VIDEO CODING WITH ADAPTIVE MOTION INFORMATION REFINEMENT

In a particular implementation, a video decoder may decode an initial motion vector predictor from the bitstream for a current block, and perform motion search in a small search window to refine the initial motion vector predictor. The initial motion vector may be rounded before being refined. The motion refinement can be based on a discontinuity measure between pixels of a current block and pixels of adjacent block, and can also be based on gradients between the current block and adjacent blocks. The motion vector for the current block is then decoded based on the refined motion vector predictor, and the motion vector difference if there is any. The motion refinement can also be performed on the motion vector for the current block directly. Through motion refinement, the decoder may increase the motion resolution. A corresponding video encoder may choose whether to use motion refinement based on encoder decisions.