Simplified depth intra mode selection for 3D video compression

A simplified depth modeling mode (DMM) selection algorithm is proposed for 3D-HEVC depth intra coding. Since DMMs are designed for coding units (CUs) with edge or sharp transition, it is not efficient for smooth CU compression. Based on the observation that most CUs in a depth frame are smooth or flat, we notice most of the DMM full-Rate-Distortion (RD) search could be skipped. Using the modes in full-RD list as the skip signal, we propose a simplified DMM selection algorithm to avoid unnecessary DMM full-RD cost calculation. Since modes in full-RD list already exist, we can derive the skip signal without any additional calculation. The test result for the proposed simplified selection algorithm shows 21.8% encoding time saving with only 0.16% bitrate increasing in coded and synthesized view for All-Intra test case.