| CPC H04N 19/70 (2014.11) [H04N 19/117 (2014.11); H04N 19/186 (2014.11); H04N 19/188 (2014.11)] | 20 Claims |

|
1. A method of video processing, comprising:
performing a conversion between a video and a bitstream of the video according to a format rule,
wherein the format rule specifies that a first syntax element specifying whether one or more chroma-related adaptation parameter set (APS) syntax elements are present in an APS syntax structure is included in the APS syntax structure,
wherein the first syntax element equal to 1 specifies that an APS network abstraction layer (NAL) unit is allowed to include the one or more chroma-related APS syntax elements and the first syntax element equal to 0 specifies that the APS NAL unit does not include the one or more chroma-related APS syntax elements,
wherein the APS NAL unit has an APS parameters type equal to a scaling list APS type, luma mapping with chroma scaling (LMCS) APS type, or adaptive loop filtering (ALF) APS type, and the one or more chroma-related APS syntax elements include scaling list chroma-related data syntax elements, LMCS chroma-related data syntax elements, or ALF chroma-related data syntax elements, and
wherein when i) the APS NAL unit has the APS parameters type equal to the scaling list APS type, ii) the first syntax element is equal to 0, iii) a variable identifier (id) is not equal to X and id % M is not equal to N, the scaling list chroma-related data syntax elements are excluded from the APS syntax structure, whereby X, M and N are integers,
wherein a value of the first syntax element is constrained depending on a chroma format index and the APS parameters type, and
wherein as for the APS NAL unit with the LMCS APS type or the ALF APS type, when the chroma format index is equal to 0, the value of the first syntax element in the APS NAL unit with the LMCS APS type or the ALF APS type is equal to 0; and
wherein as for the APS NAL unit with the scaling list APS type, when the chroma format index is equal to 0, the value of the first syntax element in the APS NAL unit with the scaling list APS type is equal to 0, and when the chroma format index is not equal to 0, the value of the first syntax element in the APS NAL unit with the scaling list APS type is equal to 1.
|