Wide angle intra prediction and position dependent intra prediction combination
Methods and apparatus for performing intra prediction in an encoder or a decoder for non-square blocks enable a combination of reference samples from a row above the non-square block and a row to the left of the non-square block to be used for the prediction. In one embodiment, a weighted combination of reference samples are used. In another embodiment, the angles of prediction are extended in the longer direction of the non-square block, such that less angles of prediction are used in the shorter direction.
1. A method, comprising:
predicting a sample of a non-square video block using at least one of N reference samples from a row above the non-square video block or at least one of M reference samples from a column left of the non-square video block; and,
encoding the non-square video block using said prediction in an intra coding mode, wherein N and M vary adaptively based on dimensions of the non-square video block, N is equal to twice the width of the non-square video block plus one sample and M is equal to twice the height of the non-square block plus one sample and wherein said prediction comprises a weighted combination of said reference samples with a greater number of prediction directions along a longer dimension of said non-square video block than a number of prediction directions along a shorter dimension of said non-square video block and prediction directions along the longer dimension of the non-square video block able to extend to angles ranging from 45 degrees down to −135 degrees.
2. The method of claim 1 , wherein said prediction comprises a weighted combination of said reference samples.
3. The method of claim 1 , wherein a ratio of N to M is substantially equal to a ratio of width to height of said non-square video block.
4. The method of claim 1 , wherein N is twice the width of the non-square video block and M is twice the height of the non-square video block.
5. The method of claim 1 , wherein intra prediction modes extend beyond angles of 45 and −135 degrees.
6. The method of claim 1 , wherein said N is greater than width of said non-square block, and wherein said N reference samples extends beyond a right edge of said non-square block.
7. The method of claim 1 , wherein said M is greater than height of said non-square block, and wherein said M reference samples extends beyond a bottom edge of said non-square block.
8. A non-transitory computer readable medium containing data content generated according to the method of claim 1 , for playback using a processor.
9. A non-transitory signal comprising video data generated according to the method of claim 1 , for playback using a processor.
10. An apparatus, comprising:
a processor, configured to:
predict a sample of a non-square video block using at least one of N reference samples from a row above the non-square video block or at least one of M reference samples from a column left of the non-square video block; and,
encode the non-square video block using said prediction in an intra coding mode, wherein N and M vary adaptively based on dimensions of the non-square video block, N is equal to twice the width of the non-square video block plus one sample and M is equal to twice the height of the non-square block plus one sample and wherein said prediction comprises a weighted combination of said reference samples with a greater number of prediction directions along a longer dimension of said non-square video block than a number of prediction directions along a shorter dimension of said non-square video block and prediction directions along the longer dimension of the non-square video block able to extend to angles ranging from 45 degrees down to −135 degrees.
11. A method, comprising:
predicting a sample of a non-square video block using at least one of N reference samples from a row above the non-square video block or at least one of M reference samples from a column left of the non-square video block; and,
decoding the non-square video block using said prediction in an intra coding mode, wherein N and M vary adaptively based on dimensions of the non-square video block, N is equal to twice the width of the non-square video block plus one sample and M is equal to twice the height of the non-square block plus one sample and wherein said prediction comprises a weighted combination of said reference samples with a greater number of prediction directions along a longer dimension of said non-square video block than a number of prediction directions along a shorter dimension of said non-square video block and prediction directions along the longer dimension of the non-square video block able to extend to angles ranging from 45 degrees down to −135 degrees.
12. A non-transitory computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of any one of claim 11 .
13. The method of claim 11 , wherein said prediction comprises a weighted combination of said reference samples.
14. The method of claim 11 , wherein a ratio of N to M is substantially equal to a ratio of width to height of said non-square video block.
15. The method of claim 11 , wherein N is twice the width of the non-square video block and M is twice the height of the non-square video block.
16. The method of claim 11 , wherein intra prediction modes extend beyond angles of 45 and −135 degrees.
17. The method of claim 11 , wherein said N is greater than width of said non-square block, and wherein said N reference samples extends beyond a right edge of said non-square block.
18. The method of claim 11 , wherein said M is greater than height of said non-square block, and wherein said M reference samples extends beyond a bottom edge of said non-square block.
19. An apparatus, comprising:
a processor, configured to:
predict a sample of a non-square video block using at least one of N reference samples from a row above the non-square video block or at least one of M reference samples from a column left of the non-square video block; and,
decode the non-square video block using said prediction in an intra coding mode, wherein N and M vary adaptively based on dimensions of the non-square video block, N is equal to twice the width of the non-square video block plus one sample and M is equal to twice the height of the non-square block plus one sample and wherein said prediction comprises a weighted combination of said reference samples with a greater number of prediction directions along a longer dimension of said non-square video block than a number of prediction directions along a shorter dimension of said non-square video block and prediction directions along the longer dimension of the non-square video block able to extend to angles ranging from 45 degrees down to −135 degrees.