Novel fast motion estimation and mode decision for H.264 real-time high-definition encoding

The H.264/AVC video coding standard aims to improve the compression performance significantly compared to all existing video coding standards. In order to achieve this, a robust rate-distortion optimization (RDO) technique is employed to select the best reference frame and coding mode for each macroblock (MB), which however leads to drastically increasing in complexity and computation. Therefore, algorithms to reduce the computational complexity without sacrificing coding efficiency are indispensable for real-time high definition implementations of H.264/AVC, especially in real-time high definition (HD) video encoding. This paper proposes a fast motion estimation (ME) and mode decision (MD) algorithm for H.264/AVC real-time high-definition encoding. It improves the speed greatly by employing improved fast SKIP mode checking strategy, innovative candidate motion vector (MV) selection approach, novel fast multi-reference frame selection algorithm, simplified sub-pixel interpolation method as well as fast variable block size mode decision based on SAD reuse. Besides, a multi-direction hybrid motion estimation for B-frame is proposed based on the multi-reference frame selection algorithm of P-frame. The simulation results demonstrate that it can achieve significant complexity reduction with negligible loss of coding efficiency for high-definition videos.