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题名:
多媒体编码和同步技术
作者: 雷力
答辩日期: 1999
专业: 计算机应用技术
授予单位: 中国科学院软件研究所
授予地点: 中国科学院软件研究所
学位: 博士
关键词: 多媒体 ; 编码 ; 同步
摘要: 多媒体技术,特别是网络环境下的分布式多媒体应用是当前计算机领域的研究热点。其核心内容是多媒体信息的编码与同步(包括分布式环境下的QoS控制)。实际上,多媒体信息处理的复杂性主要来源于连续媒体,多媒体通信对网络技术提出新的要求也主要来源于连续媒体。目前,对多媒体信息的编码已经形成了一系列的标准,本文讨论了在这些标准中所应用的基本编码方法,如自适应哈夫曼算法、离散余弦变换、脉码调制等。在此基础上介绍了当前广泛应用的静止图像压缩标准JPEG,应用于视频会议的CCITT H.261/263标准,动态视频、音频压缩标准MPEG等,特别是最后公布的MPEG-IV标准的基本内容和特点。多媒体的同步问题是本文讨论的重点。所谓多媒体同步就是保持和维护各个媒体对象之间和媒体对象内部存在的时态关系。多媒体的同步可以从多媒体同步规范和多媒体同步控制两个层次来讨论。多媒体同步规范是对多媒体系统中各媒体对象之间和媒体对象仙部存在的时序关系的精确的形式化描述。本文详细分析了多媒体同步的基本特征,给出多媒体同步的模型表示。采用了同步规范的Petri网形式化描述,用于分析多媒体的同步过程,分析了多媒体同步过程中的资源竞争问题。多媒体同步控制机器就是开发各种同步控制策略以及同步控制协议,克服诸如网络延迟与拦动等各种非确定因数带来的确负面影响。其关键是提供有效的QoS描述与QoS保证机制。本文在对分布式多媒体通信模型的详细分析基础上,讨论了如何简化和规约已有的QoS描述,从而确定整个QoS保证的关键部分。总结了设计分布式多媒体系统的QoS管理时应尊遵循的五个原则。最后,本文讨论了当前网络结构在支持多媒体通信上的缺陷,简要给出了一种有效的基于偏序的端到端多媒体通信传输网络模型。
英文摘要: Multimedia applications, especially the distributed multimedia applications on the network, are the hotspot of computer field. The core of multimedia system is how to encode and synchronize the multimedia object. In fact, the difficult of constructing multimedia system mainly come from the continuous media. Now, many international organization are working on drawing up encoding standards of multimedia. In this paper. I discuss some basic encoding algorithms used in these standards, and introduce some standards, such as JPEG、H.261/263 and MPEG, which are widely used in most multimedia systems. Especially, I discuss some features of MPEG-IV, a new promising standard. Synchronization in multimedia systems refers to maintaining the temporal relations in one complicated media object or between two or more media objects. I discuss synchronization in two levels: specifications and control. Firstly, the multimedia synchronization specification is the precise formal description of multimedia objects and temporal relations in/among them. In this paper, the feature of synchronization in multimedia system is analized in detail, and the model of synchronization is presented. Petri network, which is used to analyze synchronization processing and resource competition in multimedia system. Secondly, the multimedia synchronization control refers to developing some protocols used to alleviate the negative effect caused by network delay and other indeterminable factors. The key of multimedia synchronization control is to provide an effective mechanism to describe and warrant QoS. I discuss the methods of refining QoS description. Using these methods, we can acquire the key part assuring the nomal performance in multimedia communication. And more, I conclude five rules should be complied in designing distributed multimedia systems. At last we discuss the defect of existing network protocols, used to support multimedia communication, and present an effective end-to-end multimedia transfer model based on partial order of Petri description of multimedia objets.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.iscas.ac.cn/handle/311060/6712
Appears in Collections:中科院软件所

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Recommended Citation:
雷力. 多媒体编码和同步技术[D]. 中国科学院软件研究所. 中国科学院软件研究所. 1999-01-01.
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