New rate control Scheme based on Cauchy Rate-Distortion Optimization Model for H.264 Video Coding

Abstract

Base on the observation that Cauchy distribution provides accurate estimates of rate and distortion characteristics of video sequences, in this paper, we propose a new rate control scheme based on Cauchy based rate-distortion optimization model for the application of H.264 bit allocation. One solution which has been proposed in this paper uses the Langrange Multiplier technique as the cost function to find the rate and distortion model subject to the target bit rate constraint resulting in the optimum choice of quantization step sizes. Model parameters are estimated using statistical linear regression analysis. Accordingly we then propose a simple rate control scheme using this new Cauchy rate-distortion model. The target number of bit for each frame is determined according to their buffer status, combined with the number of bits use in the previous frame. The technique proposed has been implemented in H.264 video encoder. Experimental results showed that the proposed rate control algorithm achieves an improvement of average PSNR with smooth video quality compared with the H.264 JM8.6 rate control.