Current picture referencing block vector initialization with dual tree

1. A method, comprising:

obtaining a chroma block vector corresponding to a collocated luma block vector of a video block, wherein a block vector is a motion vector which references a current picture;

determining, in order, whether said collocated luma block, a left chroma sub-block, or an above chroma sub-block is coded partially in current picture reference mode and partially in another mode that is not current picture reference mode;

setting a current chroma block vector to said corresponding collocated luma block vector, left chroma sub-block vector, or above chroma sub-block vector, respectively for said determining step that is true; and, if none of said determining steps are true, using a default vector for said current chroma block vector, and wherein left and above chroma subblocks are taken from outside a collocated luma block when sub-blocks are localized in a same coding tree unit and for bottom-right subblocks, chroma block vectors are copied from a left subblock chroma block vector; and,

encoding said video block using said chroma block vector.

2. A non-transitory computer readable medium containing instructions causing a processor to generate data content according to the method of claim 1 , for playback using a processor.

3. An apparatus, comprising:

a processor, configured to:

obtain a chroma block vector corresponding to a collocated luma block vector of a video block, wherein a block vector is a motion vector which references a current picture;

determine, in order, whether said collocated luma block, a left chroma sub-block, or an above chroma sub-block is coded partially in current picture reference mode and partially in another mode that is not current picture reference mode;

set a current chroma block vector to said corresponding collocated luma block vector, left chroma sub-block vector, or above chroma sub-block vector, respectively for said determining step that is true; and, if none of said determining steps are true, using a default vector for said current chroma block vector, and wherein left and above chroma subblocks are taken from outside a collocated luma block when sub-blocks are localized in a same coding tree unit and for bottom-right subblocks, chroma block vectors are copied from a left subblock chroma block vector; and,

 encode said video block using said chroma block vector.

4. A method, comprising:

obtaining a chroma block vector corresponding to a collocated luma block vector of a video block, wherein a block vector is a motion vector which references a current picture;

determining, in order, whether said collocated luma block, a left chroma sub-block, or an above chroma sub-block is coded partially in current picture reference mode and partially in another mode that is not current picture reference mode;

setting a current chroma block vector to said corresponding collocated luma block vector, left chroma sub-block vector, or above chroma sub-block vector, respectively for said determining step that is true; and, if none of said determining steps are true, using a default vector for said current chroma block vector, and wherein left and above chroma subblocks are taken from outside a collocated luma block when sub-blocks are localized in a same coding tree unit and for bottom-right subblocks, chroma block vectors are copied from a left subblock chroma block vector; and,

decoding said video block using said chroma block vector.

5. The method of claim 4 , wherein dual tree mode and current picture referencing is enabled.

6. The method of claim 4 , wherein a luma vector from a neighboring subblock is applied if a collocated luma block is not coded using current picture referencing.

7. The method of claim 4 , wherein at least one chroma block vector is derived from a collocated luma block partition.

8. The method of claim 4 , wherein a same vector is applied for all chroma subblocks corresponding to a luma block.

9. The method of claim 4 , wherein an above chroma subblock vector is used when a left chroma subblock vector is not available.

10. The method of claim 4 , wherein a collocated luma block partition is used to derive the chroma block vector.

11. The method of claim 4 , wherein when a collocated luma subblock is unavailable, another collocated subblock position is checked until a block vector is found.

12. A computer program product comprising instructions stored on a non-transitory computer-readable medium which, when executed by a computer, cause the computer to carry out the method of claim 4 .

13. An apparatus, comprising:

a processor, configured to:

obtain a chroma block vector corresponding to a collocated luma block vector of a video block, wherein a block vector is a motion vector which references a current picture;

determine, in order, whether said collocated luma block, a left chroma sub-block, or an above chroma sub-block is coded partially in current picture reference mode and partially in another mode that is not current picture reference mode;

set a current chroma block vector to said corresponding collocated luma block vector, left chroma sub-block vector, or above chroma sub-block vector, respectively for said determining step that is true; and, if none of said determining steps are true, using a default vector for said current chroma block vector, and wherein left and above chroma subblocks are taken from outside a collocated luma block when sub-blocks are localized in a same coding tree unit and for bottom-right subblocks, chroma block vectors are copied from a left subblock chroma block vector; and,

decode said video block using said chroma block vector.

14. A device comprising:

an apparatus according to claim 13 ; 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.

15. The apparatus of claim 13 , wherein dual tree mode and current picture referencing is enabled.

16. The apparatus of claim 13 , wherein a luma vector from a neighboring subblock is applied if a collocated luma block is not coded using current picture referencing.

17. The apparatus of claim 13 , wherein at least one chroma block vector is derived from a collocated luma block partition.

18. The apparatus of claim 13 , wherein a same vector is applied for all chroma subblocks corresponding to a luma block.

19. The apparatus of claim 13 , wherein an above chroma subblock vector is used when a left chroma subblock vector is not available.

20. The apparatus of claim 13 , wherein a collocated luma block partition is used to derive the chroma block vector.

21. The apparatus of claim 13 , wherein when a collocated luma subblock is unavailable, another collocated subblock position is checked until a block vector is found.