Adaptive motion estimation search window size for HEVC standard

Recently standardized by the Joint Video Team (JVT) of ITU-T Video Coding Experts Group (VCEG) and ISO/IEC Moving Picture Experts Group (MPEG), the High Efficiency Video Coding (HEVC) was adopted to replace the H264/AVC with better compression performance that facilitates video transmission and storage while maintaining the same reconstructed video quality. This excellent coding efficiency is performed through an exhaustive algorithm for mode decision that requires a huge computational complexity. To accelerate the encoding process, fast motion estimation (ME) algorithms are proposed in this paper. Firstly, according to statistical results of the motion vector difference prediction distribution, an adaptive search range selection algorithm based on a depth level is presented. In addition, several motion estimation search patterns were designed to reduce the calculation redundancy of motion estimation process. Experimental results show that the proposed algorithm schemes can save the ME time up to 88% while upholding almost the same rate-distortion performances.