A novel 3-D predict hexagon search algorithm for fast block motion estimation on H.264 video coding

In the upcoming video coding standard MPEG-4 AVC/JVT/H.264, motion estimation is allowed to use multiple references and multiple block sizes to improve the rate-distortion performance. However, full exhaustive search of all block sizes is computational intensive with complexity increasing linearly to the number of allowed reference frames and block sizes. In block motion estimation, a search pattern with a different shape or size has a very important impact on search speed and distortion performance. Based on an in-depth examination for the influence of search pattern on speed performance, a novel search algorithm, three-dimensional predict hexagon search (3DPHS), is proposed in this paper. The 3DPHS depends on the characteristics of motion vector distribution; it can predict the object movement in horizontal and vertical direction with a novel search pattern. The proposed algorithm also considers the characteristics of multiple reference frames and multiple block sizes in H.264. The analysis results show that the speed improvement of 3DPHS over some popular fast search algorithms is about 25%-75%. The compression quality is almost the same compared with Full Search. Index Terms--Fast block matching algorithm, H.264, motion estimation.