A Frame Level Rate Control Algorithm for Screen Content Coding

In this paper, we propose a frame level rate control scheme for screen content video (SCV) coding. Firstly, inter frame correlation (IFC) is computed to describe the similarity of successive frames for SCV. Based on the IFC, the frames in SCV are further classified into key frames (KFs) and non-key frames (NKFs). Secondly, an efficient bit rate allocation scheme is proposed for KFs and NKFs based on the IFC and Hypothetical Reference Decoder (HRD), which can well ensure the R-D performance. Finally, rate quantization (R-Q) models for KFs and NKFs are established by considering the characteristics of the two types of frames, respectively. As such, accurate coding bits allocation at frame level can be achieved by the proposed rate control algorithm. The proposed rate control scheme introduces low coding complexity burden as well as low coding delay, enabling its application in real screen sharing scenarios. Compared with the recommended rate control scheme in HEVC, experimental results demonstrate that the proposed rate control scheme can achieve better performance in terms of both rate control accuracy and R-D performance. In particular, the average bit rate mismatch is within 1.4%, and the average R-D performance improvements are over 19%.