Intra Block Copy Hash Reduction for HEVC Screen Content Coding

To meet a wide range of needs for video applications such as remote desktop, video conference, distance education, and cloud gaming, the ISO/ITU Joint Collaborative Team on Video Coding (JCT-VC) committee is recently specifying the Screen Content Coding (SCC) standard, as one of the extensions of High Efficiency Video Coding (HEVC). In this paper, the hash search method of the standard adopted Intra Block Copy (IBC) coding tool for SCC is investigated. We collect the coded data using the current hash table and examine their efficiency and explore possible ways for further improvement. A low complexity scheme of selecting effective hash nodes and a modified hash key generation method are presented. Experimental results show that the proposed method reduces on the average 37% or at most 70% hash table memory usage but it preserves the similar BD-rate savings and encoding complexity when integrated into the SCM-3.0 test model.