Piecewise linear model for real-time rate control [video coding applications]
Most existing rate control schemes in the literature evaluate quantization parameters of macro-blocks (MB) based on models which estimate well at low bit rates (e.g. quadratic model). These models are not flexible because this model does not estimate well for different situations with different rates. This work investigates the relationships of the rate and the distortion of a residue MB with two parameters - MB quantization step size and standard deviation of MB prediction errors. A piecewise linear rate model and linear distortion model are proposed. Then, we present the proposed rate control scheme based on these models. The experimental results suggest that our scheme achieves PSNR gain over TMN8 and Li's scheme.