Fast mode decision and PU size decision algorithm for intra depth coding in 3D-HEVC

In 3D video extension of High-Efficiency-Video-Coding (3D-HEVC), intra depth coding involves huge computational complexity for the added depth modeling modes (DMMs) and the new complex processing flow. This paper proposes an algorithm including the fast mode and prediction unit (PU) size decisions to accelerate the intra depth coding. For the mode decision, after a modification of the processing flow, three strategies are adopted: (1) evaluation results for intra conventional modes (ICMs) are utilized to determine whether DMMs are skipped; (2) with a predicted direction from ICMs, a golden ratio method is adopted to simplify the DMMs searching; and (3) fast Planar mode decision is made by analyzing the relationship of DMMs and Planar mode. For the fast PU size decision, evaluation costs of ICMs and DMMs, with combination of some trained thresholds, are used to make decisions. Experimental results show the overall algorithm reduces 63.00% computational complexity, with 1.04% BD-rate increasing.