An image encoding/decoding method and apparatus are provided. An image decoding method performed by an image decoding apparatus may comprise parsing weight information specifying a weight for a reference sample from a bitstream according to a weight parameter syntax structure, and decoding a current block by performing inter prediction based on the weight information. The parsing according to the weight parameter syntax structure may comprise obtaining weight number information specifying the number of weight information obtained from the bitstream according to the weight parameter syntax structure and obtaining weight information from the weight parameter syntax structure based on the weight number information.

The present invention is concerned with decoders, encoders and corresponding methods for handling video data streams (11) comprising a first sub-bitstream (11-1) and a second sub-bitstream (11-2). The herein described concept provides solutions for mixing, within an access unit (30, 31, 32), different NAL units (301, 302, 3030, 304) of different NAL unit types. For example, RAP NAL unit types may be mixed with different IRAP NAL unit types or non-IRAP NAL unit types, and non-IRAP NAL unit types may be mixed with different non-IRAP NAL unit types.

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.

Aspects of the disclosure provide methods and apparatuses for video encoding/decoding. In some examples, an apparatus for video decoding includes processing circuitry. The processing circuitry determines that a non-interleaved separate tree structure is used for coding different color components of coding tree units (CTUs) in a bitstream. The processing circuitry decodes a first color component of a plurality of CTUs from a first portion of the bitstream, and decodes a second color component of the plurality of CTUs from a second portion of the bitstream, the second portion is located after the first portion in the bitstream.

Systems, methods and apparatus for encoding, decoding or transcoding digital video are described. One example method of video processing includes performing a conversion between a video and a bitstream of the video including multiple layers, wherein the bitstream includes a plurality of supplemental enhancement information, SEI, messages associated with an access unit, AU, or a decoding unit, DU, of a particular output layer set, OLS, or a particular layer, wherein the plurality of SEI messages, including a message type different from scalable nesting type, is based on a format rule, and wherein the format rule specifies that each of the plurality of SEI messages has a same SEI payload content due to the plurality of SEI messages being associated with the AU or the DU of the particular OLS or the particular layer.

A method of encoding a video bitstream implemented by a video encoder is disclosed. The method includes storing, in a memory of the video encoder, a set of less than five network abstraction layer (NAL) unit types available for video data; selecting, by a processor of the video encoder, a NAL unit type from the set of less than five NAL unit types for a picture from the video data; generating, by the processor of the video encoder, a video bitstream containing a NAL unit corresponding to the NAL unit type selected and containing an identifier identifying the NAL unit type selected; and transmitting, by a transmitter of the video encoder, the video bitstream toward a video decoder. A corresponding method of decoding the video bitstream is also disclosed.

An example device for decoding video data, the device including a memory configured to store video data; and one or more processors implemented in circuitry and configured to: determine that adaptive loop filter (ALF) information can be present in a picture header of a picture of the video data and cannot be present in a slice header; in response to determining that the ALF information can be present in the picture header and cannot be present in the slice header, determine that a picture header syntax structure is not present in the slice header (e.g., without decoding data representing a value for a syntax element indicating whether the picture header syntax structure is present in the slice header); and decode the picture according to the determination that the picture header syntax structure is not present in the slice header.

A method of decoding an encoded video bitstream using at least one processor includes obtaining a video coding layer (VCL) network abstraction layer (NAL) unit; determining whether the VCL NAL unit is a first VCL NAL unit of a picture unit (PU) containing the VCL NAL unit; based on determining that the VCL NAL unit is the first VCL NAL unit of the PU, determining whether the VCL NAL unit is a first VCL NAL unit of an access unit (AU) containing the PU; and based on determining that the VCL NAL unit is the first VCL NAL unit of the AU, decoding the AU based on the VCL NAL unit.

This disclosure relates to video coding and more particularly to techniques for signaling picture timing and decoding unit information for coded video. According to an aspect of an invention, a flag syntax element, specifying whether decoding unit level decoded picture buffer output delay parameters are present in a picture timing message, in a buffering period message is parsed and a first syntax element, used to compute a decoded picture buffer output time, in the picture timing message is parsed, in a case that a value of the flag syntax element is equal to one.

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, wherein the bitstream conforms to a format rule that specifies a syntax of network abstraction layer (NAL) units in the bitstream, and wherein the format rule specifies that a NAL unit of a video coding layer (VCL) NAL unit type includes a content associated with a particular type of picture or a particular type of subpicture.