For H.264/avc Motion Estimation And Rate Control Method

H.264/AVC video coding standard was developed jointly by the ITU-T and ISO/IEC. By adopting a number of new coding techniques, H.264/AVC has achieved a significant improvement in compression performance and a "network-friendly" representation relative to existing standards. As a result, this standard obtains much attention from academic and industrial fields.In this paper, author mainly research on the new techniques in H.264/AVC, emphatically on 2 core techniques: motion estimation and rate control.Block-matching motion estimation has been widely adopted by current video coding standards due to its effectiveness and simplicity for implementation. Based on the classified research on some typical block-matching motion estimation algorithms, a novel oriented adaptive cross search (OACS) algorithm was proposed, where small cross, large cross and T-shape search patterns are utilized adaptively. The proposed algorithm not only may reduce the number of searching candidates, but also can reach the global or close-to-global optimization. Experimental results have shown that the OACS algorithm can speed up 74.65%, 39.78%, 42.44%, and 7.84% over DS (Diamond Search), SDS (Square Diamond Search), CDS (Cross-Diamond Search), and SCDS (Small Cross-Diamond Search) algorithms, respectively, and at the same time, it can maintain the similar search accuracy.The target of rate control is to regulate the coded bit stream to satisfy the channel condition and improve the reconstructed video quality. Based on the research of key technology and typical algorithms of rate control, a novel macroblock layer rate control algorithm for H.264/AVC is proposed in order to solve the issues of standard rate algorithm JVT-G012. The experimental results have shown that our method has more precise rate control performance than that of JVT-G012 with the average absolute rate error reducing 0.327kbps. Furthermore, the proposed method can produce much smoother bit fluctuation with the average rate deviation reduces 0.175 and obtain much better average image quality with average PSNR improving 0.325dB (the best improvement is 0.62dB).