Research On Architecture Of SIP-based Streaming Media Application Server

With the development and maturity of IP technologies,as a typical application of Broad Band, NGN communication on behalf of VoIP is facing unprecedented opportunity for development. As one of the core control protocols in VoIP, SIP provides a comprehensive and open platform to integrate the audio, video and data. On this platform, fields such as IP telephone,IP fax,IP video conference, streaming media broadcast have made new progress in application unceasingly.SIP-based streaming media business is one of these new applications. It applies the traditional network streaming media technology to IP network, and connects with PSTN network and 3G network, which really realizes streaming media business being unified in progress to IP network. Beginning with streaming media service, this article is aimed at thoroughly studying the related system and the architecture of the server as well as the technical elements to implement it. And the discussion of implementing SIP-based streaming media application server is also included.The article includes the following main points. First, it introduces the background and significance of the research, the technology theory of streaming media, SIP and interraleted protocol, SIP/PSTN exchange; Second, according to B2BUA server mechanics, the article introduces work model and architecture of SIP-based streaming media application server; Third,each function module of the server and mutual logic treatment relation have been introduced in detail; Fourth, the modules'implementation details and some important data structures are given briefly and the related implementation details in the prototype system of the server are discussed, and these mainly include the use of the SIP stack for signaling processing, the H.264 standard for the media processing of encoding and decoding, the intermediate format technology for transfering the code,and the UDP protocol to realize the RTP/RTCP network transmission ; Fifth, load balancing is a systematic project in the field of load balance. In the road link from the media resources to the user terminal, the load balancing should be considered. Based on the characteristics of SIP, use the SIP Proxy Server as the load balancing server to balance the broadcasting server's load through the dial plan management of SIP Proxy server; Sixth, according to the characteristics of the broadcasting server, apply bit-stream and pipe cushioning mechanism to encoding and decoding.Through the testing of the server prototype system, it has basically realized the streaming media broadcast service function, after the further optimizations based on this prototype system, it may have more practical use.