Predictive search pattern selection based on edge alignment for fast motion estimation

This paper presents a novel block motion estimation scheme with edge alignment strategy on H.264/AVC video coding, whose computational complexity is linearly dependent on the number of allowed reference frames and block sizes using the full exhaustive search. Many fast block-matching algorithms reduce the computational complexity of motion estimation by carefully designing the search patterns with different shapes or sizes which have significant impact on the search speed and distortion performance. However, the search speed and the distortion performance conflict often with each other for these methods. In this paper, given a block in the current frame, we first apply a fast approximate method based on edge alignment to obtain a good initial motion vector as well as a tight initial bound of distortion measure. Then, considering the edge orientation of the block, a modified hexagon search is used to fine tune the motion vector in low computational complexity. The proposed algorithm also pays attentions to the characteristics of multiple reference frames and multiple block sizes in H.264/AVC. Computer simulation results show that the proposed method gives good performance and spans a new way to design a cost-effective real-time video coding system.