Parallel processing for video coding

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

decoding a value for a syntax element representing that tile boundaries of a reference layer picture are aligned with tile boundaries of an enhancement layer picture, wherein the representation that the tile boundaries of the reference layer picture are aligned with the tile boundaries of the enhancement layer picture represents that any first two reference layer samples of the reference layer picture, collocated with a first two respective enhancement layer samples within a first common enhancement layer tile of the enhancement layer picture, must be within a first reference layer tile of the reference layer picture when the first two reference layer samples are available and that any second two enhancement layer samples of the enhancement layer picture, which refer to a second two respective reference layer samples of the reference layer picture, must be within a second common enhancement layer tile of the enhancement layer picture when the second two enhancement layer samples are available;

determining that either the first reference layer tile is not available or the second common enhancement layer tile is not available; and

decoding the reference layer picture and the enhancement layer picture based at least in part on the value of the syntax element and the determination that either the first reference layer tile is not available or the second common enhancement layer tile is not available.

2. The method of claim 1 , wherein the value further indicates, for any second two reference layer samples that are collocated with the second two enhancement layer samples and not in the first reference layer tile, that the second two enhancement layer samples must not both be in the second common enhancement layer tile.

3. The method of claim 1 , wherein the value further indicates that for any two reference layer picture samples that lie within the first reference layer tile, the collocated enhancement layer samples also lie within the first common enhancement layer tile.

4. The method of claim 3 , wherein the syntax element comprises a tile_boundaries_aligned_flag.

5. A method of encoding video data, the method comprising:

encoding a value for a syntax element representing tile boundaries of a reference layer picture are aligned with tile boundaries of an enhancement layer picture, wherein the representation that the tile boundaries of the reference layer picture are aligned with the tile boundaries of the enhancement layer picture represents that any first two reference layer samples of the reference layer picture, collocated with a first two respective enhancement layer samples within a first common enhancement layer tile of the enhancement layer picture, must be within a first reference layer tile of the reference layer picture when the first two reference layer samples are available and that any second two enhancement layer samples of the enhancement layer picture, which refer to a second two respective reference layer samples of the reference layer picture, must be within a second common enhancement layer tile of the enhancement layer picture when the second two enhancement layer samples are available;

determining that either the first reference layer tile is not available or the second common enhancement layer tile is not available; and

encoding the reference layer picture and the enhancement layer picture based at least in part on the value of the syntax element and the determination that either the first reference layer tile is not available or the second common enhancement layer tile is not available.

6. The method of claim 5 , wherein the value further indicates, for any second two reference layer samples that are collocated with the second two enhancement layer samples and not in the first reference layer tile, that the second two enhancement layer samples must not both be in the second common enhancement layer tile.

7. The method of claim 5 , further comprising encoding wherein the value further indicates that for any two reference layer picture samples that lie within the first reference layer tile, the collocated enhancement layer samples also lie within the first common enhancement layer tile.

8. The method of claim 7 , wherein the syntax element comprises a tile_boundaries_aligned_flag.

9. A device for coding video data, the device comprising:

a memory configured to store video data; and

a video coder configured to:

code a value for a syntax element representing that tile boundaries of a reference layer picture are aligned with tile boundaries of an enhancement layer picture, wherein the representation that the tile boundaries of the reference layer picture are aligned with the tile boundaries of the enhancement layer picture represents that any first two reference layer samples of the reference layer picture, collocated with a first two respective enhancement layer samples within a first common enhancement layer tile of the enhancement layer picture, must be within a first reference layer tile of the reference layer picture when the first two reference layer samples are available and representing that any second two enhancement layer samples of the enhancement layer picture, which refer to a second two respective reference layer samples of the reference layer picture, must be within a second common enhancement layer tile of the enhancement layer picture when the second two enhancement layer samples are available,

determine that either the first reference layer tile is not available or the second common enhancement layer tile is not available, and

code the reference layer picture and the enhancement layer picture based at least in part on the value of the syntax element and the determination that either the first reference layer tile is not available or the second common enhancement layer tile is not available.

10. The device of claim 9 , wherein the value further indicates, for any second two reference layer samples that are collocated with the second two enhancement layer samples and not in the first reference layer tile, that the second two enhancement layer samples must not both be in the second common enhancement layer tile.

11. The device of claim 9 , wherein the value further indicates that for any two reference layer picture samples that lie within the first reference layer tile, the collocated enhancement layer samples also lie within the first common enhancement layer tile.

12. The device of claim 11 , wherein the syntax element comprises a tile_boundaries_aligned_flag.

13. The device of claim 11 , wherein to process the value of the syntax element, the video coder is configured to code the syntax element.

14. The device of claim 11 , wherein to process the value of the syntax element, the video coder is configured to generate the value for the syntax element for inclusion in an encoded video bitstream.

15. The device of claim 9 , wherein the video coder comprises at least one of a video encoder or a video decoder.

16. A device for coding video data, the device comprising:

means for coding a value for a syntax element representing that tile boundaries of a reference layer picture are aligned with tile boundaries of an enhancement layer picture, wherein the representation that the tile boundaries of the reference layer picture are aligned with the tile boundaries of the enhancement layer picture represents that any first two reference layer samples of the reference layer picture, collocated with a first two respective enhancement layer samples within a first common enhancement layer tile of the enhancement layer picture, must be within a first reference layer tile of the reference layer picture when the first two reference layer samples are available and that any second two enhancement layer samples of the enhancement layer picture, which refer to a second two respective reference layer samples of the reference layer picture, must be within a second common enhancement layer tile of the enhancement layer picture when the second two enhancement layer samples are available;

means for determining that either the first reference layer tile is not available or the second common enhancement layer tile is not available; and

means for coding the reference layer picture and the enhancement layer picture based at least in part on the value of the syntax element and the determination that either the first reference layer tile is not available or the second common enhancement layer tile is not available.

17. The device of claim 16 , wherein the value further indicates, for any second two reference layer samples that are collocated with the second two enhancement layer samples and not in the first reference layer tile, that the second two enhancement layer samples must not both be in the second common enhancement layer tile.

18. The device of claim 16 , wherein the value further indicates that for any two reference layer picture samples that lie within the first reference layer tile, the collocated enhancement layer samples also lie within the first common enhancement layer tile.

19. The device of claim 18 , wherein the syntax element comprises a tile_boundaries_aligned_flag.

20. The device of claim 18 , wherein the means for processing the value of the syntax element comprises means for coding the syntax element.

21. The device of claim 18 , wherein the means for processing the value of the syntax element comprises means for generating the value for the syntax element for inclusion in an encoded video bitstream.

22. A non-transitory computer-readable storage medium having stored thereon instructions that, when executed, cause a processor to:

code a value for a syntax element representing that tile boundaries of a reference layer picture are aligned with tile boundaries of an enhancement layer picture, wherein the representation that the tile boundaries of the reference layer picture are aligned with the tile boundaries of the enhancement layer picture represents that any first two reference layer samples of the reference layer picture, collocated with a first two respective enhancement layer samples within a first common enhancement layer tile of the enhancement layer picture, must be within a first reference layer tile of the reference layer picture when the first two reference layer samples are available and that any second two enhancement layer samples of the enhancement layer picture, which refer to a second two respective reference layer samples of the reference layer picture, must be within a second common enhancement layer tile of the enhancement layer picture when the second two enhancement layer samples are available;

determine that either the first reference layer tile is not available or the second common enhancement layer tile is not available; and

code the reference layer picture and the enhancement layer picture based at least in part on the value of the syntax element and the determination that either the first reference layer tile is not available or the second common enhancement layer tile is not available.

23. The non-transitory computer-readable storage medium of claim 22 , wherein the value further indicates, for any second two reference layer samples that are collocated with the second two enhancement layer samples and not in the first reference layer tile, that the second two enhancement layer samples must not both be in the second common enhancement layer tile.

24. The non-transitory computer-readable storage medium of claim 22 , wherein the value further indicates that for any two reference layer picture samples that lie within the first reference layer tile, the collocated enhancement layer samples also lie within the first common enhancement layer tile.

25. The non-transitory computer-readable storage medium of claim 24 , wherein the syntax element comprises a tile_boundaries_aligned_flag.

26. The non-transitory computer-readable storage medium of claim 24 , wherein the instructions that cause the processor to process the value of the syntax element comprise instructions that cause the processor to code the syntax element.

27. The non-transitory computer-readable storage medium of claim 24 , wherein the instructions that cause the processor to process the value of the syntax element comprise instructions that cause the processor to generate the value for the syntax element for inclusion in an encoded video bitstream.