Intra prediction
A decoder may generate, for each of a plurality of intra prediction modes determined based on a most probable mode (MPM) list for intra prediction of a block, a prediction of at least one neighboring region of the block. The decoder may determine, based on the predictions of the at least one neighboring region, a first intra prediction mode from the plurality of intra prediction modes. The decoder may decode a second intra prediction mode, that is different from the first intra prediction mode, for the block based on the first intra prediction mode and signaling information in a video bitstream.
1. A method comprising:
generating, by a decoder and for a plurality of intra prediction modes determined based on a most probable mode (MPM) list for intra prediction of a block, a plurality of predictions of at least one neighboring region of the block, wherein each of the plurality of predictions is generated using reference samples of the block and a respective intra prediction mode of the plurality of intra prediction modes;
determining, based on the plurality of predictions of the at least one neighboring region, a first intra prediction mode from the plurality of intra prediction modes;
decoding a second intra prediction mode for the block based on:
the first intra prediction mode; and
signaling information in a video bitstream; and
reconstructing the block based on a prediction of the block generated using the second intra prediction mode.
2. The method of claim 1 , wherein the determining the first intra prediction mode further comprises determining the first intra prediction mode, from the plurality of intra prediction modes, that results in a smallest prediction residual for the at least one neighboring region.
3. The method of claim 1 , wherein the signaling information indicates a difference between an index of the first intra prediction mode and an index of the second intra prediction mode, and wherein the second intra prediction mode is decoded based on the index of the first intra prediction mode and the difference.
4. The method of claim 1 , wherein the signaling information is a single, one-bit flag indicating that the second intra prediction mode is to be decoded as the determined first intra prediction mode.
5. The method of claim 1 , wherein the prediction of the block is generated from the reference samples using the second intra prediction mode.
6. The method of claim 5 , wherein the block is reconstructed from the prediction of the block and a residual of the block.
7. A decoder comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the decoder to:
generate, for a plurality of intra prediction modes determined based on a most probable mode (MPM) list for intra prediction of a block, a plurality of predictions of at least one neighboring region of the block, wherein each of the plurality of predictions is generated using reference samples of the block and a respective intra prediction mode of the plurality of intra prediction modes;
determine, based on the plurality of predictions of the at least one neighboring region, a first intra prediction mode from the plurality of intra prediction modes;
decode a second intra prediction mode for the block based on:
the first intra prediction mode; and
signaling information in a video bitstream; and
reconstruct the block based on a prediction of the block generated using the second intra prediction mode.
8. The decoder of claim 7 , wherein the instructions that, when executed by the one or more processors, cause the decoder to determine the first intra prediction mode further cause the decoder to determine the first intra prediction mode, from the plurality of intra prediction modes, that results in a smallest prediction residual for the at least one neighboring region.
9. The decoder of claim 7 , wherein the signaling information indicates a difference between an index of the first intra prediction mode and an index of the second intra prediction mode, and wherein the second intra prediction mode is decoded based on the index of the first intra prediction mode and the difference.
10. The decoder of claim 7 , wherein the signaling information is a single, one-bit flag indicating that the second intra prediction mode is to be decoded as the determined first intra prediction mode.
11. The decoder of claim 7 , wherein the prediction of the block is generated from the reference samples using the second intra prediction mode.
12. The decoder of claim 11 , wherein the block is reconstructed from the prediction of the block and a residual of the block.
13. A non-transitory computer-readable medium storing instructions that, when executed by one or more processors of a decoder, cause the decoder to:
generate, for a plurality of intra prediction modes determined based on a most probable mode (MPM) list for intra prediction of a block, a plurality of predictions of at least one neighboring region of the block, wherein each of the plurality of predictions is generated using reference samples of the block and a respective intra prediction mode of the plurality of intra prediction modes;
determine, based on the plurality of predictions of the at least one neighboring region, a first intra prediction mode from the plurality of intra prediction modes;
decode a second intra prediction mode for the block based on:
the first intra prediction mode; and
signaling information in a video bitstream; and
reconstruct the block based on a prediction of the block generated using the second intra prediction mode.
14. The non-transitory computer-readable medium of claim 13 , wherein the instructions that, when executed by the one or more processors, cause the decoder to determine the first intra prediction mode further cause the decoder to determine the first intra prediction mode, from the plurality of intra prediction modes, that results in a smallest prediction residual for the at least one neighboring region.
15. The non-transitory computer-readable medium of claim 13 , wherein the signaling information indicates a difference between an index of the first intra prediction mode and an index of the second intra prediction mode, and wherein the second intra prediction mode is decoded based on the index of the first intra prediction mode and the difference.
16. The non-transitory computer-readable medium of claim 13 , wherein the signaling information is a single, one-bit flag indicating that the second intra prediction mode is to be decoded as the determined first intra prediction mode.
17. The non-transitory computer-readable medium of claim 13 , wherein the prediction of the block is generated from the reference samples using the second intra prediction mode.