Methods and apparatuses for prediction refinement with optical flow

Abstract

Methods, apparatuses, and non-transitory computer-readable storage mediums are provided for encoding a video signal. A method includes obtaining a first reference picture associated with a video block in a current picture within the video signal and a first motion vector (MV) from the video block to a reference block; obtaining first prediction samples of the video block generated from samples of the reference block; controlling internal bit-depths of internal prediction refinement with optical flow (PROF) parameters by performing a shift operation; obtaining a prediction refinement value for the first prediction sample based on the horizontal and vertical gradient values and the horizontal and vertical motion differences; obtaining second prediction samples associated with a second MV and a prediction refinement value for a second prediction sample; and obtaining a final prediction sample of the video block based on the first prediction sample, the second prediction sample, and the prediction refinement values.