Research On Fast Intra Prediction Algorithm With High Efficiency Video Coding

With the rapid development of computer technology and network technology,the multimedia technology has been widely used in people's life,so the requirements in visual and auditory quality for people have been constantly improving.High Efficiency Video Coding(HEVC),is the current state-of-the-art video coding standard,and it aims to save 50% rate cost while maintaining the same video quality over the predecessor H.264/AVC,which makes it can satisfy the compression with high definition and ultra-high definition video.The framework of HEVC is developed on the basis of H.264,however,more new technologies are introduced.In intra prediction,HEVC adopts more flexible encoding structure by introducing quadtree coding units partitioning.At the same time,HEVC provides up more accuracy prediction direction,35 kinds of intra prediction modes instead of 9 kinds in H.264.These technologies improve the coding efficiency significantly while the coding complexity is simultaneously increased rapidly as well,which restricts its potential use in real-time applications.In order to solve this problem,this paper studies how to speed the process with the video quality and bit rate negligible loss of intra prediction in HEVC.The paper presents the research background and significance,and study status at home and abroad of the topic,and gives a brief introduction of the development with video compression coding.Summarize on the framework of HEVC coding,coding structure,and key technology is introduced,and processes of coding units partitioning and mode selection are described in detail.Considering that best coding unit(CU)partition has a strong correlation with the texture features of current treeblock.This paper provides an adaptive discretization total variation(DTV)threshold-based fast CU size determination algorithm firstly.We choose the first frame in a group of picture(GOP)as the key frame to obtain the optimal thresholds with CUs according to their sizes.For the successive frames of the current GOP,We calculate the DTV with CU firstly and then compare to thresholds,we make the splitting decision for each CU according to its comparative results with thresholds,which some CUs are not needed to further split,or we execute the normal process in HEVC reference model(HM)without any further processing,or we split the CU into four sub-blocks directly,namely the current depth level is skipped.To maintain the adaptability of the thresholds,we refresh the DTV buffers and recalculate the type classification thresholds for each GOP to make sure the thresholds can be updated as the video content.Then,based on the analysis of the complexity with mode selection process of intra prediction in HEVC,this paper proposes an orientation gradient-based fast mode decision algorithm.we reduce the candidate modes involved in the rough mode decision(RMD)and the rate distortion optimization(RDO)process at the same time by the orientation gradients of directional prediction modes,to achieve the purpose of reduce the encoder complexity.Finally,the proposed size determination method and the mode decision method are combined together as a two stages algorithm.We realize the proposed size determination method,the mode decision method and the two stages algorithm on HM10.0.The experimental results show the two-stage algorithm can significantly reduce the computational complexity with negligible video quality and bit rate loss,and they can improve the encoding speed with intra prediction in HEVC effectively.