A mode correlation-based fractional pixel motion estimation for H.264 video coding

Motion estimation (ME) consumes most of the computational cost in a video encoder system. H.264 adopts seven ME modes and quarter-pel accuracy fractional pixel search, which brings about large scale of computational cost to the fractional pixel ME. To apply H.264 in real-time environment requires not only fast integer pixel ME algorithm but also fast fractional pixel ME algorithms. A novel mode correlation-based fractional pixel motion estimation is proposed in this paper. It makes full use of the correlation of seven ME modes to reduce fractional pel search points in flat homogeneous regions of an image. Experimental results show that compared to the full fractional pixel search, the proposed method can reduce about 50% of fractional pixel search points with negligible degradation in image quality and compression rate. Moreover, this algorithm can integrate other fast integer and fractional pixel ME algorithm to achieve better performance.