An adaptive Lagrange multiplier technique for multi-view video plus depth coding

The characteristics of the depth map video are different from those of the texture and thus the empirical function of the Lagrange multiplier λ normally used in the rate-distortion optimization (RDO) of texture views might not be suitable for depth map coding. In this paper, we propose a technique whereby the Lagrange multiplier used to select the macroblock (MB) mode is adapted based on the discontinuity region of the depth map and the frame type. This technique, which was tested on various standard test sequences, preserves the depth discontinuities leading to an average depth map bit rate saving of 12.5% without incurring significant quality degradation in the synthesized views compared to using the fixed Lagrange multiplier used in the respective multi-view texture videos.