Research On Screen Content Coding

With the development of internet technology and digital device,more and more remote applications apprear in our daily life.In the case of the limited network bandwidth,it has been a challenge to efficiently compress high definition screen content videos generated by the computer.Screen content videos have some different characteristics from traditional natural videos.Therefore,screen content coding need new theories and techniques based on traditional video coding methods,which is introduced as the extension of HEVC.At present,screen content coding has introduced some new methods,such as Intra Block Copy mode,Palette mode and Hash-based block search.However,due to the introduction of new technologies,the computational complexty of screen content coding increased.It prevents screen content coding to be applied in many applactions.Thus,fast screen content coding algorithm has been a hot research topic.This paper thoroughly studies the characteristics of screen content videos and proposes a fast intra prediction algorithm based on content property analysis for screen content coding.Firstly,coding units(CU)are classified into natural content CU(NCCU)and screen content CU(SCCU),based on characteristics of the content.For NCCU,a mode skip and partition termination method based on DC and PLANR is proposed.For SCCU,based on the characterristics of the rank of the matrix,a fast decision strategy is introduced to terminate the CU splititing process.For all CU,a common partition termination method is proposed by the analysis of bpp and spatial-temporal correlation.Experimental results show that the proposed method can reduce the computational complexity and save coding time obviously for screen content video.With respect to fast inter prediction in screen content coding,this paper realizes a fast inter prediction algorithm based on prediction mode and motion characteristics analysis.Firstly,a fast mode decision and termination partition method based on the characteristics of Hash-based block search is implemented.Secondly,through the analysis of Merge mode,a SMP mode skip method is realized.Finally,motion characteristic and spatial-temporal correlation is introduced into the mode decision and depth skip strategy.Experimental results show that the method greatly enhances the coding efficiency with negligible loss of video quality.