Predictive mode reduction and selective pixel matching based motion estimation algorithm for H.264

Abstract

Motion estimation (ME) algorithm is used in H.264 to improve the coding efficiency. However, it results in very high computational load. In this paper, a novel fast ME algorithm with reduced computational complexity is proposed. First, a predictive mode reduction method is used to free the encoder from checking the small block types in the homogeneous region. Second, a selective pixel matching scheme and a simplified optimal reference frame discrimination strategy are employed to find the best full-pixel motion vector. Finally, direction based selection rule is utilized to diminish the searching points in sub-pixel ME process. Experimental results have shown that the proposed algorithm achieves a reduction of 87% ME process time on average, while incurring only 0.033 dB loss in PSNR and 0.56% increment on the total bit rate compared with that of exhaustive ME process, which is a default approach set in the JM reference software.