Predictive cross-hexagon search algorithm for fast block motion estimation

Abstract

Block-matching motion estimation plays an important role in real-time video compression and thus has significant impact on searching speed and quality of performance. In order to address these issues, we introduce a highly efficient block motion estimation algorithm, referred to as a predictive cross-hexagon search (PCHS) algorithm, that can considerably reduce the complexity of the Joint Video Team (JVT) encoder. In contrast to many classical fast motion estimation algorithms, PCHS has three desirable features: (1) prediction of a search center, (2) usage of search patterns with different sizes, and (3) early algorithm termination that makes it adaptive and effective. We set four predictor candidates for initial search point options and then increase the accuracy of the predictor. The different-size search patterns, including small cross search patterns, hexagon search patterns, and cross-hexagon search patterns, used in the searching process can better suit more motion types. Due to the high accuracy of the predictor, the proposed algorithm adapts early termination; as the predictor is good enough, the search stops early. Therefore, the PCHS algorithm is suitable for real-time video encoding, as it can speed up the encoder without sacrificing performance compared with other fast algorithms.