Edge Density Early Termination Algorithm for HEVC Coding Tree Block

High Efficiency Video Coding (HEVC) is a new generation video coding standard by Joint Collaborative Team on Video Coding (JCTVC). The development of HEVC aims at the compression for ultra high definition videos. In HEVC, the encoder adopts a quad-tree based video coding structure, in which each incoming frame is split into a set of coding tree blocks (CTB) for compression. Each CTB can be recursively split into coding unit (CU), predict unit (PU) and transform unit (TU). This paper proposes an early termination algorithm of recursive partition based on the Sobel edge density of CTB in HEVC intra coding mode. The proposed method can reduce the depth of recursive partition for each CTB and thus save a lot of encoding time. Experimental results by HM10.1 show that the average time savings is about 14.2% and the resultant increase of encoded BD-Rate is only 0.02%. The proposed method can achieve significant time savings with negligible BD-Rate increase.