LAUSR

The Lagrange optimization scheme plays a significant role in H.265/HEVC for mode decision targeting high compression performance. Here the intra-35 prediction modes are evaluated by the operations of rough mode decision (RMD) and rate-distortion optimization. For the first stage of RMD, the selection of Lagrange multiplier is however unsuitable for SATD-based intra-mode decision, which is determined by taking the square root of the Lagrange multiplier based on SSE distortion measurement. Moreover, the related bit-rate regarding RMD is only concerned with the prediction mode index with negligible residuals in Lagrange optimization. In this paper, an efficient Lagrange optimization is proposed for SATD-based intra-mode decision. Firstly the Lagrange multiplier in RMD is derived through the analysis of theoretical rate-distortion optimization. Then in terms of entropy coding principle, the bit-rate of Hadamard transformed residuals is estimated according to the related syntax elements. The experimental results demonstrate the effectiveness of the proposed Lagrange optimization for SATD-based intra-mode decision in H.265/HEVC.