SSIM-inspired two-pass rate control for High Efficiency Video Coding

We propose a perceptual two-pass rate control scheme for High Efficiency Video Coding (HEVC). The target bits are optimally allocated by hierarchically constructing a perceptual uniform space derived based on an SSIM-inspired divisive normalization mechanism for each group of pictures (GoP), each frame, and each coding unit (CU). The Lagrange multiplier λ, which controls the trade-off between perceptual distortion and bit rate, is adopted as the GoP level complexity measure. After the first pass compression, Laplacian based rate and perceptual distortion models are established to adaptively derive λ, and the target bits are dynamically allocated by maintaining an uniform Lagrange multiplier level through λ equalization. Within each GoP, rate control is further performed at frame and CU levels in the perceptually uniform space. Extensive simulations verify that, the proposed scheme can achieve high accuracy rate control and superior rate-SSIM performance.