Fast Motion Estimation Based on Confidence Interval

A new video standard called High Efficiency Video Coding (HEVC) has been recently finalized. In comparison with the H.264/AVC video coding standard, HEVC further improves the video coding rate distortion (RD) performance, but at the price of significant increase in its encoding complexity, especially in its motion estimation (ME) due to large block sizes and complicated block partition. To reduce the ME complexity in HEVC while maintaining its RD performance, in this paper we first formulate ME at the integer pixel level as a statistical inference problem and then propose a confidence interval-based ME (CIME) method. The proposed CIME method can be applied either on top of the existing fast search implemented in HEVC or on its own to replace the existing fast search implemented in HEVC. Experiments show that for the low-delay main test configuration of HEVC: 1) when applied on top of the existing fast search in HEVC, the proposed CIME method further reduces, on average, the integer-level ME time by 70% with only 1.0% increase in bit rate while maintaining the same reconstruction quality in PSNR and 2) when applied on its own to replace the existing fast search implemented in HEVC, the proposed CIME method achieves performance comparable with that of the fast search in HEVC reference software and better than that of the dynamic system fast algorithm proposed recently in the literature.