Wide angle intra prediction with sub-partitions
A method and apparatus for performing prediction for encoding or decoding uses intra prediction with sub-partitions. The sub-partitions are oriented either horizontally or vertically and can use wide-angle modes different than that of the video block they originate from. Reference samples for a sub-partition are those of the video block when reference samples for the sub-partition are not available, such as due to direction. In an embodiment, when a sub-partition is square, conventional intra prediction directions are used. Reference samples can be used from a block above and right of the video block or left and below the video block using a mapping along a prediction direction, vertically, or horizontally.
1. A method, comprising:
determining an intra prediction direction for a rectangular sub-partition of a video block based on dimensions of the rectangular sub-partition when a ratio of dimensions of said rectangular sub-partition is within a particular range, and based on dimensions of the video block when a ratio of dimensions of said rectangular sub-partition is out of said particular range, wherein sub-partitions of the video block can have unequal shapes but have height and width equal to a power of two;
mapping reference samples from above right or below left of the video block as above right or below left reference samples for prediction of said rectangular sub-partition of the video block;
predicting a sample of the rectangular sub-partition using reference samples from a row above the video block or reference samples from a column left of the video block, wherein a number of reference samples in a row above the video block or a column left of the video block are determined based on dimensions of the rectangular sub-partition; and,
encoding the rectangular sub-partition of a video block using said prediction in an intra coding mode.
2. An apparatus, comprising:
a processor, configured to perform:
determining an intra prediction direction for a rectangular sub-partition of a video block based on dimensions of the rectangular sub-partition when a ratio of dimensions of said rectangular sub-partition is within a particular range, and based on dimensions of the video block when a ratio of dimensions of said rectangular sub-partition is out of said particular range, wherein sub-partitions of the video block can have unequal shapes but have height and width equal to a power of two;
mapping reference samples from above right or below left of the video block as above right or below left reference samples for prediction of said rectangular sub-partition of the video block;
predicting a sample of the rectangular sub-partition using reference samples from a row above the video block or reference samples from a column left of the video block, wherein a number of reference samples in a row above the video block or a column left of the video block are determined based on dimensions of the rectangular sub-partition; and,
encoding the rectangular sub-partition of a video block using said prediction in an intra coding mode.
3. A method, comprising:
determining an intra prediction direction for a rectangular sub-partition of a video block based on dimensions of the rectangular sub-partition when a ratio of dimensions of said rectangular sub-partition is within a particular range, and based on dimensions of the particular range, wherein sub partitions of the video block can have unequal shapes but have height and width equal to a power of two;
mapping reference samples from above right or below left of the video block as above right or below left reference samples for prediction of said rectangular sub-partition of the video block;
predicting a sample of the rectangular sub-partition using reference samples from a row above the video block or reference samples from a column left of the video block, wherein a number of reference samples in a row above the video block or a column left of the video block are determined based on dimensions of the rectangular sub-partition; and,
decoding the rectangular sub-partition of a video block using said prediction in an intra coding mode.
4. An apparatus, comprising:
a processor, configured to perform:
determining an intra prediction direction for a rectangular sub-partition of a video block based on dimensions of the rectangular sub-partition when a ratio of dimensions of said rectangular sub-partition is within a particular range, and based on dimensions of the video block when a ratio of dimensions of said rectangular sub-partition is out of said particular range, wherein sub-partitions of the video block can have unequal shapes but have height and width equal to a power of two;
mapping reference samples from above right or below left of the video block as above right or below left reference samples for prediction of said rectangular sub-partition of the video block;
predicting a sample of the rectangular sub-partition using reference samples from a row above the video block or reference samples from a column left of the video block, wherein a number of reference samples in a row above the video block or a column left of the video block are determined based on dimensions of the rectangular sub-partition; and,
decoding the rectangular sub-partition of a video block using said prediction in an intra coding mode.
5. The method of claim 1 , wherein non-wide angle prediction modes are applied to sub-partitions that are square.
6. The method of claim 1 , wherein for sub-partitions beyond those closest to a left reference array for vertical sub-partitions or beyond those closest to a top edge for horizontal sub-partitions, missing reference samples are mapped from the video block.
7. The method of claim 6 , wherein the intra prediction direction is based on dimensions of the video block for a sub-partition with width/height ratio greater than 16 or less than 1/16.
8. A method, comprising:
determining an intra prediction direction for a rectangular sub-partition of a video block based on dimensions of the sub-partition when a ratio of dimensions of said sub-partition is within a particular range, and based on dimensions of the video block when a ratio of dimensions of said sub-partition is out of said particular range;
mapping reference samples from above right or below left of the video block as above right or below left reference samples for prediction of said sub-partition of the video block;
predicting a sample of the rectangular sub-partition using reference samples from a row above the video block or reference samples from a column left of the video block, wherein a number of reference samples in a row above the video block or a column left of the video block are determined based on dimensions of the rectangular sub-partition; and,
encoding the rectangular sub-partition of a video block using said prediction in an intra coding mode, wherein the intra prediction direction is based on dimensions of the video block for a sub-partition with width/height ratio greater than 16 or less than 1/16 and wherein for sub-partitions beyond those closest to a left reference array for vertical sub-partitions or beyond those closest to a top edge for horizontal sub-partitions, missing reference samples are mapped directly horizontally or vertically from the video block.
9. The method of claim 6 , wherein a sub-partition is at least a single row or a single column of the video block.
10. The method of claim 1 , wherein a sub-partition can use multiple reference lines.
11. A device comprising:
an apparatus according to claim 4 ; and
at least one of (i) an antenna configured to receive a signal, the signal including the video block, (ii) a band limiter configured to limit the received signal to a band of frequencies that includes the video block, and (iii) a display configured to display an output representative of a video block.
12. A non-transitory computer readable medium containing data content generated according to the method of claim 1 , for playback using a processor.
13. 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 claim 3 .
14. The method of claim 3 , wherein non-wide angle prediction modes are applied to sub-partitions that are square.
15. The method of claim 3 , wherein for sub-partitions beyond those closest to a left reference array for vertical sub-partitions or beyond those closest to a top edge for horizontal sub-partitions, missing reference samples are mapped from the video block.
16. The method of claim 3 , wherein the intra prediction direction is based on dimensions of the video block for a sub-partition with width/height ratio greater than 16 or less than 1/16.
17. The non-transitory computer program product of claim 13 , wherein non-wide angle prediction modes are applied to sub-partitions that are square.
18. The non-transitory computer program product of claim 13 , wherein for sub-partitions beyond those closest to a left reference array for vertical sub-partitions or beyond those closest to a top edge for horizontal sub-partitions, missing reference samples are mapped from the video block.
19. The non-transitory computer program product of claim 13 , wherein the intra prediction direction is based on dimensions of the video block for a sub-partition with width/height ratio greater than 16 or less than 1/16.