Abstract: Apparatuses and methods for Intra Sub-Partitions (ISP) are provided. The method includes: obtaining information of ISP, and determining a size of a chroma transform block (TB) of the coding unit based on SubWidthC and SubHeightC when at least a first condition is fulfilled. The first condition includes the information of ISP indicates that ISP is used for splitting the luma coding block. SubWidthC and SubHeightC are variables depending on chroma format information. The chroma format information indicates a chroma format of a picture the coding unit belongs to. The method can apply to all chroma format. The chroma format includes at least one of: 4:2:0, or 4:2:2, or 4:4:4. An accurate and versatile way to determine the size of the chroma transform block for the ISP is achieved.

Abstract: An image prediction method, apparatus, and system, a device, and a storage medium are provided. The method includes: (401) obtaining a split mode of a current node, where the current node is an image block in a coding tree unit in a current image; (402) determining, based on the split mode of the current node and a size of the current node, whether the current node satisfies a first condition; and (403) when it is determined that the current node satisfies the first condition, performing intra prediction on all coding blocks belonging to the current node, to obtain predictors of all the coding blocks belonging to the current node.

Abstract: A mechanism for position dependent spatial varying transform (SVT) for video coding. A prediction block and a corresponding transformed residual block are received at a decoder. A type of spatial varying transform (SVT) employed to generate the transformed residual block is determined. A position of the SVT relative to the transformed residual block is also determined. An inverse of the SVT is applied to the transformed residual block to reconstruct a reconstructed residual block. The reconstructed residual block is then combined with the prediction block to reconstruct an image block.

Abstract: The present disclosure discloses a video decoding method and a video decoder. The method includes: parsing coding tree split information to obtain a current node; determining coordinates of an upper-left corner of a region covered by a current quantization group based on a depth N of the current node; obtaining a QP delta of a current CU in the region covered by the current quantization group; and obtaining a reconstructed picture of the current CU based on the QP delta of the current CU.

Abstract: A video decoding device receives a bitstream including a prediction block and a residual block with coefficients transformed by a Spatial Varying Transform (SVT). The video decoding device determines a type of SVT employed to transform the coefficients in the residual block and determines a position of the SVT relative to the residual block by determining a candidate position step size and a position index for the SVT. The video decoding device applies an inverse transform to the coefficients based on the SVT type and position to create a reconstructed residual block. The video decoding device applies the reconstructed residual block to the prediction block to reconstruct a video block and reconstructs a video sequence for display, the video sequence including a video frame that includes the reconstructed video block.

Abstract: A method of coding implemented by a decoding device or encoding device, the method comprising obtaining a bitstream, the bitstream comprises a transform unit syntax; the syntax comprises at least two cbf flags for chroma blocks (in an example, transform unit syntax correspond to either transform unit or sub-transform units which include two chroma cbf flags: tu_cbf_cb and tu_cbf_cb—one flag for each chroma plane), a chroma cbf flag specifies whether certain block has residue in correspondent color plane; deriving a value of a luma cbf flag tu_cbf_luma based on one or any combination of a value of a cu_cbf flag, values of two chroma cbf flags corresponding to a current transform unit or sub-transform unit, location of the sub-transform unit within transform unit, values of luma and chroma cbf flags correspondent to previous sub-transform units in the current transform unit.

Abstract: A picture encoding/decoding method and a related apparatus are provided. The picture decoding method includes obtaining a current picture from a video, the current picture being segmented using random access points into multiple video segments supporting a random access function; selecting, from a knowledge base, K reference pictures of the current picture, wherein at least one reference picture in the knowledge base does not belong to a random access segment in which the current picture is located, the random access segment comprising a picture sequence arranged in a decoding order from a closest random access point before the current picture to a closest random access point after the current picture; and decoding the current picture according to the K reference pictures.

Abstract: The present disclosure discloses a video decoding method, including: parsing a received bitstream to obtain prediction information of a CU; obtaining a target transform mode of a residual TU; parsing the received bitstream to obtain transform coefficients of the residual TU; applying an inverse quantization to the transform coefficients of the residual TU to obtain dequantized coefficients; applying, based on the target transform mode, an inverse transform to the dequantized coefficients to obtain a residual block of the residual TU; obtaining a prediction block of the CU based on the prediction information; and obtaining a video block based on the residual block and the prediction block; and outputting a video sequence, the video sequence including a video frame that includes the video block.

Abstract: This application discloses a quantization parameter (QP) setting method includes: determining that a current coding unit (CU) is a chroma CU; and separately performing the following processing on at least one luma CU: when the at least one luma CU has no residual, and both a previous luma CU and a luma-chroma CU that have been encoded before the at least one luma CU in the current quantization group (QG) have no residual, modifying a basic QP of the at least one luma CU to a predictive QP; setting a basic QP of the current CU to the basic QP of the at least one luma CU corresponding to the preset position of the current CU; and performing encoding processing on the current CU based on the basic QP of the current CU.

Abstract: The present disclosure discloses a video decoding method, including: parsing a received bitstream to obtain prediction information of a CU; obtaining a target transform mode of a residual TU; parsing the received bitstream to obtain transform coefficients of the residual TU; applying an inverse quantization to the transform coefficients of the residual TU to obtain dequantized coefficients; applying, based on the target transform mode, an inverse transform to the dequantized coefficients to obtain a residual block of the residual TU; obtaining a prediction block of the CU based on the prediction information; and obtaining a video block based on the residual block and the prediction block; and outputting a video sequence, the video sequence including a video frame that includes the video block.

Abstract: Techniques are described of a linear model prediction mode. A set of reconstructed neighboring luma samples are determined. Two pairs of luma value and chroma value are determined according to N reconstructed neighboring luma samples, N reconstructed neighboring chroma samples, M reconstructed neighboring luma samples, and M reconstructed neighboring chroma samples. The minimum value of the N reconstructed neighboring luma samples is not less than the maximum luma value of the remaining reconstructed neighboring luma samples of the set of reconstructed neighboring luma samples. The maximum value of the M reconstructed neighboring luma samples is not larger than the minimum luma value of the remaining reconstructed neighboring luma samples of the set of reconstructed neighboring luma samples. M>1 and N>1. Linear model parameters are determined based on the two pairs of luma value and chroma value, and a predictive block is determined based on the linear model parameters.

Abstract: A context modeling method and apparatus of a split flag are provided. The method includes: obtaining a height and a width of a current node, a height of a first leaf node in a first direction, and a width of a second leaf node in a second direction; determining whether the current node meets a first preset condition and a second preset condition, where the first preset condition includes the height of the current node is greater than the height of the first leaf node, and the second preset condition includes the width of the current node is greater than the width of the second leaf node; and determining a context model of a split flag of the current node based on whether the first and second preset conditions are met.

Abstract: A picture partitioning method and apparatus are described. The method includes determining a split mode of a current node, where the current node includes a luma block and a chroma block. The method further includes determining, based on the split mode of the current node and a size of the current node, that the chroma block of the current node is not further split. In accordance with the chroma block of the current node not being further split, the method includes splitting the luma block of the current node based on the split mode of the current node. In accordance with the chroma block of the current node not being further split, the method may be used to split only the luma block of the current node, thereby improving encoding and decoding efficiency, reducing a maximum throughput of a codec, and facilitating implementation of the codec.

Abstract: A mechanism for position dependent spatial varying transform (SVT) for video coding. A prediction block and a corresponding transformed residual block are received at a decoder. A type of spatial varying transform (SVT) employed to generate the transformed residual block is determined. A position of the SVT relative to the transformed residual block is also determined. An inverse of the SVT is applied to the transformed residual block to reconstruct a reconstructed residual block. The reconstructed residual block is then combined with the prediction block to reconstruct an image block.

Abstract: Embodiments of this application disclose a decoding method includes: obtaining a bitstream including picture data; parsing the bitstream to obtain node split mode information of a first-level coding tree and node split mode information of a second-level coding tree, if the split mode corresponding to the first node is no further splitting, parsing the bitstream to obtain encoding information of the first node; and decoding and reconstructing, based on the encoding information of the first node, a coding unit corresponding to the first node, to obtain a picture corresponding to the picture data.

Abstract: A method includes parsing a transform coefficient of a transform block in a current coding unit to obtain a first transform coefficient matrix. The method also includes obtaining a quantity K of non-zero transform coefficients in a top-left preset region of the first transform coefficient matrix. The method also includes parsing an index value based on the quantity K being greater than a threshold. The method also includes determining a transform matrix based on the index value. The method also includes multiplying N transform coefficients of the first transform coefficient matrix by the transform matrix to obtain M transform coefficients. The method also includes updating the first transform coefficient matrix by using the M transform coefficients to obtain a second transform coefficient matrix. The method also includes performing an inverse transform on the second transform coefficient matrix to obtain residual samples of the current coding unit.

Abstract: A video decoding method includes determining a usage of an SVT-vertical (V) or an SVT-horizontal (H) for a residual block; determining a transform block position of a transform block of the residual block; determining a transform type of the transform block, wherein the transform type indicates a horizontal transform and a vertical transform for the transform block, wherein at least one of the horizontal transform or the vertical transform is a discrete sine transform (DST)-7; and reconstructing the residual block based on the transform type, the transform block position, and transform coefficients of the transform block.

Abstract: A picture encoding/decoding method and a related apparatus are provided. The picture decoding method includes obtaining a current picture; selecting, from a knowledge base, K reference pictures of the current picture, where at least one picture in the knowledge base does not belong to a random access segment in which the current picture is located and wherein K is an integer greater than or equal to 1; and decoding the current picture according to the K reference pictures.

Abstract: This application discloses a method for constructing an MPM list, a method for obtaining an intra prediction mode of a chroma block, and an apparatus. In a specific implementation, a MIP mode is used for a current block, and the method for constructing an MPM list includes: obtaining intra prediction mode information of a neighboring block; determining, based on the intra prediction mode information of the neighboring block, whether an intra prediction mode of the neighboring block is the MIP mode; and skipping using the intra prediction mode of the neighboring block for MPM list construction of the current block if the intra prediction mode of the neighboring block is not the MIP mode; or using the intra prediction mode of the neighboring block for MPM list construction of the current block if the intra prediction mode of the neighboring block is the MIP mode.

Abstract: Embodiments of this application disclose a decoding method includes: obtaining a bitstream including picture data; parsing the bitstream to obtain node split mode information of a first-level coding tree and node split mode information of a second-level coding tree, if the split mode corresponding to the first node is no further splitting, parsing the bitstream to obtain encoding information of the first node; and decoding and reconstructing, based on the encoding information of the first node, a coding unit corresponding to the first node, to obtain a picture corresponding to the picture data.