A New Rate Control Algorithm Based on Region of Interest for HEVC

Although the existing rate control algorithm in HEVC (High Efficiency Video Coding) has achieved relatively high coding efficiency, it is not efficient in ensuring a higher quality for the visually important parts than others in a frame. In this paper, we propose a new rate control algorithm for HEVC based on ROI (Region of Interest), aiming at improving the visual quality while still maintaining the accuracy of rate control. Firstly, a novel method is developed for saliency estimation of the current frame based on spatial and temporal saliency estimation. Then the saliency map is utilized to determine ROI and guide the bits allocation process at the frame level and LCU (Largest Coding Unit) level. Finally the Lagrange multiplier and the quantization parameter will be clipped in a narrow range for smooth visual quality. Experimental results show that the proposed algorithm can make the output bit rate meet the target number and effectively raise the PSNR of ROI. As a result, the overall visual quality of the encoded sequence is highly improved compared to the original HEVC encoder.