A fast mixed integer-pixel search algorithm based on centered prediction for H.264

H.264 video coding standard can achieve considerably higher coding efficiency than previous standards. However, this comes at a cost in considerably increased complexity at the encoder and thus increases the difficulty in hardware implementation. The computation complexity is mainly due to motion estimation in combination of variable block sizes and multi-reference frames. With the initialized searching point prediction, searching direction decision, adaptive search window changing and half-stop principle, a fast integer-pixel search algorithm based on centered prediction are provided in this paper to reduce computation in block-matching process. Experimental results show that, the proposed algorithm can reduce about 91.67% of computation complexity compared to full search and 46.52% of computation complexity compared to UMHexagonS but only with little peak signal-to-noise ratio degradation and bit rate increase.