Methods for constructing a merge candidate list
A video processing method is provided. The method includes inserting a set of spatial merge candidates to a first merge candidate list of a coding block, wherein the first merge candidate list is constructed by: adding a top neighboring block B 1 to the first merge candidate list when the top neighboring block B 1 is available; adding a left neighboring block A 1 to the first merge candidate list when the left neighboring block A 1 is available; adding a top neighboring block B 0 to the first merge candidate list when the top neighboring block B 0 is available; adding a left neighboring block A 0 to the first merge candidate list when the left neighboring block A 0 is available; and adding an above-left neighboring block B 2 to the first merge candidate list when the above-left neighboring block B 2 is available.
1. A method of encoding a video sequence into a bitstream, the method comprising:
receiving a video sequence;
encoding one or more pictures of the video sequence; and
generating a bitstream, wherein the encoding comprises:
inserting a set of spatial merge candidates to a merge candidate list of a coding block, wherein:
when a first coding mode is applied to the coding block, the set of spatial merge candidates are inserted according to a first construction order;
when a second coding mode is applied to the coding block, the set of spatial merge candidates are inserted according to a second construction order, the first construction order being different from the second construction order; and
adding to the merge candidate list a history-based motion vector predictor (HMVP) from a first-in-first-out (FIFO) table, wherein
motion information of a previously coded block is stored in the FIFO table and used as the motion vector predictor for a current coding unit; or
motion information associated with a non-subblock inter-coded coding unit is added to the last entry of the FIFO table as a new HMVP candidate.
2. The method according to claim 1 , wherein the first coding mode and second coding mode are two different modes selected from:
a regular merge mode, a merge mode with motion vector difference (MMVD), and a triangle partition mode (TPM).
3. The method according to claim 2 , wherein when the MMVD is selected, the method further comprising:
selecting a merge candidate from the merge candidate list;
refining the merge candidate by signaled motion vector difference (MVD) information; and
signaling a merge candidate flag to specify which MMVD candidate in the merge candidate list is used as a base motion vector.
4. The method according to claim 2 , wherein when the TPM is selected, a coding unit is split evenly into two triangle-shaped partitions, using at least one of a diagonal split or an anti-diagonal split.
5. The method according to claim 1 , further comprising:
adding to the merge candidate list at least one of: a temporal merge candidate from collocated coding units, a pairwise average candidate, or a zero motion vector.
6. The method according to claim 5 , wherein when the pairwise average candidate is added, the pairwise average candidate is generated by averaging pairs of candidates in the merge candidate list and is added to the merge candidate list after one or more HMVPs being added to the merge candidate list in response to the merge candidate list not being full.
7. The method according to claim 5 , wherein when the zero motion vector is added, the zero motion vector is inserted in an end of the merge candidate list until a maximum merge candidate number is reached.
8. A method of decoding a bitstream to output one or more pictures for a video stream, the method comprising:
receiving a bitstream; and
decoding, using coded information of the bitstream, one or more pictures, wherein the decoding comprises:
inserting a set of spatial merge candidates to a merge candidate list of a coding block, wherein:
when a first coding mode is applied to the coding block, the set of spatial merge candidates are inserted according to a first construction order; and
when a second coding mode is applied to the coding block, the set of spatial merge candidates are inserted according to a second construction order, the first construction order being different from the second construction order; and
adding to the merge candidate list a history-based motion vector predictor (HMVP) from a first-in-first-out (FIFO) table, wherein
motion information of a previously coded block is stored in the FIFO table and used as the motion vector predictor for a current coding unit; or
motion information associated with a non-subblock inter-coded coding unit is added to the last entry of the FIFO table as a new HMVP candidate.
9. The method according to claim 8 , wherein the first coding mode and second coding mode are two different modes selected from:
a regular merge mode, a merge mode with motion vector difference (MMVD), and a triangle partition mode (TPM).
10. The method according to claim 9 , wherein when the MMVD is selected, the method further comprising:
selecting a merge candidate from the merge candidate list;
refining the merge candidate by decoded motion vector difference (MVD) information; and
decoding a merge candidate flag to specify which MMVD candidate in the merge candidate list is used as a base motion vector.
11. The method according to claim 9 , wherein when the TPM is selected, a coding unit is split evenly into two triangle-shaped partitions, using at least one of a diagonal split or an anti-diagonal split.
12. The method according to claim 8 , further comprising:
adding to the merge candidate list at least one of: a temporal merge candidate from collocated coding units, a pairwise average candidate, or a zero motion vector.
13. The method according to claim 12 , wherein when the pairwise average candidate is added, the pairwise average candidate is generated by averaging pairs of candidates in the merge candidate list and is added to the merge candidate list after one or more HMVPs being added to the merge candidate list in response to the merge candidate list not being full.
14. The method according to claim 12 , wherein when the zero motion vector is added, the zero motion vector is inserted in an end of the merge candidate list until a maximum merge candidate number is reached.
15. A non-transitory computer readable storage medium storing a bitstream of a video for processing according to a method comprising:
inserting a set of spatial merge candidates to a merge candidate list of a coding block, wherein:
when a first coding mode is applied to the coding block, the set of spatial merge candidates are inserted according to a first construction order;
when a second coding mode is applied to the coding block, the set of spatial merge candidates are inserted according to a second construction order, the first construction order being different from the second construction order; and
adding to the merge candidate list a history-based motion vector predictor (HMVP) from a first-in-first-out (FIFO) table, wherein
motion information of a previously coded block is stored in the FIFO table and used as the motion vector predictor for a current coding unit; or
motion information associated with a non-subblock inter-coded coding unit is added to the last entry of the FIFO table as a new HMVP candidate.
16. The non-transitory computer readable medium according to claim 15 , wherein the first coding mode and second coding mode are two different modes selected from: a regular merge mode, a merge mode with motion vector difference (MMVD), and a triangle partition mode (TPM).
17. The non-transitory computer readable medium according to claim 16 , wherein when the MMVD is selected, the method further comprises:
selecting a merge candidate from the merge candidate list;
refining the merge candidate by signaled motion vector difference (MVD) information; and
signaling a merge candidate flag to specify which MMVD candidate in the merge candidate list is used as a base motion vector.
18. The non-transitory computer readable medium according to claim 16 , wherein when the TPM is selected, a coding unit is split evenly into two triangle-shaped partitions, using at least one of a diagonal split or an anti-diagonal split.
19. The non-transitory computer readable medium according to claim 15 , wherein the method further comprises:
adding to the merge candidate list at least one of: a temporal merge candidate from collocated coding units, a pairwise average candidate, and a zero motion vector.
20. The non-transitory computer readable medium according to claim 19 , wherein when the pairwise average candidate is added, the pairwise average candidate is generated by averaging pairs of candidates in the merge candidate list and is added to the merge candidate list after one or more HMVPs being added to the merge candidate list in response to the merge candidate list not being full.