A new full-pixel and sub-pixel motion vector search algorithm for fast block-matching motion estimation in H.264

H.264 is a new recommendation for moving picture coding proposed by JVT. In this standard, full pixel and sub-pixel motion estimation are the most important parts. The unequal-arm adaptive rood pattern search (APRS-3) algorithm has shown a good performance on search speed-up. In this paper, we propose an improved algorithm called APRS-4 which applies an early termination technology on APRS-3 by using adaptive threshold. This early termination technology is also applied on sub-pixel motion estimation, and a new fast sub-pixel motion estimation algorithm is proposed which uses the motion vector information of the neighbor blocks. Experimental results show that both algorithms have achieved a good speed-up ratio. Compared with full-pixel motion estimation, our new algorithm could keep image quality well with almost the same bit rate.