RTSP协议网络数据包分析

今天，28.8Kbps调制解调器是Internet连接的基本速率，cable   modem、   ADSL、DSS、ISDN等发展快，内容提供商不得不要么限制发布媒体质量，要么限制连接人数。根据RealNetwork站点统计，对28.8Kbps调制解调器，实际流量为10bps到26Kbps，呈钟形分布，高峰在20Kbps。这意味着若内容提供商选择20Kbps固定速率，将有大量用户得不到好质量信号，并可能停止媒体流而引起客户端再次缓冲，直到接收足够数据。 一种解决方法是服务器减少发送给客户端的数据而阻止再缓冲，在RealSystem   5.0中，这种方法称为“视频流瘦化”。这种方法的限制是RealVideo文件为一种数据速率设计，结果可通过抽取内部帧扩展到更低速率，导致质量较低。离原始数据速率越远，质量越差。另一种解决方法是根据不同连接速率创建多个文件，根据用户连接，服务器发送相应文件，这种方法带来制作和管理上的困难，而且，用户连接是动态变化的，服务器也无法实时协调。智能流技术通过两种途径克服带宽协调和流瘦化。首先，确立一个编码框架，允许不同速率的多个流同时编码，合并到同一个文件中；第二，采用一种复杂客户/服务器机制探测带宽变化。流媒体技术作为Internet上的重要媒体传输技术,已被广泛应用于视频会议、远程教育、交互式电视等许多领域。 内容来自think58

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RTSP（实时流媒体协议）是由Real network 和Netscape共同提出的如何有效地在IP网络上传输流媒体数据的应用层协议。它通过使用纯文本来发送信息，对流媒体提供了诸如暂停，快进等控制。本文从流媒体技术入手,利用Sniffer工具抓包，并对RTSP数据包进行分析，了解特征。最后VC和Winpcap开发库开发程序，对RTSP包进行分析。  本文来自think58 [版权所有：http://think58.com]

 

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关 键 词：Sniffer；RTSP；Winpcap；流媒体
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Today, 28.8Kbps modem is a basic Internet connection speed, cable modem, ADSL, DSS, ISDN and other rapid development, content providers have to restrict the publication or media quality, or limit the number of connections. According to RealNetwork site statistics, on the 28.8Kbps modem, the actual flow rate 10bps to 26Kbps, was bell-shaped distribution, the peak at 20Kbps. This means that if the content providers to choose a fixed rate of 20Kbps, there will be a large number of users to get good quality signal, and may stop the stream once again caused the client buffer until receiving adequate data. One solution is to reduce the sending server to the client's data to prevent re-buffer, in the RealSystem 5.0, this method is called "thin-based video streaming." Limitations of this approach is the RealVideo file as a data rate design, the results can be extended to the lower extraction rate of the internal frame, resulting in lower quality. Farther away from the raw data rate, quality worse. Another solution is to create multiple rates for different connection files, the user connection, the server sends the relevant documents, this approach brings the production and management difficulties, and the user connection is dynamic, the server can not be real-time coordination . Intelligent Streaming Technology in two ways to overcome the coordination and flow of lean of the bandwidth. First, establish a coding framework that allows multiple streams of different rates while coding, merging into a single file; the second, using a complex client / server mechanism for detecting change of bandwidth. Internet on streaming media technology as an important media delivery technology, has been widely used in video conferencing, distance education, interactive television and many other fields.

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RTSP (Real Time Streaming Protocol) is a Real network and Netscape co-sponsor of how to effectively transfer the IP network streaming data application layer protocol. It is through the use of plain text to send information, such as streaming media offers pause, fast-forward control. This article from the streaming media technology and using the Ethereal Sniffer tools, and analysis of RTSP packets to understand features. The final development of VC and Winpcap library development program, on the RTSP packets for analysis. think58

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KEY WORDS: Sniffer; RTSP; Winpcap; streaming media

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TYPE OF THESIS: Application Research