Model-based rate control implementation for low-power video communications systems

This paper focuses on a major requirement of rate control (RC) algorithms when implementing a low-power video coding system: RC must be compatible with a one-pass, sequential and local processing of the frame data. This requirement prevents direct use of the most efficient RC algorithms, i.e., the ones that rely on rate-distortion (R-D) models whose parameters are computed from a pre-analysis of the input frame. The paper proposes to circumvent the problem by predicting the R-D model parameter(s) without accessing the current input frame data. It avoids the pre-analysis stage while keeping the benefit from R-D based rate control. The method is designed and illustrated for standardized and conventional hybrid coding schemes (H.26x, MPEG-x). Specifically, the mean absolute difference (MAD) of the motion prediction error, which is the key R-D model parameter, is predicted before the sequential processing of the input blocks. In order to validate the prediction, the behaviors of rate control systems using either the actual (computed) or the estimated (predicted) MAD parameter are compared.