Multi-direction search algorithm for block motion estimation in H.264 encoder

In this paper, we propose a novel and fast search algorithm, called multi-direction search (MDS) algorithm, which uses a multi-direction search first to find all possible locally optimal points and then uses the extended hexagon search to refine these points for the final optimal motion vector. The experimental results indicate that a significant improvement in computation reduction (approximately 30% and 50% reduction for MDS and fast MDS respectively) can be achieved while maintaining better coding performance, compared to the hybrid UMHexagonS algorithm adopted in H.264/AVC reference software.