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1、毕业设计（论文）题 目 IP 语音电话设计与实现 学 院 理学院 专 业 信息与计算科学 班 级 2010 级 2 班 学 生 学 号 指导教师 重 庆 交 通 大 学2014 年 6 月2014 届信息与计算科学专业毕业设计（论文）I摘 要随着 Internet 的迅速发展以及个人计算机处理能力的增强，软件实现方式的 IP 可视电话系统成为网络视频应用研究的一大热点。但是，目前的 IP 网还存在网络服务质量欠缺、网络带宽瓶颈、网络访问限制等问题，这使得 IP 可视电话系统的普及变得困难。针对以上问题，本文从视频流的压缩编码、传输与调度入手，研究具有高伸缩性、高质量、低成本的 IP 可视电话系
2、统的设计与实现方法。首先，视频的编码传输是实现整个系统的基础。为了提高视频传输的实时性和效率，本文给出了一种 Internet 网上的基于 MPEG-4 视频压缩编码的视频流传输模型，保证了在低比特率及 Internet 网下能够提供良好的图像质量以及网络资源的有效利用。其次，根据 MPEG-4 视频流特点和网络的拥塞程度，本文给出了一种改进的适合MPEG-4 视频传输区分服务的模型，弥补了传统的 IP 网络“尽力而为”传输方式的不足，保证了网络服务质量。然后，本文给出了一种新的穿越 NAT 的方法。通过 SIP 协议及 TCP/IP 协议实现了局域网与局域网、局域网与互联网、互联网与互联网之
3、间的数据通信，从而解决了网络访问障碍问题。并且，服务器根据客户端之间的网络连接方式动态地决定采取单播或多播或 P2P 方案，减少了客户端与服务器间的通信量，从而减少了服务端的下行带宽，带宽瓶颈问题得以较好地解决。最后，本文给出了 IP 可视电话系统的一个具体实现及其性能测试。为分析该系统的性能，论文建立了一个客户端仿真模型，利用仿真程序对系统进行性能测试。测试结果表明，该系统能够在宽带网上提供适时的良好质量的视频服务。关键词：流媒体，IP 可视电话，QoS，MPEG-4，NAT ，RTCP/RTP王军成：IP 语音电话设计与实现IIAbstractWith the rapid developm
4、ent of Internet and the improvement in the processing ability of PC, IP videophone system, one of the ways of software realization, has become a focus on the research of the network video application. However, for the moment, some problems still exist, such as service quality, bandwidth bottleneck,
5、network access limits and so on, which increase the difficulty in making IP videophone system popular.Aimed at the problems mentioned above, starting with the video streams compression and coding, transportation and scheduling, this thesis works on the design and realization of the IP videophone sys
6、tem with good scalability, high quality and low costs.Firstly, with the target to improve the real-time and effectiveness of video transportation, the video compression and coding and transportation are the foundation of put the whole system into motion. The thesis presents one model of video stream
7、 transportation, which is based on the MPEG-4 video compression coding. This model ensures to provide pictures of high quality and make effective use of the Internet resources in low bit rate on the Internet.Secondly, according to the features of video stream and the congestion level of Internet, th
8、is thesis provides one improved model, fit for MPEG-4 video transportation DiffServ, which makes up the disadvantage of the traditional IP Internet transportation characterized by its “best-effort” and assures the Internet service quality.Thirdly, the thesis proposes a new method to traverse NAT. Th
9、rough SIP and TCP/IP, the problem of access obstacles on Internet is solved by the communication between LAN and LAN, LAN and internet network, internet network and internet network. Whats more, the server decides if unicast or multicast or P2P will be used according to the Internet linking style am
10、ong the clients, which reduces the amount of the communication between the client and servers output-bandwidth. Thus, the problem of bandwidth bottleneck is well solved.Lastly, this thesis provides an approach to the actual realization and performance testing of the IP videophone system. To analyze
11、its performance, a simulation model on the clients side is created and simulation program is employed to test the systems performance. Results proved that the system is able to, when needed, supply video service of good quality on broadband Internet.2014 届信息与计算科学专业毕业设计（论文）IIIKeywords：Streaming Media, IP videophone system conferencing, QoS, MPEG-4, NAT, RTCP/RTP王军成：IP 语音电话设计与实现IV目 录第 1 章 绪 论 .11.1 课题的研究背景 .11.2 国内外研究现状 .11.3 论文的组织结构 .2第 2 章 端到端的 MPEG-4 视频流传输框架研究 .32.1 引言 .32.2 MPEG-4 视频传输框架 .32.2.1 概述 .32.2.2 RTP/RTCP 协议 .42.2.3 反馈控制 .52.2.4 源编码率控制 .62.2.5 MPEG-4 比特流打包 .72.2.6 错误控制 .
