Weighting factors for prediction sample filtering in intra mode
A video processing method is provided to include: deriving weighting factors for neighboring samples of samples of a current video block of a video according to a rule; and performing a conversion between the current video block and a coded representation of the video, and wherein the rule specifies that, in case that the current video block is coded using a planar mode or a DC mode, the weighting factors are determined from at least one of a dimension of the current video block or positions of the samples of the current video block, wherein the current video block uses a PDPC method that combines the neighboring samples with a prediction signal of the current video block to generate a refined prediction signal, and wherein a weighting factor of a prediction signal of a sample is determined based on weighting factors of corresponding neighboring samples of the sample.
1. A method of video processing, comprising:
generating, for a conversion between a current video block of a video and a bitstream of the video, predicted samples of the current video block,
generating, using a position-dependent intra prediction sample filtering process, modified predicted samples of the current video block, and
performing the conversion based on the modified predicted samples,
wherein in the filtering process, a first predicted sample and at least one neighboring sample of the current video block are combined to generate a modified first predicted sample based on a weighting factor of the first predicted sample and at least one weighting factor of the at least one neighboring sample, and
wherein in case that the current video block is coded using one of INTRA_ANGULAR18, INTRA_ANGULAR50, a planar mode or a DC mode, a width of the current video block is greater than or equal to 4 and a height of the current video block is greater than or equal to 4, a reference line index is equal to 0, and a bdpcm flag is equal to 0, the filtering process is allowed for the current video block, and the at least one weighting factor of the at least one neighboring sample is determined from only dimensions of the current video block and a position of the first predicted sample,
wherein in case that the current video block is coded using an intra prediction mode greater than INTRA_ANGULAR50, or is coded using an intra prediction mode less than INTRA_ANGULAR18 and not equal to a planar mode and not equal to a DC mode, a width of the current video block is greater than or equal to 4 and a height of the current video block is greater than or equal to 4, a reference line index is equal to 0, and a bdpcm flag is equal to 0, the filtering process is allowed for the current video block, and the at least one weighting factor of the at least one neighboring sample is determined from more than dimensions of the current video block and a position of the first predicted sample,
wherein in case that the current video block is coded using an intra prediction mode greater than INTRA_ANGULAR18 and less than INTRA_ANGULAR50, the filtering process is disallowed for the current video block,
wherein in case that the current video block is coded using a DC mode, for a position (x, y) of the first predicted sample, a weighting factor for a top-left neighboring sample is zero.
2. The method of claim 1 , wherein the dimensions of the current video block include a width and a height of the current video block.
3. The method of claim 1 , wherein in case that the current video block is coded using one of INTRA_ANGULAR18, INTRA_ANGULAR50, a planar mode or a DC mode, for a position (x, y) of the first predicted sample, a weighting factor for an above neighboring sample of the at least one neighboring sample is wT[y]=N1>>((y<<N2)>>nScale),
wherein nScale=((Log 2(W)+Log 2(H)−N3)>>N4),
where W denotes a width of the current video block,
where H denotes a height of the current video block, and
where N1, N2, N3 and N4 are non-negative integers.
4. The method of claim 3 , wherein the above neighboring sample is a sample located in position (x, −1).
5. The method of claim 3 , wherein for a position (x, y) of the first predicted sample, a weighting factor for a left neighboring sample of the at least one neighboring sample is wL[x]=N1>>((x<<N2)>>nScale).
6. The method of claim 5 , wherein the left neighboring sample is a sample located in position (−1, y).
7. The method of claim 5 , wherein, N1=32, N2=1, N3=2, or N4=2.
8. The method of claim 1 , wherein the conversion includes encoding the current video block into the bitstream.
9. The method of claim 1 , wherein the conversion includes decoding the current video block from the bitstream.
10. The method of claim 1 , wherein in case that the current video block is coded using an intra prediction mode greater than INTRA_ANGULAR50, or is coded using an intra prediction mode less than INTRA_ANGULAR18 and not equal to a planar mode and not equal to a DC mode, the at least one weighting factor of the at least one neighboring sample is further determined from a variable of invAngle, wherein the variable of invAngle is determined based on the intra prediction mode.
11. The method of claim 10 , wherein in case that the current video block is coded using an intra prediction mode greater than INTRA_ANGULAR50, the at least one weighting factor of the at least one neighboring sample is determined from Min(2, Log 2(H)−Floor(Log 2(3*invAngle−2))+8),
where Floor(x) specifies the largest integer less than or equal to x, and
where H denotes a height of the current video block.
12. The method of claim 10 , wherein in case that the current video block is coded using an intra prediction mode less than INTRA_ANGULAR18 and not equal to a planar mode and not equal to a DC mode, the at least one weighting factor of the at least one neighboring sample is determined from Min(2, Log2(W)−Floor(Log 2(3*invAngle−2))+8), wherein Floor(x) specifies the largest integer less than or equal to x,
where Floor(x) specifies the largest integer less than or equal to x, and
where W denotes a width of the current video block.
13. 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:
generate, for a conversion between a current video block of a video and a bitstream of the video, predicted samples of the current video block,
generate, using a position-dependent intra prediction sample filtering process, modified predicted samples of the current video block, and
perform the conversion based on the modified predicted samples,
wherein in the filtering process, a first predicted sample and at least one neighboring sample of the current video block are combined to generate a modified first predicted sample based on a weighting factor of the first predicted sample and at least one weighting factor of the at least one neighboring sample, and
wherein in case that the current video block is coded using one of INTRA_ANGULAR18, INTRA_ANGULAR50, a planar mode or a DC mode, a width of the current video block is greater than or equal to 4 and a height of the current video block is greater than or equal to 4, a reference line index is equal to 0, and a bdpcm flag is equal to 0, the filtering process is allowed for the current video block, and the at least one weighting factor of the at least one neighboring sample is determined from only dimensions of the current video block and a position of the first predicted sample,
wherein in case that the current video block is coded using an intra prediction mode greater than INTRA_ANGULAR50, or is coded using an intra prediction mode less than INTRA_ANGULAR18 and not equal to a planar mode and not equal to a DC mode, a width of the current video block is greater than or equal to 4 and a height of the current video block is greater than or equal to 4, a reference line index is equal to 0, and a bdpcm flag is equal to 0, the filtering process is allowed for the current video block, and the at least one weighting factor of the at least one neighboring sample is determined from more than dimensions of the current video block and a position of the first predicted sample,
wherein in case that the current video block is coded using an intra prediction mode greater than INTRA_ANGULAR18 and less than INTRA_ANGULAR50, the filtering process is disallowed for the current video block,
wherein in case that the current video block is coded using a DC mode, for a position (x, y) of the first predicted sample, a weighting factor for a top-left neighboring sample is zero.
14. The apparatus of claim 13 , wherein the dimensions of the current video block include a width and a height of the current video block.
15. The apparatus of claim 13 , wherein, in case that the current video block is coded using one of INTRA_ANGULAR18, INTRA_ANGULAR50, a planar mode or a DC mode, for a position (x, y) of the first predicted sample, a weighting factor for an above neighboring sample of the at least one neighboring sample is wT[y]=N1>>((y<<N2)>>nScale),
wherein nScale=((Log 2(W)+Log 2(H)−N3)>>N4),
where W denotes a width of the current video block,
where H denotes a height of the current video block, and
where N1, N2, N3 and N4 are non-negative integers.
16. The apparatus of claim 15 , wherein the above neighboring sample is a sample located in position (x, −1).
17. The apparatus of claim 15 , wherein for a position (x, y) of the first predicted sample, a weighting factor for a left neighboring sample of the at least one neighboring sample is wL[x]=N1>>((x<<N2)>>nScale).
18. The apparatus of claim 17 , wherein the left neighboring sample is a sample located in position (−1, y).
19. A non-transitory computer-readable storage medium storing instructions that cause a processor to:
generate, for a conversion between a current video block of a video and a bitstream of the video, predicted samples of the current video block,
generate, using a position-dependent intra prediction sample filtering process, modified predicted samples of the current video block, and
perform the conversion based on the modified predicted samples,
wherein in the filtering process, a first predicted sample and at least one neighboring sample of the current video block are combined to generate a modified first predicted sample based on a weighting factor of the first predicted sample and at least one weighting factor of the at least one neighboring sample, and
wherein in case that the current video block is coded using one of INTRA_ANGULAR18, INTRA_ANGULAR50, a planar mode or a DC mode, a width of the current video block is greater than or equal to 4 and a height of the current video block is greater than or equal to 4, a reference line index is equal to 0, and a bdpcm flag is equal to 0, the filtering process is allowed for the current video block, and the at least one weighting factor of the at least one neighboring sample is determined from only dimensions of the current video block and a position of the first predicted sample,
wherein in case that the current video block is coded using an intra prediction mode greater than INTRA_ANGULAR50, or is coded using an intra prediction mode less than INTRA_ANGULAR18 and not equal to a planar mode and not equal to a DC mode, a width of the current video block is greater than or equal to 4 and a height of the current video block is greater than or equal to 4, a reference line index is equal to 0, and a bdpcm flag is equal to 0, the filtering process is allowed for the current video block, and the at least one weighting factor of the at least one neighboring sample is determined from more than dimensions of the current video block and a position of the first predicted sample,
wherein in case that the current video block is coded using an intra prediction mode greater than INTRA_ANGULAR18 and less than INTRA_ANGULAR50, the filtering process is disallowed for the current video block,
wherein in case that the current video block is coded using a DC mode, for a position (x, y) of the first predicted sample, a weighting factor for a top-left neighboring sample is zero.
20. 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 predicted samples of a current video block of the video,
generating, using a position-dependent intra prediction sample filtering process, modified predicted samples of the current video block, and
generating the bitstream based on the modified predicted samples,
wherein in the filtering process, a first predicted sample and at least one neighboring sample of the current video block are combined to generate a modified first predicted sample based on a weighting factor of the first predicted sample and at least one weighting factor of the at least one neighboring sample, and
wherein in case that the current video block is coded using one of INTRA_ANGULAR18, INTRA_ANGULAR50, a planar mode or a DC mode, a width of the current video block is greater than or equal to 4 and a height of the current video block is greater than or equal to 4, a reference line index is equal to 0, and a bdpcm flag is equal to 0, the filtering process is allowed for the current video block, and the at least one weighting factor of the at least one neighboring sample is determined from only dimensions of the current video block and a position of the first predicted sample,
wherein in case that the current video block is coded using an intra prediction mode greater than INTRA_ANGULAR50, or is coded using an intra prediction mode less than INTRA_ANGULAR18 and not equal to a planar mode and not equal to a DC mode, a width of the current video block is greater than or equal to 4 and a height of the current video block is greater than or equal to 4, a reference line index is equal to 0, and a bdpcm flag is equal to 0, the filtering process is allowed for the current video block, and the at least one weighting factor of the at least one neighboring sample is determined from more than dimensions of the current video block and a position of the first predicted sample,
wherein in case that the current video block is coded using an intra prediction mode greater than INTRA_ANGULAR18 and less than INTRA_ANGULAR50, the filtering process is disallowed for the current video block;
wherein in case that the current video block is coded using a DC mode, for a position (x, y) of the first predicted sample, a weighting factor for a top-left neighboring sample is zero.