Fast Algorithm for Sub-Pixel Motion Estimation Using Parabola Model for H.264/MPEG4 AVC

摘要

In this paper, a fast sub-pixel motion estimation algorithm is presented for H.264/MPEG4 AVC video coding. The proposed methods are based on mathematical models of the motion compensated errors distribution function to predict the possible searching direction. Here we select the parabola in horizontal direction not but the paraboloid in two dimension by five integerpixels, for the parabola can more exactly describe the moving and texture characteristic in the compression pictures without strict limitation on the very low bit rate coding. In order to decide the coefficients of the paraboloid model which is suitable for most of sequences, the Minimum Mean Square Error (MMSE) from the best integer-pixel motion vector and its horizontally adjacent two half-pixel motion vectors are computed, then the MMSE correlation among three elements are compared and analyzed respectively. By an accurate modeling, we can effectively predict the further searching mode instead of full search. For the quarterpixel accuracy motion vector, an approximation method is used to get the results from the half-pixel middle results directly. Experimental results show that the proposed method reduces the computational complexity down to 54% averagely, similar performance compared with other fast algorithms in speed, and degradation in the reconstructed video quality is negligible. At the same time, our proposed method does not depend on the integerpixel searching mode.