Adaptive search range selection in motion estimation

An adaptive search range (SR) selection algorithm in motion estimation for video encoding is proposed in this work with an objective to achieve excellent coding performance with reduced memory access bandwidth. In modern fast motion search algorithms, a motion vector predictor (MVP) is obtained from the motion vectors (MVs) of spatially and temporally neighboring blocks, which is called the predictive MV set. By exploiting the relationship between the variance of the predictive MV set and the SR, we develop an adaptive SR selection algorithm. That is, a larger variance implies lower accuracy of the MVP and, thus, a larger SR. The superior performance of the proposed SR selection algorithm is demonstrated by experimental results.