Real-time media streaming over challenged networks

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School of Science | Master's thesis
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Real-time media streaming is one of today's popular Internet applications. This application can yield satisfactory performance only under certain Quality of Service (QoS) provisions. In challenged networks - e.g., mobile wireless networks, which are characterized by intermittent connectivity, unpredictable delays and high error rates - it is very difficult for media streaming applications to achieve satisfactory performance. In this thesis, we focus on RTSPIRTP streaming, and present an approach to enable RTSP/RTP streaming to accomplish smooth play back over challenged networks. We develop a performance enhancement proxy (PEP) to work in conjunction with CHIANTI infrastructure. While CHIANTI infrastructure takes care of transmitting application data reliably without loss, our proxy is trying to diminish the resulting long delay by performing "caching and pre-fetching" operation. The proxy consists of two parts - the client module and the server module. The server module retrieves more media data than those needed for real-time playback, and forwards them to the client module; the client module keeps those media data in a local cache, and then streams them to the media client at ordinary rate. The extra media data cached ahead of schedule can bridge the long delay caused by network interruptions. The practical contribution of this thesis is a multi-purpose RTSP/RTP proxy application. The application implements the above PEP. It relays and modifies RTSP messages, retrieves and caches RTP packets, and then streams them towards the media player according to flexible speed and schedule. In addition, our application implements built in SOCKS proxies in order to allow the PEP function as CHIANTI Chain Modules. The application can also be configured to operate over a DTN overlay network.
Ylä-Jääski, Antti
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Ott, Jörg
RTSP/RTP streaming, proxy, caching, CHIANTI, SOCKS, DTN
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