Modification of the disparity vector derivation process in 3D-HEVC

The up-and-coming extension of HEVC for 3D video (3D-HEVC) includes various tools to exploit different redundancies in a 3D video signal. Inter-view redundancies are in particular exploited using Inter-View Motion Prediction (IVMP) and Inter-View Residual Prediction (IVRP). Both of these tools compensate disparity-wise the current prediction unit (PU) in order to find its corresponding PU in a base view, from which some prediction information for the current PU is retrieved. The disparity vector (DV) used for disparity compensation is currently derived using a neighboring search process (NBDV) for a DV across spatial and temporal neighbors. The first DV found is selected as the final DV used in IVMP and IVRP, with no guarantee of optimality. In this paper, the NBDV derivation process is changed: all found DVs from different neighbors are stored in a list. Redundant vectors in this list are removed, and a median computation on the remaining vectors is performed. The resulting DV is set as the DV used for IVMP. Average bitrate reductions of 0.6% and 0.8% for the two dependent views and 0.2% on synthesized views are reported with only a slight increase in encoder and decoder runtimes.