Motion vector prediction method and related apparatus

An encoding device, comprising:

• one or more processors;
• and
• a computer-readable storage medium coupled to the one or more processors and storing programming instructions for execution by the one or more processors to cause the encoding device to:
• when an affine model of a current block is a 2×K-parameter affine transform model, and an affine transform model of a neighboring block of the current block is a 2×N-parameter affine transform model, obtain, according to the 2×N-parameter affine transform model for the neighboring block, candidate motion vectors of K control points of the current block, wherein the 2×N-parameter affine transform model is obtained based on motion vectors of N control points of the neighboring block, Nis an integer equal to 2, K is an integer equal to 3, the neighboring block is an encoded image block spatially adjacent to the current block, and the current block comprises a plurality of subblocks;
• construct a control point motion vector candidate list,
• wherein the control point motion vector candidate list comprises the candidate motion vectors of K control points of the current block;
• determine, in the control point motion vector candidate list, target candidate motion vectors of the K control points based on a rate-distortion cost;
• and
• encode a syntax element related to the current block into a bitstream, wherein the syntax element comprises an index value indicating a location of the target candidate motion vectors of the K control points in the control point motion vector candidate list.

A non-transitory computer-readable medium storing computer instructions for encoding of a video image, that when executed by one or more processors, cause the one or more processors to perform operations comprising:

• when an affine model of a current block is a 2×K-parameter affine transform model, and an affine transform model of a neighboring block of the current block is a 2×N-parameter affine transform model, obtaining, according to the 2×N-parameter affine transform model for the neighboring block, candidate motion vectors of K control points of the current block, wherein the 2×N-parameter affine transform model is obtained based on motion vectors of N control points of the neighboring block, Nis an integer equal to 2, K is an integer equal to 3, the neighboring block is an encoded image block spatially adjacent to the current block, and the current block comprises a plurality of subblocks;
• constructing a control point motion vector candidate list, wherein the control point motion vector candidate list comprises the candidate motion vectors of K control points of the current block;
• determining, in the control point motion vector candidate list, target candidate motion vectors of the K control points based on a rate-distortion cost;
• and
• encoding a syntax element related to the current block into a bitstream, wherein the syntax element comprises an index value indicating a location of the target candidate motion vectors of the K control points in the control point motion vector candidate list.

A non-transitory computer-readable medium comprising a bitstream generated by a video image encoding method, wherein the video image encoding method comprises:

• when an affine model of a current block is a 2×K-parameter affine transform model, and an affine transform model of a neighboring block of the current block is a 2×N-parameter affine transform model, obtaining, according to the 2×N-parameter affine transform model for the neighboring block, candidate motion vectors of K control points of the current block, wherein the 2×N-parameter affine transform model is obtained based on motion vectors of N control points of the neighboring block, Nis an integer equal to 2, K is an integer equal to 3, the neighboring block is an encoded image block spatially adjacent to the current block, and the current block comprises a plurality of subblocks;
• constructing a control point motion vector candidate list, wherein the control point motion vector candidate list comprises the candidate motion vectors of K control points of the current block;
• determining, in the control point motion vector candidate list, target candidate motion vectors of the K control points based on a rate-distortion cost;
• and
• encoding a syntax element related to the current block into a bitstream, wherein the syntax element comprises an index value indicating a location of the target candidate motion vectors of the K control points in the control point motion vector candidate list.