A Novel Rate Control Algorithm for the Dirac Video Codec Based upon the Quality Factor Optimization

In this paper, we propose a novel rate control algorithm for the wavelet-based open source Dirac video codec by using the quality factor (QF) optimization method. We derived a mathematical model which we call Rate-QF (R-QF) model to generate the optimum QF for the current coding frame according to the target bitrate. The proposed algorithm is completely one pass process and does not require complex mathematical calculation. The process of calculating the QF is quite simple and does not require calculating for each and every frames being coded. The experimental results show that the proposed algorithm can control the bitrate precisely (within 1% of the target bitrate in average). Moreover, the bitrate fluctuating which is the variation of bitrate over each and every group of pictures (GOPs) is lower than that of H.264, which is one of the desirable features to avoid buffer over flow and under flow in real time broadcasting.