US20220377353A1 - Constraints for video coding and decoding - Google Patents

Constraints for video coding and decoding Download PDF

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US20220377353A1
US20220377353A1 US17/861,728 US202217861728A US2022377353A1 US 20220377353 A1 US20220377353 A1 US 20220377353A1 US 202217861728 A US202217861728 A US 202217861728A US 2022377353 A1 US2022377353 A1 US 2022377353A1
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picture
flag
sub
palette
equal
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Kai Zhang
Zhipin Deng
Hongbin Liu
Li Zhang
Jizheng Xu
Ye-Kui Wang
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Beijing ByteDance Network Technology Co Ltd
ByteDance Inc
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    • H—ELECTRICITY
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    • 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
    • H04N19/186—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 a colour or a chrominance component
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    • 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
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    • 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
    • H04N19/132—Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
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    • 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
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    • H04N19/1883—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 relating to sub-band structure, e.g. hierarchical level, directional tree, e.g. low-high [LH], high-low [HL], high-high [HH]
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    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
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    • H04N19/96—Tree coding, e.g. quad-tree coding

Definitions

  • This document is related to video and image coding and decoding 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 sub-picture based coding or decoding is performed.
  • a method of video processing includes performing a conversion between a block of a video and a bitstream of the video.
  • the bitstream conforms to a formatting rule specifying that a size of a merge estimation region (MER) is indicated in the bitstream.
  • the size of the MER is based on a dimension of a video unit, and the MER comprises a region used for deriving a motion candidate for the conversion.
  • a method of video processing includes performing a conversion between a block of a video and a bitstream of the video in a palette coding mode in which a palette of representative sample values is used for coding the block of video in the bitstream.
  • a maximum number of palette size or palette predictor size used in the palette mode is restricted to m ⁇ N, m and N being positive integers.
  • a method of video processing includes determining, for a conversion between a current block of a video and a bitstream of the video, that a deblocking filtering process is disabled for a boundary of the current block in case the boundary coincides with a boundary of a sub-picture having a sub-picture index X and a loop filtering operation is disabled across boundaries of the subpicture, X being a non-negative integer.
  • the method also includes performing the conversion based on the determining.
  • a method of video processing includes determining, for a video block in a first video region of a video, whether a position at which a temporal motion vector predictor is determined for a conversion between the video block and a bitstream representation of the current video block using an affine mode is within a second video region; and performing the conversion based on the determining.
  • another method of video processing includes determining, for a video block in a first video region of a video, whether a position at which an integer sample in a reference picture is fetched for a conversion between the video block and a bitstream representation of the current video block is within a second video region, wherein the reference picture is not used in an interpolation process during the conversion; and performing the conversion based on the determining.
  • another method of video processing includes determining, for a video block in a first video region of a video, whether a position at which a reconstructed luma sample value is fetched for a conversion between the video block and a bitstream representation of the current video block is within a second video region; and performing the conversion based on the determining.
  • another method of video processing includes determining, for a video block in a first video region of a video, whether a position at which a check regarding splitting, depth derivation or split flag signaling for the video block is performed during a conversion between the video block and a bitstream representation of the current video block is within a second video region; and performing the conversion based on the determining.
  • another method of video processing includes performing a conversion between a video comprising one or more video pictures comprising one or more video blocks, and a coded representation of the video, wherein the coded representation complies with a coding syntax requirement that the conversion is not to use sub-picture coding/decoding and a dynamic resolution conversion coding/decoding tool or a reference picture resampling tool within a video unit.
  • another method of video processing includes performing a conversion between a video comprising one or more video pictures comprising one or more video blocks, and a coded representation of the video, wherein the coded representation complies with a coding syntax requirement that a first syntax element subpic_grid_idx[i][j] is not larger than a second syntax element max_subpics_minus1.
  • another method of video processing includes performing a conversion between a first video region of a video and a coded representation of the video, wherein a set of parameters defining coding characteristics of the first video region is included at the first video region level in the coded representation.
  • the above-described method may be implemented by a video encoder apparatus that comprises a processor.
  • the above-described method may be implemented by a video decoder 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 region constraint in temporal motion vector prediction (TMVP) and sub-block TMVP.
  • FIG. 2 shows an example of a hierarchical motion estimation scheme.
  • FIG. 3 is a block diagram of an example of a hardware platform used for implementing techniques described in the present document.
  • FIG. 4 is a flowchart for an example method of video processing.
  • FIG. 5 shows an example of a picture with 18 by 12 luma CTUs that is partitioned into 12 tiles and 3 raster-scan slices (informative).
  • FIG. 6 shows an example of a picture with 18 by 12 luma CTUs that is partitioned into 24 tiles and 9 rectangular slices (informative).
  • FIG. 7 shows an example of a picture that is partitioned into 4 tiles, 11 bricks, and 4 rectangular slices (informative).
  • FIG. 8 shows an example of a block coded in palette mode.
  • FIG. 9 shows an example of using of predictor palette to signal palette entries.
  • FIG. 10 shows an example of horizontal and vertical traverse scans.
  • FIG. 11 shows an example of coding of palette indices.
  • FIG. 12 shows an example of merge estimation region (MER).
  • FIG. 13 is a block diagram showing an example video processing system in which various techniques disclosed herein may be implemented.
  • FIG. 14 is a block diagram that illustrates an example video coding system.
  • FIG. 15 is a block diagram that illustrates an encoder in accordance with some embodiments of the present disclosure.
  • FIG. 16 is a block diagram that illustrates a decoder in accordance with some embodiments of the present disclosure.
  • FIG. 17 is a flowchart representation of a method for video processing in accordance with the present technology.
  • FIG. 18 is a flowchart representation of another method for video processing in accordance with the present technology.
  • FIG. 19 is a flowchart representation of yet 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 employing base colors based representation in video coding. It may be applied to the existing video coding standard like High Efficiency Video Coding (HEVC), or the standard Versatile Video Coding (VVC) to be finalized. It may be also applicable to future video coding standards or video codec.
  • HEVC High Efficiency Video Coding
  • VVC Versatile Video Coding
  • 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[ 1 , 2 ].
  • AVC H.264/MPEG-4 Advanced Video Coding
  • H.265/HEVC standards H.265/HEVC standards[ 1 , 2 ].
  • 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. 1 illustrates example region constraint in TMVP and sub-block TMVP.
  • TMVP and sub-block TMVP it is constrained that a temporal motion vector (MV) can generally only be fetched from the collocated coding tree unit (CTU) plus a column of 4 ⁇ 4 blocks as shown in FIG. 1 .
  • CTU collocated coding tree unit
  • sub-picture-based coding techniques based on flexible tiling approach can be implemented. Summary of the sub-picture-based coding techniques includes the following:
  • SPS sequence parameter set
  • Whether in-loop filtering across sub-picture boundaries is disabled can be controlled by the bitstream for each sub-picture.
  • the deblocking filter (DBF), sample adaptive offset (SAO), and adaptive loop filter (ALF) processes are updated for controlling of in-loop filtering operations across sub-picture boundaries.
  • the sub-picture width, height, horizontal offset, and vertical offset are signalled in units of luma samples in SPS.
  • Sub-picture boundaries are constrained to be slice boundaries.
  • Treating a sub-picture as a picture in the decoding process is specified by slightly updating the coding_tree_unit( ) syntax, and updates to the following decoding processes:
  • Sub-picture identifiers are explicitly specified in the SPS and included in the tile group headers to enable extraction of sub-picture sequences without the need of changing video coding layer (VCL) network abstraction layer (NAL) units.
  • VCL video coding layer
  • NAL network abstraction layer
  • OSPS Output sub-picture sets
  • NumSubPicGridCols (pic_width_max_in_luma_samples+subpic_grid_col_width-minus1*4+3)/(subpic_grid_col_width_minus1*4+4) (7-5)
  • subpic_grid_row_height_minus1 plus 1 specifies the height of each element of the sub-picture identifier grid in units of 4 samples.
  • the length of the syntax element is Ceil(Log 2(pic_height_max_in_luma_samples/4)) bits.
  • NumSubPicGridRows is derived as follows:
  • NumSubPicGridRows (pic_height_max_in_luma_samples+subpic_grid_row_height_minus1*4+3)/(subpic_grid_row_height_minus1*4+4) (7-6)
  • subpic_grid_idx[i][j] specifies the sub-picture index of the grid position (i, j).
  • the length of the syntax element is Ceil(Log 2(max_subpics_minus1+1)) bits.
  • the variables SubPicTop[subpic_grid_idx[i][j]], SubPicLeft[subpic_grid_idx[i][j]], SubPicWidth[subpic_grid_idx [i][j]], SubPicHeight[subpic_grid_idx[i][j]], and NumSubPics are derived as follows:
  • subpic_treated_as_pic_flag[i] 0 specifies that the i-th sub-picture of each coded picture in the Coded Vide Sequence (CVS) is not treated as a picture in the decoding process excluding in-loop filtering operations.
  • the value of subpic_treated_as_pic_flag[i] is inferred to be equal to 0.
  • loop_filter_across_subpic_enabled_flag[i] 1 specifies that in-loop filtering operations may be performed across the boundaries of the i-th sub-picture in each coded picture in the CVS.
  • loop_filter_across_subpic_enabled_flag[i] 0 specifies that in-loop filtering operations are not performed across the boundaries of the i-th sub-picture in each coded picture in the CVS.
  • the value of loop_filter_across_subpic_enabled_pic_flag[i] is inferred to be equal to 1.
  • Ctbtosubpicidx[ctbAddrRs] for ctbAddrRs ranging from 0 to PicSizeInCtbsY ⁇ 1, inclusive, specifying the conversion from a coding tree block (CTB) address in picture raster scan to a sub-picture index, is derived as follows:
  • the value of num_bricks_in_slice_minus1 may be in the range of 0 to NumBricksInPic ⁇ 1, inclusive.
  • rect_slice_flag is equal to 0 and single_brick_per_slice_flag is equal to 1, the value of num_bricks_in_slice_minus1 is inferred to be equal to 0.
  • single_brick_per_slice_flag is equal to 1
  • the value of num_bricks_in_slice_minus1 is inferred to be equal to 0.
  • NumBricksInCurrSlice which specifies the number of bricks in the current slice
  • SliceBrickIdx[i] which specifies the brick index of the i-th brick in the current slice
  • SubPicIdx CtbToSubPicIdx[ CtbAddrBsToRs[ FirstCtbAddrBs[ SliceBrickIdx[ 0 ] ] ] ] if( subpic_treated_as_pic_flag[ SubPicIdx ] ) ⁇
  • SubPicLeftBoundaryPos SubPicLeft[ SubPicIdx ] * ( subpic_grid_col_width_minus1 + 1 ) * 4
  • SubPicRightBoundaryPos ( SubPicLeft[ SubPicIdx ] + SubPicWidth[ SubPicIdx ] ) * ( subpic_grid_col_width_minus1 + 1 ) * 4
  • SubPicTopBoundaryPos SubPicTop[ SubPicIdx ] * ( subpic_grid_row_height_minus1 + 1 )* 4 SubPicBot
  • slice_temporal_mvp_enabled_flag is equal to 0 or (cbWidth*cbHeight) is less than or equal to 32, both components of mvLXCol are set equal to 0 and availableFlagLXCol is set equal to 0.
  • botBoundaryPos subpic_treated_as_pic_flag[SubPicIdx]?SubPicBotBoundaryPos: pic_height_in_luma_samples ⁇ 1 (8-424)
  • the variable picW is set equal to pic_width_in_luma_samples and the variable picH is set equal to pic_height_in_luma_samples.
  • the luma interpolation filter coefficients fb L [p] for each 1/16 fractional sample position p equal to xFrac L or yFrac L are specified in Table 8-10.
  • x Int i Clip3(SubPicLeftBoundaryPos,SubPicRightBoundaryPos, x Int L +i ) (8-460)
  • x Sb x Cb+ x SbIdx*sbWidth+sbWidth/2 (8-551)
  • y ColSb Clip3( y Ctb,Min(CurPicHeightInSamples Y ⁇ 1, y Ctb+(1 ⁇ CtbLog 2SizeY) ⁇ 1), (8-553)
  • x ColSb Clip3( x Ctb,Min(SubPicRightBoundaryPos, x Ctb+(1 ⁇ CtbLog 2Size Y )+3), (8-554)
  • x ColSb Clip3( x Ctb,Min(CurPicWidthInSamples Y ⁇ 1, x Ctb+(1 ⁇ CtbLog 2Size Y )+3 (8-555)
  • variable currPic specifies the current picture.
  • availableFlagA 1 is equal to TRUE, the following applies:
  • y ColCb Clip3( y Ctb,Min(CurPicHeightInSamples Y ⁇ 1, y Ctb+(1 ⁇ CtbLog 2Size Y ) ⁇ 1), (8-560)
  • x ColCb Clip3( x Ctb,Min(SubPicRightBoundaryPos, x Ctb+(1 ⁇ CtbLog 2Size Y )+3), (8-561)
  • x ColCb Clip3( x Ctb,Min(CurPicWidthInSamples Y ⁇ 1, x Ctb+(1 ⁇ CtbLog 2Size Y )+3), (8-562)
  • subpic_treated_as_pic_flag[SubPicIdx] is equal to 1, the following applies:
  • x Int i Clip3(SubPicLeftBoundaryPos,SubPicRightBoundaryPos, x Int L +i ⁇ 3) (8-771)
  • subpic_treated_as_pic_flag[SubPicIdx] is equal to 1, the following applies:
  • x Int i Clip3(SubPicLeftBoundaryPos/SubWidth C ,SubPicRightBoundaryPos/SubWidth C,x Int L +i ) (8-785)
  • an encoder-only temporal filter can be implemented.
  • the filtering is done at the encoder side as a pre-processing step.
  • Source pictures before and after the selected picture to encode are read and a block based motion compensation method relative to the selected picture is applied on those source pictures.
  • Samples in the selected picture are temporally filtered using sample values after motion compensation.
  • the overall filter strength is set depending on the temporal sub layer of the selected picture as well as the quantization parameter (QP). Generally, only pictures at temporal sub layers 0 and 1 are filtered and pictures of layer 0 are filtered by a stronger filter than pictures of layer 1.
  • the per sample filter strength is adjusted depending on the difference between the sample value in the selected picture and the co-located samples in motion compensated pictures so that small differences between a motion compensated picture and the selected picture are filtered more strongly than larger differences.
  • a temporal filter is introduced directly after reading picture and before encoding. Below are the steps described in more detail.
  • RA random access
  • POC picture order count
  • LD low delay
  • AI Artificial intelligence
  • the overall filter strength, s o is set according to the equation below for RA.
  • n is the number of pictures read.
  • Operation 3 Two pictures before and/or after the selected picture (referred to as original picture further down) are read. In the edge cases e.g., if it is the first picture or close to the last picture, generally only the available pictures are read.
  • Operation 4 Motion of the read pictures before and after, relative to the original picture is estimated per 8 ⁇ 8 picture block.
  • a hierarchical motion estimation scheme is used and the layers L0, L1 and L2, are illustrated in FIG. 2 .
  • Subsampled pictures are generated by averaging each 2 ⁇ 2 block for all read pictures and the original picture, e.g. L1 in FIG. 1 .
  • L2 is derived from L1 using the same subsampling method.
  • FIG. 2 shows examples of different layers of the hierarchical motion estimation.
  • L0 is the original resolution.
  • L1 is a subsampled version of L0.
  • L2 is a subsampled version of L1.
  • motion estimation is done for each 16 ⁇ 16 block in L2.
  • the squared difference is calculated for each selected motion vector and the motion vector corresponding to the smallest difference is selected.
  • the selected motion vector is then used as initial value when estimating the motion in L1.
  • the same is done for estimating motion in L0.
  • subpixel motion is estimated for each 8 ⁇ 8 block by using an interpolation filter on L0.
  • VTM 6-tap interpolation filter can used:
  • Operation 5 Motion compensation is applied on the pictures before and after the original picture according to the best matching motion for each block, e.g., so that the sample coordinates of the original picture in each block have the best matching coordinates in the referenced pictures.
  • Operation 6 The samples are processed one by one for the luma and chroma channels as described in the following steps.
  • Operation 7 The new sample value, In, is calculated using the following formula.
  • I o is the sample value of the original sample
  • I r (i) is the intensity of the corresponding sample of motion compensated picture i
  • w r (i, a) is the weight of motion compensated picture i when the number of available motion compensated pictures is a.
  • the weights, w r (i, a), is defined as follows:
  • w r ( i , a ) s l ⁇ s o ( n ) ⁇ s r ( i , a ) ⁇ e - ⁇ ⁇ I ( i ) 2 2 ⁇ ⁇ l ( QP ) 2
  • weights, w r (i, a), is defined as follows:
  • w r ( i , a ) s c ⁇ s o ( n ) ⁇ s r ( i , a ) ⁇ e - ⁇ ⁇ I ( i ) 2 2 ⁇ ⁇ c 2
  • Operation 8 The filter is applied for the current sample.
  • the resulting sample value is stored separately.
  • Operation 9 The filtered picture is encoded.
  • a picture is divided into one or more tile rows and one or more tile columns.
  • a tile is a sequence of CTUs that covers a rectangular region of a picture.
  • a tile is divided into one or more bricks, each of which consist of a number of CTU rows within the tile.
  • a tile that is not partitioned into multiple bricks is also referred to as a brick.
  • a brick that is a true subset of a tile is not referred to as a tile.
  • a slice either contains a number of tiles of a picture or a number of bricks of a tile.
  • a sub-picture contains one or more slices that collectively cover a rectangular region of a picture.
  • a slice contains a sequence of tiles in a tile raster scan of a picture.
  • a slice contains a number of bricks of a picture that collectively form a rectangular region of the picture. The bricks within a rectangular slice are in the order of brick raster scan of the slice.
  • FIG. 5 shows an example of raster-scan slice partitioning of a picture, where the picture is divided into 12 tiles and 3 raster-scan slices.
  • FIG. 6 shows an example of rectangular slice partitioning of a picture, where the picture is divided into 24 tiles (6 tie columns and 4 tile rows) and 9 rectangular slices.
  • FIG. 7 shows an example of a picture partitioned into tiles, bricks, and rectangular slices, where the picture is divided into 4 tiles (2 tile columns and 2 tile rows), 11 bricks (the top-left tile contains 1 brick, the top-right tile contains 5 bricks, the bottom-left tile contains 2 bricks, and the bottom-right tile contain 3 bricks), and 4 rectangular slices.
  • slice_header( ) ⁇ slice_pic_parameter_set_id ue (v) if( rect_slice_flag NumBricksInPic > 1 ) slice_address u (v) if( !rect_slice_flag && !single_brick_per_slice_flag ) num_bricks_in_slice_minus1 ue (v) non_reference_picture_flag u (1) slice_type ue (v) ... single_tile_in_pic_flag equal to 1 specifies that there is only one tile in each picture referring to the PPS. single_tile_in_pic_flag equal to 0 specifies that there is more than one tile in each picture referring to the PPS.
  • each of the slice header syntax elements slice_pic_parameter_set_id, non_reference_picture_flag, colour_plane_id, slice_pic_order_cnt_lsb, recovery_poc_cnt, no_output_of_prior_pics_flag, pic_output_flag, and slice_temporal_mvp_enabled_flag may be the same in all slice headers of a coded picture.
  • the variable CuQpDeltaVal specifying the difference between a luma quantization parameter for the coding unit containing cu_qp_delta_abs and its prediction, is set equal to 0.
  • the variables CuQpOffset Cb , CuQpOffset Cr , and CuQpOffset CbCr specifying values to be used when determining the respective values of the Qp′ Cb , Qp′ Cr , and Qp′ CbCr quantization parameters for the coding unit containing cu_chroma_qp_offset_flag, are all set equal to 0.
  • slice_pic_parameter_set_id specifies the value of pps_pic_parameter_set_id for the PPS in use.
  • the value of slice_pic_parameter_set_id may be in the range of 0 to 63, inclusive.
  • slice_address specifies the slice address of the slice. When not present, the value of slice_address is inferred to be equal to 0. If rect_slice_flag is equal to 0, the following applies:
  • SubPicIdx CtbToSubPicIdx[ CtbAddrBsToRs[ FirstCtbAddrBs[ SliceBrickIdx[ 0 ] ] ] ] if( subpic_treated_as_pic_flag[ SubPicIdx ] ) ⁇
  • SubPicLeftBoundaryPos SubPicLeft[ SubPicIdx ] * ( subpic_grid_col_width_minus1 + 1 ) * 4
  • SubPicRightBoundaryPos ( SubPicLeft[ SubPicIdx ] + SubPicWidth[ SubPicIdx ] ) * ( subpic_grid_col_width_minus1 + 1 ) * 4 (7-93)
  • SubPicTopBoundaryPos SubPicTop[ SubPicIdx ] * ( subpic_grid_row_height_minus1 + 1 )* 4 Sub
  • SubpicIdList[ i ] sps_subpic_id_present_flag? (7-39)
  • Inputs to this process are the reconstructed picture prior to deblocking, i.e., the array recPicture L and, when ChromaArrayType is not equal to 0, the arrays recPicture Cb and recPicture Cr .
  • Outputs of this process are the modified reconstructed picture after deblocking, i.e., the array recPicture L and, when ChromaArrayType is not equal to 0, the arrays recPicture Cb and recPicture Cr .
  • 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.
  • the edges are filtered by the following ordered steps: 1.
  • the variable filterEdgeFlag is derived as follows:
  • TPM triangular Prediction Mode
  • HMVP History-based Motion vector Prediction
  • VVC maintains a table of motion information to be used for motion vector prediction.
  • the table is updated after decoding an inter-coded block, but it is not updated if the inter-coded block is TPM-coded.
  • GEO geometric partition mode
  • ALF Adaptive Loop-Filter
  • Virtual Boundary (VB) is adopted in VVC to make ALF friendly to hardware design.
  • VB Virtual Boundary
  • ALF is conducted in an ALF processing unit bounded by two ALF virtual boundaries.
  • Cross-Component ALF as filters the chroma samples by referring to the information of luma samples.
  • the sub-picture level information SEI message contains information about the level that sub-pictures in the bitstream conform to when testing conformance of extracted bitstreams containing the sub-pictures according to Annex A.
  • a sub-picture level information SEI message may be present for the first picture of the CLVS.
  • the sub-picture level information SEI message persists for the current layer in decoding order from the current picture until the end of the CLVS. All sub-picture level information SEI messages that apply to the same CLVS may have the same content.
  • sli_seq_parameter_set_id indicates and may be equal to the sps_seq_parameter_set_id for the SPS that is referred to by the coded picture associated with the sub-picture level information SEI message.
  • the value of sli_seq_parameter_set_id may be equal to the value of pps_seq_parameter_set_id in the PPS referenced by the ph_pic_parameter_set_id of the PH of the coded picture associated with the sub-picture level information SEI message.
  • subpic_treated_as_pic_flag[i] may be equal to 1 for each value of i in the range of 0 to sps_num_subpics_minus1, inclusive.
  • num_ref_levels_minus1 plus 1 specifies the number of reference levels signalled for each of the sps_num_subpics_minus1+1 sub-pictures.
  • explicit_fraction_present_flag 1 specifies that the syntax elements ref_level_fraction_minus1[i] are present.
  • explicit_fractionpresent_flag 0 specifies that the syntax elements ref_level_fraction_minus1[i] are not present.
  • ref_level_idc[i] indicates a level to which each sub-picture conforms as specified in Annex A. Bitstreams may not contain values of ref_level_idc other than those specified in Annex A. Other values of ref_level_idc[i] are reserved for future use by ITU-T
  • ref_level_fraction_minus1[i][j] plus 1 specifies the fraction of the level limits associated with ref_level_idc[i] that the j-th sub-picture conforms to as specified in clause A.4.1.
  • the variable SubPicSizeY[j] is set equal to (subpic_width_minus1[j]+1)*(subpic_height_minus1[j]+1).
  • the value of ref_level_fraction_minus1[i][j] is inferred to be equal to Ceil(256*SubPicSizeY[j]+PicSizeInSamplesY*MaxLumaPs(general_level_ide)+MaxLumaPs(ref_level_idc[i]) ⁇ 1.
  • the variable RefLevelFraction[i][j] is set equal to ref_level_fraction_minus1[i][j]+1.
  • the variables SubPicNumTileCols[j] and SubPicNumTileRows[j] are derived as follows:
  • SubPicNumTileCols[ i ] 1
  • SubPicNumTileCols[ i ]++ (D.5) for( ctbAddrRs ( subpic_ctu_top_left_y[ i ] + 1 )
  • SubPicCpbSizeVcl[ i ][ j ] Floor(CpbVclFactor*MaxCPB*RefLevelFraction[ i ][ j ]+256) (D.6)
  • SubPicCpbSizeNal[ i ][ j ] Floor(CpbNalFactor*MaxCPB*RefLevelFraction[ i ][ j ]+256) (D.7)
  • SubPicSetAccLevelFraction[ i ] 0
  • SubPicSetCpbSizeVcl[ i ] 0
  • SubPicIdx SubPicSetIndices[ j ]
  • SubPicSetAccLevelFraction[ i ] + RefLevelFraction[ i ] [ SubPicIdx ](D.8)
  • SubPicSetCpbSizeVcl[ i ] + SubPicSetCpbSizeVcl[ i ][ SubPicIdx ]
  • SubPicSetCpbSizeNal[ i ] + SubPicSetCpbSizeNal[ i ][ SubPicSetCpbSizeNal[ i ][ SubPicSetCpbSizeN
  • the sub-picture set bitstream conforming to a profile with general_tier_flag equal to 0 and a level equal to SubPicSetLevelIdc may obey the following constraints for each bitstream conformance test as specified in Annex C:
  • the basic idea behind a palette mode is that the pixels in the CU are represented by a small set of representative colour values. This set is referred to as the palette. And it is also possible to indicate a sample that is outside the palette by signalling an escape symbol followed by (possibly quantized) component values. This kind of pixel is called an escape pixel.
  • the palette mode is illustrated in FIG. 10 . As depicted in FIG. 10 , for each pixel with three color components (luma, and two chroma components), an index to the palette is founded, and the block could be reconstructed based on the founded values in the palette.
  • quantization is applied to samples/pixels and quantized values are signaled; and dequantization (at decoder) is applied.
  • a predictor palette is maintained which is updated after decoding a palette coded block.
  • the predictor palette is initialized at the beginning of each slice and each tile.
  • the maximum size of the palette as well as the predictor palette is signalled in the SPS.
  • a palette_predictor_initializer_present_flag is introduced in the PPS. When this flag is 1, entries for initializing the predictor palette are signalled in the bitstream.
  • the size of predictor palette is reset to 0 or initialized using the predictor palette initializer entries signalled in the PPS.
  • a predictor palette initializer of size 0 was enabled to allow explicit disabling of the predictor palette initialization at the PPS level.
  • palette_mode_enabled_flag 1 specifies that the decoding process for palette mode may be used for intra blocks
  • palette_mode_enabled-flag 0 specifies that the decoding process for palette mode is not applied.
  • palette_max_size specifies the maximum allowed palette size.
  • palette_max_size When not present, the value of palette_max_size is inferred to be 0.
  • delta-palette-max-predictor_size specifies the difference between the maximum allowed palette predictor size and the maximum allowed palette size. When not present, the value of delta_palette_max predictor_size is inferred to be 0.
  • PaletteMaxPredictorSize is derived as follows:
  • PaletteMaxPredictorSize palette_max_size+delta_palette_max predictor_size (0-57)
  • delta_palette_max_predictor_size may be equal to 0 when palette_max_size is equal to 0.
  • sps_palette_predictor_initializer present_flag 1 specifies that the sequence palette predictors are initialized using the sps_palette_predictor_initializers.
  • sps_palette_predictor_initializer_flag 0 specifies that the entries in the sequence palette predictor are initialized to 0.
  • the value of sps_palette_predictor_initializer_flag is inferred to be equal to 0.
  • sps_palette_predictor_initializerpresent_flag may be equal to 0 when palette_max_size is equal to 0.
  • sps_num_palette_predictor_initializer_minus1 plus 1 specifies the number of entries in the sequence palette predictor initializer. It may be a requirement of bitstream conformance that the value of sps_num_palette_predictor_initializer_minus1 plus 1 may be less than or equal to PaletteMaxPredictorSize.
  • sps_palette_predictor_initializers[comp][i] specifies the value of the comp-th component of the i-th palette entry in the SPS that is used to initialize the array PredictorPaletteEntries.
  • the value of the sps_palette_predictor_initializers[0][i] may be in the range of 0 to (1 ⁇ BitDepth Y ) ⁇ 1, inclusive
  • the values of sps_palette_predictor_initializers[ 1 ][i] and sps_palette_predictor_initializers[ 2 ][i] may be in the range of 0 to (1 ⁇ BitDepth C ) ⁇ 1, inclusive.
  • pps_palette_predictor_initializer_flag 0 specifies that the palette predictor initializers used for the pictures referring to the PPS are inferred to be equal to those specified by the active SPS.
  • the value of pps_palette_predictor_initializerpresent_flag is inferred to be equal to 0. It may be a requirement of bitstream conformance that the value of pps_palette_predictor_initializer_present_flag may be equal to 0 when either palette_max_size is equal to 0 or palette_mode_enabled_flag is equal to 0.
  • pps_num_palette_predictor_initializer specifies the number of entries in the picture palette predictor initializer. It may be a requirement of bitstream conformance that the value of pps_num_palette_predictor_initializer may be less than or equal to PaletteMaxPredictorSize.
  • the palette predictor variables are initialized as follows:
  • a reuse flag is signalled to indicate whether it is part of the current palette. This is illustrated in FIG. 9 .
  • the reuse flags are sent using run-length coding of zeros.
  • the number of new palette entries are signalled using Exponential Golomb (EG) code of order 0, i.e., EG-0.
  • EG-0 Exponential Golomb
  • the palette indices are coded using horizontal and vertical traverse scans as shown in FIG. 15 .
  • 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 palette sample modes: ‘COPY_LEFT’ and ‘COPY_ABOVE’.
  • ‘COPY_LEFT’ mode the palette index is assigned to a decoded index.
  • ‘COPY_ABOVE’ mode the palette index of the sample in the row above is copied.
  • a run value is signaled which specifies the number of subsequent samples that are also coded using the same mode.
  • the value of an index for the escape sample is the number of palette entries.
  • escape symbol is part of the run in ‘COPY_LEFT’ or ‘COPY_ABOVE’ mode, the escape component values are signaled for each escape symbol.
  • the coding of palette indices is illustrated in FIG. 16 .
  • 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 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. The binarization of escape samples is EG coding with 3 rd order, i.e., EG-3.
  • 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 index adjustment process in the palette index coding.
  • the left neighboring index or the above neighboring index should be different from the current index. Therefore, the range of the current palette index could be reduced by 1 by removing one possibility. After that, the index is signaled with truncated binary (TB) binarization.
  • TB truncated binary
  • the variable PaletteIndexMap[xC][yC] specifies a palette index, which is an index to the array represented by CurrentPaletteEntries.
  • the array indices xC, yC specify the location (xC, yC) of the sample relative to the top-left luma sample of the picture.
  • the value of PaletteIndexMap[xC][yC] may be in the range of 0 to MaxPaletteIndex, inclusive.
  • variable adjustedRefPaletteIndex is derived as follows:
  • CurrPaletteIndex is derived as follows:
  • MER is adopted into HEVC.
  • the way the merge candidate list is constructed introduces dependencies between neighboring blocks.
  • the motion estimation stage of neighboring blocks is typically performed in parallel or at least pipelined to increase the throughput.
  • the motion estimation stage for the merge mode would typically just consist of the candidate list construction and the decision which candidate to choose, based on a cost function. Due to the aforementioned dependency between neighboring blocks, merge candidate lists of neighboring blocks cannot be generated in parallel and represent a bottleneck for parallel encoder designs.
  • a parallel merge estimation level was introduced in HEVC that indicates the region in which merge candidate lists can be independently derived by checking whether a candidate block is located in that merge estimation region (MER).
  • MER merge estimation region
  • a candidate block that is in the same MER is not included in the merge candidate list.
  • this level is e.g. 32
  • all prediction units in a 32 ⁇ 32 area can construct the merge candidate list in parallel since all merge candidates that are in the same 32 ⁇ 32 MER, are not inserted in the list.
  • FIG. 12 illustrates that example showing a CTU partitioning with seven CUs and ten PUs. All potential merge candidates for the first PU0 are available because they are outside the first 32 ⁇ 32 MER.
  • merge candidate lists of PUs 2-6 cannot include motion data from these PUs when the merge estimation inside that MER should be independent. Therefore, when looking at a PU5 for example, no merge candidates are available and hence not inserted in the merge candidate list. In that case, the merge list of PU5 consists only of the temporal candidate (if available) and zero MV candidates.
  • the parallel merge estimation level is adaptive and signaled as log 2_parallel_merge_level_minus2 in the picture parameter set. The following MER sizes are allowed: 44 (no parallel merge estimation possible), 8 ⁇ 8, 16 ⁇ 16, 32 ⁇ 32 and 64 ⁇ 64.
  • the merge estimation region is larger than a 4 ⁇ 4 block, another modification of the merge list construction to increase the throughput kicks in.
  • a single merge candidate list is used for all PUs inside that CU.
  • the signaled syntax elements related to sub-picture may be arbitrarily large, which may cause an overflow problem.
  • the sub-picture and sub-picture grid is defined in units of 4 samples. And the length of syntax element is dependent on the picture height divided by 4. However, since the current pic_width_in_luma_samples and pic_height_in_luma_samples may be an integer multiple of Max(8, MinCbSizeY), the sub-picture grid may need to be defined in units of 8 samples.
  • the SPS syntax, pic_width_max_in_luma_samples and pic_height_max_in_luma_samples may need to be restricted to be no smaller than 8.
  • the information could be inferred without signaling in some cases.
  • the IDs of two sub-pictures may be identical.
  • pic_width_max_in_luma_samples/CtbSizeY may be equal to 0, resulting in a meaningless Log 2( ) operation.
  • ID in PH is more preferable than in PPS, but less preferable than in SPS, which is inconsistent.
  • log 2_transform_skip_max_size_minus2 in PPS is parsed depending on sps_transform_skip_enabled_flag in SPS, resulting in a parsing dependency.
  • loop_filter_across_subpic_enabled_flag for deblocking only consider the current sub-picture, without considering the neighbouring sub-picture.
  • sub-pictures are designed to provide a flexibility that regions at the same positions in pictures of a sequences can be decoded or extracted independently.
  • the region may be under some special requirements. For example, it may be a Region of Interest (ROI), which requires a high quality.
  • ROI Region of Interest
  • it may serve as a trace for fast skimming the video.
  • it may provide a low-resolution, low-complexity and low power-consuming bit-stream, which may be fed to a complexity-sensitive end user. All those applications may require that the region of a sub-picture should be encoded with a configuration different to other parts.
  • temporal filter is used to represent filters that require samples in other pictures.
  • Max(x, y) returns the larger one of x and y.
  • Min(x, y) returns the smaller one of x and y.
  • SubpicIdList[ i ] sps_subpic_id_present_flag?
  • SubpicIdList[ i ] sps_subpic_id_present_flag?
  • SubpicIdList[ i ] sps_subpic_id_present_flag?
  • the newly added texts are bold italicized and the deleted texts are marked by “[[ ]]”.
  • Clip H ((sps_ref_wraparound_offset_minus1+1)*MinCbSize Y ,pic W,x Int L ): x Int L )
  • the predicted luma sample value predSampleLX L is derived as follows:
  • predSampleLX L refPicLX L [ x Int][ y Int] ⁇ shift3 (8-784)
  • currPic[ x CuCb ⁇ 1][Min( y CuCb+ i ,[[pic_height_in_luma_samples ⁇ 1]] )] with i 0 . . . sizeY ⁇ 1, and cnt is set equal to sizeY
  • subpic_grid_col_width_minus1 plus 1 specifies the width of each element of the sub-picture identifier grid in units of samples.
  • the length of the syntax element is Ceil(Log 2(pic_width_max_in_luma_samples/ )) bits.
  • NumSubPicGridCols is derived as follows:
  • NumSubPicGridCols (pic_width_max_in_luma_samples+subpic_grid_col_width_minus1*[[4+3]] /(subpic_grid_col_width_minus1*[[4+3]] ) (7-5)
  • subpic_grid_row_height_minus1 plus 1 specifies the height of each element of the sub-picture identifier grid in units of 4 samples.
  • the length of the syntax element is Ceil(Log 2(pic_height_max_in_luma samples/ ) bits
  • NumSubPicGridRows is derived as follows:
  • NumSubPicGridRows (pic_height_max_in_luma_samples+subpic_grid_row_height_minus1* )/(subpic_grid_row_height_minus1*[[4+3] )
  • SubPicIdx SubPicLeftBoundaryPos
  • SubPicTopBoundaryPos SubPicRightBoundaryPos
  • SubPicBotBoundaryPos are derived as follows:
  • SubPicIdx CtbToSubPicIdx[ CtbAddrBsToRs[ FirstCtbAddrBs[ SliceBrickIdx[ 0 ] ] ] ] if( subpic_treated_as_pic_flag[ SubPicIdx ] ) ⁇
  • SubPicTopBoundaryPos SubPicTop[ SubPicIdx ] * ( subpic_grid_row_height_minus1 + 1 )* SubPicBotB
  • pic_width_max_in_luma_samples specifies the maximum width, in units of luma samples, of each decoded picture referring to the SPS.
  • pic_width_max_in_luma_samples may not be equal to 0 and may be an integer multiple of [[MinCbSizeY]]
  • pic_height_max_in_luma_samples specifies the maximum height, in units of luma samples, of each decoded picture referring to the SPS.
  • pic_height_max_in_luma_samples may not be equal to 0 and may be an integer multiple of [[MinCbSizeY]]
  • variable allowBtSplit is derived as follows:
  • variable allowTtSplit is derived as follows:
  • Inputs to this process are the reconstructed picture prior to deblocking, i.e., the array recPicture L and, when ChromaArrayType is not equal to 0, the arrays recPicture Cb and recPicture Cr .
  • Outputs of this process are the modified reconstructed picture after deblocking, i.e., the array recPicture L and, when ChromaArrayType is not equal to 0, the arrays recPicture Cb and recPicture Cr .
  • 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.
  • Outputs of this process are the modified reconstructed picture after deblocking, i.e:
  • the edges are filtered by the following ordered steps:
  • ⁇ p Clip3( ⁇ ( t C >>1), t C >>1,((( p 2 +p 0 +1)>>1) ⁇ p 1 + ⁇ )>>1) (8-1160)
  • ⁇ q Clip3( ⁇ ( t C >>1), t C >>1,((( q 2 +q 0 +1)>>1) ⁇ q 1 ⁇ )>>1) (8-1162)
  • pred_mode_plt_flag of the coding unit that includes the coding block containing the sample p i is equal to 1
  • pred_mode_plt_flag of the coding unit that includes the coding block containing the sample q i is equal to 1
  • This process is only invoked when ChromaArrayType is not equal to 0. Inputs to this process are:
  • pred_mode_plt_flag of the coding unit that includes the coding block containing the sample p i is equal to 1
  • pred_mode_plt_flag of the coding unit that includes the coding block containing the sample q i is equal to 1
  • Inputs to this process are the reconstructed picture prior to deblocking, i.e., the array recPicture L and, when ChromaArrayType is not equal to 0, the arrays recPicture Cb and recPicture Cr .
  • Outputs of this process are the modified reconstructed picture after deblocking, i.e., the array recPicture L and, when ChromaArrayType is not equal to 0, the arrays recPicture Cb and recPicture Cr .
  • the deblocking filter process is applied to all coding subblock edges and transform block edges of a picture, except the following types of edges:
  • FIG. 3 is a block diagram of a video processing apparatus 300 .
  • the apparatus 300 may be used to implement one or more of the methods described herein.
  • the apparatus 300 may be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on.
  • the apparatus 300 may include one or more processors 302 , one or more memories 304 and video processing hardware 306 .
  • the processor(s) 302 may be configured to implement one or more methods described in the present document.
  • the memory (memories) 304 may be used for storing data and code used for implementing the methods and techniques described herein.
  • the video processing hardware 306 may be used to implement, in hardware circuitry, some techniques described in the present document.
  • FIG. 4 is a flowchart for a method 400 of processing a video.
  • the method 400 includes determining ( 402 ), for a video block in a first video region of a video, whether a position at which a temporal motion vector predictor is determined for a conversion between the video block and a bitstream representation of the current video block using an affine mode is within a second video region, and performing ( 404 ) the conversion based on the determining.
  • a method of video processing comprising: determining, for a video block in a first video region of a video, whether a position at which a temporal motion vector predictor is determined for a conversion between the video block and a bitstream representation of the current video block using an affine mode is within a second video region; and performing the conversion based on the determining.
  • a method of video processing comprising: determining, for a video block in a first video region of a video, whether a position at which an integer sample in a reference picture is fetched for a conversion between the video block and a bitstream representation of the current video block is within a second video region, wherein the reference picture is not used in an interpolation process during the conversion; and performing the conversion based on the determining.
  • a method of video processing comprising: determining, for a video block in a first video region of a video, whether a position at which a reconstructed luma sample value is fetched for a conversion between the video block and a bitstream representation of the current video block is within a second video region; and performing the conversion based on the determining.
  • a method of video processing comprising: determining, for a video block in a first video region of a video, whether a position at which a check regarding splitting, depth derivation or split flag signaling for the video block is performed during a conversion between the video block and a bitstream representation of the current video block is within a second video region; and performing the conversion based on the determining.
  • a method of video processing comprising: performing a conversion between a video comprising one or more video pictures comprising one or more video blocks, and a coded representation of the video, wherein the coded representation complies with a coding syntax requirement that the conversion is not to use sub-picture coding/decoding and a dynamic resolution conversion coding/decoding tool or a reference picture resampling tool within a video unit.
  • a video decoding apparatus comprising a processor configured to implement a method recited in one or more of solutions 1 to 31.
  • a video encoding apparatus comprising a processor configured to implement a method recited in one or more of solutions 1 to 31.
  • a computer program product having computer code stored thereon, the code, when executed by a processor, causes the processor to implement a method recited in any of solutions 1 to 31.
  • FIG. 13 is a block diagram showing an example video processing system 1300 in which various techniques disclosed herein may be implemented.
  • the system 1300 may include input 1302 for receiving video content.
  • the video content may be received in a raw or uncompressed format, e.g., 8 or 10 bit multi-component pixel values, or may be in a compressed or encoded format.
  • the input 1302 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interface include wired interfaces such as Ethernet, passive optical network (PON), etc. and wireless interfaces such as Wi-Fi or cellular interfaces.
  • the system 1300 may include a coding component 1304 that may implement the various coding or encoding methods described in the present document.
  • the coding component 1304 may reduce the average bitrate of video from the input 1302 to the output of the coding component 1304 to produce a coded representation of the video.
  • the coding techniques are therefore sometimes called video compression or video transcoding techniques.
  • the output of the coding component 1304 may be either stored, or transmitted via a communication connected, as represented by the component 1306 .
  • the stored or communicated bitstream (or coded) representation of the video received at the input 1302 may be used by the component 1308 for generating pixel values or displayable video that is sent to a display interface 1310 .
  • the process of generating user-viewable video from the bitstream representation is sometimes called video decompression.
  • video processing operations are referred to as “coding” operations or tools, it will be appreciated that the coding tools or operations are used at an encoder and corresponding decoding tools or operations that reverse the results of the coding will be performed by a decoder.
  • peripheral bus interface or a display interface may include universal serial bus (USB) or high definition multimedia interface (HIDMI) or Displayport, and so on.
  • storage interfaces include SATA (serial advanced technology attachment), Peripheral Component Interconnect (PCI), Integrated Device Electronics (IDE) interface, and the like.
  • SATA serial advanced technology attachment
  • PCI Peripheral Component Interconnect
  • IDE Integrated Device Electronics
  • FIG. 14 is a block diagram that illustrates an example video coding system 100 that may utilize the techniques of this disclosure.
  • video coding system 100 may include a source device 110 and a destination device 120 .
  • Source device 110 generates encoded video data which may be referred to as a video encoding device.
  • Destination device 120 may decode the encoded video data generated by source device 110 which may be referred to as a video decoding device.
  • Source device 110 may include a video source 112 , a video encoder 114 , and an input/output (I/O) interface 116 .
  • Video source 112 may include a source such as a video capture device, an interface to receive video data from a video content provider, and/or a computer graphics system for generating video data, or a combination of such sources.
  • the video data may comprise one or more pictures.
  • Video encoder 114 encodes the video data from video source 112 to generate a bitstream.
  • the bitstream may include a sequence of bits that form a coded representation of the video data.
  • the bitstream may include coded pictures and associated data.
  • the coded picture is a coded representation of a picture.
  • the associated data may include sequence parameter sets, picture parameter sets, and other syntax structures.
  • I/O interface 116 may include a modulator/demodulator (modem) and/or a transmitter.
  • the encoded video data may be transmitted directly to destination device 120 via I/O interface 116 through network 130 a .
  • the encoded video data may also be stored onto a storage medium/server 130 b for access by destination device 120 .
  • Destination device 120 may include an I/O interface 126 , a video decoder 124 , and a display device 122 .
  • I/O interface 126 may include a receiver and/or a modem. I/O interface 126 may acquire encoded video data from the source device 110 or the storage medium/server 130 b . Video decoder 124 may decode the encoded video data. Display device 122 may display the decoded video data to a user. Display device 122 may be integrated with the destination device 120 , or may be external to destination device 120 which be configured to interface with an external display device.
  • Video encoder 114 and video decoder 124 may operate according to a video compression standard, such as the HEVC standard, VVC standard and other current and/or further standards.
  • a video compression standard such as the HEVC standard, VVC standard and other current and/or further standards.
  • FIG. 15 is a block diagram illustrating an example of video encoder 200 , which may be video encoder 114 in the system 100 illustrated in FIG. 14 .
  • Video encoder 200 may be configured to perform any or all of the techniques of this disclosure.
  • video encoder 200 includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of video encoder 200 .
  • a processor may be configured to perform any or all of the techniques described in this disclosure.
  • the functional components of video encoder 200 may include a partition unit 201 , a predication unit 202 which may include a mode select unit 203 , a motion estimation unit 204 , a motion compensation unit 205 and an intra prediction unit 206 , a residual generation unit 207 , a transform unit 208 , a quantization unit 209 , an inverse quantization unit 210 , an inverse transform unit 211 , a reconstruction unit 212 , a buffer 213 , and an entropy encoding unit 214 .
  • a partition unit 201 may include a mode select unit 203 , a motion estimation unit 204 , a motion compensation unit 205 and an intra prediction unit 206 , a residual generation unit 207 , a transform unit 208 , a quantization unit 209 , an inverse quantization unit 210 , an inverse transform unit 211 , a reconstruction unit 212 , a buffer 213 , and an entropy encoding unit 214 .
  • video encoder 200 may include more, fewer, or different functional components.
  • predication unit 202 may include an intra block copy (IBC) unit.
  • the IBC unit may perform predication in an IBC mode in which at least one reference picture is a picture where the current video block is located.
  • IBC intra block copy
  • motion estimation unit 204 and motion compensation unit 205 may be highly integrated, but are represented in the example of FIG. 15 separately for purposes of explanation.
  • Partition unit 201 may partition a picture into one or more video blocks.
  • Video encoder 200 and video decoder 300 may support various video block sizes.
  • Mode select unit 203 may select one of the coding modes, intra or inter, e.g., based on error results, and provide the resulting intra- or inter-coded block to a residual generation unit 207 to generate residual block data and to a reconstruction unit 212 to reconstruct the encoded block for use as a reference picture.
  • Mode select unit 203 may select a combination of intra and inter predication (CIIP) mode in which the predication is based on an inter predication signal and an intra predication signal.
  • CIIP intra and inter predication
  • Mode select unit 203 may also select a resolution for a motion vector (e.g., a sub-pixel or integer pixel precision) for the block in the case of inter-predication.
  • motion estimation unit 204 may generate motion information for the current video block by comparing one or more reference frames from buffer 213 to the current video block.
  • Motion compensation unit 205 may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from buffer 213 other than the picture associated with the current video block.
  • Motion estimation unit 204 and motion compensation unit 205 may perform different operations for a current video block, for example, depending on whether the current video block is in an I slice, a P slice, or a B slice.
  • motion estimation unit 204 may perform uni-directional prediction for the current video block, and motion estimation unit 204 may search reference pictures of list 0 or list 1 for a reference video block for the current video block. Motion estimation unit 204 may then generate a reference index that indicates the reference picture in list 0 or list 1 that contains the reference video block and a motion vector that indicates a spatial displacement between the current video block and the reference video block. Motion estimation unit 204 may output the reference index, a prediction direction indicator, and the motion vector as the motion information of the current video block. Motion compensation unit 205 may generate the predicted video block of the current block based on the reference video block indicated by the motion information of the current video block.
  • motion estimation unit 204 may perform bi-directional prediction for the current video block, motion estimation unit 204 may search the reference pictures in list 0 for a reference video block for the current video block and may also search the reference pictures in list 1 for another reference video block for the current video block. Motion estimation unit 204 may then generate reference indexes that indicate the reference pictures in list 0 and list 1 containing the reference video blocks and motion vectors that indicate spatial displacements between the reference video blocks and the current video block. Motion estimation unit 204 may output the reference indexes and the motion vectors of the current video block as the motion information of the current video block. Motion compensation unit 205 may generate the predicted video block of the current video block based on the reference video blocks indicated by the motion information of the current video block.
  • motion estimation unit 204 may output a full set of motion information for decoding processing of a decoder.
  • motion estimation unit 204 may not output a full set of motion information for the current video. Rather, motion estimation unit 204 may signal the motion information of the current video block with reference to the motion information of another video block. For example, motion estimation unit 204 may determine that the motion information of the current video block is sufficiently similar to the motion information of a neighboring video block.
  • motion estimation unit 204 may indicate, in a syntax structure associated with the current video block, a value that indicates to the video decoder 300 that the current video block has the same motion information as another video block.
  • motion estimation unit 204 may identify, in a syntax structure associated with the current video block, another video block and a motion vector difference (MVD).
  • the motion vector difference indicates a difference between the motion vector of the current video block and the motion vector of the indicated video block.
  • the video decoder 300 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.
  • video encoder 200 may predictively signal the motion vector.
  • Two examples of predictive signaling techniques that may be implemented by video encoder 200 include advanced motion vector predication (AMVP) and merge mode signaling.
  • AMVP advanced motion vector predication
  • merge mode signaling merge mode signaling
  • Intra prediction unit 206 may perform intra prediction on the current video block. When intra prediction unit 206 performs intra prediction on the current video block, intra prediction unit 206 may generate prediction data for the current video block based on decoded samples of other video blocks in the same picture.
  • the prediction data for the current video block may include a predicted video block and various syntax elements.
  • Residual generation unit 207 may generate residual data for the current video block by subtracting (e.g., indicated by the minus sign) the predicted video block(s) of the current video block from the current video block.
  • the residual data of the current video block may include residual video blocks that correspond to different sample components of the samples in the current video block.
  • residual generation unit 207 may not perform the subtracting operation.
  • Transform processing unit 208 may generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to a residual video block associated with the current video block.
  • quantization unit 209 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values associated with the current video block.
  • QP quantization parameter
  • Inverse quantization unit 210 and inverse transform unit 211 may apply inverse quantization and inverse transforms to the transform coefficient video block, respectively, to reconstruct a residual video block from the transform coefficient video block.
  • Reconstruction unit 212 may add the reconstructed residual video block to corresponding samples from one or more predicted video blocks generated by the predication unit 202 to produce a reconstructed video block associated with the current block for storage in the buffer 213 .
  • loop filtering operation may be performed reduce video blocking artifacts in the video block.
  • Entropy encoding unit 214 may receive data from other functional components of the video encoder 200 . When entropy encoding unit 214 receives the data, entropy encoding unit 214 may perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream that includes the entropy encoded data.
  • FIG. 16 is a block diagram illustrating an example of video decoder 300 which may be video decoder 114 in the system 100 illustrated in FIG. 14 .
  • the video decoder 300 may be configured to perform any or all of the techniques of this disclosure.
  • the video decoder 300 includes a plurality of functional components.
  • the techniques described in this disclosure may be shared among the various components of the video decoder 300 .
  • a processor may be configured to perform any or all of the techniques described in this disclosure.
  • video decoder 300 includes an entropy decoding unit 301 , a motion compensation unit 302 , an intra prediction unit 303 , an inverse quantization unit 304 , an inverse transformation unit 305 , a reconstruction unit 306 and a buffer 307 .
  • Video decoder 300 may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder 200 (e.g., FIG. 15 ).
  • Entropy decoding unit 301 may retrieve an encoded bitstream.
  • the encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data).
  • Entropy decoding unit 301 may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit 302 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit 302 may, for example, determine such information by performing the AMVP and merge mode.
  • Motion compensation unit 302 may produce motion compensated blocks, possibly performing interpolation based on interpolation filters. Identifiers for interpolation filters to be used with sub-pixel precision may be included in the syntax elements.
  • Motion compensation unit 302 may use interpolation filters as used by video encoder 200 during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. Motion compensation unit 302 may determine the interpolation filters used by video encoder 200 according to received syntax information and use the interpolation filters to produce predictive blocks.
  • Motion compensation unit 302 may use some of the syntax information to determine sizes of blocks used to encode frame(s) and/or slice(s) of the encoded video sequence, partition information that describes how each macroblock of a picture of the encoded video sequence is partitioned, modes indicating how each partition is encoded, one or more reference frames (and reference frame lists) for each inter-encoded block, and other information to decode the encoded video sequence.
  • Intra prediction unit 303 may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks.
  • Inverse quantization unit 304 inverse quantizes, i.e., de-quantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 301 .
  • Inverse transform unit 305 applies an inverse transform.
  • Reconstruction unit 306 may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit 202 or intra-prediction unit 303 to form decoded blocks. If desired, a deblocking filter may also be applied to filter the decoded blocks in order to remove blockiness artifacts.
  • the decoded video blocks are then stored in buffer 307 , which provides reference blocks for subsequent motion compensation/intra predication and also produces decoded video for presentation on a display device.
  • FIG. 17 is a flowchart representation of a method 1700 for video processing in accordance with the present technology.
  • the method 1700 includes, at operation 1710 , performing a conversion between a block of a video and a bitstream of the video.
  • the bitstream conforms to a formatting rule specifying that a size of a merge estimation region (MER) is indicated in the bitstream and the size of the MER is based on a dimension of a video unit.
  • the MER comprises a region used for deriving a motion candidate for the conversion.
  • the video unit comprises a coding unit or a coding tree unit.
  • the dimension of the video unit comprises at least a width, a height, or an area of the video unit.
  • the dimension of the MER is constrained to be smaller than the dimension of the video unit. In some embodiments, the dimension of the MER is constrained to be smaller than or equal to the dimension of the video unit.
  • the dimension of the MER is indicated as an index value in the bitstream.
  • the index value has a one-to-one mapping relationship with the dimension of the MER.
  • the dimension of the MER or the index value is coded in the bitstream based on an exponential Golomb code.
  • the dimension of the MER or the index value is coded in the bitstream based on a unary code, a rice code, or a fixed length code.
  • the index indicating the dimension of the MER is represented as S-A or M-S in the bitstream representation, where S represents the dimension of the MER, and A and/or M are integer values.
  • the A and/or M are determined based on the dimension of the maximum or minimum video unit. In some embodiments, A is equal to the dimension of the minimum video unit. In some embodiments, M is equal to the dimension of the maximum video unit. In some embodiments, A is equal to (the dimension of the minimum video unit+offset), offset being an integer. In some embodiments, M is equal to (the dimension of the maximum video unit+offset), offset being an integer. In some embodiments, the offset is equal to 1 or ⁇ 1.
  • FIG. 18 is a flowchart representation of a method 1800 for video processing in accordance with the present technology.
  • the method 1800 includes, at operation 1810 , performing a conversion between a block of a video and a bitstream of the video in a palette coding mode in which a palette of representative sample values is used for coding the block of video in the bitstream.
  • a maximum number of palette size or palette predictor size used in the palette mode is restricted to m ⁇ N, m and N being positive integers.
  • N is equal to 8.
  • a value associated with m is signaled as a syntax element in the bitstream.
  • the value comprises m or m+offset, where offset is an integer.
  • the syntax element is binarized in the bitstream based on unary coding, exponential Golomb coding, rice coding, or fixed length coding.
  • FIG. 19 is a flowchart representation of a method 1900 for video processing in accordance with the present technology.
  • the method 1900 includes, at operation 1910 , determining, for a conversion between a current block of a video and a bitstream of the video, that a deblocking filtering process is disabled for a boundary of the current block in case the boundary coincides with a boundary of a sub-picture having a sub-picture index X and a loop filtering operation is disabled across boundaries of the subpicture, X being a non-negative integer.
  • the method 1900 also includes, at operation 1920 , performing the conversion based on the determining.
  • the deblocking filtering process is applicable to vertical boundaries, and the deblocking filtering process is disabled for a left boundary of the current block in case the left boundary coincides with a left or a right boundary of the sub-picture having the sub-picture index X and the loop filtering operation is disabled across boundaries of the subpicture.
  • the deblocking filtering process is applicable to horizontal boundaries, and the deblocking filtering process is disabled for a top boundary of the current block in case the top boundary coincides with a top or a bottom boundary of the sub-picture having the sub-picture index X and the loop filtering operation is disabled across boundaries of the sub-picture.
  • the conversion generates the video from the bitstream representation. In some embodiments, the conversion generates the bitstream representation from the video.
  • a method for storing bitstream of a video includes generating a bitstream of the video from a block and storing the bitstream in a non-transitory computer-readable recording medium.
  • the bitstream conforms to a formatting rule that specifies a size of a merge estimation region (MER) is indicated in the bitstream and the size of the MER is based on a dimension of a size of a video unit.
  • the MER comprises a region used for deriving a motion candidate for the conversion.
  • a method for storing bitstream of a video includes applying, during a conversion between a block of a video and a bitstream of the video, a palette coding mode in which a palette of representative sample values is used for coding the block of video in the bitstream, generating the bitstream from the block based on the applying, and storing the bitstream in a non-transitory computer-readable recording medium.
  • a maximum number of palette size or palette predictor size used in the palette mode is restricted to m ⁇ N, m and N being positive integers.
  • a method for storing bitstream of a video includes determining that a deblocking filtering process is disabled for a boundary of a current block in case the boundary coincides with a boundary of a sub-picture having a sub-picture index X and a loop filtering operation is disabled across boundaries of the subpicture, X being a non-negative integer.
  • the method also includes generating the bitstream from the current block based on the determining and storing the bitstream in a non-transitory computer-readable recording medium.
  • Some embodiments of the disclosed technology include making a decision or determination to enable a video processing tool or mode.
  • the encoder when the video processing tool or mode is enabled, the encoder will use or implement the tool or mode in the processing of a block of video, but may not necessarily modify the resulting bitstream based on the usage of the tool or mode. That is, a conversion from the block of video to the bitstream representation of the video will use the video processing tool or mode when it is enabled based on the decision or determination.
  • the decoder when the video processing tool or mode is enabled, the decoder will process the bitstream with the knowledge that the bitstream has been modified based on the video processing tool or mode. That is, a conversion from the bitstream representation of the video to the block of video will be performed using the video processing tool or mode that was enabled based on the decision or determination.
  • Some embodiments of the disclosed technology include making a decision or determination to disable a video processing tool or mode.
  • the encoder will not use the tool or mode in the conversion of the block of video to the bitstream representation of the video.
  • the decoder will process the bitstream with the knowledge that the bitstream has not been modified using the video processing tool or mode that was enabled based on the decision or determination.
  • the disclosed and other solutions, examples, embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them.
  • the disclosed and other embodiments can be implemented as one or more computer program products, e.g., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus.
  • the computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them.
  • data processing apparatus encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers.
  • the apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.
  • a propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.
  • a computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.
  • a computer program does not necessarily correspond to a file in a file system.
  • a program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code).
  • a computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
  • the processes and logic flows described in this document can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output.
  • the processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).
  • processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer.
  • a processor will receive instructions and data from a read only memory or a random-access memory or both.
  • the essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data.
  • a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
  • mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
  • a computer need not have such devices.
  • Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks.
  • semiconductor memory devices e.g., EPROM, EEPROM, and flash memory devices
  • magnetic disks e.g., internal hard disks or removable disks
  • magneto optical disks e.g., CD ROM and DVD-ROM disks.
  • the processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

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MX2022008384A (es) 2022-08-08
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