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 the coding block is part of low-delay pictures, the set of spatial merge candidates are inserted according to a first construction order;
when the coding block is part of non-low-delay pictures, 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 a zero motion vector, wherein the zero motion vector is inserted an end of the merge candidate list until a maximum merge candidate number is reached.
2. The method according to claim 1 , wherein the first construction order and the second construction order are used for a merge mode with motion vector difference (MMVD).
3. 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 history-based motion vector predictor (HMVP) from a first-in-first-out (FIFO) table, or a pairwise average candidate.
4. The method according to claim 3 , wherein when the HMVP from the FIFO table is added, 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.
5. The method according to claim 3 , wherein when the HMVP from the FIFO table is added, 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.
6. The method according to claim 3 , 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. 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 the coding block is part of low-delay pictures, the set of spatial merge candidates are inserted according to a first construction order;
when the coding block is part of non-low-delay pictures, 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 a zero motion vector, wherein the zero motion vector is inserted at an end of the merge candidate list until a maximum merge candidate number is reached.
8. The method according to claim 7 , wherein the first construction order and the second construction order are used for a merge mode with motion vector difference (MMVD).
9. The method according to claim 7 , further comprising:
adding to the merge candidate list at least one of: a temporal merge candidate from collocated coding units, a history-based motion vector predictor (HMVP) from a first-in-first-out (FIFO) table, or a pairwise average candidate.
10. The method according to claim 9 , wherein when the HMVP from the FIFO table is added, 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.
11. The method according to claim 9 , wherein when the HMVP from the FIFO table is added, 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.
12. The method according to claim 9 , 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.
13. 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 the coding block is part of low-delay pictures, the set of spatial merge candidates are inserted according to a first construction order;
when the coding block is part of non-low-delay pictures, 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 a zero motion vector, wherein the zero motion vector is inserted at an end of the merge candidate list until a maximum merge candidate number is reached.
14. The non-transitory computer readable medium according to claim 13 , wherein the first construction order and the second construction order are used for a merge mode with motion vector difference (MMVD).
15. The non-transitory computer readable medium according to claim 13 , wherein the method further comprises:
adding to the merge candidate list at least one of: a temporal merge candidate from collocated coding units, a history-based motion vector predictor (HMVP) from a first-in-first-out (FIFO) table, or a pairwise average candidate.
16. The non-transitory computer readable medium according to claim 15 , wherein when the HMVP from the FIFO table is added, 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.
17. The non-transitory computer readable medium according to claim 15 , wherein when the HMVP from the FIFO table is added, 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.
18. The non-transitory computer readable medium according to claim 15 , 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.