Rate Control via Adjustment of Lagrange Multiplier for Video Coding

In this paper, we propose to improve the performance of the rate-control mechanism in video encoders by adaptively adjusting the Lagrange multiplier λ based on the stochastic subgradient method. Using this λ value for each coding unit, the quantization parameter (QP) is sought in the process of rate-distortion optimization (RDO). A log-linear model can be utilized to predict the most probable QP and accordingly narrow the search range. The generated bit number is used to update the λ value for the next coding unit. The extensive experimental results show that the proposed rate-control mechanism significantly enhances the rate-distortion performance compared with the H.264/AVC (Advanced Video Coding) reference software.