Modification of the merge candidate list for dependent views in 3D-HEVC

A test model for an HEVC-based 3D video coding standard (3D-HEVC) has recently been drafted. 3D-HEVC exploits inter-view redundancies by including disparity-compensated prediction (DCP) for efficient dependent view coding. It also uses the Merge coding mode to reduce the cost of motion / disparity parameters. However, the candidates in the Merge list are mostly temporal motion vectors. DCP does not often benefit from accurate predictors and is thus costly. Consequently, motion-compensated prediction (MCP) remains largely preferred. In this paper, we propose to reduce the cost of DCP by modifying the Merge candidate list to always include a disparity vector candidate. Two methods are proposed: the new candidate is either added in the secondary or in the primary list of candidates. The latter method, which achieves average bitrate reductions of 0.6% for dependent views, and 0.2% for coded and synthesized views, was adopted in both the 3D-HEVC working draft and software.