Abstract:A ROI-based rate allocation algorithm for the MPEG-4 FGS enhancement layer is proposed in this paper. On the basis of the ROI-oriented rate-distortion model, the proposed algorithm can perform optimal rate allocation for the enhancement layer after selective enhancement under equal image quality constraint. The experimental results show that, compared with the conventional average rate allocation algorithm, the proposed algorithm can significantly eliminate the quality fluctuation of ROI. Simultaneously, the computational complexity of the proposed method is low enough to meet the requirements of the real time rate allocation at the video server.