A region-based intra-frame rate control scheme by jointing inter-frame dependency and inter-frame correlation

During I frame switching, the subjective quality between I frame and P frames usually have obvious fluctuation due to different coding methods. The periodic temporal visual fluctuation will cause video flicker. According to extensive experiments, we observe that I frame flicker possess a strong regional characteristics and different region have different degree of flicker. Based on this observation, a region-based I frame rate control scheme is proposed to suppress I frame flicker according to the different characteristics of the moving and non-moving regions. Firstly, by jointly considering the inter-frame dependency between I frame and subsequent un-encoded P frames and the inter-frame correlation between I frame and previous encoded P frame, an optimization model is proposed to achieve the optimal QPs for different regions. Secondly, a region-based inter-frame dependency model is proposed to separately describe the inter-frame dependency of different regions, which can accurately describe their description of the inter-frame dependency. The experimental results demonstrate that the proposed scheme can efficiently suppress I frame flicker and maintain the smoothness of subjective quality. Moreover, the proposed scheme can achieve a PSNR gain by 0.26 dB on average when compared with the rate control scheme adopted by the HEVC reference software HM15.0.