Huawei Technologies Co., Limited

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Ye-Kui Wang

Jianle Chen

A method of decoding a coded video bitstream implemented by a video decoder is provided. The method includes parsing a flag; parsing candidates for a first reference picture list structure; determining that candidates for a second reference picture list structure are not present in the coded video bitstream and inferring that the candidates for the second reference picture list structure are the same as the candidates for the first reference picture list structure when the flag has a first value; determining that the candidates for the second reference picture list structure are present in the coded video bitstream when the flag has a second value; generating a reference picture list using the candidates for the first reference picture list structure or the candidates for the second reference picture list structure; and performing inter-prediction based on the reference picture list to generate a reconstructed block.

Candidate signaling for reference picture list structures

A video coding mechanism is disclosed. The mechanism includes receiving a bitstream comprising a current picture including a plurality of video coding layer (VCL) network abstraction layer (NAL) units that do not have a same NAL unit type. Active entries of reference picture lists are obtained for slices positioned in a sub-picture A (subpicA) in subsequent pictures following the current picture in decoding order. The active entries do not refer to any reference picture preceding the current picture in decoding order when the subpicA at the current picture is associated with an intra-random access point (IRAP) NAL unit type. The subsequent pictures are decoded based on the reference picture list active entries. The subsequent pictures are forwarded for display as part of a decoded video sequence.

Mixed NAL unit picture constraints in video coding

A method of decoding a coded video bitstream implemented by a video decoder is provided. The method includes the video decoder determining whether a gradual decoding refresh (GDR) picture in the coded video bitstream is an initial picture in decoding order or the initial picture following an end of sequence (EOS) network abstraction layer (NAL) unit in the decoding order; setting a flag to a value to prevent the GDR picture from being output when the GDR picture is the initial picture in decoding order or the initial picture following the EOS NAL unit in the decoding order; decoding the GDR picture; and storing the GDR picture in a decoded picture buffer (DPB).

Gradual decoding refresh in video coding

A video coding mechanism is disclosed. The mechanism includes receiving a bitstream comprising one or more sub-pictures partitioned from a picture and a sub-picture level indicator indicating resource requirements for decoding a current sub-picture. The bitstream is parsed to obtain the sub-picture level indicator and the current sub-picture. Resources are allocated to decode the current sub-picture based on the sub-picture level indicator. The current sub-picture is decoded to create a video sequence by employing the allocated resources. The video sequence is forwarded for display.

Sub-picture level indicator signaling in video coding

A video coding mechanism is disclosed. The mechanism includes receiving a bitstream comprising a slice and a luma mapping with chroma scaling (LMCS) adaptation parameter set (APS) including LMCS parameters. The mechanism further includes determining that the LMCS APS is referenced in data related to the slice. The mechanism further includes decoding the slice using LMCS parameters from the LMCS APS based on the reference to the LMCS APS. The mechanism further includes forwarding the slice for display as part of a decoded video sequence.

Luma mapping with chroma scaling adaptation parameter set in video coding

A method of decoding a coded video bitstream implemented by a video decoder. The coded video bitstream includes a plurality of reference picture list structures each containing a plurality of reference picture entries. The method includes parsing a flag that specifies a sign value of an absolute value of a delta picture order count (POC) associated with a short-term reference picture entry from the plurality of reference picture entries; parsing the absolute value of the delta POC associated with the short-term reference picture entry; generating a reference picture list based on the sign value of the absolute value of the delta POC and the absolute value of the delta POC; and performing inter-prediction based on the reference picture list to generate a reconstructed block.

Signaling a sign value and an absolute value for a delta picture order count

A method implemented in an encoder for encoding a video bitstream that includes coded data for a plurality of pictures, each of the plurality of pictures comprises at least one slice. The method includes encoding a flag that indicates whether tile information for a picture is present in a picture parameter set or present in a slice header, where the tile information indicates a location of a slice within the picture; encoding the tile information in only the picture parameter set when the flag indicates that the tile information for the picture is encoded in the picture parameter set; encoding the tile information in only the slice header when the flag indicates that the tile information for the picture is encoded in the slice header; and encoding data of the picture in the video bitstream based on the tile information.

Tile group signaling in video coding

A method for storing a coded video bitstream. The method includes obtaining the coded video bitstream and storing the coded video bitstream in at least one storage medium. The coded video bitstream includes a first reference picture list syntax structure and a second reference picture list syntax structure. Each reference picture list syntax structure contains a number of entries. A first reference picture list of a current slice and a second reference picture list of the current slice are derived based on the first reference picture list syntax structure and the second reference picture list syntax structure. The first reference picture list and the second reference picture list are derived for bitstream conformance checking instead of for decoding a current picture or pictures following the current picture in decoding order when the current slice comprises an intra (I) slice of a non-intra random access point (IRAP) picture.

Reference picture management in video coding

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.

A method of decoding includes receiving a first picture parameter set and a second picture parameter set each referring to same sequence parameter set, the first picture parameter set and the second picture parameter set having same values of a conformance window when the first picture parameter set and the second picture parameter set have same values of picture width and picture height, and applying the conformance window to a current picture corresponding to the first picture parameter set or the second picture parameter set.

Handling of multiple picture size and conformance windows for reference picture resampling in video coding

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.

On intra random access point pictures and leading pictures in video coding

A video coding mechanism is disclosed. The mechanism includes receiving at a decoder, a bitstream including a video coding layer (VCL) network abstraction layer (NAL) unit containing a slice of image data divided into a plurality of tiles. A number of the tiles in the VCL NAL unit are determined. A number of entry point offsets for the tiles is also determined as one less than the number of the tiles in the VCL NAL unit. Each entry point offset indicates a starting location of a corresponding tile in the VCL NAL unit. The number of entry point offsets is not explicitly signaled in the bitstream. The entry point offsets for the tiles are obtained based on the number of entry point offsets. The tiles are decoded at the entry point offsets to generate a reconstructed image.

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