SAD and Termination Based H.264 Intra Mode Decision

H.264 provides higher compression ratio in all video coding standards. In order to achieve this high compression ratio, Ratio Distortion Optimization (RDO) is employed to choose the best mode for every macro block, which results in high computation complexity, and makes it difficult for real-time applications. Experiments show that, a best mode always tends to be the mode with a smaller Sum of Absolute Differences (SAD), and when a best mode has a larger SAD, this mode usually is a most-probable mode too. Based on this feature, a fast SAD and termination based H.264 intra mode decision method is presented and embedded in H.264 reference code JM9.3. Simulations show that, this method can reduce ~ 49% computational complexity on average, with negligible degradation on PSNR and Bitrate.