Multi-parameter adaptive loop filtering in video processing

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 bitstream of a video comprising one or more video regions and the video,
• wherein a clipping parameter for filtering a reconstruction of a first video unit of a video region using a non-linear adaptive loop filter is derived based on first side information included in the bitstream and a first adaptation parameter set identification, and
• wherein filtering coefficients for filtering the reconstruction of the first video unit using the non-linear adaptive loop filter are derived based on second side information included in the bitstream and the first adaptation parameter set identification used for deriving the clipping parameter,
• wherein in a case that a prediction from data information associated with the first adaptation parameter set identification is enabled for at least some of the filtering coefficients of the first video unit, the data information associated with the first adaptation parameter set identification is also used for predicting the clipping parameter, and
• wherein a value of the clipping parameter corresponding to a first clipping index under a first bit-depth is equal to a value resulting from applying a shifting operation on another clipping parameter corresponding to the first clipping index under a second bit-depth.

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

• perform a conversion between a bitstream of a video comprising one or more video regions and the video,
• wherein a clipping parameter for filtering a reconstruction of a first video unit of a video region using a non-linear adaptive loop filter is derived based on first side information included in the bitstream and a first adaptation parameter set identification, and
• wherein filtering coefficients for filtering the reconstruction of the first video unit using the non-linear adaptive loop filter are derived based on second side information included in the bitstream and the first adaptation parameter set identification used for deriving the clipping parameter,
• wherein in a case that a prediction from data information associated with the first adaptation parameter set identification is enabled for at least some of the filtering coefficients of the first video unit, the data information associated with the first adaptation parameter set identification is also used for predicting the clipping parameter, and
• wherein a value of the clipping parameter corresponding to a first clipping index under a first bit-depth is equal to a value resulting from applying a shifting operation on another clipping parameter corresponding to the first clipping index under a second bit-depth.

A method for storing a bitstream of a video, wherein the method comprises:

• generating the bitstream of the video comprising one or more video regions;
• and
• storing the bitstream in a non-transitory computer-readable recording medium,
• wherein a clipping parameter for filtering a reconstruction of a first video unit of a video region using a non-linear adaptive loop filter is derived based on first side information included in the bitstream and a first adaptation parameter set identification, and
• wherein filtering coefficients for filtering the reconstruction of the first video unit using the non-linear adaptive loop filter are derived based on second side information included in the bitstream and the first adaptation parameter set identification used for deriving the clipping parameter,
• wherein in a case that a prediction from data information associated with the first adaptation parameter set identification is enabled for at least some of the filtering coefficients of the first video unit, the data information associated with the first adaptation parameter set identification is also used for predicting the clipping parameter, and
• wherein a value of the clipping parameter corresponding to a first clipping index under a first bit-depth is equal to a value resulting from applying a shifting operation on another clipping parameter corresponding to the first clipping index under a second bit-depth.