Signaling of in-loop reshaping information using parameter sets

An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:

• perform a conversion between a current video block of a video region of a video and a bitstream of the video,
• wherein the conversion uses a coding tool in which the current video block is constructed based on at least one of:
• 1) A forward mapping process for a luma component of the current video block, in which samples of the luma component are converted from an original domain to a reshaped domain,
• 2) An inverse mapping process, which is an inverse operation of the forward mapping process to convert the samples of the luma component in the reshaped domain to the original domain, or
• 3) A scaling process, in which residual samples of a chroma component of the current video block are scaled before being used to reconstruct the chroma component of the current video block,
• wherein an adaptation parameter set is included in the bitstream which comprises parameter information for the coding tool and a first identifier of the adaptation parameter set,
• wherein the first identifier of the adaptation parameter set is fixed-length coded and has a range between 0 to M, wherein M is 2K−1, and
• wherein the parameter information includes at least one of an indication of information of a reshaper model which is used in the forward mapping process to map the samples of the luma component into particular values or chroma residual scaling factors which are used in the scaling process to derive scaled residual samples of the chroma component.

A non-transitory computer-readable storage medium storing instructions that cause a processor to:

• perform a conversion between a current video block of a video region of a video and a bitstream of the video,
• wherein the conversion uses a coding tool in which the current video block is constructed based on at least one of:
• 1) A forward mapping process for a luma component of the current video block, in which samples of the luma component are converted from an original domain to a reshaped domain,
• 2) An inverse mapping process, which is an inverse operation of the forward mapping process to convert the samples of the luma component in the reshaped domain to the original domain, or
• 3) A scaling process, in which residual samples of a chroma component of the current video block are scaled before being used to reconstruct the chroma component of the current video block,
• wherein an adaptation parameter set is included in the bitstream which comprises parameter information for the coding tool and a first identifier of the adaptation parameter set,
• wherein the first identifier of the adaptation parameter set is fixed-length coded and has a range between 0 to M, wherein M is 2K−1, and
• wherein the parameter information includes at least one of an indication of information of a reshaper model which is used in the forward mapping process to map the samples of the luma component into particular values or chroma residual scaling factors which are used in the scaling process to derive scaled residual samples of the chroma component.

A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:

• generating the bitstream based on a current video block of a video region of the video,
• wherein during the generating, a coding tool is used, in the coding tool, the current video block is constructed based on at least one of:
• 1) A forward mapping process for a luma component of the current video block, in which samples of the luma component are converted from an original domain to a reshaped domain,
• 2) An inverse mapping process, which is an inverse operation of the forward mapping process to convert the samples of the luma component in the reshaped domain to the original domain, or
• 3) A scaling process, in which residual samples of a chroma component of the current video block are scaled before being used to reconstruct the chroma component of the current video block,
• wherein an adaptation parameter set is included in the bitstream which comprises parameter information for the coding tool and a first identifier of the adaptation parameter set,
• wherein the first identifier of the adaptation parameter set is fixed-length coded and has a range between 0 to M, wherein M is 2K−1, and
• wherein the parameter information includes at least one of an indication of information of a reshaper model which is used in the forward mapping process to map the samples of the luma component into particular values or chroma residual scaling factors which are used in the scaling process to derive scaled residual samples of the chroma component.