Abstract: An example method of video processing includes performing a conversion between a video and a bitstream representation of the video. The bitstream representation conforms to a format rule that specifies, in case a first syntax element is included in a first video unit in the bitstream representation, whether a corresponding second syntax element in a second video unit is included in the bitstream representation.

Abstract: Devices, systems and methods for video processing are described. An exemplary method for video processing includes determining, for a block of a video, a quantization parameter associated with the block, coding the block of the video into a bitstream representation of the video as a palette coded block in part based on a modified value of the quantization parameter, and signaling coded information related to the quantization parameter in the bitstream representation.

Abstract: Systems, methods and apparatus for video processing are described. The video processing may include video encoding, video decoding, or video transcoding. One example method of video processing includes performing a conversion between a video and a bitstream of the video according to a format rule. The format rule specifies that constraints on values of one or more first syntax elements in an adaptation parameter set are defined based on semantics of second syntax elements in a picture header and/or a slice header if a picture or a slice referring to the adaptation parameter set.

Abstract: A video processing method includes determining, fora conversion between a video block of a video and a coded representation of the video, factors of a scaling tool based on a coding mode of the video block; and performing the conversion using the scaling tool, wherein the use of the scaling tool comprises: scaling at least some coefficients representing the video block during encoding or descaling at least some coefficients from the coded representation during decoding.

Abstract: Devices, systems and methods for digital video coding, which includes matrix-based intra prediction methods for video coding, are described. In a representative aspect, a method for video processing includes generating, for a conversion between a current video block of a video including multiple video blocks and a bitstream representation of the video, a most probable mode (MPM) list for a matrix based intra prediction (MIP) tool based on a rule, where, the MIP tool includes determining, during the conversion, a prediction block of the current video block by performing, on previously coded samples of the video, a boundary downsampling operation, followed by a matrix vector multiplication operation, and selectively followed by an upsampling operation, and where the rule specifies a mapping between a number of MIP modes and dimensions of the multiple video blocks; and performing the conversion based on the generating.

Abstract: A method of video processing is described. The method includes determining, for a conversion between a current video block of a video and a coded representation of the video, whether a certain partitioning scheme is allowed for the current video block according to a rule that depends on a coding mode type used for representing the current video block in the coded representation and a dimension of the current video block; and performing the conversion based on the determining.

Abstract: A method of video processing is described. The method includes determining, for a conversion between a current video block of a current picture of a video and a coded representation of the video, an applicability of an alternative interpolation filter, wherein the applicability of the alternative interpolation filter indicates whether to apply the alternative interpolation filter in the conversion; and performing the conversion based on the determining; wherein the applicability of the alternative interpolation filter is determined based on whether a reference picture resampling in which a reference picture of the current picture is resampled to perform the conversion is used.

Abstract: A video processing method includes performing a conversion between a video including one or more pictures and a bitstream of the video. The bitstream conforms to a format rule specifying that one or more syntax elements indicative of coding information are selectively included in a picture parameter set of the bitstream responsive to whether it is indicated that each picture referring to the picture parameter set includes a single slice.

Abstract: A method of video processing is described. The method includes determining, for a conversion between a video region of a video and a coded representation of the video, an intra coding characteristic of the video region based on a color format of the video according to a rule; and performing the conversion according to the intra coding characteristic.

Abstract: Devices, systems and methods for video processing are described. An example method for video processing includes performing a conversion between a video comprising luma blocks and corresponding chroma blocks and a bitstream representation of the video according to a rule that specifies that, for a case that a current luma block is coded using a palette coding mode and a corresponding current chroma block coded with a derived mode, the current luma block is treated as having a default intra prediction mode and the current chroma block is coded with the default intra prediction mode.

Abstract: A method for video processing is provided. The method includes performing downsampling on chroma and luma samples of a neighboring block of the current video block; determining, for a conversion between a current video block of a video that is a chroma block and a coded representation of the video, parameters of cross-component linear model (CCLM) based on the downsampled chroma and luma samples obtained from the downsampling; applying the CCLM on luma samples located in a luma block corresponding to the current video block to derive prediction values of the current video block; and performing the conversion based on the prediction values.

Abstract: A method for video processing includes performing a conversion between a current video block and a bitstream representation of the current video block using an inter-prediction coding scheme based on an n-order polynomial model using a first variable associated with the current video block, where n is an integer greater than or equal to zero, wherein the conversion includes generating the current video block from the bitstream representation or generating the bitstream representation from the current video block; and performing illumination compensation for the current video block using the n-order polynomial model during the conversion.

Abstract: A method of video processing is provided to include: deciding a coding mode used for representing a current video block of a video in a coded representation of the video; and coding the current video block into the coded representation according to the coding mode, wherein use of alternative half-pel accuracy filters in addition to a default half-pel accuracy filter for representing motion information is disabled for the current video block due to use of the coding mode.

Abstract: A method of video processing is described. The method includes: making a first determination about whether a collocated video block of a video block of a video is coded using an inter coding mode or a non-inter coding mode; making a second determination, based on the first determination, about availability of motion vectors of the collocated video block or a mode of derivation of motion vectors for the collocated video block; and performing a conversion between the video block and a coded representation of the video based on the second determination.

Abstract: A video processing method includes performing a conversion between a video block of a video and a coded representation of the video, wherein the coded representation conforms to a format rule, wherein the format rule specifies that applicability of a transform skip mode to the video block is determined by a coding condition of the video block, wherein the format rule specifies that a syntax element indicative of applicability of the transform skip mode is omitted from the coded representation, and wherein the transform skip mode includes, skipping applying a forward transform to at least some coefficients prior to encoding into the coded representation, or during decoding, skipping applying an inverse transform to at least some coefficients prior to decoding from the coded representation.

Abstract: Systems, methods and apparatus for video processing are described. The video processing may include video encoding, video decoding, or video transcoding. One example method of video processing includes performing a conversion between a video including one or more video regions and a bitstream of the video according to a format rule. The format rule specifies that a variable X indicates whether B slice is allowed or used in a video region. The format rule further specifies that the variable X is based on values of a reference picture list information present flag and/or a field indicating a number of entries in a reference picture list syntax structure.

Abstract: Systems, methods and apparatus for video processing are described. The video processing may include video encoding, video decoding, or video transcoding. One example method of video processing includes performing a conversion between a video and a bitstream of the video according to a format rule. The format rule specifies that a first field at a sequence level or a picture level or a slice level controls a value of a second field in an adaptation parameter set.

Abstract: Techniques for coding and deriving (e.g., determining) one or more coded-block-flags associated with video content are described herein. A coded-block-flag of a last node may be determined when coded-block-flags of preceding nodes are determined to be a particular value and when a predetermined condition is satisfied. In some instances, the predetermined condition may be satisfied when log2(size of current transform unit) is less than log2(size of maximum transform unit) or log2(size of current coding unit) is less than or equal to log2(size of maximum transform unit)+1. The preceding nodes may be nodes that precede the last node on a particular level in a residual tree.

Abstract: Devices, systems and methods for digital video coding, which includes matrix-based intra prediction methods for video coding, are described. In a representative aspect, a method for video processing includes performing a conversion between a current video block of a video and a bitstream representation of the current video block using a matrix based intra prediction (MIP) mode in which a prediction block of the current video block is determined by performing, on reference boundary samples located to a left of the current video block and located to a top of the current video block, a boundary downsampling operation, followed by a matrix vector multiplication operation, and selectively followed by an upsampling operation, where instead of reduced boundary samples calculated from the reference boundary samples of the current video block in the boundary downsampling operation, the reference boundary samples are directly used for a prediction process in the upsampling operation.

Abstract: Devices, systems and methods for palette mode coding are described. An exemplary method for video processing includes performing a conversion between a block of a video and a bitstream representation of the video. The bitstream representation is processed according to a format rule that specifies a first indication of usage of a palette mode and a second indication of usage of an intra block copy (IBC) mode are signaled dependent of each other.