A sequence-based rate control framework for consistent quality real-time video

Most model-based rate control solutions have the generally questionable assumption that video sequence is stationary. In addition, they often suffer from the fundamental problem of model parameter misestimation. In this paper, we propose a sequence-based frame-level bit allocation framework employing a rate-complexity model that has the capability of tracking the nonstationary characteristics in the video source without look-ahead encoding. In addition, a new nonlinear model parameter estimation approach is proposed to overcome the existing problems in previous model parameter estimation schemes where quantization parameter (QP) is determined to achieve the allocated bits for a frame. Furthermore, a general concept of bit allocation guarantee is discussed and its importance is highlighted. The proposed rate control solution can achieve smoother video quality with less quality flicker and motion jerkiness. Both a complete solution where requantization is employed to guarantee the achievement of the allocated bits, and a simplified solution without requantization are studied. Experimental results show that they both provide significantly better performance, in terms of average peak-signal-to-noise ratio and quality smoothness, than the MPEG-4 Annex L frame-level rate control solution.