The Design And Realization Of Multi-Media Communication System Base On SIP

There are many multi-media real time communication software on Internet at present. Major of them can realize communicate with others by text, audio and video. But the following questions generally exist in these software. First of all, they can not communicate with each other because they adopt themselves protocol. Secondly, lots of IM are difficult to adapt to the complicated network environment. This article analyses the above two problems carefully, adopt Session Initiation protocol to resolve the first problem, and design a solution to resolve the problem of NAT-Travel.The target of this article is not only to realize a communication system of multi-media, but also to resolve the problems above, the system include three subsystems, each subsystem realize a special function. The first subsystem is the control subsystem base on sip. sip is proposed by IETF .it is the core protocol of soft-switch. As a key protocol it have strong ability to integrate various services. The article adopt sip to solve the first problem. The second subsystem is the multi-media communication subsystem base on directshow technology . DirectShow adopt development mode of package, can accelerate multimedia software development and flexible to meet various kinds of business demands the main function of the subsystem is to deal with audio and video capture, compress, decompress and transform. The last subsystem is the subsystem that is to solve the problem of NAT-travel .the subsystem provide the basic transform function finally , the whole system is formed by integrating the three subsystems.The article introduce SIP protocol, design stack of sip and realize sip user proxy; adapt to the thought of software engineer, adopt DirectShow technology to realize the function of multi-media communication; Base on a large number of test and analogy, the article design a solution to resolve the problem of NAT-Travel.The article design and realize a multi-media communication system, also have resolved the two problems above. It is proved that the system is valuable in reality.