# US 11,445,208 B2 · Method and apparatus for video coding > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,445,208 B2 - Document ID: US11445208B2 - Status: Granted - Kind: B2 - Application number: 17/060,652 - Filed: 2020-10-01 - Published: 2021-06-24 - Granted: 2022-09-13 - Earliest claimed: 2019-12-23 - Assignees: Tencent America LLC - Applicants: Tencent America LLC - Inventors: Guichun Li; Xiang Li; Shan Liu; Xiaozhong Xu - Web page: https://patentgrep.com/patent/US11445208B2 ## CPC - H04N 19/44: Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder - H04N 19/119: Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks - H04N 19/132: Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/186: the unit being a colour or a chrominance component - H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N 19/96: Tree coding, e.g. quad-tree coding - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Aspects of the disclosure provide a method and an apparatus including processing circuitry for video decoding. The processing circuitry decodes partition information from a coded video bitstream. The partition information indicates that a chroma coding tree structure in a dual tree is applied to a chroma block and indicates a block size of the chroma block in luma samples and a minimum allowed chroma quaternary tree (QT) leaf node size in luma samples. The processing circuitry determines whether the block size of the chroma block in luma samples is less than or equal to the minimum allowed chroma QT leaf node size in luma samples. In response to the block size of the chroma block in luma samples being less than or equal to the minimum allowed chroma QT leaf node size in luma samples, the processing circuitry determines that a QT split is disallowed for the chroma block. ## Claims ### Claim 1 A method for video decoding in a decoder, comprising: decoding partition information from a coded video bitstream, the partition information indicating that a chroma coding tree structure in a dual tree is applied to a chroma block, the partition information further indicating a block size cbSize of the chroma block in luma samples and a minimum allowed chroma quaternary tree (QT) leaf node size MinQtSizeC in luma samples, the MinQtSizeC indicating a minimum allowed chroma block size for QT splitting; determining whether the block size cbSize of the chroma block in luma samples is less than or equal to the minimum allowed chroma QT leaf node size MinQtSizeC in luma samples such that cbSize<=MinQtSizeC; and in response to the block size cbSize of the chroma block in luma samples being less than or equal to the minimum allowed chroma QT leaf node size MinQtSizeC in luma samples, determining that a QT split is disallowed for the chroma block. ### Claim 2 (depends on 1) The method of claim 1, wherein the partition information further indicates a multi-type tree (MTT) depth indicating whether the chroma block is a MTT node from a MTT split, a chroma horizontal subsampling factor, and a prediction mode type for the chroma block; and in response to the block size cbSize of the chroma block in luma samples being larger than the minimum allowed chroma QT leaf node size MinQtSizeC in luma samples, determining that the QT split is disallowed for the chroma block based on at least one of (i) the MTT depth indicating that the chroma block is the MTT node, (ii) the block size cbSize of the chroma block in luma samples divided by the chroma horizontal subsampling factor being less than or equal to 4, and (iii) the prediction mode type indicating that an intra prediction mode and an intra block copy (IBC) mode are allowed. ### Claim 3 (depends on 1) The method of claim 1, wherein the partition information further indicates a minimum allowed chroma coding block size in luma samples and a minimum allowed luma coding block size in luma samples; and the minimum allowed chroma coding block size in luma samples is less than the minimum allowed luma coding block size in luma samples. ### Claim 4 (depends on 3) The method of claim 3, wherein the coded video bitstream includes a chroma syntax element indicating the minimum allowed chroma coding block size in luma samples and a luma syntax element indicating the minimum allowed luma coding block size in luma samples. ### Claim 5 (depends on 3) The method of claim 3, wherein the minimum allowed chroma coding block size in luma samples is derived based on the minimum allowed luma coding block size in luma samples. ### Claim 6 (depends on 1) The method of claim 1, wherein the partition information further indicates a minimum allowed luma QT leaf node size MinQtSizeY in luma samples, and the MinQtSizeC in luma samples is less than the MinQtSizeY in luma samples. ### Claim 7 A method for video decoding in a decoder, comprising: decoding partition information from a coded video bitstream, the partition information indicating that a chroma coding tree structure in a dual tree is applied to a chroma block, the partition information further indicating a block size of the chroma block in luma samples, a chroma vertical subsampling factor, and a minimum allowed chroma quaternary tree (QT) leaf node size; determining a parameter that is equal to the minimum allowed chroma QT leaf node size in luma samples multiplied by the chroma vertical subsampling factor and divided by a chroma horizontal subsampling factor; and determining that a QT split is disallowed for the chroma block in response to the block size of the chroma block in luma samples being less than or equal to the parameter; and in response to the QT split being disallowed for the chroma block, determining whether at least one of a binary tree split and a ternary tree split is disallowed for the chroma block. ### Claim 8 (depends on 7) The method of claim 7, wherein the minimum allowed chroma QT leaf node size is in luma samples, the partition information further indicates the chroma horizontal subsampling factor, and the determining whether the QT split is disallowed includes determining whether the QT split is disallowed for the chroma block based at least on the block size of the chroma block in luma samples, the chroma vertical subsampling factor, the chroma horizontal subsampling factor, and the minimum allowed chroma QT leaf node size in luma samples. ### Claim 9 (depends on 8) The method of claim 8, wherein the partition information further indicates a multi-type tree (MTT) depth indicating whether the chroma block is a MTT node from a MTT split and a prediction mode type for the chroma block; and the determining whether the QT split is disallowed includes determining whether the QT split is disallowed for the chroma block further based on the MTT depth and the prediction mode type. ### Claim 10 (depends on 7) The method of claim 7, wherein the partition information further indicates a minimum allowed chroma coding block size in luma samples and a minimum allowed luma coding block size in luma samples; and the minimum allowed chroma coding block size in luma samples is less than the minimum allowed luma coding block size in luma samples. ### Claim 11 (depends on 10) The method of claim 10, wherein the coded video bitstream includes a chroma syntax element indicating the minimum allowed chroma coding block size in luma samples and a luma syntax element indicating the minimum allowed luma coding block size in luma samples. ### Claim 12 (depends on 10) The method of claim 10, wherein the minimum allowed chroma coding block size in luma samples is derived based on the minimum allowed luma coding block size in luma samples. ### Claim 13 (depends on 7) The method of claim 7, wherein the partition information further includes a minimum allowed luma QT leaf node size in luma samples; and the minimum allowed chroma QT leaf node size in luma samples is less than the minimum allowed luma QT leaf node size in luma samples. ### Claim 14 (depends on 7) The method of claim 7, wherein the minimum allowed chroma QT leaf node size is in chroma samples; and the determining whether the QT split is disallowed includes determining that the QT split is disallowed for the chroma block based on the block size of the chroma block in luma samples divided by the chroma vertical subsampling factor being less than or equal to the minimum allowed chroma QT leaf node size in chroma samples. ### Claim 15 (depends on 14) The method of claim 14, wherein the partition information further indicating the chroma horizontal subsampling factor, a MTT depth indicating whether the chroma block is a MTT node from a MTT split, and a prediction mode type for the chroma block; and in response to the block size of the chroma block in luma samples divided by the chroma vertical subsampling factor being larger than the minimum allowed chroma QT leaf node size in chroma samples, the method further includes: determining whether the QT split is disallowed for the chroma block based on the block size of the chroma block in luma samples, the chroma horizontal subsampling factor, the MTT depth, and the prediction mode type. ### Claim 16 An apparatus for video decoding, comprising processing circuitry configured to: decode partition information from a coded video bitstream, the partition information indicating that a chroma coding tree structure in a dual tree is applied to a chroma block, the partition information further indicating a block size cbSize of the chroma block in luma samples and a minimum allowed chroma quaternary tree (QT) leaf node size MinQtSizeC in luma samples, the MinQtSizeC indicating a minimum allowed chroma block size for QT splitting; determine whether the block size cbSize of the chroma block in luma samples is less than or equal to the minimum allowed chroma QT leaf node size MinQtSizeC in luma samples such that cbSize<=MinQtSizeC; and in response to the block size cbSize of the chroma block in luma samples being less than or equal to the minimum allowed chroma QT leaf node size MinQtSizeC in luma samples, determine that a QT split is disallowed for the chroma block. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the partition information further indicates a multi-type tree (MTT) depth indicating whether the chroma block is a MTT node from a MTT split, a chroma horizontal sub sampling factor, and a prediction mode type for the chroma block; and in response to the block size cbSize of the chroma block in luma samples being larger than the minimum allowed chroma QT leaf node size MinQtSizeC in luma samples, the processing circuitry is configured to determine that the QT split is disallowed for the chroma block based on at least one of (i) the MTT depth indicating that the chroma block is the MTT node, (ii) the block size cbSize of the chroma block in luma samples divided by the chroma horizontal subsampling factor being less than or equal to 4, and (iii) the prediction mode type indicating that an intra prediction mode and an intra block copy (IBC) mode are allowed. ### Claim 18 (depends on 16) The apparatus of claim 16, wherein the partition information further indicates a minimum allowed chroma coding block size in luma samples and a minimum allowed luma coding block size in luma samples; and the minimum allowed chroma coding block size in luma samples is less than the minimum allowed luma coding block size in luma samples. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein the coded video bitstream includes a chroma syntax element indicating the minimum allowed chroma coding block size in luma samples and a luma syntax element indicating the minimum allowed luma coding block size in luma samples. ### Claim 20 (depends on 18) The apparatus of claim 18, wherein the minimum allowed chroma coding block size in luma samples is derived based on the minimum allowed luma coding block size in luma samples.