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: 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: A method of decoding a coded video bitstream implemented by a video decoder is disclosed. The method includes determining that a coded video sequence (CVS) of the coded video bitstream includes a video coding layer (VCL) network abstraction layer (NAL) unit having a gradual decoding refresh (GDR) network abstraction layer (NAL) unit type (GDR_NUT), the VCL NAL unit having the GDR_NUT containing a GDR picture; initiating decoding of the CVS at the GDR picture; and generating an image according to the CVS as decoded. A corresponding method of encoding is also disclosed.

Abstract: Methods, systems, apparatus for video processing are described. The processing may include encoding, decoding or transcoding. One example video processing method includes performing a conversion between a video including one or more pictures and a bitstream of the video according to a format rule. The format rule specifies to include, in a general constrain syntax structure, a syntax element indicating whether each picture includes only one slice, and whether a picture header syntax structure is present in a slice header.

Abstract: A mechanism for processing video data is disclosed. A value of an annotated region (AR) object label index of an i-th AR object index (ar_object_label_idx[ar_object_idx[i]]) syntax element is determined. The ar_object_label_idx[ar_object_idx[i]] syntax element is specified to be in a range of N to M, where N and M are integers and N is less than M. A conversion is performed between a visual media data and a bitstream based on the ar_object_label_idx[ar_object_idx[i]] syntax element.

Abstract: Methods, systems, apparatuses for video processing are described. A method for processing video includes performing a conversion between a video and a bitstream of the video according to a format rule, and wherein the format rule specifies to include, in a general constraint syntax structure associated with the video, one or more general constraint flags indicating whether corresponding syntax elements are included in a sequence parameter set (SPS) and/or a picture parameter set (PPS) and/or a picture header (PH) and/or a slice header (SH) or to constrain values of the syntax elements in the SPS and/or the PPS and/or the PH and/or the SH.

Abstract: Methods, systems and apparatus for video processing are described. One example video processing method includes performing a conversion between a video comprising a video block and a bitstream of the video according to a rule, wherein the video block is a coding tree node that includes one or more coding units, and wherein the rule specifies that a coded information of the video block is indicative of whether a coding mode is enabled for the one or more coding units of the video block.

Abstract: A video coding mechanism is disclosed. The mechanism includes receiving an extracted bitstream that is a result of a sub-bitstream extraction process from an input bitstream containing a set of sub-pictures. The extracted bitstream contains only a subset of the sub-pictures of the input bitstream to the sub-bitstream extraction process. A flag from the extracted bitstream is set to indicate that sub-picture information related to the subset of the sub-pictures is present in the extracted bitstream. One or more sub-picture identifiers (IDs) for the subset of the sub-pictures are obtained based on the flag. The subset of the sub-pictures is decoded based on the sub-picture IDs.

Abstract: A method of decoding a coded video bitstream includes obtaining a reference picture list structure for a current slice represented in the coded video bitstream, wherein the reference picture list structure contains a number of entries; obtaining a default number of active entries in a reference picture list for the current slice; constructing a reference picture list for the current slice, the reference picture list containing a number of active and inactive entries; setting the number of active entries in the reference picture list equal to the number of entries in the reference picture list structure when the default number of active entries in the reference picture list is greater than the number of entries in the reference picture list structure; and obtaining, based on at least one active entry of the reference picture list, at least one reconstructed block of the current slice.

Abstract: Methods and apparatus for processing of video are described. The processing may include video encoding, decoding, or transcoding. One example video processing method includes performing a conversion between a video including one or more pictures including one or more subpictures and a bitstream of the video. The bitstream conforms to a format rule that specifies that a subpicture cannot be a random access type of subpicture in response to the subpicture not being a leading subpicture of an intra random access point subpicture. The leading subpicture precedes the intra random access point subpicture in output order.

Abstract: Devices, systems and methods related to digital video coding, and specifically, to signaling of slice types in video picture headers are described. One example method of video processing includes performing a conversion between a video including one or more video pictures including one or more slices and a bitstream of the video, wherein the bitstream conforms to a format rule, and wherein the format rule specifies that for a video picture of the one or more video pictures having all slices coded as I slices, P slice and B slice related syntax elements are omitted from a picture header for the video picture.

Abstract: Methods, systems, apparatus for video processing are described. A method for processing video includes performing a conversion between a video and a bitstream of the video according to a format rule, and wherein the format rule specifies whether a syntax element in a sequence parameter set (SPS) based on a value of a general constraint flag.

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: Embodiments for video processing, including video coding, video decoding and video transcoding are described. One example method includes performing a conversion between a video comprising one or more video pictures comprising one or more subpictures and a bitstream of the video, wherein the conversion conforms to a rule that specifies that one or more parameters for a scaling window applicable to a subpicture are determined from one or more syntax elements during a subpicture sub-bitstream extraction process.

Abstract: A video coding mechanism is disclosed. The mechanism includes receiving a bitstream including image data coded in a plurality of slices. A top left tile identifier (ID) and a bottom right tile ID of a first slice are determined. Boundaries of the first slice are determined based on the top left tile ID and the bottom right tile ID. The first slice is decoded to generate a reconstructed image based on the boundaries of the first slice.

Abstract: A video coding mechanism is disclosed. The mechanism includes receiving an extracted bitstream that is a result of a sub-bitstream extraction process from an input bitstream containing a set of sub-pictures. The extracted bitstream contains only a subset of the sub-pictures of the input bitstream to the sub-bitstream extraction process. A flag from the extracted bitstream is set to indicate that sub-picture information related to the subset of the sub-pictures is present in the extracted bitstream. One or more sub-picture identifiers (IDs) for the subset of the sub-pictures are obtained based on the flag. The subset of the sub-pictures is decoded based on the sub-picture IDs.

Abstract: Methods, systems and apparatus for video processing are described. One example video processing method includes performing a conversion between a video including a video block and a bitstream of the video according to a rule, wherein the rule specifies whether to include, in a slice header (SH), a first syntax element that indicates whether a transform skip based residual coding is disabled for a slice, and wherein the rule specifies that whether to include the first syntax element in the SH is selectively based on a second syntax element in a sequence parameter set (SPS) that indicates whether a TS mode is enabled for the video block.

Abstract: A mechanism for processing video data is disclosed. A value of an i-th depth nonlinear representation model (depth_nonlinear_representation_model[i]) syntax element is determined. The depth_nonlinear_representation_model[i] syntax element is specified to be in a range of A to B, where A and B are integers and A is less than B. A conversion is performed between a visual media data and a bitstream based on the depth_nonlinear_representation_model[i] syntax element.

Abstract: A method of decoding includes encountering an end of tile bit with a first value and byte alignment bits in a video bitstream, which indicate that a current coding tree block (CTB) is a last CTB in a tile; encountering an end of CTB row bit with the first value and the byte alignment bits in the video bitstream, which indicate that waveform parallel processing (WPP) is enabled and that the current CTB is the last CTB in a CTB row but not the last CTB in the tile; and reconstructing the plurality of CTBs in the tile based on the end of tile bit with the first value, the end of CTB row bit with the first value, and the byte alignment bits.

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 comprising one or more pictures comprising one or more slices and a bitstream of the video. The bitstream conforms to a predefined order between a position of a first network abstraction layer (NAL) unit in a picture unit carrying an adaptation parameter set information and a second NAL unit that is a last video coding layer (VCL) NAL unit in the picture unit.