Content based fast prediction unit quadtree depth decision algorithm for HEVC

The nested quadtree based partitioning scheme of HEVC contributes a lot to the coding efficiency improvement, however, it adds significant complexity to the encoder. This paper introduces a fast prediction unit (PU) level quadtree depth decision (FPDD) algorithm. It is achieved by making use of the inherited correlation of PU quadtree structure between current largest coding unit (LCU) and its spatial and temporal neighbors. To reduce error propagation, we also propose a confidence grading scheme to prevent LCUs with bad prediction from being referred to by others. Results show that our proposed algorithm provides averagely 20.0% (up to 39.3%) encoding time reduction whilst causing negligible RD performance loss (0.2% BD-Rate increase on average) compared with HM 7.0.