【作者】 卢仁甫； 冯刚；

【Author】 Lu Ren Fu1+, Feng Gang2 1(Department of Computer Science, Hua Zhong Normal University, WuHan 430079, China) 2(Department of Computer Science, Hua Zhong Normal University, WuHan 430079, China)

【机构】 华中师范大学计科系；

【摘要】 由联合视频小组(JointVideoTeam)制定的最新视频编解码标准H.264/MPEG4-AVC,由于其出色的编码效率及良好的网络适应性,很快得到了应用。本文简要讨论了H.264编解码标准及其用到的错误恢复技术。更多还原

【Abstract】 H.264/AVC is newest video codec standard of the Joint Video Team. There are two main improvement: enhanced compression performance and network-friendly. In this paper, we describe the overview of the H.264/AVC video codec standard and error resilience technical in it. H.264/AVC has two separate layers: Video Coding Layer and Network Abstraction Layer. The Video Coding Layer (VCL) is specified to efficiently represent the content of the video data. The Network Abstraction Layer (NAL) is specified to format that data and provide header information in a manner appropriate for conveyance by the transport layers or storage media. H.264/AVC has three profiles: baseline profile, main profile and extended profile. Each profile includes several levels. A profile defines a set of coding tools or algorithms that can be used in generating a conforming bitstream, whereas a level places constraints on certain key parameters of the bitstream . H.264 includes many enhanced coding method that improve coding efficiency, for example: variable block-size motioncompensation with small block sizes, quarter-sample-accurate motion compensation, motion vectors over picture boundaries, multiple reference picture motion compensation, decoupling of referencing order from display order, decoupling of picture representation methods from picture referencing capability, weighted prediction, improved “skipped” and “direct” motion inference, directional spatial prediction for intra coding etc. Compressed video streams are intended for transmission over communication networks. Networks has varying bandwidth and easy to occur bit errors, so H.264 uses many error concealment and resilience techniques, for example: parameter set structure, NAL unit syntax structure, flexible slice size, flexible macroblock ordering (FMO), arbitrary slice ordering (ASO), redundant pictures, data partitioning, SP/SI synchronization/switching pictures etc.更多还原