Signaling of Matrix Intra Prediction parameters in video coding

A method of encoding video data using a codec, the method comprising:

• determining a plurality of available Matrix Intra Prediction (MIP) parameter sets (MPS's) for a picture of the video data, wherein:
• the plurality of available MPS's is a union of (i) a subset of all default MPS's and (ii) a set of one or more additional MPS's that are signaled in the bitstream,
• each of the default MPS's is associated with a respective predefined MIP mode in the codec, and
• each of the set of one or more additional MPS's is associated with a new MIP mode in a set of one or more new MIP modes;
• signaling the set of one or more additional MPS's in a bitstream that comprises an encoded representation of the video data;
• using a MIP mode associated with an MPS in the plurality of available MPS's to generate a prediction block for a current block of the picture, wherein:
• the MIP mode is in the set of one or more new MIP modes and is an explicit MIP (E-MIP) mode, and
• a syntax element in the bitstream indicates whether the MIP mode is specified with respect to an already-specified MIP mode or whether the MIP mode is specified independently;
• based on the syntax element indicating that the MIP mode is specified with respect to the already-specified MIP mode, deriving parameters of the MIP mode using parameters of the already-specified MIP mode;
• and
• generating residual data for the current block based on the prediction block for the current block and samples of the current block.

A device for decoding video data, the device comprising:

• a memory to store the video data;
• and
• one or more processors implemented in circuitry, the one or more processors configured to:
• obtain a bitstream that includes an encoded representation of the video data that is encoded using a codec;
• determine a plurality of available Matrix Intra Prediction (MIP) parameter sets (MPS's) for a picture of the video data, wherein:
• the plurality of available MPS's is a union of (i) a subset of all default MPS's and (ii) a set of one or more additional MPS's that are signaled in the bitstream,
• each of the default MPS's is associated with a respective predefined MIP mode in the codec, and
• each of the set of one or more additional MPS's is associated with a new MIP mode in a set of one or more new MIP modes, wherein the one or more new MIP modes are explicit MIP (E-MIP) modes;
• use a MIP mode associated with an MPS in the plurality of available MPS's to generate a prediction block for a current block of the picture, wherein:
• the MIP mode is in the set of one or more new MIP modes, and
• a syntax element in the bitstream indicates whether the MIP mode is specified with respect to an already-specified MIP mode or whether the MIP mode is specified independently;
• based on the syntax element indicating that the MIP mode is specified with respect to the already-specified MIP mode, derive parameters of the MIP mode using parameters of the already-specified MIP mode;
• and
• reconstruct the current block based on the prediction block for the current block and residual data for the current block.

A device for encoding video data using a codec, the device comprising:

• a memory to store the video data;
• and
• one or more processors implemented in circuitry, the one or more processors configured to:
• determine a plurality of available Matrix Intra Prediction (MIP) parameter sets (MPS's) for a picture of the video data, wherein:
• the plurality of available MPS's is a union of (i) a subset of all default MPS's and (ii) a set of one or more additional MPS's that are signaled in the bitstream,
• each of the default MPS's is associated with a respective predefined MIP mode in the codec, and
• each of the set of one or more additional MPS's is associated with a new MIP mode in a set of one or more new MIP modes;
• signal the set of one or more additional MPS's in a bitstream that comprises an encoded representation of the video data;
• using a MIP mode associated with an MPS in the plurality of available MPS's to generate a prediction block for a current block of the picture, wherein:
• the MIP mode is in the set of one or more new MIP modes and is an explicit MIP (E-MIP) mode, and
• a syntax element in the bitstream indicates whether the MIP mode is specified with respect to an already-specified MIP mode or whether the MIP mode is specified independently;
• based on the syntax element indicating that the MIP mode is specified with respect to the already-specified MIP mode, derive parameters of the MIP mode using parameters of the already-specified MIP mode;
• and
• generate residual data for the current block based on the prediction block for the current block and samples of the current block.