A perceptual two-pass VBR MPEG-2 video encoder

This paper presents a perceptual two-pass VBR MPEG-2 video encoder suitable for digital storage applications. The proposed algorithm aims to achieve perceptually uniform distortion among adjacent macroblocks within a frame and smoothen the inter-frame visual quality fluctuation as soon as possible. In the first-pass coding, we analyze the video sequence and collect some useful coding parameters to accurately measure the frame coding complexity. In the second-pass coding, the target bits are allocated to all frames optimally according to the coding complexity, certainly with decoder buffer considered. The human visual system characteristics including both the spatial and temporal masking effects are employed to improve the proposed adaptive quantization algorithm. Furthermore, an improved iteration based Qp selection algorithm is proposed to search for the optimal frame-level reference Qp resulting in satisfactory iteration speed and iteration precision. Experimental results show that the proposed algorithm can achieve superior visual quality both objectively and subjectively compared with the reference algorithms.