Rate-distortion optimized multi-stage rate control algorithm for H.264/AVC video coding

For real H.264/AVC codec, the bit allocation in rate control is crucial to coding efficiency. Meanwhile, the rate-distortion-optimization (RDO) based mode-decision technique also affects performance considerably. This paper presents a R-D optimized multi-stage rate control scheme where both bit allocation and the Lagrange multiplier (λ_MODE) selection are considered. At the first stage, frame layer bit allocation is executed by analyzing frame complexity which is represented by mean-absolute-difference (MAD). Secondly, in order to a select suitable mode to generate reasonable bits, λ_MODE is further adjusted by using coded and remaining bits information. At the last stage, bits are allocated on macroblock (MB) layer and the computed quantization parameter (QP) is further adjusted. Simulation results verify the performance of the proposed algorithm. Compared with the recommended rate control in H.264/AVC reference software, a gain up to 0.89dB in PSNR is achieved, and the subjective coding quality is also improved.