ N (cols) , let r i, j , 0 ⁇ i ⁇ M-1, 0 ⁇ j ⁇ N-1 be the prediction residual after performing intra prediction horizontally (copying left neighbor pixel value across the the predicted block line by line) or vertically (copying top neighbor line to each line in the predicted block) using unfiltered samples from above or left block boundary samples.
  • the residual quantized samples are sent to the decoder.
  • the inverse quantized residuals, Q -1 (Q (r i, j ) ) are added to the intra block prediction values to produce the reconstructed sample values.
  • the main benefit of this scheme is that the inverse DPCM can be done on the fly during coefficient parsing simply adding the predictor as the coefficients are parsed or it can be performed after parsing.
  • an Adaptive Loop Filter (ALF) with block-based filter adaption is applied.
  • ALF Adaptive Loop Filter
  • VTM5 two diamond filter shapes (as shown in FIG. 14) are used.
  • the 7 ⁇ 7 diamond shape is applied for luma component and the 5 ⁇ 5 diamond shape is applied for chroma components.
  • each 4 ⁇ 4 block is categorized into one out of 25 classes.
  • the classification index C is derived based on its directionality D and a quantized value of activity as follows:
  • indices i and j refer to the coordinates of the upper left sample within the 4 ⁇ 4 block and R (i, j) indicates a reconstructed sample at coordinate (i, j) .
  • the subsampled 1-D Laplacian calculation is applied. As shown in FIG. 15 (a) - (d) , the same subsampled positions are used for gradient calculation of all directions.
  • D maximum and minimum values of the gradients of horizontal and vertical directions are set as:
  • Step 1 If both and are true, D is set to 0.
  • Step 2 If continue from Step 3; otherwise continue from Step 4.
  • Step 3 If D is set to 2; otherwise D is set to 1.
  • the activity value A is calculated as:
  • A is further quantized to the range of 0 to 4, inclusively, and the quantized value is denoted as
  • no classification method is applied, i.e. a single set of ALF coefficients is applied for each chroma component.
  • K is the size of the filter and 0 ⁇ k, l ⁇ K-1 are coefficients coordinates, such that location (0, 0) is at the upper left corner and location (K-1, K-1) is at the lower right corner.
  • the transformations are applied to the filter coefficients f (k, l) and to the clipping values c (k, l) depending on gradient values calculated for that block. The relationship between the transformation and the four gradients of the four directions are summarized in the following table.
  • ALF filter parameters are signaled in Adaptation Parameter Set (APS) .
  • APS Adaptation Parameter Set
  • up to 25 sets of luma filter coefficients and clipping value indexes, and up to one set of chroma filter coefficients nd clipping value indexes could be signaled.
  • filter coefficients of different classification can be merged.
  • slice header the indices of the APSs used for the current slice are signaled.
  • Clipping value indexes which are decoded from the APS, allow determining clipping values using a Luma table of clipping values and a Chroma table of clipping values. These clipping values are dependent of the internal bitdepth. More precisely, the Luma table of clipping values and Chroma table of clipping values are obtained by the following formulas:
  • the filtering process can be controlled at CTB level.
  • a flag is always signaled to indicate whether ALF is applied to a luma CTB.
  • a luma CTB can choose a filter set among 16 fixed filter sets and the filter sets from APSs.
  • a filter set index is signaled for a luma CTB to indicate which filter set is applied.
  • the 16 fixed filter sets are pre-defined and hard-coded in both the encoder and the decoder.
  • the filter coefficients are quantized with norm equal to 128.
  • a bitstream conformance is applied so that the coefficient value of the non-central position shall be in the range of -2 7 to 2 7 -1, inclusive.
  • the central position coefficient is not signaled in the bitstream and is considered as equal to 128.
  • each sample R (i, j) within the CU is filtered, resulting in sample value R′ (i, j) as shown below,
  • R′ (i, j) R (i, j) + ( ( ⁇ k ⁇ 0 ⁇ l ⁇ 0 f (k, l) ⁇ K (R (i+k, j+l) -R (i, j) , c (k, l) ) +64) >> 7) (2-9-14)
  • K (x, y) is the clipping function
  • c (k, l) denotes the decoded clipping parameters.
  • the variable k and l varies between and where L denotes the filter length.
  • the clipping function K (x, y) min (y, max (-y, x) ) which corresponds to the function Clip3 (-y, y, x) .
  • VTM5 to reduce the line buffer requirement of ALF, modified block classification and filtering are employed for the samples near horizontal CTU boundaries.
  • a virtual boundary is defined as a line by shifting the horizontal CTU boundary with “N” samples as shown in FIG. 16, with N equal to 4 for the Luma component and 2 for the Chroma component.
  • Modified block classification is applied for the Luma component as depicted in FIG. 2-11.
  • For the 1D Laplacian gradient calculation of the 4x4 block above the virtual boundary only the samples above the virtual boundary are used.
  • For the 1D Laplacian gradient calculation of the 4x4 block below the virtual boundary only the samples below the virtual boundary are used.
  • the quantization of activity value A is accordingly scaled by taking into account the reduced number of samples used in 1D Laplacian gradient calculation.
  • symmetric padding operation at the virtual boundaries are used for both Luma and Chroma components. As shown in FIG. 17, when the sample being filtered is located below the virtual boundary, the neighboring samples that are located above the virtual boundary are padded. Meanwhile, the corresponding samples at the other sides are also padded, symmetrically.
  • Sample adaptive offset is applied to the reconstructed signal after the deblocking filter by using offsets specified for each CTB by the encoder.
  • the HM encoder first makes the decision on whether or not the SAO process is to be applied for current slice. If SAO is applied for the slice, each CTB is classified as one of five SAO types as shown in Table 2-6.
  • the concept of SAO is to classify pixels into categories and reduces the distortion by adding an offset to pixels of each category.
  • SAO operation includes Edge Offset (EO) which uses edge properties for pixel classification in SAO type 1-4 and Band Offset (BO) which uses pixel intensity for pixel classification in SAO type 5.
  • EO Edge Offset
  • BO Band Offset
  • Each applicable CTB has SAO parameters including sao_merge_left_flag, sao_merge_up_flag, SAO type and four offsets. If sao_merge_left_flag is equal to 1, the current CTB will reuse the SAO type and offsets of the CTB to the left. If sao_merge_up_flag is equal to 1, the current CTB will reuse SAO type and offsets of the CTB above.
  • Edge offset uses four 1-D 3-pixel patterns for classification of the current pixel p by consideration of edge directional information, as shown in FIG. 18. From left to right these are: 0-degree, 90-degree, 135-degree and 45-degree.
  • Each CTB is classified into one of five categories according to Table 2-7.
  • Band offset classifies all pixels in one CTB region into 32 uniform bands by using the five most significant bits of the pixel value as the band index.
  • the pixel intensity range is divided into 32 equal segments from zero to the maximum intensity value (e.g. 255 for 8-bit pixels) .
  • Four adjacent bands are grouped together and each group is indicated by its most left-hand position as shown in FIG. 19. The encoder searches all position to get the group with the maximum distortion reduction by compensating offset of each band.
  • VTM5 when a CU is coded in merge mode, if the CU contains at least 64 luma samples (that is, CU width times CU height is equal to or larger than 64) , and if both CU width and CU height are less than 128 luma samples, an additional flag is signaled to indicate if the combined inter/intra prediction (CIIP) mode is applied to the current CU.
  • the CIIP prediction combines an inter prediction signal with an intra prediction signal.
  • the inter prediction signal in the CIIP mode P inter is derived using the same inter prediction process applied to regular merge mode; and the intra prediction signal P intra is derived following the regular intra prediction process with the planar mode.
  • the intra and inter prediction signals are combined using weighted averaging, where the weight value is calculated depending on the coding modes of the top and left neighbouring blocks (depicted in FIG. 20) as follows:
  • the CIIP prediction is formed as follows:
  • LMCS luma mapping with chroma scaling
  • FIG. 21 shows the LMCS architecture from decoder’s perspective.
  • the light-blue shaded blocks in FIG. 21 indicate where the processing is applied in the mapped domain; and these include the inverse quantization, inverse transform, luma intra prediction and adding of the luma prediction together with the luma residual.
  • the light-yellow shaded blocks in FIG. 21 are the new LMCS functional blocks, including forward and inverse mapping of the luma signal and a luma-dependent chroma scaling process.
  • LMCS can be enabled/disabled at the sequence level using an SPS flag.
  • One palette flag is usually used to indicate whether the palette mode is employed on the current CU, which can have different limitations and variances on its entropy coding. However, how to better code the palette flag has not been fully studied in the previous video coding standards.
  • the palette samples may have visual artifact if they are processed by post loop filtering process.
  • the palette scanning order could be improved for non-square blocks.
  • Indication of usage of palette mode for a transform unit/prediction unit/coding block/region may be coded separately from the prediction mode.
  • the prediction mode may be coded before the indication of usage of palette.
  • the indication of usage of palette may be conditionally signaled based on the prediction mode.
  • the prediction mode is the intra block copy mode (i.e., MODE_IBC)
  • the signalling of the indication of usage of palette mode may be skipped.
  • the indication of usage of palette may be inferred to false when the current prediction mode is MODE_IBC.
  • the prediction mode is the inter mode (i.e., MODE_INTER)
  • the signalling of the indication of usage of palette mode may be skipped.
  • the indication of usage of palette mode may be inferred to false when the current prediction mode is MODE_INTER.
  • the prediction mode is the intra mode (i.e., MODE_INTRA)
  • the signalling of the indication of usage of palette mode may be skipped.
  • the indication of usage of palette mode may be inferred to false when the current prediction mode is MODE_INTRA.
  • the prediction mode is the skip mode (i.e., the skip flag equal to 1)
  • the signalling of the indication of usage of palette mode may be skipped.
  • the indication of usage of palette mode may be inferred to false when the skip mode is employed on the current CU.
  • the indication of usage of palette mode may be signaled.
  • the prediction mode is the intra mode (e.g., MODE_INTRA)
  • the indication of usage of palette mode may be signaled.
  • the prediction mode is the inter mode or intra block copy mode
  • the signalling of the indication of usage of palette mode may be skipped.
  • the indication of usage of palette mode may be signaled.
  • the indication of usage of palette mode may be signaled before the indication of usage of the PCM mode.
  • the signalling of usage of PCM mode may be skipped.
  • the prediction mode is the inter mode or intra block copy mode
  • the signalling of the indication of usage of palette mode may be skipped.
  • the prediction mode is the inter mode (e.g MODE_INTER)
  • the indication of usage of palette mode may be signaled.
  • the prediction mode is the intra mode
  • the signalling of the indication of usage of palette mode may be skipped.
  • the indication of usage of palette mode may be signaled.
  • the prediction mode is the inter mode or intra mode
  • the signalling of the indication of usage of palette mode may be skipped.
  • the indication of usage of palette mode may be conditionally signaled based on the picture/slice/tile group type.
  • the prediction mode may be coded after the indication of usage of palette mode.
  • indication of usage of palette mode may be signaled when the prediction mode is INTRA mode or INTER_MODE.
  • the indication of usage of palette mode may be coded after the skip flag, prediction mode and the flag of PCM mode.
  • the indication of usage of palette mode may be coded after the skip flag, prediction mode, before the flag of PCM mode
  • the indications of palette and IBC modes may be further signaled.
  • one bit flag may be signaled to indicate whether palette or IBC mode is signaled.
  • signalling of the bit flag may be skipped under certain conditions, such as block dimension, whether IBC or palette mode is enabled for one tile/tile group/slice/picture/sequence.
  • the prediction mode (such as whether it is intra or inter mode) may be coded firstly, followed by the conditional signalling of whether it is palette mode or not.
  • another flag may be further signaled to indicate whether it is palette mode or not.
  • the ‘another flag’ may be signaled when the palette mode is enabled for one video data unit (e.g., sequence/picture/tile group/tile) .
  • the ‘another flag’ may be signaled under the condition of block dimension.
  • one flag may be further signaled to indicate whether it is PCM mode or not.
  • the ‘another flag’ may be context coded according to information of neighboring blocks. Alternatively, the ‘another flag’ may be context coded with only one context. Alternatively, the ‘another flag’ may be bypass coded, i.e., without context.
  • the prediction mode is the inter mode
  • another flag may be further signaled to indicate whether it is IBC mode or not.
  • the ‘another flag’ may be signaled when the IBC mode is enabled for one video data unit (e.g., sequence/picture/tile group/tile) .
  • the ‘another flag’ may be signaled under the condition of block dimension
  • the prediction modes may include intra, intra block copy and palette modes for intra slices/I pictures/intra tile groups.
  • the prediction modes may include intra, palette modes for intra slices/I pictures/intra tile groups.
  • the prediction modes may include intra, intra block copy and palette modes for 4x4 blocks.
  • the prediction modes may include intra, inter, intra block copy and palette modes for inter slices/P and/or B pictures/inter tile groups.
  • the prediction modes may include intra, inter, intra block copy modes for inter slices/P and/or B pictures/inter tile groups.
  • the prediction modes may include at least two of intra, inter, intra block copy and palette mode.
  • the inter mode may be not included in the prediction modes for 4x4 blocks.
  • the prediction mode index may be signaled.
  • the binarization of the four modes is defined as: intra (1) , inter (00) , IBC (010) and Palette (011) .
  • the binarization of the four modes is defined as: intra (10) , inter (00) , IBC (01) and Palette (11) , as shown in FIG. 10.
  • the binarization of the Palette and intra modes is defined as: Palette (1) and intra (0) .
  • the binarization of the Palette, inter and intra modes is defined as: intra (1) , inter (00) , and Palette (01) .
  • the binarization of the Palette and intra modes is defined as: IBC (1) , Palette (01) , and intra (00) .
  • the binarization of the four modes is defined as: inter (1) , intra (01) , IBC (001) and Palette (000) .
  • the binarization of the four modes is defined as: intra (1) , inter (01) , IBC (001) and Palette (000) .
  • the binarization of the four modes is defined as: inter (0) , intra (10) , IBC (111) and Palette (110) , as shown in FIG. 11.
  • the signaling of the indication of usage of palette/IBC mode may depend on the information of other mode.
  • the indication of usage of palette mode may be signaled when the current prediction mode is an intra mode and not a IBC mode.
  • the indication of usage of IBC mode may be signaled when the current prediction mode is an intra mode and not a palette mode.
  • one flag may be signaled to indicate whether it is IBC mode. If it is not the IBC mode, another flag may be further signaled to indicate whether it is palette or intra mode.
  • one flag may be signaled to indicate whether it is intra mode. If it is not the intra mode, another flag may be further signaled to indicate whether it is palette or IBC mode.
  • the indication of usage of palette mode may be signaled and/or derived based on the following conditions.
  • the indication of usage of palette mode may be signaled only for blocks with width*height smaller than or equal to a threshold, such as 64*64.
  • the indication of usage of palette mode may be signaled only for blocks with both width and height larger than or equal to a threshold, such as 64
  • the indication of usage of palette mode may be signaled only for blocks with all below conditions are true:
  • width and/or height larger than or equal to a threshold, such as 16;
  • width and/or height smaller than or equal to a threshold, such as 32 or 64
  • the indication of usage of palette mode may be signaled only for blocks with width equal to height (i.e., square blocks)
  • the indication of usage of IBC mode may be signaled and/or derived based on the following conditions.
  • the indication of usage of IBC mode may be signaled only for blocks with both width or height smaller than 128
  • the palette mode may be treated as intra mode (e.g MODE_INTRA) in the deblocking decision process.
  • the boundary strength is set to 2.
  • the boundary strength is set to 2
  • the palette mode may be treated as inter mode (e.g MODE_INTER) in the deblocking decision process.
  • the palette mode may be treated as a separate mode (e.g MODE_PLT) in the deblocking decision process.
  • the boundary strength is set to 0.
  • the boundary strength is set to 0.
  • the boundary strength is set to 1, vice versa.
  • the boundary strength is set to 2, vice versa.
  • the palette mode may be treated as a transform-skip block in the deblocking process
  • the palette mode may be treated as a BDPCM block in the deblocking process.
  • the indication of usage of palette mode for a block may be signaled and/or derived based on the slice/tile group/picture level flag
  • the flag indicates whether fractional motion vector difference (MVD) is allowed in the merge with motion vector difference (MMVD, a.k.a., UMVE) and/or adaptive motion vector resolution (AMVR) mode, (e.g. slice_fracmmvd_flag) .
  • MMVD motion vector difference
  • AMVR adaptive motion vector resolution
  • slice_fracmmvd_flag adaptive motion vector resolution
  • the flag indicates whether palette mode is enabled for the slice/tile group/picture. Alternatively, furthermore, when such a flag indicates palette mode is disabled, the signaling of usage of palette mode for a block is skipped and palette mode is inferred to be disabled.
  • the indication of usage of intra block copy mode (IBC) for a block may be signaled and/or derived based on the slice/tile group/picture level flag.
  • the flag indicates whether fractional motion vector difference (MVD) is allowed in the merge with motion vector difference (MMVD, a.k.a., UMVE) and/or adaptive motion vector resolution (AMVR) mode, (e.g. slice_fracmmvd_flag) .
  • MMVD motion vector difference
  • AMVR adaptive motion vector resolution
  • slice_fracmmvd_flag adaptive motion vector resolution
  • the flag indicates whether IBC mode is enabled for the slice/tile group/picture. Alternatively, furthermore, when such a flag indicates IBC mode is disabled, the signaling of usage of IBC mode for a block is skipped and IBC mode is inferred to be disabled.
  • the sample associated with one palette entry may have different bit depths from the internal bit depth and/or the bit depth of original/reconstructed samples.
  • denote the sample associated with one may have the bit depth equal to N, the following may apply:
  • N may be a integer number (e.g. 8) .
  • N may be larger than the internal bit depth and/or the bit depth of original/reconstructed samples.
  • N may be smaller than the internal bit depth and/or the bit depth of original/reconstructed samples.
  • N may depend on
  • the sample associated with multiple palette entries may have different bit depths.
  • C0, C1 be two palette entries in the current palette, and they may have bit depth equal to b0 and b1, respectively.
  • b0 may be unequal to b1
  • b0 may be larger/smaller than the internal bit depth and/or the bit depth of original/reconstructed samples and/or b1 may be larger/smaller than the internal bit depth and/or the bit depth of original/reconstructed samples.
  • the samples may be reconstructed according to the shifted values of samples associated with palette entries.
  • the samples may be reconstructed by left shifting the samples in the palette entries by M bits.
  • the reconstructed value may be (C ⁇ M) + (1 ⁇ (M-1) ) , wherein C is the palette entry.
  • the samples may be reconstructed by right shifting the samples in the palette entries by M bits.
  • the reconstructed value may be clip ( (C+ (1 ⁇ (M-1) ) ) >>M, 0, (1 ⁇ N) -1) , wherein C is the palette entry and N is the bit-depth of reconstruction.
  • the M may depend on the bit depth difference between samples associated with palette entries and the internal bit depth of reconstructed samples/original samples.
  • M may be equal to the internal bit depth minus the bit depth of samples in the palette entries
  • M may be equal to the bit depth of samples in the palette entries minus the internal bit depth
  • M may be equal to the bit depth of the original samples minus the bit depth of samples in the palette entries
  • M may be equal to the bit depth of samples in the palette entries minus the bit depth of the original samples.
  • M may be equal to the bit depth of the reconstructed samples minus the bit depth of samples in the palette entries
  • M may be equal to the bit depth of samples in the palette entries minus the bit depth of the reconstructed samples
  • M may be an integer number (e.g. 2) .
  • the M may depend on
  • a look up operation based on the samples in the palette entries may be used during the sample’s reconstruction.
  • the values in the look up table may be signaled in the Sequence Parameter Set (SPS) /Video Parameter Set (VPS) /Picture Parameter Set (PPS) /picture header/slice header/tile group header/LCU row/group of LCUs.
  • SPS Sequence Parameter Set
  • VPS Video Parameter Set
  • PPS Picture Parameter Set
  • the values in the look up table may be inferred in the SPS/VPS/PPS/picture header/slice header/tile group header/LCU row/group of LCUs.
  • the signaled/derived quantization parameter (QP) for palette coded blocks may be firstly modified before being used to derive escape pixel/samples, such as being clipped.
  • the applied QP range for palette coded blocks may be treated in the same way as transform skip mode, and/or BDPCM mode.
  • the applied QP for palette coded blocks may be revised to be max (Qp, 4 + T) , where T is an integer value and Qp is the signaled or derived quantization parameter for the block.
  • T may be a predefined threshold.
  • T may be equal to (4 + min_qp_prime_ts_minus4) wherein min_qp_prime_ts_minus4 may be signaled.
  • escape sample may be signaled with fixed length.
  • an escape sample may be signaled in fixed length using N bits.
  • N may be an integer number (e.g. 8 or 10) and may depend on
  • the code length to signal an escape pixel/sample may depend on internal bit depth.
  • the code length to signal an escape pixel/sample may depend on input bit depth.
  • the code length to signal an escape pixel/sample may depend on the quantization parameter.
  • the code length for signalling an escape pixel/sample may be f (Qp)
  • the function f may be defined as (internal bitdepth - (Qp -4) /6) .
  • the quantization and/or inverse quantization process for palette coded blocks and non-palette coded blocks may be defined in different ways.
  • right bit-shifting may be used for quantizing escape sample instead of using the quantization process for transform coefficients or residuals.
  • left bit-shifting may be used for inverse quantizing escape sample instead of using the inverse quantization process for transform coefficients or residuals.
  • the escape pixel/sample value may be signaled as f (p, Qp) , where p is the pixel/sample value.
  • the function f may be defined as p>> ( (Qp-4) /6) , where p is the pixel/sample value and Qp is the quantization parameter.
  • the escape pixel/sample value may be signaled as p>>N, where p is the pixel/sample value.
  • N may be an integer number (e.g. 2) and may depend on
  • the escape pixel/sample value may be signaled as f (bd, p, Qp)
  • the function f may be defined as clip (0, (1 ⁇ (bd- (Qp-4) /6) ) -1, (p + (1 ⁇ (bd-1) ) ) >> ( (Qp-4) /6) ) .
  • the escape pixel/sample value may be reconstructed as f (p, Qp) , where p is the decoded escape pixel/sample value.
  • f may be defined as p ⁇ ( (Qp-4) /6)
  • the escape pixel/sample value may be reconstructed as f (bd, p, Qp) , where p is the decoded escape pixel/sample value.
  • the function clip may be defined as clip (0, (1 ⁇ bd) -1, p ⁇ ( (Qp-4) /6) )
  • the clip function clip (a, i, b) may be defined as (i ⁇ a ? a: (i > b? b: i) ) .
  • p may be the pixel/sample value
  • bd may be the internal bit depth or input bit depth
  • Qp is the quantization parameter
  • a palette-coded block may be treated as an intra block (e.g. MODE_INTRA) during the list construction process of most probable modes (MPM) .
  • a neighboring block e.g., left and/or above
  • conventional intra-coded block e.g. MODE_INTRA
  • the default mode may be DC/PLANAR/VER/HOR mode.
  • the default mode may be any one intra prediction mode.
  • the default mode may be signaled in the Dependency Parameter Set (DPS) /SPS/VPS/PPS/APS/picture header/slice header/tile group header/Largest coding unit (LCU) /Coding unit (CU) /LCU row/group of LCUs/TU/PU block/Video coding unit.
  • DPS Dependency Parameter Set
  • a palette-coded block may be treated as a non-intra block (e.g. treated as a block with prediction mode equal to MODE_PLT) during the list construction process of most probable modes (MPM) .
  • MPM most probable modes
  • a neighboring block e.g., left and/or above
  • it may be treated in the same way or a similar way as those coded with inter mode.
  • a neighboring block e.g., left and/or above
  • a neighboring block e.g., left and/or above
  • it may be treated in the same way or a similar way as those coded with IBC mode.
  • the luma block coded with palette mode corresponding to a chroma block coded with the DM mode may be interpreted as having a default intra prediction mode.
  • the corresponding luma block coded with palette mode may be treated as an intra block (e.g. MODE_INTRA) or a palette block (e.g. MODE_PLT) when a chroma block is coded with the DM mode.
  • an intra block e.g. MODE_INTRA
  • a palette block e.g. MODE_PLT
  • the default prediction mode may be DC/PLANAR/VER/HOR mode.
  • the default prediction mode may be any one intra prediction mode.
  • the default prediction mode may be signaled in the DPS/SPS/VPS/PPS/APS/picture header/slice header/tile group header/Largest coding unit (LCU) /Coding unit (CU) /LCU row/group of LCUs/TU/PU block/Video coding unit.
  • a palette-coded block may be treated as an unavailable block during the list construction of history-based motion vector prediction (HMVP) , the merge (MERGE) and/or the advanced motion vector prediction (AMVP) modes.
  • HMVP history-based motion vector prediction
  • MERGE merge
  • AMVP advanced motion vector prediction
  • an unavailable block may denote a block which does not have any motion information or its motion information could not be used as a prediction for other blocks.
  • a block coded with palette mode may be treated as an intra block (e.g. MODE_INTRA) or a palette block (e.g. MODE_PLT) in the process of list construction in HMVP, MERGE and/or AMVP modes.
  • an intra block e.g. MODE_INTRA
  • a palette block e.g. MODE_PLT
  • a neighboring block coded with palette mode may be treated as a block with an invalid reference index.
  • a neighboring block coded with palette mode may be treated as a inter block with a reference index equal to 0.
  • a neighboring block coded with palette mode may be treated as a inter block with a zero-motion vector.
  • Video contents e.g. screen contents or natural contents
  • g. Coding tree structure (such as dual tree or single tree)
  • Color component e.g. may be only applied on luma component and/or chroma component
  • Context coded bins for palette coded blocks may be restricted to be within a certain range.
  • a counter is assigned to a block to record how many bins have been context coded. When the counter exceeds a threshold, bypass coding is applied instead of using context coding.
  • NumColorComp counters may be assigned to record how many bins have been context coded for each color component.
  • NumColorComp is the number of color components to be coded in one block (e.g., for one CU in YUV format, NumColorComp is set to 3) .
  • a counter may be initialized to be zero, and after coding one bin with context, the counter is increased by one.
  • a counter may be initialized with some value greater than zero (e.g., W*H*K) and after coding one bin with context, the counter is decreased by one.
  • W*H*K some value greater than zero
  • bypass coding is applied instead of using context coding.
  • T is set to 0 or 1.
  • T is set according to decoded information or number of coding passes, etc. al.
  • the palette coded blocks may have a same or different threshold compared with TS coded blocks or non-TS coded blocks in terms of context coded bins.
  • number of context coded bins for a palette coded block may be set to (W*H*T) wherein W and H are the width and height of one block, respectively and T is an integer. In one example, T is set to be the same as that used for TS coded blocks, such as 1.75 or 2.
  • number of context coded bins for a palette coded block may be set to (W*H*NumColorComp*T) wherein W and H are the width and height of one block, respectively; NumColorComp is the number of color components to be coded in one block (e.g., for one CU in YUV format, NumColorComp is set to 3) . and T is an integer. In one example, T is set to be the same as that used for TS coded blocks, such as 1.75 or 2.
  • the threshold of palette-coded blocks may be smaller than TS coded blocks or non-TS coded blocks in terms of context coded bins.
  • the threshold of palette-coded blocks may be larger than TS coded blocks or non-TS coded blocks in terms of context coded bins.
  • a palette-coded block may be treated as a non-intra block (e.g. treated as a block with prediction mode equal to MODE_PLT) during the process of counting neighboring intra blocks in CIIP mode.
  • a non-intra block e.g. treated as a block with prediction mode equal to MODE_PLT
  • a neighboring block e.g., left and/or above
  • a neighboring block e.g., left and/or above
  • it may be treated in the same way or a similar way as those coded with inter mode.
  • a neighboring block e.g., left and/or above
  • palette mode when fetching the intra modes of neighboring blocks during counting neighboring intra blocks in CIIP mode, if a neighboring block (e.g., left and/or above) is coded with palette mode, it may be treated in the same way or a similar way as those coded with IBC mode.
  • a palette-coded block may be treated as an intra block during the process of counting neighboring intra blocks in CIIP mode.
  • the palette coded samples may be not deblocked.
  • the palette coded samples may be not compensated an offset in the SAO process.
  • the palette coded samples may be not filtered in the ALF process.
  • the classification in the ALF process may skip palette coded samples.
  • the LMCS may be disabled for palette coded samples.
  • reverse horizontal transverse scanning order defined as follows may be used.
  • the scanning direction for the odd rows may be from left to right.
  • the scanning direction for the even rows may be from right to left.
  • the scanning order for a 4x4 block may be as shown in Fig. 22.
  • reverse vertical transverse scanning order defined as follows may be used.
  • the scanning direction for the odd rows may be from top to bottom.
  • the scanning direction for the even rows may be from bottom to top.
  • the scanning order for a 4x4 block may be as shown in Fig. 23.
  • the combination of allowed scanning orders may depend on block shape.
  • a when the ratio between width and height of a block is larger than a threshold, only horizontal traverse and reverse horizontal traverse scanning orders may be applied.
  • the threshold is equal to 1.
  • the threshold is equal to 4.
  • the threshold is equal to 1.
  • the threshold is equal to 4.
  • the indication of direction of QR-BDPCM may be inferred for a non-square block.
  • the indication of direction of QR-BDPCM may be inferred to vertical direction for a block with width larger than height.
  • the indication of direction of QR-BDPCM may be inferred to horizontal direction for a block with width smaller than height.
  • Th is an integer number (e.g. 4 or 8) and may be based on
  • Video contents e.g. screen contents or natural contents
  • Coding tree structure (such as dual tree or single tree)
  • Color component e.g. may be only applied on luma component and/or chroma component
  • the newly added texts are bold italicized and the deleted texts are marked by “ [ [] ] ” .
  • This section shows an example embodiment in which the bitstream representation of video may be changed as compared to the baseline bitstream syntax.
  • sps_plt_enabled_flag 1 specifies that palette mode may be used in decoding of pictures in the CVS.
  • sps_plt_enabled_flag 0 specifies that palette mode is not used in the CVS.
  • sps_plt_enabled_flag not present, it is inferred to be equal to 0.
  • pred_mode_scc_flag 1 specifies that the current coding unit is coded by a screen contnet coding mode.
  • pred_mode_scc_flag 0 specifies that the current coding unit is not coded by a screen content coding mode When pred_mode_scc_flag is not present, it is inferred to be equal to 0.
  • pred_mode_plt_flag 1 specifies that the current coding unit is coded in the palette mode.
  • pred_mode_plt_flag 0 specifies that the current coding unit is not coded in the palette mode.
  • pred_mode_plt_flag When pred_mode_plt_flag is not present, it is inferred to be equal to the value of sps_plt_enabled_flag when decoding an I tile group, and 0 when decoding a P or B tile group, respectively.
  • pred_mode_scc_flag When pred_mode_scc_flag is equal to 1 and sps_ibc_enabled_flag is euqal to 0, the pred_mode_plt_flag is inferred to be equal to 1.
  • pred_mode_plt_flag 1 specifies that the current coding unit is coded in the palette mode.
  • pred_mode_plt_flag 0 specifies that the current coding unit is not coded in the palette mode.
  • pred_mode_plt_flag When pred_mode_plt_flag is not present, it is inferred to be equal to the value of sps_plt_enabled_flag when decoding an I tile group, and 0 when decoding a P or B tile group, respectively.
  • pred_mode_plt_flag 1 specifies that the current coding unit is coded in the palette mode.
  • pred_mode_plt_flag 0 specifies that the current coding unit is not coded in the palette mode.
  • pred_mode_plt_flag When pred_mode_plt_flag is not present, it is inferred to be equal to the value of sps_plt_enabled_flag when decoding an I tile group, and 0 when decoding a P or B tile group, respectively.
  • plt_mode_flag 1 specifies that the current coding unit is coded in palette mode.
  • intra_mode_plt_flag 0 specifies that the current coding unit is coded in the palette mode.
  • plt_mode_flag When plt_mode_flag is not present, it is inferred to be equal to false.
  • pred_mode_flag 0 specifies that the current coding unit is coded in inter prediction mode or IBC prediction mode.
  • pred_mode_flag 1 specifies that the current coding unit is coded in intra prediction mode or PLT mode.
  • pred_mode_flag When pred_mode_flag is not present, it is inferred to be equal to 1 when decoding an I tile group, and equal to 0 when decoding a P or B tile group, respectively.
  • Table 9-4 Syntax elements and associated binarization.
  • This embodiment decribes the modeType.
  • a variable modeType specifying whether Intra, IBC, Palette and Inter coding modes can be used (MODE_TYPE_ALL) , or whether only Intra, Palette and IBC coding modes can be used (MODE_TYPE_INTRA) , or whether only Inter coding modes can be used (MODE_TYPE_INTER) for coding units inside the coding tree node.
  • This embodiment decribes the coding unit syntax.
  • the pred_mode_plt_flag is signaled after the pred_mode_ibc_flag.
  • This embodiment decribes the coding unit syntax.
  • the pred_mode_plt_flag is signaled after the pred_mode_ibc_flag and the pred_mode_plt_flag is signaled only when the current prediction mode is MODE_INTRA.
  • This embodiment decribes the coding unit syntax.
  • the pred_mode_ibc_flag is signaled after the pred_mode_plt_flag.
  • This embodiment decribes the coding unit syntax.
  • the pred_mode_ibc_flag is signaled after the pred_mode_plt_flag and the pred_mode_plt_flag is signaled only when the current prediction mode is MODE_INTRA.
  • This embodiment decribes the coding unit syntax.
  • the pred_mode_plt_flag and pred_mode_ibc_flag are signaled when the prediction mode is MODE_INTRA.
  • This embodiment decribes the coding unit syntax.
  • the pred_mode_plt_flag and pred_mode_ibc_flag are signaled when the prediction mode is not MODE_INTRA.
  • This embodiment decribes the coding unit syntax.
  • the pred_mode_plt_flag and pred_mode_ibc_flag are signaled when the prediction mode is MODE_INTER.
  • This embodiment describes the semantic of the pred_mode_plt_flag.
  • pred_mode_plt_flag specifies the use of palette mode in the current coding unit.
  • pred_mode_plt_flag not present, it is inferred to be equal to 0.
  • This embodiment describes the semantic of the pred_mode_plt_flag.
  • pred_mode_plt_flag specifies the use of palette mode in the current coding unit.
  • pred_mode_plt_flag not present, it is inferred to be equal to 0.
  • This embodiment describes the boundary strength derivation.
  • nCbW specifying the width of the current coding block
  • nCbH specifying the height of the current coding block
  • variable edgeType specifying whether a vertical (EDGE_VER) or a horizontal (EDGE_HOR) edge is filtered
  • variable cIdx specifying the colour component of the current coding block
  • Output of this process is a two-dimensional (nCbW) x (nCbH) array bS specifying the boundary filtering strength.
  • bS [xD i ] [yD j ] is set equal to 2.
  • the block edge is also a transform block edge and the sample p 0 or q 0 is in a coding block with ciip_flag equal to 1, bS [xD i ] [yD j ] is set equal to 2.
  • bS [xD i ] [yD j ] is set equal to 1.
  • the block edge is also a transform block edge and the sample p 0 and q 0 are in two coding blocks with pred_mode_plt_flag equal to 1, bS [xD i ] [yD j ] is set equal to 0.
  • bS [xD i ] [yD j ] is set equal to 1:
  • the coding subblock containing the sample p 0 and the coding subblock containing the sample q 0 are both coded in IBC prediction mode, and the absolute difference between the horizontal or vertical component of the motion vectors used in the prediction of the two coding subblocks is greater than or equal to 4 in units of quarter luma samples.
  • One motion vector is used to predict the coding subblock containing the sample p 0 and one motion vector is used to predict the coding subblock containing the sample q 0 , and the absolute difference between the horizontal or vertical component of the motion vectors used is greater than or equal to 4 in units of quarter luma samples.
  • Two motion vectors and two different reference pictures are used to predict the coding subblock containing the sample p 0
  • two motion vectors for the same two reference pictures are used to predict the coding subblock containing the sample q 0
  • the absolute difference between the horizontal or vertical component of the two motion vectors used in the prediction of the two coding subblocks for the same reference picture is greater than or equal to 4 in units of quarter luma samples.
  • Two motion vectors for the same reference picture are used to predict the coding subblock containing the sample p 0
  • two motion vectors for the same reference picture are used to predict the coding subblock containing the sample q 0 and both of the following conditions are true:
  • the absolute difference between the horizontal or vertical component of list 0 motion vectors used in the prediction of the two coding subblocks is greater than or equal to 4 in quarter luma samples, or the absolute difference between the horizontal or vertical component of the list 1 motion vectors used in the prediction of the two coding subblocks is greater than or equal to 4 in units of quarter luma samples.
  • the absolute difference between the horizontal or vertical component of list 0 motion vector used in the prediction of the coding subblock containing the sample p 0 and the list 1 motion vector used in the prediction of the coding subblock containing the sample q 0 is greater than or equal to 4 in units of quarter luma samples, or the absolute difference between the horizontal or vertical component of the list 1 motion vector used in the prediction of the coding subblock containing the sample p 0 and list 0 motion vector used in the prediction of the coding subblock containing the sample q 0 is greater than or equal to 4 in units of quarter luma samples.
  • variable bS [xD i ] [yD j ] is set equal to 0.
  • This embodiment describes the boundary strength derivation
  • nCbW specifying the width of the current coding block
  • nCbH specifying the height of the current coding block
  • variable edgeType specifying whether a vertical (EDGE_VER) or a horizontal (EDGE_HOR) edge is filtered
  • variable cIdx specifying the colour component of the current coding block
  • Output of this process is a two-dimensional (nCbW) x (nCbH) array bS specifying the boundary filtering strength.
  • bS [xD i ] [yD j ] is set equal to 2.
  • the block edge is also a transform block edge and the sample p 0 or q 0 is in a coding block with ciip_flag equal to 1, bS [xD i ] [yD j ] is set equal to 2.
  • bS [xD i ] [yD j ] is set equal to 1.
  • the block edge is also a transform block edge and the sample p 0 or q 0 is in a coding blocks with pred_mode_plt_flag equal to 1, bS [xD i ] [yD j ] is set equal to 0.
  • the coding subblock containing the sample p 0 and the coding subblock containing the sample q 0 are both coded in IBC prediction mode, and the absolute difference between the horizontal or vertical component of the motion vectors used in the prediction of the two coding subblocks is greater than or equal to 4 in units of quarter luma samples.
  • One motion vector is used to predict the coding subblock containing the sample p 0 and one motion vector is used to predict the coding subblock containing the sample q 0 , and the absolute difference between the horizontal or vertical component of the motion vectors used is greater than or equal to 4 in units of quarter luma samples.
  • Two motion vectors and two different reference pictures are used to predict the coding subblock containing the sample p 0
  • two motion vectors for the same two reference pictures are used to predict the coding subblock containing the sample q 0
  • the absolute difference between the horizontal or vertical component of the two motion vectors used in the prediction of the two coding subblocks for the same reference picture is greater than or equal to 4 in units of quarter luma samples.
  • Two motion vectors for the same reference picture are used to predict the coding subblock containing the sample p 0
  • two motion vectors for the same reference picture are used to predict the coding subblock containing the sample q 0 and both of the following conditions are true:
  • the absolute difference between the horizontal or vertical component of list 0 motion vectors used in the prediction of the two coding subblocks is greater than or equal to 4 in quarter luma samples, or the absolute difference between the horizontal or vertical component of the list 1 motion vectors used in the prediction of the two coding subblocks is greater than or equal to 4 in units of quarter luma samples.
  • the absolute difference between the horizontal or vertical component of list 0 motion vector used in the prediction of the coding subblock containing the sample p 0 and the list 1 motion vector used in the prediction of the coding subblock containing the sample q 0 is greater than or equal to 4 in units of quarter luma samples, or the absolute difference between the horizontal or vertical component of the list 1 motion vector used in the prediction of the coding subblock containing the sample p 0 and list 0 motion vector used in the prediction of the coding subblock containing the sample q 0 is greater than or equal to 4 in units of quarter luma samples.
  • variable bS [xD i ] [yD j ] is set equal to 0.
  • This embodiment describes escape samples coding and reconstruction.
  • a variable startComp specifies the first colour component in the palette table
  • nCbW and nCbH specifying the width and height of the current block, respectively.
  • nSubWidth and nSubHeight are derived as follows:
  • nSubWidth is set to 1 and nSubHeight is set to 1.
  • nSubWidth is set to SubWidthC and nSubHeight is set to SubHeightC.
  • the variables xL and yL are derived as follows:
  • xL palette_transpose_flag? x*nSubHeight: x*nSubWidth (8-69)
  • yL palette_transpose_flag? y*nSubWidth: y*nSubHeight (8-70)
  • variable bIsEscapeSample is derived as follows:
  • PaletteIndexMap [xCb + xL] [yCb + yL] is equal to MaxPaletteIndex and palette_escape_val_present_flag is equal to 1, bIsEscapeSample is set equal to 1.
  • cu_transquant_bypass_flag if cu_transquant_bypass_flag is equal to 1, the following applies:
  • the derivation process for quantization parameters as specified in clause 8.7.1 is invoked with the location (xCb, yCb) specifying the top-left sample of the current block relative to the top-left sample of the current picture.
  • the quantization parameter qP is derived as follows:
  • bitDepth is derived as follows:
  • cIdx is equal to 0 and numComps is equal to 1;
  • cIdx is equal to 3;
  • variable PredictorPaletteSize [startComp] and the array PredictorPaletteEntries are derived or modified as follows:
  • PredictorPaletteSize [startComp] shall be in the range of 0 to PaletteMaxPredictorSize, inclusive.
  • variable startComp specifies the first colour component in the palette table
  • nCbW and nCbH specifying the width and height of the current block, respectively.
  • nSubWidth and nSubHeight are derived as follows:
  • nSubWidth is set to 1 and nSubHeight is set to 1.
  • nSubWidth is set to SubWidthC and nSubHeight is set to SubHeightC.
  • xL palette_transpose_flag? x*nSubHeight: x*nSubWidth (8-234)
  • yL palette_transpose_flag? y*nSubWidth: y*nSubHeight (8-235)
  • variable bIsEscapeSample is derived as follows:
  • PaletteIndexMap [xCb + xL] [yCb + yL] is equal to MaxPaletteIndex and palette_escape_val_present_flag is equal to 1, bIsEscapeSample is set equal to 1.
  • the quantization parameter qP is derived as follows:
  • min_qp_prime_ts_minus4 specifies the minimum allowed quantization parameter for transform skip mode as follows:
  • bitDepth is derived as follows:
  • variable PredictorPaletteSize [startComp] and the array PredictorPaletteEntries are derived or modified as follows:
  • PredictorPaletteSize [startComp] shall be in the range of 0 to PaletteMaxPredictorSize, inclusive.
  • IntraPredModeY [xPb] [yPb] is derived by the following ordered steps:
  • the neighbouring locations (xNbA, yNbA) and (xNbB, yNbB) are set equal to (xPb -1, yPb) and (xPb, yPb -1) , respectively.
  • the candidate intra prediction mode candIntraPredModeX is derived as follows:
  • candIntraPredModeX is set equal to INTRA_DC.
  • candIntraPredModeB is set equal to INTRA_DC.
  • variable cbWidth specifying the width of the current coding block in luma samples
  • variable cbHeight specifying the height of the current coding block in luma samples.
  • the candidate intra prediction mode candIntraPredModeX is derived as follows:
  • candIntraPredModeX is set equal to INTRA_PLANAR.
  • variable availableX is equal to FALSE.
  • pred_mode_plt_flag is equal to 1.
  • intra_mip_flag [xNbX] [yNbX] is equal to 1.
  • yCb -1 is less than ( (yCb >> CtbLog2SizeY) ⁇ CtbLog2SizeY) .
  • candIntraPredModeX is set equal to IntraPredModeY [xNbX] [yNbX] .
  • variable cbWidth specifying the width of the current coding block in luma samples
  • variable cbHeight specifying the height of the current coding block in luma samples.
  • the candidate intra prediction mode candIntraPredModeX is derived as follows:
  • candIntraPredModeX is set equal to [ [INTRA_PLANAR] ] INTRA_DC.
  • variable availableX is equal to FALSE.
  • intra_mip_flag [xNbX] [yNbX] is equal to 1.
  • yCb -1 is less than ( (yCb >> CtbLog2SizeY) ⁇ CtbLog2SizeY) .
  • candIntraPredModeX is set equal to IntraPredModeY [xNbX] [yNbX] .
  • variable cbWidth specifying the width of the current coding block in luma samples
  • variable cbHeight specifying the height of the current coding block in luma samples.
  • the candidate intra prediction mode candIntraPredModeX is derived as follows:
  • candIntraPredModeX is set equal to [ [INTRA_PLANAR] ] INTRA_DC.
  • variable availableX is equal to FALSE.
  • intra_mip_flag [xNbX] [yNbX] is equal to 1.
  • pred_mode_plt_flag is equal to 1.
  • yCb -1 is less than ( (yCb >> CtbLog2SizeY) ⁇ CtbLog2SizeY) .
  • candIntraPredModeX is set equal to IntraPredModeY [xNbX] [yNbX] .
  • This embodiment decribes the coding unit syntax.
  • the pred_mode_plt_flag is signaled after the pred_mode_ibc_flag.
  • This embodiment decribes the coding unit syntax.
  • the pred_mode_plt_flag is signaled after the pred_mode_ibc_flag.
  • This embodiment decribes the coding unit syntax.
  • the palette syntax is signaled if the current prediction mode is MODE_PLT.
  • This embodiment decribes the derivation process of chroma intra prediction mode.
  • a luma location (xCb, yCb) specifying the top-left sample of the current chroma coding block relative to the top-left luma sample of the current picture
  • variable cbWidth specifying the width of the current coding block in luma samples
  • variable cbHeight specifying the height of the current coding block in luma samples.
  • the corresponding luma intra prediction mode lumaIntraPredMode is derived as follows:
  • lumaIntraPredMode is set equal to INTRA_PLANAR.
  • lumaIntraPredMode is set equal to IntraPredModeY [xCb + cbWidth /2] [yCb + cbHeight/2] .

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Abstract

L'invention concerne des dispositifs, des systèmes et des procédés de traitement vidéo. Un exemple de procédé de traitement vidéo consiste à déterminer, pour une conversion entre un bloc courant d'une vidéo et une représentation de flux binaire de la vidéo, qu'un bloc voisin du bloc courant qui est codé dans un mode palette est traité comme un bloc intra-codé ayant un mode par défaut pendant une construction d'une liste de candidats de modes les plus probables (MPM) du bloc courant dans le cas où le bloc voisin est situé au-dessus ou à gauche du bloc courant. Le procédé consiste également à procéder à la conversion sur la base de la détermination.
PCT/CN2020/102968 2019-07-20 2020-07-20 Détermination de mode pour codage en mode palette WO2021013119A1 (fr)

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US17/580,314 US11677935B2 (en) 2019-07-23 2022-01-20 Mode determination for palette mode coding
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