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, wherein the bitstream includes network abstraction layer (NAL) units for multiple video layers according to a rule; wherein the rule defines a sub-bitstream extraction process by which NAL units are removed from the bitstream to generate an output bitstream, and wherein the rule specifies to remove all supplemental enhancement information (SEI) NAL units that contain a non-scalable-nested SEI message with a particular payload type, responsive to a list of NAL unit header layer identifier values in an output layer set (OLS) with a target OLS index not including all values of NAL unit header layer identifiers in all video coding layer (VCL) NAL units in the bitstream that is input to the sub-bitstream extraction process.

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, wherein the bitstream comprises one or more supplemental enhancement information, SEI, network abstraction layer (NAL) units according to a rule, wherein the rule specifies that, responsive to an SEI NAL unit including a non-scalable-nested SEI message of a first payload type, the SEI NAL unit is disallowed to include another SEI message of a second payload type.

Abstract: A method of decoding is provided. The method includes receiving a sub-bitstream having a sequence parameter set (SPS) with a profile tier level (PTL) syntax structure for an output layer set (OLS) with only one layer; setting a number of layers in the OLS equal to one based on the OLS having the only one layer; obtaining the PTL syntax structure for the OLS with the only one layer from the SPS when the number of layers in the OLS has been set equal to one; and decoding a picture from the only one layer using the PTL syntax structure to obtain a decoded picture. A corresponding method of encoding is also provided.

Abstract: A video coding mechanism is disclosed. The mechanism includes receiving a bitstream comprising one or more layers and a scalable nesting supplemental enhancement information (SEI) message. The scalable nesting SEI message includes one or more scalable-nested SEI messages and a scalable nesting output layer set (OLS) flag. The scalable nesting OLS flag is set to specify whether the scalable-nested SEI messages apply to specific OLSs or specific layers. A coded picture is decoded from the one or more layers to produce a decoded picture. The decoded picture is forwarded for display as part of a decoded video sequence.

Abstract: Techniques for video processing, including video coding, video decoding and video transcoding are described. One example method includes performing a conversion between a video picture that includes one or more tiles and one or more rectangular slices and a bitstream of the video according to a rule. The rule specifies that, for iteratively determining information about the one or more rectangular slices, a variable indicating a tile index is updated only for slices having indices that are smaller than a value equal to a number of slices in the video picture minus 1.

Abstract: A video coding mechanism is disclosed. The mechanism includes encoding a coded layer video sequence (CLVS) for a layer in a bitstream. A sequence parameter set (SPS) referred to by the CLVS is also encoded into the bitstream. The SPS is constrained to have a network abstraction layer (NAL) unit header layer identifier (nuh_layer_id) value equal to a nuh_layer_id value of the CLVS when the layer does not use inter-layer prediction. The bitstream is stored for communication toward a decoder.

Abstract: A method of decoding a coded video bitstream is provided. The method includes receiving the coded video bitstream, wherein the coded video bitstream contains a gradual decoding refresh (GDR) picture and a first flag having a first value; setting a second value of a second flag equal to the first value of the first flag; emptying any previously-decoded pictures from a decoded picture buffer (DPB) based on the second flag having the second value; and decoding a current picture after the DPB has been emptied. A corresponding method of encoding is also provided.

Abstract: Embodiments of the present disclosure provide a solution for video processing. A method for video processing is proposed. The method comprises: performing a conversion between a current video block of a video and a bitstream of the video based on general constraints information (GCI) for the video, the GCI comprising one or more syntax elements, wherein each of the one or more syntax elements is absent from the bitstream and has a value equal to a first predetermined value. Compared with the conventional solution, the proposed method can advantageously improve the coding efficiency.

Abstract: A method includes performing a conversion between a video comprising a video picture that includes one or more subpictures and a bitstream of the video according to a format rule. The format rule specifies that whether each of the one or more subpictures in the video picture includes a single slice is determined based on a constraint flag.

Abstract: A video coding mechanism is disclosed. The mechanism includes receiving a bitstream comprising a sub-picture partitioned from a picture and a sequence parameter set (SPS) comprising a sub-picture size and a sub-picture location. The SPS is parsed to obtain the sub-picture size of the sub-picture and the sub-picture location of the sub-picture. The sub-picture is decoded based on the sub-picture size and the sub-picture location to create a video sequence. The video sequence is forwarded for display.

Abstract: A video coding mechanism is disclosed. The mechanism includes encoding into a bitstream a gradual decoding refresh (GDR) access unit (AU) and a buffering period (BP) supplemental enhancement information (SEI) message associated with the GDR AU. A hypothetical reference decoder (HRD) is initialized based on the BP SEI message. A HRD conformance test is performed on the bitstream using the HRD. The bitstream is stored for communication toward a decoder.

Abstract: A method of decoding is provided. The method includes receiving, by the video decoder, a video bitstream including a video parameter set (VPS) and a plurality of layers, where each layer is included in at least one output layer set (OLS) specified by the VPS; and decoding, by the video decoder, a picture from one of the plurality of layers. A method of encoding is also provided. The method of encoding includes generating, by the video encoder, a plurality of layers and a video parameter set (VPS) specifying one or more output layer sets (OLSs), wherein each layer from the plurality of layers is included in at least one of the OLSs specified by the VPS; encoding, by the video encoder, the plurality of layers and the VPS into a video bitstream; and storing, by the video encoder, the video bitstream for communication toward a video decoder.

Abstract: A video coding mechanism is disclosed. The mechanism includes partitioning a picture into a plurality of first level tiles. A subset of the first level tiles is partitioned into a plurality of second level tiles. The first level tiles and the second level tiles are assigned into one or more tile groups such that all tiles in an assigned tile group containing the second level tiles are constrained to cover a rectangular region of the picture. The first level tiles and the second level tiles are encoded into a bitstream. The bitstream is stored for communication toward a decoder.

Abstract: Methods, systems, and apparatus for video processing are described. One example video processing method includes performing a conversion between a video comprising a luma block and a bitstream of the video according to a rule. The rule specifies that whether a slice header (SH) includes a first syntax element is based on a second syntax element. The first syntax element indicates whether use of a delta quantization parameter (QP) is enabled for one or more coding units (CUs) of a specific slice of the luma block.

Abstract: A method of decoding implemented by a video decoder is provided. The method includes receiving a bitstream including a sequence parameter set (SPS) containing a first flag and an indicator of a length of a picture order count (POC) most significant bits (MSB) value when present in a header referring to the SPS, where a value of the first flag specifies that a second flag is present in the header referring to the SPS, and where a value of the second flag specifies that the POC MSB value is present in the header; determining a POC value based on the POC MSB value; identifying a picture from the bitstream based on the POC value; and decoding the picture to obtain a decoded picture.

Abstract: A video coding mechanism is disclosed. The mechanism includes receiving a bitstream comprising an output layer set (OLS) and a video parameter set (VPS). The OLS includes one or more layers of coded pictures and the VPS includes an OLS mode identification code (ols_mode_idc) specifying that for each OLS, all layers in the each OLS are output layers. The output layers are determined based on the ols_mode_idc in the VPS. A coded picture from the output layers is decoded to produce a decoded picture. The decoded picture is forwarded for display as part of a decoded video sequence.

Abstract: Embodiments of the present disclosure provide a solution for media processing. A method for media processing comprises: performing a conversion between a media file of a media and a media presentation of the media, wherein each main stream representation (MSR) in the media presentation is associated with an external stream representation (ESR) in the media presentation. Compared with the conventional solution, the proposed method can advantageously support the extended dependent random access point (EDRAP)-based technology more efficiently.

Abstract: Embodiments of the present disclosure provide a solution for media processing. A method for media processing is proposed. The method comprises: performing a conversion between a media file of a media and a media presentation of the media, wherein the media presentation comprises a main stream representation (MSR) and an external stream representation (ESR) associated with the MSR, a concatenation of a first segment in the ESR, a second segment in the MSR corresponding to the first segment, and subsequent segments following the second segment in the MSR results in a file conforming to a file format standard. Compared with the conventional solution, the proposed method can advantageously support the extended dependent random access point (EDRAP)-based technology more efficiently.

Abstract: A method of decoding is provided. The method includes receiving a video bitstream including a plurality of layers, a video parameter set (VPS) specifying a plurality of output layer sets (OLSs) each including one or more layers from the plurality of layers, and a sequence parameter set (SPS) including a set of decoded picture buffer (DPB) parameters for each of the one or more layers only once when one or more of the one or more layers have been included in more than one of the plurality of OLSs; and decoding a picture from one of the plurality of layers to obtain a decoded picture. A corresponding method of encoding is also provided.

Abstract: A video coding mechanism is disclosed. The mechanism includes encoding a bitstream comprising a video parameter set (VPS) and one or more sublayers. A buffering period (BP) supplemental enhancement information (SEI) message comprising a BP maximum sublayers minus one (bp_max_sublayers_minus1) is also encoded into the bitstream. The bp_max_sublayers_minus1 is set to a value in a range of zero to a maximum number of sublayers indicated in the VPS. A hypothetical reference decoder (HRD) is initialized based on the BP SEI message. A set of bitstream conformance tests are performed on the sublayers. The bitstream is stored for communication toward a decoder.