A video encoder, a video decoder, and a corresponding method are provided. The method includes: parsing a bitstream to obtain an index, where the index indicates a target candidate motion vector group of a current coding block; determining the target candidate motion vector group in an affine candidate motion vector list based on the index, where the affine candidate motion vector list includes at least a first candidate motion vector group, the first candidate motion vector group is obtained based on a first group of control points of a first neighboring affine coding block, and the first group of control points is determined based on a CTU located relative to the current coding block, wherein the first neighboring affine coding block is located in the CTU; and predicting a predicted sample value of the current coding block based on the target candidate motion vector group.