Rate control scheme based on cauchy R-D optimization model for H.264/AVC under low delay constraint

The motivation of this work is based on the observation that Cauchy distribution provides more accurate estimates of rate and distortion characteristics of video sequences than the previously used distribution such as Laplacian distribution. In this paper, we propose a new rate control scheme for H.264 low-delay video transmission using Cauchy rate-distortion optimization model. Our proposed method uses the Lagrange Multiplier technique to optimize the cost function, and be able 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. The target number of bits for each frame is determined according to their buffer status, the number of bits use in the previous frame, and basic unit complexity. The proposed scheme has been implemented on H.264 video coder. Simulation results show that the proposed rate control algorithm achieves, on the average, an improvement in PSNR for up to 1.68dB with lesser number of frames skipped as compared with the default H.264 JM8.6 rate control scheme.