A method for video decoding by a decoder, characterized by comprising: decoding prediction information of a current block in a current picture from a coded video bitstream, the prediction information being indicative of an affine merge mode with offset; decoding, from the coded video bitstream, a set of parameters that is used to determine a motion vector difference; applying the motion vector difference to first motion vectors of multiple control points of a base predictor of the current block to determine second motion vectors at corresponding multiple control points of the current block; wherein the first motion vectors refer to a first reference picture and the second motion vectors refer to the first reference picture; calculating a scaling factor based on a first picture number difference of the first reference picture and the current picture and a second picture number difference of a second reference picture and the current picture; applying the motion vector difference that is scaled according to the scaling factor to third motion vectors of the control points of the base predictor that refer to the second reference picture to determine fourth motion vectors at the corresponding multiple control points of the current block that refer to the second reference picture; determining parameters of an affine model referring to the first reference picture based on the second motion vectors at the corresponding multiple control points of the current block; determining parameters of an affine model referring to the second reference picture based on the fourth motion vectors at the corresponding multiple control points of the current block; and reconstructing at least a sample of the current block according to the affine models. decoding prediction information of a current block in a current picture from a coded video bitstream, the prediction information being indicative of an affine merge mode with offset; decoding, from the coded video bitstream, a set of parameters that is used to determine a motion vector difference; applying the motion vector difference to first motion vectors of multiple control points of a base predictor of the current block to determine second motion vectors at corresponding multiple control points of the current block; wherein the first motion vectors refer to a first reference picture and the second motion vectors refer to the first reference picture; calculating a scaling factor based on a first picture number difference of the first reference picture and the current picture and a second picture number difference of a second reference picture and the current picture; applying the motion vector difference that is scaled according to the scaling factor to third motion vectors of the control points of the base predictor that refer to the second reference picture to determine fourth motion vectors at the corresponding multiple control points of the current block that refer to the second reference picture; determining parameters of an affine model referring to the first reference picture based on the second motion vectors at the corresponding multiple control points of the current block; determining parameters of an affine model referring to the second reference picture based on the fourth motion vectors at the corresponding multiple control points of the current block; and reconstructing at least a sample of the current block according to the affine models.