Fast Sub-pixel Motion Estimation for H.264

Abstract

Due to the variable block sizes and multi-reference frame used in the H.264/AVC standard; the motion estimation process becomes even more computationally intensive, resulting in a very low encoding speed. To overcome this low encoding speed, fast motion estimation algorithms such as UMHexagonS [1] and EPZS [2] have been proposed. Since the integer-pixel motion estimation speed has significantly decreased, the fractional or sub-pixel motion estimation speed is no longer non-negligible. We propose a fast sub-pixel motion estimation algorithm using an adaptive rood pattern based on the fractional motion vector of adjacent blocks and also a simplified small diamond search. Our algorithm is able to reduce the number of sub-pixel search points by more than 50%, while restricting the PSNR loss to less than 0.1 dB, compared to the hierarchical fractional pixel search.KeywordsMotion VectorMotion EstimationSearch PointAdjacent BlockMinimum Cost FunctionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.