Method and apparatus for video coding
An apparatus for video decoding includes processing circuitry. The processing circuitry is configured to receive a syntax element in a bit stream indicating a maximum number of merge candidates on a merge candidate list for a set of coding blocks, and receive a merge with motion vector difference (MMVD) flag syntax element in the bit stream indicating that an MMVD mode is used to generate a motion vector predictor of a current block included in the set of coding blocks. The processing circuitry is further configured to infer a base candidate index of the MMVD mode to be a predetermined value when the maximum number of the merge candidates is less than 2.
1. A method of video decoding in a decoder, comprising:
receiving a syntax element in a bit stream indicating a maximum number of merge candidates on a merge candidate list for a set of coding blocks;
receiving a merge with motion vector difference (MMVD) flag syntax element in the bit stream indicating that an MMVD mode is used to generate a motion vector predictor of a current block included in the set of coding blocks; and
when the maximum number of the merge candidates is less than 2, inferring a base candidate index of the MMVD mode to be a predetermined value.
2. The method of claim 1 , wherein the predetermined value is 0.
3. The method of claim 1 , further comprising:
when the maximum number of the merge candidates is greater than 1, receiving a syntax element indicating the base candidate index of the MMVD mode.
4. The method of claim 3 , wherein the syntax element has a value of 0 or 1.
5. The method of claim 1 , further comprising:
receiving a syntax element in the bit stream indicating a distance index of the MMVD mode; and
receiving a syntax element in the bit stream indicating a direction index of the MMVD mode.
6. The method of claim 5 , further comprising:
determining the motion vector predictor of the current block based on the base candidate index, the distance index, and the direction index.
7. The method of claim 1 , further comprising:
receiving a skip flag syntax element or a merge flag syntax element indicating a skip mode or merge mode, respectively, is enabled for the set of coding blocks.
8. An apparatus of video decoding, comprising:
processing circuitry configured to:
receive a syntax element in a bit stream indicating a maximum number of merge candidates on a merge candidate list for a set of coding blocks;
receive a merge with motion vector difference (MMVD) flag syntax element in the bit stream indicating that an MMVD mode is used to generate a motion vector predictor of a current block included in the set of coding blocks; and
when the maximum number of the merge candidates is less than 2, infer a base candidate index of the MMVD mode to be a predetermined value.
9. The apparatus of claim 8 , wherein the predetermined value is 0.
10. The apparatus of claim 8 , wherein the processing circuitry is further configured to:
when the maximum number of the merge candidates is greater than 1, receive a syntax element indicating the base candidate index of the MMVD mode.
11. The apparatus of claim 10 , wherein the syntax element has a value of 0 or 1.
12. The apparatus of claim 8 , wherein the processing circuitry is further configured to:
receive a syntax element in the bit stream indicating a distance index of the MMVD mode; and
receive a syntax element in the bit stream indicating a direction index of the MMVD mode.
13. The apparatus of claim 12 , wherein the processing circuitry is further configured to:
determine the motion vector predictor of the current block based on the base candidate index, the distance index, and the direction index.
14. The apparatus of claim 8 , wherein the processing circuitry is further configured to:
receive a skip flag syntax element or a merge flag syntax element indicating a skip mode or merge mode, respectively, is enabled for the set of coding blocks.
15. A non-transitory computer-readable medium storing a program executable by a processor to perform a method of video decoding, the method comprising:
receiving a syntax element in a bit stream indicating a maximum number of merge candidates on a merge candidate list for a set of coding blocks;
receiving a merge with motion vector difference (MMVD) flag syntax element in the bit stream indicating that an MMVD mode is used to generate a motion vector predictor of a current block included in the set of coding blocks; and
when the maximum number of the merge candidates is less than 2, inferring a base candidate index of the MMVD mode to be a predetermined value.
16. The non-transitory computer-readable medium of claim 15 , wherein the predetermined value is 0.
17. The non-transitory computer-readable medium of claim 15 , wherein the method further comprises:
when the maximum number of the merge candidates is greater than 1, receiving a syntax element indicating the base candidate index of the MMVD mode.
18. The non-transitory computer-readable medium of claim 17 , wherein the syntax element has a value of 0 or 1.
19. The non-transitory computer-readable medium of claim 15 , wherein the method further comprises:
receiving a syntax element in the bit stream indicating a distance index of the MMVD mode; and
receiving a syntax element in the bit stream indicating a direction index of the MMVD mode.
20. The non-transitory computer-readable medium of claim 19 , wherein the method further comprises:
determining the motion vector predictor of the current block based on the base candidate index, the distance index, and the direction index.