The three-dimensional high-efficiency video coding (3-D-HEVC) is an emerging compression standard for multiview video plus depth data. In addition to the quad-tree coding structure inherited from HEVC, some tools are integrated, which significantly improve the coding efficiency but also result in remarkably high computational complexity. We propose a fast coding unit (CU) size decision algorithm for both depth and texture components in dependent views, where hole-filling maps created through view synthesis are utilized. First, after coding the base view, warp it onto each dependent view via depth image based rendering, during which hole-filling maps are generated. Then for depth in dependent views, CU splitting can be early terminated considering the disoccluded information from hole-filling maps; for texture in dependent views, combining the disoccluded information and the interview correlations, the CU partitioning process can also be accelerated. Experimental results show that the proposed algorithm can achieve on average 54.3% time reduction, with a negligible Bjøntegaard delta bitrate increase of 0.15% on synthesized views, and a 0.05% increase on all the coded plus synthesized views compared with the original encoding scheme in a 3-D-HEVC test model.
The latest high-efficiency video coding (HEVC) standard adopts a recursive quad-tree block structure with the coding-unit (CU) size variable depending on video content. It substantially improves the coding efficiency and also dramatically increases complexity. Therefore, a fast CU size selection algorithm based on hierarchical quad-tree correlations (HQTCs) is proposed. First, for each coding tree unit, the partition information at each depth is recorded in a table that reflects the appearance of the quad-tree structure. Then, by using two techniques called top omitting and bottom pruning, the size of the current CU can be determined according to the subtree distributions of adjacent CUs instead of traversing all the depths. Additionally, a gray level co-occurrence matrix-based method is also introduced to further speedup the searching process. Experimental results show that the proposed algorithm can achieve on average a 26% computational time reduction under all configurations with a negligible BD-rate (Bjøntegaard Delta bitrate) increase of 0.47% compared with the original encoding scheme in HEVC test model HM13.0.