Device and method for coding video data

1. A method of decoding a bitstream by an electronic device, the method comprising:

determining a block unit from an image frame according to the bitstream;

selecting, based on a set flag, one of a plurality of candidate groups;

determining a plurality of merge mode with motion vector difference (MMVD) indications of the block unit according to the bitstream;

selecting a plurality of MMVD prediction parameters of the block unit based on the plurality of MMVD indications and the selected one of the plurality of candidate groups; and

reconstructing the block unit based on the plurality of MMVD prediction parameters,

wherein:

each of the plurality of candidate groups includes one or more first MMVD candidate lists each including a plurality of first MMVD candidate parameters;

one or more of the plurality of MMVD prediction parameters are selected from the plurality of first MMVD candidate parameters in the one or more first MMVD candidate lists of the selected one of the plurality of candidate groups; and

MMVD prediction parameters other than the one or more of the plurality of MMVD prediction parameters are selected from a plurality of second MMVD candidate parameters in one or more second MMVD candidate lists each of which is different from the one or more first MMVD candidate lists.

2. The method according to claim 1 , wherein a base candidate index, a motion difference index, and a prediction direction index are determined from the plurality of MMVD indications.

3. The method according to claim 2 , wherein a set index included in the plurality of MMVD indications indicates one or more of the base candidate index, the motion difference index, and the prediction direction index.

4. The method according to claim 3 , wherein the set index is identical to one of the base candidate index, the motion difference index, and the prediction direction index for selecting one of the plurality of MMVD prediction parameters, when a number of the one or more of the base candidate index, the motion difference index, and the prediction direction index is equal to one.

5. An electronic device for decoding a bitstream, the electronic device comprising:

at least one processor; and

a storage device coupled to the at least one processor and storing a plurality of instructions which, when executed by the at least one processor, causes the at least one processor to:

determine a block unit from an image frame according to the bitstream;

select, based on a set flag, one of a plurality of candidate groups;

determine a plurality of merge mode with motion vector difference (MMVD) indications of the block unit according to the bitstream;

select a plurality of MMVD prediction parameters of the block unit based on the plurality of MMVD indications and the selected one of the plurality of candidate groups; and

reconstruct the block unit based on the plurality of MMVD prediction parameters,

wherein:

each of the plurality of candidate groups includes one or more first MMVD candidate lists each including a plurality of first MMVD candidate parameters;

one or more of the plurality of MMVD prediction parameters are selected from the plurality of first MMVD candidate parameters in the one or more first MMVD candidate lists of the selected one of the plurality of candidate groups; and

MMVD prediction parameters other than the one or more of the plurality of MMVD prediction parameters are selected from a plurality of second MMVD candidate parameters in one or more second MMVD candidate lists excluded from the selected one of the plurality of candidate groups.

6. The electronic device according to claim 5 , wherein a base candidate index, a motion difference index, and a prediction direction index are determined from the plurality of MMVD indications.

7. The electronic device according to claim 6 , wherein a set index included in the plurality of MMVD indications indicates one or more of the base candidate index, the motion difference index, and the prediction direction index.

8. The electronic device according to claim 7 , wherein the set index is identical to one of the base candidate index, the motion difference index, and the prediction direction index for selecting one of the plurality of MMVD prediction parameters, when a number of the one or more of the base candidate index, the motion difference index, and the prediction direction index is equal to one.