An apparatus includes processing circuitry that obtains motion information of a group of blocks in a picture from a coded video bitstream, the motion information indicating base motion vectors for the group of blocks, and the base motion vectors pointing to a reference picture in a prediction list. The processing circuitry determines a range of target motion vectors for the group of blocks along a particular coordinate direction according to the base motion vectors and a target difference, where, for any two motion vectors within the range, a difference of integer-pixel parts thereof along the particular coordinate direction is equal to or less than the target difference. The processing circuitry further converts the base motion vectors into the target motion vectors according to the range for reconstructing samples of the group of blocks.