Low complexity depth mode decision for HEVC-based 3D video coding

The emerging international standard high efficiency video coding (HEVC) based 3D video coding (3D-HEVC) was recently standardized by the Joint Collaborative Team on 3D video coding (JCT-3V) as an extension of HEVC for coding the multi-view video plus depth content. In test model of 3D-HEVC, new depth inter and intra modes including disparity estimation (DE), depth modeling modes (DMM) and region boundary Chain coding (RBC) are exploited for depth map coding. These new inter and intra modes achieve the highest possible coding efficiency, but it results in extremely large encoding time which obstructs 3D-HEVC from practical application. In this paper, we propose a low complexity depth mode decision algorithm for both inter and intra prediction to reduce the computational complexity of 3D-HEVC. The basic idea of the proposed algorithm is to utilize the depth map changes characteristic to predict the current depth treeblock prediction mode and early skip unnecessary inter and intra modes, such as DE, DMM and RBC. Experimental results show that the proposed low complexity algorithm can reduce the encoding time by up to 35% for 3D-HEVC mode decision, with negligible loss of rate-distortion (RD) performance.