Multistage mode decision for intraprediction in H.264 codec
Changsung Kim, Hsuan-Huei Shih, C.‐C. Jay Kuo · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2004
A multistage mode decision method to reduce the complexity of Intra prediction in H.264/JVT is proposed in this work. The rate-distortion optimized (RDO) mode decision is adopted by H.264 to achieve the optimal coding gain at the cost of a very high computational complexity. Our research goal is to reduce the complexity of intra prediction without significant RD performance loss. The proposed fast intra prediction algorithm uses two features, i.e. the sum of absolute residual coefficients (SATD) and the sum of absolute gradients (SAG), and a simplified RDO method to determine the best mode for 4x4 blocks. It incorporates an early termination mechanism at various intermediate decision steps to avoide unnecessary computations when a good decision can be made at an earlier stage. It is demonstrated by experimental results that the proposed scheme performs approximately 10 to 30 times faster than the current RDO mode decision (JM7.3a) with little degradation in the coding gain.