【作者】 王丽丽；

【导师】 王洪君；

【作者基本信息】 山东大学 ， 信号与信息处理， 2007， 硕士

【摘要】 在过去的十几年中,国际标准化组织制定了一系列的国际视频编码标准并广泛应用到各种领域。其中,ITU-T制定了满足实时视频通信应用的标准,例如H.261、H.263、H.263+、H.263++;ISO制定了满足视频存储、广播视频和视频流需要的MPEG标准,包括MPEG-1、MPEG-2及MPEG-4等。而H.264/AVC是ITU-T和ISO联合推出的新标准,采用了近几年视频编码方面的先进技术,以较高编码效率和网络友好性成为新一代国际视频编码标准。H.264/AVC设计的最初目标是在相同解码质量下,能够提供比MPEG-4和H.263高一倍的压缩性能。无论从客观还是主观度量,H.264都可以提供比现有的视频压缩编码标准高的多的解码质量。为了实现高效压缩,H.264/AVC中采用了大量的新技术。这些技术包括:帧内预测;可变块大小的运动补偿;1/4像素精度的运动矢量;整数4×4变换;切换条带;上下文自适应二进制算术编码。采用了这些先进的编码技术后,压缩性能和解码质量都获得了很大的提高。一些研究的实验数据表明,H.264/AVC在信噪比,压缩效率和视觉效果方面,都远远好于现有的其它视频编码标准。H.264/AVC中采用的这些先进编码技术既增加了基本模块的复杂度,也成倍增加算法的复杂度,这就限制了H.264的应用,尤其是在实时视频通信和一些资源或功耗受限的嵌入式应用中。基于此,本文进行了一下研究:首先,为了解决H.264/AVC帧内预测模式多,计算复杂和预测不精确的问题,本文提出了一种帧内预测算法。该算法利用边缘检测算子和空间相邻块的相关性快速选出所需的候选预测模式,对于每种候选预测模式又改进了预测算法。试验结果表明:新的预测算法可以提高帧内预测编码所需要的时间。其次,H.264/AVC采用了多参考帧运动估计来提高编码效率,增加的计算量与参考帧数目成正比。为了避免搜索多余的参考帧,本文提出了一种低复杂度参考帧确定算法来快速确定当前宏块所需的参考帧。试验结果表明,本算法在保持率失真性能的前提下有效地减少了多参考帧预测的计算复杂度并节省了时间。更多还原

【Abstract】 In the past about ten years, a series of international video coding standards are developed and widely used in a variety of domains. Some standards for real-time telecommunication applications have been established by ITU-T, including H.261, H.263, H.263+, H.263++. Others for video storage, broadcast and stream application by ISO/IEC, such as MPEG-1/2/4.H.264/AVC is the newest standard approved by the ITU-T and ISO/IEC organizations, which represents a number of advances in video coding technology and becomes the newest international video coding standard because of both high coding efficiency and network friendliness.It can provide both objective and subjective image quality superior to existing standards. The main goals of this standardization are to develop a simple and straightforward video coding design with enhanced compression performance. Compared to MPEG-4 advanced simple profile, up to 50% of bit-rate reduction can be achieved.Some new techniques, such as spatial prediction in intra coding, adaptive block size motion compensation with small block sizes, Quarter-pel accurate motion compensation, 4x4 integer transformation, synchronization/switching pictures, multiples reference pictures and context adaptive binary arithmetic coding (CABAC), are used in this standard.With the use of these techniques, both compression efficiency and encoding quality are greatly improved. The testing results show that H.264 can greatly outperform existing video coding standards in PSNR, visual quality and compression efficiency.The new features of H.264/AVC increase not only the complexity of coding basic modules, but also the one of algorithms by times. That makes it very difficult for practical applications such as in real time video communication application or in some embedded system. So major works are as follows:First, in order to solve the problem that there are many prediction modes, the complexity of computation and which can’t predict pixels located at the boundary of moving objects accurately in H.264/AVC intra prediction, an intra prediction algorithm is presented. The test result indicates that the adjacent pixels-based intra prediction algorithm can improve intra coding efficiency remarkably.Second, H.264/AVC uses multi-reference frames to enhance the coding efficiency. the quantity of increased computation is linearly proportional to the number of reference frames. On the study of the multi-macro-block motion estimation of H.264 standard, a low-complexity and fast multi-frame selection method is proposed. The experimental results show that the speed of the proposed method is over two times faster than that of the original scheme adopted in JVT reference software JM12.2 and JM10.2 while keeping the similar video quality and bit-rate.更多还原