Unified position dependent prediction combination process

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 including an intra prediction direction for the current block;

determining a usage of a position dependent prediction combination (PDPC) process according to the intra prediction direction of the current block; and

reconstructing, with circuitry of the decoder, the current block based on the usage of the PDPC process on the current block, wherein

the PDPC process is performed on a first number of columns of samples in the current block in a case that the intra prediction direction is closer to a vertical intra prediction direction than a horizontal intra prediction direction, and

the PDPC process is performed on a second number of rows of samples in the current block in a case that the intra prediction direction is closer to the horizontal intra prediction direction than the vertical intra prediction direction.

2. The method of claim 1 , wherein the intra prediction direction is one of a diagonal intra prediction direction or a neighboring intra prediction direction adjacent to the diagonal intra prediction direction, and the diagonal intra prediction direction is one of a bottom-left intra prediction direction and a top-right intra prediction direction.

3. The method of claim 2 , wherein when the diagonal intra prediction direction is the bottom-left intra prediction direction, a mode index of the neighboring intra prediction direction is below a mode index of a horizontal intra prediction direction.

4. The method of claim 2 , wherein when the diagonal intra prediction direction is the top-right intra prediction direction, a mode index of the neighboring intra prediction direction is above a mode index of a vertical intra prediction direction.

5. The method of claim 1 , further comprising:

when the intra prediction direction is a neighboring intra prediction direction,

determining whether the intra prediction direction points to a fractional position; and

determining an early termination of the PDPC process in response to a determination that the intra prediction direction points to the fractional position.

6. The method of claim 1 , further comprising:

when a current sample in the current block is to be filtered by the PDPC process,

determining whether a reference sample of the current sample is located within a preset range according to a per-row or per-column checking.

7. The method of claim 6 , wherein the per-column checking depends on at least one of (i) a total number of available reference samples that are located left to the current block, (ii) a block height of the current block, and (iii) a horizontal coordinate value of the current sample.

8. The method of claim 6 , wherein the per-row checking depends on at least one of (i) a total number of available reference samples that are located above the current block, (ii) a block width of the current block, (iii) and a vertical coordinate value of the current sample.

9. The method of claim 1 , wherein an angle of the intra prediction direction is equal to or greater than a preset value.

10. The method of claim 9 , wherein:

the first number is determined according to the preset value and a block size of the current block; and

the second number is determined according to the preset value and the block size of the current block.

11. An apparatus, comprising a 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 including an intra prediction direction for the current block;

determine a usage of a position dependent prediction combination (PDPC) process according to the intra prediction direction of the current block; and

reconstruct the current block based on the usage of the PDPC process on the current block, wherein

the PDPC process is performed on a first number of columns of samples in the current block in a case that the intra prediction direction is closer to a vertical intra prediction direction than a horizontal intra prediction direction, and

the PDPC process is performed on a second number of rows of samples in the current block in a case that the intra prediction direction is closer to the horizontal intra prediction direction than the vertical intra prediction direction.

12. The apparatus of claim 11 , wherein the intra prediction direction is one of a diagonal intra prediction direction or a neighboring intra prediction direction adjacent to the diagonal intra prediction direction, and the diagonal intra prediction direction is one of a bottom-left intra prediction direction and a top-right intra prediction direction.

13. The apparatus of claim 12 , wherein when the diagonal intra prediction direction is the bottom-left intra prediction direction, a mode index of the neighboring intra prediction direction is below a mode index of a horizontal intra prediction direction.

14. The apparatus of claim 12 , wherein when the diagonal intra prediction direction is the top-right intra prediction direction, a mode index of the neighboring intra prediction direction is above a mode index of a vertical intra prediction direction.

15. The apparatus of claim 11 , wherein the processing circuitry is further configured to:

when the intra prediction direction is a neighboring intra prediction direction,

determine whether the intra prediction direction points to a fractional position; and

determine an early termination of the PDPC process in response to a determination that the intra prediction points to the fractional position.

16. The apparatus of claim 11 , wherein the processing circuitry is further configured to:

when a current sample in the current block is to be filtered by the PDPC process,

determine whether a reference sample of the current sample is located within a preset range according to a per-row or per-column checking.

17. The apparatus of claim 16 , wherein the per-column checking depends on at least one of (i) a total number of available reference samples that are located left to the current block, (ii) a block height of the current block, and (iii) a horizontal coordinate value of the current sample.

18. The apparatus of claim 16 , wherein the per-row checking depends on at least one of (i) a total number of available reference samples that are located above the current block, (ii) a block width of the current block, (iii) and a vertical coordinate value of the current sample.

19. The apparatus of claim 11 , wherein an angle of the intra prediction direction is equal to or greater than a preset value.

20. A non-transitory computer-readable storage medium storing a program that, when executed by at least one processor, causes 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 including an intra prediction direction for the current block;

determining a usage of a position dependent prediction combination (PDPC) process according to the intra prediction direction of the current block; and

reconstructing the current block based on the usage of the PDPC process on the current block, wherein

the PDPC process is performed on a first number of columns of samples in the current block in a case that the intra prediction direction is closer to a vertical intra prediction direction than a horizontal intra prediction direction, and

the PDPC process is performed on a second number of rows of samples in the current block in a case that the intra prediction direction is closer to the horizontal intra prediction direction than the vertical intra prediction direction.