Inter mode selection for depth map coding in 3D video

3D video (3DV) data usually includes both conventional 2D videos and corresponding depth maps. In 3DV coding, color videos and depth maps need to be jointly coded. Usually, the system of 3DV coding uses the two-channel coding method which encodes color videos and depth maps based on two parallel codec implementations. The complexity and hardware requirements are nearly two times higher than coding 2D color videos. While low-complexity color video coding has been broadly studied, depth map coding has received much less attention. The depth map represents the distance from cameras to objects, which has characteristics of both data on Z-axis in world coordinate and the video signal. Thus, there is a high correlation among motion information (the prediction mode, reference frame and motion vector) from color videos and depth maps. Based on this observation, we propose one method to reduce depth coding complexity. An experimental analysis is performed to study the prediction mode correlation in coding information from color videos and depth maps. Based on the correlation, we propose an efficient mode decision algorithm. With almost the same RD performance, the proposed algorithm can reduce about 70% computational complexity of depth coding, which is beneficial for real-time realization through a hardware or software implementation for the 3DV applications.