Method and apparatus for video coding using planar intra prediction mode for intra sub-partition coding mode
Aspects of the disclosure provide methods, apparatuses, and non-transitory computer-readable storage mediums for video encoding/decoding. Prediction information for a current block in a current picture that is a part of a coded video sequence is decoded. The prediction information indicates an intra sub-partition (ISP) mode for the current block. The ISP mode indicates that the current block is to be partitioned in one of a vertical mode and a horizontal mode. The current block is partitioned into a plurality of sub-partitions based on the ISP mode. Each sub-partition is associated with at least one different reference sample that is in one of (1) a row above the current block and (2) a column left to the current block. Each sub-partition is reconstructed based on the at least one different reference sample associated with the respective sub-partition. The current block is reconstructed based on the reconstructed plurality of sub-partitions.
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 an intra sub-partition (ISP) mode for the current block, the ISP mode indicating that the current block is to be partitioned in one of a vertical mode and a horizontal mode, and the prediction information indicating that the current block is coded in one of a Planar intra prediction mode or a DC ultra prediction mode;
partitioning the current block into a plurality of sub-partitions based on the ISP mode, each of the plurality of sub partitions being associated with at least one different reference sample that is in one of (1) a row above the current block or (2) a column left to the current block;
in response to the current block being coded in the Planar intra prediction mode,
reconstructing each of the plurality of sub-partitions based on the at least one different reference sample associated with the respective sub-partition and at least one shared reference sample that is shared among the plurality of sub-partitions;
in response to the current block being coded in the DC intra prediction mode,
reconstructing each of the plurality of sub-partitions based on a respective DC value calculated according to the at least one different reference sample associated with the respective sub-partition; and
reconstructing the current block based on the reconstructed plurality of sub-partitions.
2. The method of claim 1 , wherein the current block is coded in the Planar intra prediction mode, and the at least one different reference sample associated with the respective sub-partition includes a reference sample that is adjacent to (1) a top right corner of the respective sub-partition in a case that the current block is partitioned in the vertical mode or (2) a bottom left corner of the respective sub-partition in a case that the current block is partitioned in the horizontal mode.
3. The method of claim 1 , wherein the current block is coded in the Planar intra prediction mode, and the at least one shared reference sample includes a reference sample that is adjacent to (1) a bottom left corner of the current block in a case that the current block is partitioned in the vertical mode or (2) a top right corner of the current block in a case that the current block is partitioned in the horizontal mode.
4. The method of claim 1 , wherein
the current block is coded in the DC intra prediction mode and partitioned in the vertical mode, and
the at least one different reference sample associated with a sub-partition in the plurality of sub-partitions is in the row above the current block based on the sub-partition not being adjacent to the left side of the current block.
5. The method claim 1 , wherein
the current block is coded in the DC intra prediction mode and partitioned in the horizontal mode, and
the at least one different reference sample associated with a sub-partition in the plurality of sub-partitions is in the column left to the current block based on the sub-partition not being adjacent to the top side of the current block.
6. The method of claim 1 , wherein the reconstructing each of the plurality of sub-partitions comprises:
reconstructing a sub-partition in the plurality of sub-partitions based on another sub-partition in the plurality of sub-partitions that is reconstructed.
7. The method of claim 1 , wherein the at least one different reference sample for each of the plurality of sub-partitions includes reference samples adjacent to the respective sub-partition.
8. 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 an intra sub-partition (ISP) mode for the current block, the ISP mode indicating that the current block is to be partitioned in one of a vertical mode and a horizontal mode, and the prediction information indicating that the current block is coded in one of a Planar intra prediction mode or a DC intra prediction mode;
partition the current block into a plurality of sub-partitions based on the ISP mode, each of the plurality of sub-partitions being associated with at least one different reference sample that is in one of (1) a row above the current block or (2) a column left to the current block;
in response to the current block being coded in the Planar intra prediction mode,
reconstruct each of the plurality of sub-partitions based on the at least one different reference sample associated with the respective sub-partition and at least one shared reference sample that is shared among the plurality of sub-partitions;
in response to the current block being coded in the DC intra prediction mode,
reconstruct each of the plurality of sub-partitions based on a respective DC value calculated according to the at least one different reference sample associated with the respective sub-partition; and
reconstruct the current block based on the reconstructed plurality of sub-partitions.
9. The apparatus of claim 8 , wherein the current block is coded in the Planar intra prediction mode, and the at least one different reference sample associated with the respective sub-partition includes a reference sample that is adjacent to (1) a top right corner of the respective sub-partition in a case that the current block is partitioned in the vertical mode or (2) a bottom left corner of the respective sub-partition in a case that the current block is partitioned in the horizontal mode.
10. The apparatus of claim 8 , wherein the current block is coded in the Planar intra prediction mode, and the at least one shared reference sample includes a reference sample that is adjacent to (1) a bottom left corner of the current block in a case that the current block is partitioned in the vertical mode or (2) a top right corner of the current block in a case that the current block is partitioned in the horizontal mode.
11. The apparatus of claim 8 , wherein
the current block is coded in the DC intra prediction mode and partitioned in the vertical mode, and
the at least one different reference sample associated with a sub-partition in the plurality of sub-partitions is in the row above the current block based on the sub-partition not being adjacent to the left side of the current block.
12. The apparatus of claim 8 , wherein
the current block is coded in the DC intra prediction mode and partitioned in the horizontal mode, and
the at least one different reference sample associated with a sub-partition in the plurality of sub-partitions is in the column left to the current block based on the sub-partition not being adjacent to the top size of the current block.
13. The apparatus of claim 8 , wherein the processing circuitry is further configured to:
reconstruct a sub-partition in the plurality of sub-partitions based on another sub-partition in the plurality of sub-partitions that is reconstructed.
14. The apparatus of claim 8 , wherein the at least one different reference sample for each of the plurality of sub-partitions includes reference samples adjacent to the respective sub-partition.
15. A non-transitory computer-readable storage medium storing a program executable by 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 an intra sub-partition (ISP) mode for the current block, the ISP mode indicating that the current block is to be partitioned in one of a vertical mode and a horizontal mode, and the prediction information indicating that the current block is coded in one of a Planar intra prediction mode or a DC intra prediction mode:
partitioning the current block into a plurality of sub-partitions based on the ISP mode, each of the plurality of sub-partitions being associated with at least one different reference sample that is in one of (1) a row above the current block or (2) a column left to the current block;
in response to the current block being coded in the Planar intra prediction mode,
reconstructing each of the plurality of sub-partitions based on the at least one different reference sample associated with the respective sub-partition and at least one shared reference sample that is shared among the plurality of sub-partitions;
in response to the current block being coded in the DC intra prediction mode,
reconstructing each of the plurality of sub-partitions based on a respective DC value calculated according to the at least one different reference sample associated with the respective sub-partition; and
reconstructing the current block based on the reconstructed plurality of sub-partitions.
16. The non-transitory computer-readable storage medium of claim 15 , wherein the at least one different reference sample for each of the plurality of sub-partitions includes reference samples adjacent to the respective sub-partition.