Method and apparatus for signaling of multi-hypothesis for skip and merge mode and signaling of distance offset table in merge with motion vector difference

1. A method of video decoding performed in a video decoder, the method comprising:

receiving a coded video bitstream including signaling information for a current block, the signaling information indicating (i) that the current block is coded in a merge mode, and (ii) whether the current block is coded in a multi-hypothesis mode;

determining block reconstruction information for the current block based on the signaling information; and

reconstructing the current block using the determined block reconstruction information wherein in response to a determination that the signaling information indicates that the current block is coded in the multi-hypothesis mode, the signaling information further includes a merge index having a maximum value of a maximum number of candidates in a merge candidate list minus two.

2. The method according to claim 1 , wherein the merge index is coded in a unary code.

3. The method according to claim 1 , wherein the merge mode is signaled with a first flag, and the multi-hypothesis mode is signaled with a second flag.

4. The method according to claim 1 , wherein the block reconstruction information includes a first merge candidate specified by the merge index, and a second merge candidate derived from the merge index.

5. The method according to claim 1 , wherein the current block is determined not to be coded in the multi-hypothesis mode in response to a determination that a number of candidates in the merge candidate list is less than two.

6. The method according to claim 1 , wherein the current block is determined not to be coded in the multi-hypothesis mode in response to a determination that a merge index has a value greater than or equal to the maximum number of candidates in the merge candidate list minus 1.

7. The method according to claim 1 , wherein the current block is coded with a merge motion vector difference (MMVD) mode, and the signaling information includes an order code for an MMVD distance table.

8. The method of claim 7 , wherein the block reconstruction information includes a motion vector obtained using the MMVD distance table.

9. The method according to claim 7 , wherein the order code is a binary order code that specifies one or more elements of the MMVD distance table.

10. The method according to claim 9 , wherein at least one element of the MMVD distance table is inferred from the binary order code.

11. The method according to claim 7 , wherein the order code is a base order code, and a final order code that specifies one or more elements of the MMVD distance table is determined from a sum of the base order code and a difference between the final order code and the base order code.

12. The method according to claim 11 , wherein the difference between the final order code and the base order code is included in the signaling information.

13. The method according to claim 7 , wherein the order code is included in one of a header of a picture parameter set (PPS) and a header of a sequence parameter set (SPS).

14. A video decoder for video decoding, comprising:

processing circuitry configured to:

receive a coded video bitstream including signaling information for a current block, the signaling information indicating (i) that the current block is coded in a merge mode, and (ii) whether the current block is coded in a multi-hypothesis mode,

determine block reconstruction information for the current block based on the signaling information, and

reconstruct the current block using the determined block reconstruction information,

wherein in response to a determination that the signaling information indicates that the current block is coded in the multi-hypothesis mode, the signaling information further includes a merge index having a maximum value of a maximum number of candidates in a merge candidate list minus two.

15. The video decoder according to claim 14 , wherein the merge index is coded in a unary code.

16. A non-transitory computer readable medium having instructions stored therein, which when executed by a processor in a video decoder causes the processor to execute a method comprising:

receiving a coded video bitstream including signaling information for a current block, the signaling information indicating (i) that the current block is coded in a merge mode, and (ii) whether the current block is coded in a multi-hypothesis mode;

determining block reconstruction information for the current block based on the signaling information; and

reconstructing the current block using the determined block reconstruction information

wherein in response to a determination that the signaling information indicates that the current block is coded in the multi-hypothesis mode, the signaling information further includes a merge index having a maximum value of a maximum number of candidates in a merge candidate list minus two.