Abstract: An example method of video processing includes performing a conversion between a block of a chroma component of a video and a bitstream representation of the video. During the conversion, a deblocking filter process is applied to at least some samples along an edge of the block, and wherein chroma quantization parameter (QP) offsets are added to outputs from a chroma QP table to determine parameters for the deblocking filter process.

Abstract: Methods, devices and systems for video coding and encoding, which include constraints, restrictions and signaling for subpictures, slices, and tiles, are described. One example method of video processing includes performing a conversion between a video including one or more pictures and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule conditionally allows coding of a picture in one layer using reference pictures from other layers based on a first syntax element indicating whether the reference pictures from the other layers are present in the bitstream, and wherein the first syntax element is conditionally signaled in the bitstream based on a second syntax element that indicates whether an identifier of a parameter set associated with the picture is not equal to zero.

Abstract: Video coding and decoding methods are described. An example method includes determining, based on an applicability rule, that a differential coding mode is applicable to a conversion between a chroma video block of a video and a bitstream representation of the chroma video block, and performing, based on the determining, the conversion between the chroma video block and the bitstream representation of the chroma video block using the differential coding mode, where the chroma video block is represented in the bitstream representation using a difference between a quantized residual of an intra prediction of the chroma video block and a prediction of the quantized residual in the differential coding mode, where the intra prediction is performed in a first direction and the prediction of the quantized residual is performed in a second direction, and where the difference is represented using a differential pulse coding modulation (DPCM) representation.

Abstract: Devices, systems and methods for coefficient coding in transform skip mode are described. An exemplary method for visual media processing includes: for encoding a current video block in a video region of a visual media data into a bitstream representation of the visual media data, identifying usage of a coding mode and/or an intra prediction mode and/or a set of allowable intra prediction modes; and upon identifying the usage, making a decision of whether to include or exclude, in the bitstream representation, a syntax element indicative of selectively applying a transform skip mode to the current video block, wherein, in the transform skip mode, a residual of a prediction error between the current video block and a reference video block is represented in the bitstream representation of the visual media data without applying a transformation.

Abstract: A video processing method includes performing a conversion between a video having one or more video layers including one or more video pictures and a bitstream of the video according to a format rule. The format rule specifies that a first video picture is an associated intra random access point picture of a second picture and that the second picture are constrained to belong to a same video layer.

Abstract: Methods, systems and devices for signaling of coded buffer picture information in video bitstream processing are disclosed. An example method of video processing includes performing a conversion between a video comprising one or more pictures and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that a first syntax element, when included in the bitstream, is access unit (AU) specific, wherein the value of the first syntax element is based on whether an associated AU is an intra random access points (IRAP) AU or a gradual decoding refresh (GDR) AU, and wherein the value of the first syntax element specifies (i) whether a second syntax element is present in a buffering period supplemental enhancement information (SEI) message, and (ii) whether alternative timing information is present in a picture timing SEI message in a current buffering period.

Abstract: Examples of video encoding methods and apparatus and video decoding methods and apparatus are described. An example method of video processing includes performing a conversion between a video and a bitstream of the video. The bitstream includes one or more layers including one or more network abstraction layer (NAL) units according to a format rule that specifies that a first layer identifier in a header of an end of sequence network abstraction layer (EOS NAL) unit is required to be equal to a second layer identifier of one of the one or more layers in the bitstream.

Abstract: An example method of video processing includes determining, for a conversion between a block of a chroma component of a video and a bitstream representation of the video, whether or how to apply a filtering process to an edge of the block based on a first quantization information for a first video region comprising samples on one side of the edge and/or a second quantization information for a second video region comprising samples on the other side of the edge according to a rule that is based on a coding mode applicable to the block for coding the samples on the one side or the samples on the other side of the edge. The rule specifies that multiple QP offsets at different video unit levels are used to determine the first quantization information or the second quantization information. The method also includes performing the conversion based on the determining.

Abstract: A method of video processing includes performing a conversion between a video including a picture and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that an indication of whether a first flag is signalled at a beginning of a picture header associated with the picture, wherein the first flag is indicative of whether the picture is an intra random access point (IRAP) picture or a gradual decoding refresh (GDR) picture.

Abstract: Examples of video encoding methods and apparatus and video decoding methods and apparatus are described. An example method of video processing includes performing a conversion between a video including one or more layers and a bitstream of the video according to a rule, wherein the rule specifies, in a process of sub-bitstream extraction to output an output sub-bitstream, whether to generate non-scalable nested supplementary enhancement information (SEI) messages by extracting scalable-nested SEI messages from a scalable nesting SEI message based on a first flag indicating whether the SEI message applies to specific output layer sets (OLSs) and a second flag indicating whether the SEI message applies to all subpictures or only to specific subpictures.

Abstract: Embodiments for video encoding and video decoding are described. One example method includes performing a conversion between a video and a bitstream of the video, wherein the bitstream includes one or more pictures including one or more subpictures according to a rule, and wherein the rule specifies that, responsive to a condition, a rewriting operation is performed on referenced one or more sequence parameter sets during a subpicture sub-bitstream extraction process by which a target output sub-bitstream is extracted from the bitstream.

Abstract: A method of video processing includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that a first syntax element, which indicates a number of parameters for an output layer set (OLS) hypothetical reference decoder (HRD) in a video parameter set (VPS) associated with the video, is less than a first predetermined threshold.

Abstract: A method implemented by a video coding apparatus includes applying a neural network (NN) filter to an unfiltered sample of a video unit to generate a filtered sample. The NN filter is applied based on a syntax element of the video unit. The method also includes converting between a video media file and a bitstream based on the filtered sample that was generated.

Abstract: Examples of video encoding methods and apparatus and video decoding methods and apparatus are described. An example method of video processing includes performing a conversion between a video and a bitstream of the video. The bitstream conforms to a format rule. The bitstream includes one or more layers including one or more picture units (PUs). The format rule specifies that, responsive to a first PU in a layer of the bitstream following an end of sequence network abstraction layer (EOS NAL) unit in the layer in a decoding order, a variable of the first PU is set to a particular value, wherein the variable indicates whether the first PU is a coded layer video sequence start (CLVSS) PU.

Abstract: Methods, systems, and devices for performing entropy coding for a palette escape symbol in palette mode coding and decoding are described. An example method for video processing includes performing a conversion between a video having one or more video regions including a current video block and a bitstream representation of the video, wherein the bitstream representation conforms to a format rule that the current video block is coded using a palette mode coding tool, wherein a binarization of an escape symbol for the current video block uses an exponential-Golomb (EG) code of order K, wherein K is a non-negative integer that is unequal to three, and wherein the palette mode coding tool represents the current video block using a palette of representative color values and wherein the escape symbol is used for a sample of the current video block coded without using the representative color values.

Abstract: Methods, systems, and devices for picture output ordering constraints in video bitstreams are described. An example method of video processing includes performing a conversion between a video including one or more pictures and a bitstream of the video according to a rule, wherein the rule specifies that the bitstream includes at least a first picture that is output, wherein the first picture is in an output layer, wherein the first picture includes a syntax element equaling one, and wherein the syntax element affects a decoded picture output and a removal process associated with a hypothetical reference decoder (HRD).

Abstract: Several techniques for video encoding and video decoding are described. A method for video processing includes performing a conversion between a video block of a video and a bitstream of the video, wherein the video block uses a low frequency non-separable transform for the conversion, wherein the bitstream conforms to a format rule that specifies that a syntax element is included at a syntax level for the bitstream, wherein the syntax element is indicative of whether use of a scaling matrix which is derived from a reference scaling list is enabled for the video block, and wherein the syntax level is a sequence level, a picture level, or a slice level.

Abstract: A method of video processing includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that a sub-bitstream extraction process is implemented to generate a sub-bitstream for decoding, wherein the sub-bitstream extraction process is configured to extract, from the bitstream, a sub-bitstream with a target highest temporal identifier, and wherein, the rule specifies that, during the extracting, upon removing a video coding layer (VCL) network abstraction layer (NAL) unit, filler data units and filler supplemental enhancement information (SEI) messages in SEI NAL units that are associated with the VCL NAL unit are also removed.

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 previously coded samples of the video, a boundary downsampling operation, followed by a matrix vector multiplication operation, and followed by an upsampling operation, where the upsampling operation is performed, in both a vertical direction and a horizontal direction in a fixed order, on samples obtained from the matrix vector multiplication operation.

Abstract: Methods, systems, and devices for picture header constraints for multi-layer coding are described. An example method of video processing 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. The format rule specifies a constraint on a value of a first syntax element that specifies whether a second syntax element is present in a picture header syntax structure of a current picture. The second syntax element specifies a value of a picture order count (POC) most significant bit (MSB) cycle of the current picture.