Image Characteristic Based Rate Control Algorithm for HEVC

Rate control plays an important role in high quality video coding. In this paper, a rate control algorithm based on video characteristics is proposed. Firstly, we put forward a novel bit allocation algorithm for intra frame by analyzing the relationship among the image characteristic, bit per pixel and quantization step. The image gradient is used as image characteristic. In frame layer, different bit allocation model are applied according to frame type and assign the rational bit to frame according the complexity of video content. In largest coding unit (LCU) layer, it also chooses different strategies of bit allocation according to the type of LCU. To be more specific, the bit of a LCU without previously coded collocated LCU is assigned on the basis of its image complexity. Otherwise, the bit of a LCU is assigned by using the gradient of residual belonging to collocated LCU. Experimental results show that the proposed algorithm is better than the state-of-the-art rate control algorithm in terms of the accuracy of rate control and the coding quality, the average of PSNR has been improved by 0.15dB. Maximal PSNR gaining can reach 0.67dB. Key-Words: high efficiency video coding, rate control, image characteristic, largest coding unit