Adaptive fractional-Pixel motion estimation skipped algorithm for efficient HEVC motion estimation

High-Efficiency Video Coding (HEVC) efficiently addresses the storage and transmit problems of high-definition videos, especially for 4K videos. The variable-size Prediction Units (PUs)–based Motion Estimation (ME) contributes a significant compression rate to the HEVC encoder and also generates a huge computation load. Meanwhile, high-level encoding complexity prevents widespread adoption of the HEVC encoder in multimedia systems. In this article, an adaptive fractional-pixel ME skipped scheme is proposed for low-complexity HEVC ME. First, based on the property of the variable-size PUs–based ME process and the video content partition relationship among variable-size PUs, all inter- PU modes during a coding unit encoding process are classified into root-type PU mode and children-type PU modes. Then, according to the ME result of the root-type PU mode, the fractional-pixel ME of its children-type PU modes is adaptively skipped. Simulation results show that, compared to the original ME in HEVC reference software, the proposed algorithm reduces ME encoding time by an average of 63.22% while encoding efficiency performance is maintained.