Method and apparatus of motion vector prediction for scalable video coding
Inter-layer motion mapping information may be used to enable temporal motion vector prediction (TMVP) of an enhancement layer of a bitstream. For example, a reference picture and a motion vector (MV) of an inter-layer video block may be determined. The reference picture may be determined based on a collocated base layer video block. For example, the reference picture may be a collocated inter-layer reference picture of the reference picture of the collocated base layer video block. The MV may be determined based on a MV of the collocated base layer video block. For example, the MV may be determined by determining the MV of the collocated base layer video block and scaling the MV of the collocated base layer video block according to a spatial ratio between the base layer and the enhancement layer. TMVP may be performed on the enhancement layer picture using the MV of the inter-layer video block.
1. A method comprising:
receiving a bitstream, the bitstream comprising a base layer and an enhancement layer;
obtaining an inter-layer picture for temporal motion vector prediction (TMVP) of an enhancement layer picture;
generating a reference picture list for the inter-layer picture based on a reference picture list of a corresponding base layer picture;
determining a reference picture index that refers to the reference picture list of the inter-layer picture; and
performing TMVP of the enhancement layer picture using the reference picture index and the reference picture list of the inter-layer picture.
2. The method of claim 1 , wherein the reference picture list for the inter-layer picture is generated by:
adding a reference picture in the reference picture list of the corresponding base layer picture to the reference picture list of the inter-layer picture, and wherein the reference picture is added to the reference picture list of the inter-layer picture with the same index as a corresponding reference picture index that refers to the reference picture list of the corresponding base layer picture.
3. The method of claim 2 , wherein the reference picture in the reference picture list of the inter-layer picture has the same picture order count (POC) value as a corresponding reference picture in the reference picture list of the corresponding base layer picture.
4. The method of claim 1 , further comprising adding the inter-layer picture into a reference picture list of the enhancement layer picture, wherein the inter-layer picture is used as a collocated picture for TMVP of the enhancement layer picture.
5. The method of claim 1 , wherein performing TMVP of the enhancement layer picture comprises determining a motion vector (MV) of the inter-layer picture based on a MV of the corresponding base layer picture, wherein TMVP of the enhancement layer picture is further based on the MV of the inter-layer picture.
6. The method of claim 1 , wherein performing TMVP of the enhancement layer picture comprises:
temporally scaling a MV of the inter-layer picture using the reference picture list; and
determining a MV of the enhancement layer picture using the temporally scaled MV of the inter-layer picture, wherein TMVP of the enhancement layer picture is further based on the MV of the enhancement layer picture.
7. A video processing apparatus comprising:
a processor configured to:
receive a bitstream, the bitstream comprising a base layer and an enhancement layer;
obtain an inter-layer picture for temporal motion vector prediction (TMVP) of an enhancement layer picture;
generate a reference picture list for the inter-layer picture based on a reference picture list of a corresponding base layer picture;
determine a reference picture index that refers to the reference picture list of the inter-layer picture; and
perform TMVP of the enhancement layer picture using the reference picture index and the reference picture list of the inter-layer picture.
8. The video processing apparatus of claim 7 , wherein the processor, to generate the reference picture list for the inter-layer picture, is configured to:
add a reference picture in the reference picture list of the corresponding base layer picture to the reference picture list of the inter-layer picture with the same index as a corresponding reference picture index that refers to the reference picture list of the corresponding base layer picture.
9. The video processing apparatus of claim 8 , wherein the processor is configured to assign the same picture order count (POC) value to the reference picture in the reference picture list of the inter-layer picture as a corresponding reference picture in the reference picture list of the corresponding base layer picture.
10. The video processing apparatus of claim 7 , wherein the processor is further configured to add the inter-layer picture into a reference picture list of the enhancement layer picture, wherein the inter-layer picture is used as a collocated picture for TMVP of the enhancement layer picture.
11. The video processing apparatus of claim 7 , wherein the processor is further configured to determine a motion vector (MV) of the inter-layer picture based on a MV of the corresponding base layer picture, wherein TMVP of the enhancement layer picture is further based on the MV of the inter-layer picture.
12. The video processing apparatus of claim 7 , wherein the processor is configured to determine a temporally scaled MV using the reference picture list, wherein TMVP of the enhancement layer picture is further based on the temporally scaled MV.
13. The video processing apparatus of claim 7 , wherein the processor is configured to:
temporally scale a MV of the inter-layer picture using the reference picture list; and
determine a MV of the enhancement layer picture using the temporally scaled MV of the inter-layer picture, wherein TMVP of the enhancement layer picture is further based on the MV of the enhancement layer picture.
14. The video processing apparatus of claim 7 , wherein the processor is further configured to:
spatially scale a MV of the corresponding base layer picture according to a spatial ratio between the base layer and the enhancement layer to determine a MV of the inter-layer picture;
temporally scale the MV of the inter-layer picture based on a temporal distance between the enhancement layer picture and a reference picture of the enhancement layer picture, and a temporal distance between the inter-layer picture and a reference picture in the reference picture list of the inter-layer picture;
and determine a MV of the enhancement layer picture using the temporally scaled MV of the inter-layer picture, wherein TMVP of the enhancement layer picture is further based on the MV of the enhancement layer picture and the reference picture of the enhancement layer picture.
15. A video processing apparatus comprising:
a processor configured to:
receive a bitstream, the bitstream comprising a base layer and an enhancement layer;
identify an enhancement layer video block of an enhancement layer picture;
determine a motion vector (MV) of a collocated base layer video block;
spatially scale the MV of the collocated base layer video block according to a spatial ratio between the base layer and the enhancement layer to generate a MV of a processed base layer video block;
generate a reference picture list for the processed base layer video block based on a reference picture list of the collocated base layer video block;
determine a reference picture index associated with the reference picture list of the processed base layer video block based on a reference picture index associated with the reference picture list of the collocated base layer video block;
perform temporal motion vector prediction (TMVP) to generate a MV field for the enhancement layer picture using the MV and the reference picture index of the processed base layer video block by:
temporally scaling the MV of the processed base layer video block based on the reference picture index of the processed base layer video block, and
generating a MV of the enhancement layer video block using the temporally scaled MV of the processed base layer video block; and
decode the enhancement layer picture using the MV field of the enhancement layer picture.
16. The video processing apparatus of claim 15 , wherein the processor is configured to:
determine a temporal distance between the processed base layer video block and a reference picture of the processed base layer video block based on the reference picture index of the processed base layer video block; and
temporally scale the MV of the processed base layer video block based on a ratio between a temporal distance between the enhancement layer picture and a reference picture of the enhancement layer video block, and the temporal distance between the processed base layer video block and a reference picture of the processed base layer video block.
17. The video processing apparatus of claim 7 , wherein a smallest prediction unit (SPU) in the inter-layer picture corresponds to a plurality of SPUs in the corresponding base layer picture; and
wherein the processor is configured to select a reference picture for the SPU in the inter-layer picture based on reference picture indices of corresponding SPUs in the corresponding base layer picture.
18. The video processing apparatus of claim 7 , wherein the reference picture index refers to a reference picture associated with a video block that is collocated with a current video block in the enhancement layer picture.
19. The video processing apparatus of claim 7 , wherein the processor is further configured to determine a motion vector (MV) associated with the inter-layer picture, wherein TMVP of the enhancement layer picture is further based on the MV associated with the inter-layer picture.
20. A method comprising:
receiving a bitstream, the bitstream comprising a base layer and an enhancement layer;
identifying an enhancement layer video block of an enhancement layer picture;
determining a motion vector (MV) of a collocated base layer video block;
spatially scaling the MV of the collocated base layer video block according to a spatial ratio between the base layer and the enhancement layer to generate a MV of a processed base layer video block;
generating a reference picture list for the processed base layer video block based on a reference picture list of the collocated base layer video block;
determining a reference picture index associated with the reference picture list of the processed base layer video block based on a reference picture index associated with the reference picture list of the collocated base layer video block;
performing temporal motion vector prediction (TMVP) to generate a MV field for the enhancement layer picture using the MV and the reference picture index of the processed base layer video block by:
temporally scaling the MV of the processed base layer video block based on the reference picture index of the processed base layer video block, and
generating a MV of the enhancement layer video block using the temporally scaled MV of the processed base layer video block; and
decoding the enhancement layer picture using the MV field of the enhancement layer picture.
21. The method of claim 20 , further comprising:
determining a temporal distance between the processed base layer video block and a reference picture of the processed base layer video block based on the reference picture index of the processed base layer video block; and
temporally scaling the MV of the processed base layer video block based on a ratio between a temporal distance between the enhancement layer picture and a reference picture of the enhancement layer video block, and the temporal distance between the processed base layer video block and a reference picture of the processed base layer video block.
22. The method of claim 20 , wherein the processed base layer video block comprises texture from the collocated base layer video block and the spatially scaled MV of the collocated base layer video block.