A method of decoding a bitstream by an electronic device is provided. A block unit is determined from an image frame according to the bitstream. One of a plurality of candidate groups is selected based on a set flag in the bitstream. A plurality of merge mode with motion vector difference (MMVD) indications of the block unit is determined according to the bitstream. A plurality of MMVD prediction parameters of the block unit is determined based on the plurality of MMVD indications and the selected candidate group. The block unit is reconstructed based on the plurality of MMVD prediction parameters.