Research And Implementation Of IP Video Phone Based On SIP

With the development of the network and multimedia area, VoIP technology has been widely applied on Internet. VoIP is the abbreviation of Voice communication Over IP network. It refers to not merely the IP Phone, but also a comprehensive application platform that provides various multimedia services inlcuding video exchange.Most of present VoIP systems in use are based on H.323 protocol. H.323 take the strategy of convergence and layered control, which conforms to the traditional design idea in communication fields. This design idea doesn't suit for the opened and distributed Internet. SIP is proposed by IETF as a new signaling technology, which is conforming to Internet circumstance. Comparing to H.323 protocol, SIP has the advantage of easy implementation, high flexibility, scalability and mobility. VoIP application based on SIP protocol has a broad prospect.Under the background of VoIP application, SIP protocol is researched in detail in this thesis. IP Video phone scheme based on SIP application is designed and implemented. Summarily this dissertation completes the work as follows:(1) VoIP architecture, key technology and their characteristics are introduced. And two VoIP signaling technology, H.323 and SIP protocol, are discussed.(2) The function structure, realization principle, message mechanism and signaling flow of SIP protocol are researched, and the advantage of SIP-based application is analyzed from the view of its opening ability expansibility, mobility and flexibility.(3) The implementation of the OSIP parser and state-machine are analyzed based on OSIP open source. Then SIP UA module is designed and realized, which can establish, modify and terminate sessions according to the regulations of RFC3261.(4) The IP video phone solution based on SIP is designed and implemented on the Windows platform, which consists of three key modules: the SIP signaling module, the audio/video capture and coder and network transmission.(5) Real-time G.729A vocoder is implemented on ARM9 platform and SIP UA is transplanted from Windows platform to Arm-Linux platform, which can be applied to SIP hardware phone.