An improved distortion model for rate control of DCT-based video coding

This paper presents a rate control algorithm for the dominant discrete cosine transform (DCT)-based video coding. It is developed based on a more accurate rate-distortion (R-D) model, specifically a new distortion-quantization (D-Q) model. Different from previous work that employs a uniform D-Q model or an empirical distortion model, our work proposes an accurate distortion model, which can quantitatively describe the relationship of distortion with respect to video source information and the selected quantization resolution. Based on understanding the distribution of source frequency coefficients and the quantization theory, our distortion model is proposed. This distortion model is combined with the classical R-D theory to generate a new rate model. Finally, the proposed model is implemented on an MPEG-4 encoder to perform rate control for a low-delay visual communication system. We also compare the proposed rate control with the VM18 rate control and it has been shown to be more efficient.