Affine linear weighted intra prediction mode

1. A method for video decoding in a decoder, comprising:

decoding prediction information for a current block in a current picture that is a part of a coded video sequence, the prediction information indicating whether the current block is coded in matrix based intra prediction (MIP);

based on the prediction information indicating that the current block is coded in MIP, determining an MIP mode index according to index information included in the prediction information, the MIP mode index indicating an MIP mode in a mode candidate list associated with the current block;

determining an intra prediction candidate mode for the current block to be a Planar intra prediction mode based on the prediction information indicating that the current block is not coded in MIP; and

reconstructing the current block according to (i) the MIP mode in the mode candidate list based on the prediction information indicating that the current block is coded in MIP and (ii) the Planar intra prediction mode based on the prediction information indicating that the current block is not coded in MIP.

2. The method of claim 1 , wherein the index information is signaled based on one of a truncated binary codeword, a fixed length codeword, or a truncated unary codeword.

3. The method of claim 2 , wherein the index information is signaled using a 5-bit fix-length codeword.

4. The method of claim 2 , wherein:

a subset of the mode candidate list is signaled using M1 bit fix-length codeword, and

remaining candidate modes in the mode candidate list that are not included in the subset are signaled using M2 fix-length codeword, wherein M1 and M2 are non-negative integers.

5. The method of claim 1 , wherein:

based on the prediction information indicating that the current block is coded in MIP,

candidate modes in the mode candidate list are determined based on at least one of a width or a height of the current block, and

orders of the candidate modes in the mode candidate list are determined based on at least one of the width or the height of the current block.

6. The method of claim 1 , further comprising:

based on the prediction information indicating that the current block is coded in MIP,

constructing the mode candidate list including a mode that is determined based on neighboring blocks of the current block.

7. The method of claim 6 , wherein the mode candidate list includes one of:

a first preset mode in response to the neighboring blocks not being coded in MIP,

an intra prediction mode of one of a left neighboring block and an above neighboring block of the neighboring blocks in response to the left neighboring block and the above neighboring block being coded in MIP, and

a second preset mode in response to the left neighboring block and the above neighboring block not being coded in MIP.

8. The method of claim 1 , wherein a total number of candidate modes in the mode candidate list is equal to 2 k , k being determined based on a size of the current block.

9. The method of claim 1 , further comprising:

based on the prediction information indicating that the current block is not coded in MIP and neighboring blocks of the current block being coded in MIP,

constructing the mode candidate list based on one of a Planar intra prediction mode, a DC intra prediction mode, a Horizontal intra prediction mode, or a Vertical intra prediction mode.

10. The method of claim 1 , wherein a total number of candidate modes in the mode candidate list is determined based on one of intra prediction modes of neighboring blocks of the current block, a reference line index of the neighboring blocks, and a MIP flag of the neighboring blocks.

11. The method of claim 1 , further comprising:

based on (i) the prediction information indicating that a luma block of the current block is coded in MIP and (ii) a derived mode being used for an associated chroma block of the current block,

setting a prediction mode of the associated chroma block to be a preset intra prediction mode.

12. The method of claim 1 , further comprising:

based on (i) a chroma block of the current block being associated with a plurality of luma blocks, (ii) a derived mode being used for the chroma block of the current block, and (iii) the prediction information indicating that none of the plurality of luma blocks is coded in MIP,

setting a prediction mode of the chroma block of the current block to be a preset intra prediction mode.

13. An apparatus, comprising:

processing circuitry configured to:

decode prediction information for a current block in a current picture that is a part of a coded video sequence, the prediction information indicating whether the current block is coded in matrix based intra prediction (MIP);

based on the prediction information indicating that the current block is coded in MIP, determine an MIP mode index according to index information included in the prediction information, the MIP mode index indicating an MIP mode in a mode candidate list associated with the current block;

determine an intra prediction candidate mode for the current block to be a Planar intra prediction mode based on the prediction information indicating that the current block is not coded in MIP; and

reconstruct the current block according to (i) the MIP mode in the mode candidate list based on the prediction information indicating that the current block is coded in MIP and (ii) the Planar intra prediction mode based on the prediction information indicating that the current block is not coded in MIP.

14. The apparatus of claim 13 , wherein the index information is signaled based on one of a truncated binary codeword, a fixed length codeword, or a truncated unary codeword.

15. The apparatus of claim 14 , wherein the index information is signaled using a 5-bit fix-length codeword.

16. The apparatus of claim 14 , wherein:

a subset of the mode candidate list is signaled using M1 bit fix-length codeword, and

remaining candidate modes in the mode candidate list that are not included in the subset are signaled using M2 fix-length codeword, wherein M1 and M2 are non-negative integers.

17. The apparatus of claim 13 , wherein:

based on the prediction information indicating that the current block is coded in MIP,

candidate modes in the mode candidate list are determined based on at least one of a width or a height of the current block, and

orders of the candidate modes in the mode candidate list are determined based on at least one of the width or the height of the current block.

18. The apparatus of claim 13 , wherein the processing circuitry is configured to:

based on the prediction information indicating that the current block is coded in MIP,

construct the mode candidate list including a mode that is determined based on neighboring blocks of the current block.

19. The apparatus of claim 18 , wherein the mode candidate list includes one of:

a first preset mode in response to the neighboring blocks not being coded in MIP,

an intra prediction mode of one of a left neighboring block and an above neighboring block of the neighboring blocks in response to the left neighboring block and the above neighboring block being coded in MIP, and

a second preset mode in response to the left neighboring block and the above neighboring block not being coded in MIP.

20. A non-transitory computer readable storage medium storing instructions which when executed by at least one processor cause the at least one processor to perform:

decoding prediction information for a current block in a current picture that is a part of a coded video sequence, the prediction information indicating whether the current block is coded in matrix based intra prediction (MIP);

based on the prediction information indicating that the current block is coded in MIP, determining an MIP mode index according to index information included in the prediction information, the MIP mode index indicating an MIP mode in a mode candidate list associated with the current block;

determining an intra prediction candidate mode for the current block to be a Planar intra prediction mode based on the prediction information indicating that the current block is not coded in MIP; and

reconstructing the current block according to (i) the MIP mode in the mode candidate list based on the prediction information indicating that the current block is coded in MIP and (ii) the Planar intra prediction mode based on the prediction information indicating that the current block is not coded in MIP.