Intra Coding Optimization Of HEVC

Composed with text, image and sound, video is playing the more and moreimportant role in the daily life. Video is the necessary part in mobile TV, survillance,TV shows, online video, teleconference and video chart. As carrying plenty ofinformation, storage and transport of the video are limited. To solve the problem,digital video coding is produced. High Efficiency Video Coding(HEVC) is theemerging digital vidoe coding standard, which is based on the well-knownblock-based hybrid coding architecture, combining motion-compensated predictionand transform coding with high-efficiency entropy coding. Compared withH.264/AVC, the videos compressed by HEVC occupy less storage and bandwidth.When the storage and bandwidth are limited, videos compressed by HEVC havebetter visual quality and higher resolution. However the improvement of codingefficiency is obtained at the expense of increased computational complexity, and theencoding time of HEVC is as nearly2or3times as that of H.264/AVC. Intraprediction is the key technology in HEVC. High efficient intra prediction canimprove not only quality of current frame but also quality of reference frames. Thecomputational complexity of intra prediction in HEVC is due to large coding unitsand flexible partition of blocks. In addition, HEVC adopts more precise directionalprediction. There are35prediction modes in HEVC and only9prediction modes inH.264/AVC. To reduce the complexity of intra prediction in HEVC, threeoptimization algorithms of intra prediction in HEVC are proposed. Experimentalresults show that our proposed algorithm can achieve average54%(up to57%)encoding time saving while causing negligible RD performance loss (1.0%BD-rateof luma increase on average) in All Intra High Efficiency test condition comparedwith HM10.0. The main content and novelties are listed below:1. A fast mode decision method of intra prediction in HEVC is proposed.Correlation of prediction modes and correlation of Sum of Absolute Differencewith Hadamard transform are used and a fast mode decision method of intraprediction in HEVC is proposed. Experimental results show that our proposedalgorithm can achieve average29.8%encoding time saving while causing negligibleRD performance loss (0.5%BD-rate of luma increase on average) in All Intra HighEfficiency test condition compared with HM10.0.2. A depth range prediction of coding tree unit in HEVC is proposed.Correlation of neighboring coding tree units are considered and the codingdepth of neighboring coding tree units are used, a depth range prediction of coding tree units in HEVC is proposed. Experimental results show that our proposedalgorithm can achieve average8.98%encoding time saving while without causingRD performance loss in luma and with causing RD performance gain in chroma inAll Intra High Efficiency test condition compared with HM10.0.3. A coding unit size decision method based on statistics in HEVC is proposed.The final partition of coding units in HEVC is achieved by compute the ratedistortion of every different size coding unit recursively. A coding unit size decisionmethod based on statistics in HEVC is proposed. Experimental results show that ourproposed algorithm can achieve average26.93%encoding time saving whilecausing negligible RD performance loss (0.52%BD-rate of luma increase onaverage) in All Intra High Efficiency test condition compared with HM10.0.