Simplification of segment-wise DC coding of large prediction blocks in 3D video coding

1. A method of decoding depth data for video decoding, the method comprising:

decoding a block of depth data according to an intra segment-wise DC coding (SDC) mode in a three-dimensional extension of a high efficiency video coding standard (3D-HEVC), at least in part by:

determining that the block of depth data has a size of 64×64 pixels;

based on the block of depth data having the size of 64×64 pixels, determining that the block of depth data exceeds a maximum transform size defined in the high efficiency video coding standard (HEVC);

intra-predicting samples of depth data for four sub-blocks of the block of depth data, wherein each respective sub-block of the four sub-blocks has a respective size of 32×32 pixels, and wherein the four sub-blocks correspond to an upper left sub-block, an upper right sub-block, a lower left sub-block, and a lower right sub-block of the block of depth data;

receiving DC residual data for the block of depth data, the DC residual data indicating a difference between an average value of sample values of the block of depth data and an average value of the intra-predicted samples of one or more of the four sub-blocks; and

reconstructing the block of depth data based on the received DC residual data and the intra-predicted samples of the one or more of the four sub-blocks.

2. The method of claim 1 , wherein reference samples that are available for intra-prediction of the intra-predicted samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks other than the at least one sub-block.

3. The method of claim 1 , wherein reference samples that are available for intra-prediction of the intra-predicted samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks that neighbor the at least one sub-block.

4. The method of claim 1 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of four sub-blocks that neighbor the at least one sub-block and reconstructed samples that neighbor the block of depth data and the at least one sub-block.

5. The method of claim 1 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include reconstructed samples that neighbor the block of depth data.

6. The method of claim 1 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include reconstructed samples that neighbor the block of depth data and do not neighbor the at least one sub-block.

7. The method of claim 1 , wherein intra-predicting the samples of depth data for a first sub-block of the four sub-blocks comprises intra-predicting the samples using intra-predicted reference samples from one or more of the four sub-blocks other than the first sub-block.

8. The method of claim 1 , wherein intra-predicting the samples of depth data for a first sub-block of the four sub-blocks comprises intra-predicting the samples using intra-predicted reference samples from one or more of the four sub-blocks that neighbor the first sub-block.

9. The method of claim 1 , wherein intra-predicting the samples of depth data for a first sub-block of the four sub-blocks comprises intra-predicting the samples using reference samples from one or more of the four sub-blocks that neighbor the first sub-block and reconstructed samples that neighbor the block of depth data and the first sub-block.

10. The method of claim 1 , wherein intra-predicting the samples of depth data for a first sub-block of the four sub-blocks comprises intra-predicting the samples using reconstructed samples that neighbor the block of depth data.

11. The method of claim 1 , wherein intra-predicting the samples of depth data for the four sub-blocks comprises intra-predicting the samples using reconstructed samples that neighbor the block of depth data and do not neighbor the first sub-block.

12. A method of encoding depth data for video encoding, the method comprising:

encoding a block of depth data according to an intra segment-wise DC coding (SDC) mode in a three-dimensional extension of a high efficiency video coding standard (3D-HEVC), at least in part by:

determining that the block of depth data has a size of 64×64 pixels;

based on the block of depth data having the size of 64×64 pixels, determining that the block of depth data exceeds a maximum transform size defined in the high efficiency video coding standard (HEVC);

intra-predicting samples of depth data for four sub-blocks of the block of depth data, wherein each respective sub-block of the four sub-blocks has a respective size of 32×32 pixels, and wherein the four sub-blocks correspond to an upper left sub-block, an upper right sub-block, a lower left sub-block, and a lower right sub-block of the block of depth data;

generating DC residual data for the block of depth data, the DC residual data being based on a difference between an average value of sample values of the block and an average value of the intra-predicted samples of one or more of the four sub-blocks;

encoding the block of depth data according to the intra SDC mode and using the DC residual data; and

signaling the DC residual data in an encoded video bitstream.

13. The method of claim 12 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks other than the at least one sub-block.

14. The method of claim 12 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks that neighbor the at least one sub-block.

15. The method of claim 12 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks that neighbor the at least one sub-block and reconstructed samples that neighbor the block of depth data and the at least one sub-block.

16. The method of claim 12 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include reconstructed samples that neighbor the block of depth data.

17. The method of claim 12 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include reconstructed samples that neighbor the block of depth data and do not neighbor the at least one sub-block.

18. The method of claim 12 , wherein intra-predicting the samples of depth data for a first sub-block of the four sub-blocks comprises intra-predicting the samples using intra-predicted reference samples from one or more of the four sub-blocks other than the first sub-block.

19. The method of claim 12 , wherein intra-predicting the samples of depth data for a first sub-block of the four sub-blocks comprises intra-predicting the samples using intra-predicted reference samples from one or more of the four sub-blocks that neighbor the first sub-block.

20. The method of claim 12 , wherein intra-predicting the samples of depth data for a first sub-block of the four sub-blocks comprises intra-predicting the samples using reference samples from one or more of the four sub-blocks that neighbor the first sub-block and reconstructed samples that neighbor the block of depth data and the first sub-block.

21. The method of claim 12 , wherein intra-predicting the samples of depth data for a first sub-block of the four sub-blocks comprises intra-predicting the samples using reconstructed samples that neighbor the block of depth data.

22. The method of claim 12 , wherein intra-predicting the samples of depth data for the four sub-blocks comprises intra-predicting the samples using reconstructed samples that neighbor the block of depth data and do not neighbor the first sub-block.

23. A device for coding depth data for video coding, the device comprising:

a memory storing depth data for video content; and

one or more processors in communication with the memory, the one or more processors being configured to:

code a block of the depth data stored to the memory according to an intra segment-wise DC coding (SDC) mode in a three-dimensional extension of a high efficiency video coding standard (3D-HEVC), wherein to code the block of the depth data, the one or more processors are configured to:

determine that the block of depth data has a size of 64×64 pixels;

determine, based on the block of depth data having the size of 64×64 pixels, that the block of depth data exceeds a maximum transform size defined in the high efficiency video coding standard (HEVC);

intra-predict samples of depth data for four sub-blocks of the block of depth data, wherein each respective sub-block of the four sub-blocks has a respective size of 32×32 pixels, and wherein the four sub-blocks correspond to an upper left sub-block, an upper right sub-block, a lower left sub-block, and a lower right sub-block of the block of depth data;

determine DC residual data for the block of depth data, the DC residual data indicating a difference between an average value of sample values of the block of depth data and an average value of intra-predicted samples of one or more of the four sub-blocks; and

code the block of depth data according to the intra-prediction mode based on the DC residual data and the intra-predicted samples of the one or more of the four sub-blocks.

24. The device of claim 23 , wherein the device is a video decoder, wherein the video decoder further comprises an interface in communication with the one or more processors, and wherein the one or more processors are further configured to:

receive, via the interface, syntax information identifying the intra SDC mode;

receive, via the interface, the DC residual data; and

reconstruct the block of depth data based on the intra-predicted samples of the one or more of the four sub-blocks and the DC residual data to code the block of depth data.

25. The device of claim 23 , wherein the device is a video encoder, wherein the video encoder further comprises an interface in communication with the one or more processors, and wherein the one or more processors are further configured to:

select the intra SDC mode from a plurality of intra-prediction modes;

generate the DC residual data;

encode the block of depth data according to the intra SDC mode, using the residual data, to code the block of depth data; and

signal the DC residual data via the interface.

26. The device of claim 23 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks other than the at least one sub-block.

27. The device of claim 23 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of four sub-blocks that neighbor the at least one sub-block.

28. The device of claim 23 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks that neighbor the at least one sub-block and reconstructed samples that neighbor the block of depth data and the at least one sub-block.

29. The device of claim 23 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include reconstructed samples that neighbor the block of depth data.

30. The device of claim 23 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include reconstructed samples that neighbor the block of depth data and do not neighbor the at least one sub-block.

31. The device of claim 23 , wherein the one or more processors are configured to intra-predict the samples of depth data for a first sub-block of the four sub-blocks using intra-predicted reference samples from one or more of the four sub-blocks other than the first sub-block.

32. The device of claim 23 , wherein the one or more processors are configured to intra-predict the samples of depth data for a first sub-block of the four sub-blocks using intra-predicted reference samples from one of more of the four sub-blocks other than the first sub-block that neighbor the first sub-block.

33. The device of claim 23 , wherein the one or more processors are configured to intra-predict the samples of depth data for a first sub-block of the four sub-blocks using reference samples from one of more of the four sub-blocks that neighbor the first sub-block and reconstructed samples that neighbor the block of depth data and the first sub-block.

34. The device of claim 23 , wherein the one or more processors are configured to intra-predict the samples of depth data for a first sub-block of the four sub-blocks using reconstructed samples that neighbor the block of depth data.

35. The device of claim 23 , wherein the one or more processors are configured to intra-predict the samples of depth data for a first sub-block of the four sub-block using reconstructed samples that neighbor the block of depth data and do not neighbor the first sub-block.

36. A device for coding depth data for video coding, the device comprising:

means for storing depth data for video content;

means for coding a block of the stored depth data according to an intra segment-wise DC coding (SDC) mode in a three-dimensional extension of a high efficiency video coding standard (3D-HEVC), wherein the means for coding comprises:

means for determining that the block of depth data has a size of 64×64 pixels;

means for determining, based on the block of depth data having the size of 64×64 pixels, that the block of depth data exceeds a maximum transform size defined in the high efficiency video coding standard (HEVC);

means for intra-predicting samples of depth data for four sub-blocks of the block of the stored depth data, wherein each respective sub-block of the four sub-blocks has a respective size of 32×32 pixels, and wherein the four sub-blocks correspond to an upper left sub-block, an upper right sub-block, a lower left sub-block, and a lower right sub-block of the block of depth data;

means for determining DC residual data for the block of the stored depth data, the DC residual data indicating a difference between an average value of sample values of the block of depth data and an average value of intra-predicted samples of one or more of the four sub-blocks; and

means for coding the block of the stored depth data according to the intra SDC mode based on the residual data and the intra-predicted samples of the one or more of the four sub-blocks.

37. A non-transitory computer-readable storage medium encoded with instructions that, when executed, cause one or more processors of a video coding device to:

store, to the non-transitory computer-readable storage medium, depth data for video content;

code a block of the stored depth data according to an intra segment-wise DC coding (SDC) mode in a three-dimensional extension of a high efficiency video coding standard (3D-HEVC), wherein the instructions to code the block of the stored depth data comprise instructions that, when executed, cause the one or more processors to:

determine that the block of depth data has a size of 64×64 pixels;

determine, based on the block of depth data having the size of 64×64 pixels, that the block of depth data exceeds a maximum transform size defined in the high efficiency video coding standard (HEVC);

intra-predict samples of depth data for four sub-blocks of the block of the stored depth data, wherein each respective sub-block of the four sub-blocks has a respective size of 32×32 pixels, and wherein the four sub-blocks correspond to an upper left sub-block, an upper right sub-block, a lower left sub-block, and a lower right sub-block of the block of depth data;

determine DC residual data for the block of the stored depth data, the DC residual data indicating a difference between an average value of sample values of the block of the stored depth data and an average value of intra-predicted samples of one or more of the four sub-blocks; and

code the block of depth data according to the intra SDC mode based on the DC residual data and the intra-predicted samples of the one or more of the four sub-blocks.

38. The device of claim 36 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks other than the at least one sub-block.

39. The device of claim 36 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks that neighbor the at least one sub-block.

40. The device of claim 36 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks that neighbor the at least one sub-block and reconstructed samples that neighbor the block of depth data and the at least one sub-block.

41. The non-transitory computer-readable storage medium of claim 37 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks other than the at least one sub-block.

42. The non-transitory computer-readable storage medium of claim 37 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks that neighbor the at least one sub-block.

43. The non-transitory computer-readable storage medium of claim 37 , wherein reference samples that are available for intra-prediction of the samples of at least one of the four sub-blocks include intra-predicted reference samples from one or more of the four sub-blocks that neighbor the at least one sub-block and reconstructed samples that neighbor the block of depth data and the at least one sub-block.