Rate-distortion optimized composition of HEVC-encoded video

This paper proposes a global rate control scheme to maximize the overall encoding quality of a network-based video composition system. The input video sources are encoded using HEVC. The rate-distortion function for each input video source is modelled based on the known PSNR and bitrates at two quantization points and the R-λ model in HEVC. By solving an R-D optimization problem, the proposed scheme is able to optimally allocate rate for each video source and maximize the overall video quality of the composition with respect to the global bandwidth budget. We have evaluated the proposed scheme against a coding scheme where the same quantization parameter (QP) is employed for all video sources. The experimental results show that up to 14.3% average bitrate reduction is achieved by the proposed rate allocation scheme.