Research On Fast Intra Prediction Algorithm For HEVC

As high definition and ultra high definition video appeared, the requirements of people on the visual and all kinds of application for video are higher and higher. The High Efficiency Video Coding standard was developed by JCT-VC in 2010 and was officially released in 2013 with the aim to improve the efficiency of video compression significantly. Compared to the existing standard H.264/AVC, HEVC can reduce about 50% bit-rate for equal perceptual video quality. In order to improve the efficiency of coding, HEVC introduces a lot of advanced coding technology. But the advanced technology is at the expense of the high algorithm complexity, especially in the intra prediction. Therefore, we need to reduce the algorithm complexity to improve the speed of coding and meet the requirement of practical storage and transport.This thesis studies on the Rough Mode Decision process and fast coding unit size decision based on the HEVC intra prediction process, then present a corresponding improvement algorithm as below.1. A Fast Mode Decision Algorithm For Intra prediction in HEVC:In order to solve the complexity in intra prediction, long encoding time and a series of problems in HEVC, a fast packet-based intra mode decision algorithm has been proposed. According to the size of the PU block, we discuss the result of rough mode decision. Our method needs to packet the candidate modes of the small size block worked by RMD, and then reselect the mode of minimum RMD cost in each packet as a candidate mode. The method can effectively reduce the number of candidates for rate distortion optimization process and the computational complexity of intra prediction, save the coding time. Experimental results that compared with the HM10.0 original algorithm, in all I frames case, the proposed algorithm saves 17.06% encoding time on average with negligible quality loss of image.2. A Fast CU Size Decision Algorithm For the HEVC Intra Encoding:In order to solve the complexity in intra prediction and long encoding time in HEVC, a fast CU size decision algorithm has been proposed. According to the global edge complexities in horizontal, vertical,45° and 135°directions to decide the partitioning of a CU, and also decrease a part of candidate modes. The method can effectively reduce the computational complexity of intra prediction, save the encoding time. Experimental results show that compared with the HM10.0 original algorithm, in all I frames case; the proposed algorithm saves 48.06% encoding time on average with negligible quality loss of image.