Design And Realization Of The Communication Platform Of Peer-to-peer Video Conferencing System Based On H.323

With the development of informationization, IP technology gradual became the major means of communication on next generation network. Now the Internet has become the mainstream of multimedia communication network, application system with function of multimedia communication based on IP will become the main development trend, especially the multimedia video conference which received extensive attention at domestic and abroad. At present, the main implementation for the video conference has hardware and software. Solution of hardware has its advantages in the system on stability and transmission quality, but the price is expensive. But with the enhancement of network bandwidth, and progress of compression technology of video and audio, the research of video conference software system will become industry hotspot.This thesis developed a small communication platform system of peer-to-peer video conferencing software based on the H.323 protocol, the design of the platform compatible with H.323 protocol, Realizing real-time data transmission and signaling interaction on the LAN between meeting terminal. On the side of network, communication platform realize that of the call establishment,communication control, real-time data transmission.on the side of meeting user, communication platform handle with control information, video and audio data stream from each client, and provides convenient user interface. Thesis firstly discusses the development of video conference, relevant protocol, standard and its working theory. mainly analyzed two important protocol involved in the communication process, call -signal protocol H.255.0 and media-control protocol H.245. Then given design scheme of each module of video conferencing terminal, and process of program implementation. In the module of video and audio process, respectively realizing function of capture, compression and playback for audio and video by using waveformaudioAPI and VFW package which provided by Microsoft. In the module of data transmission, have realized network programming based on winsock technical, adopted technology of multi-processing and multicast transmission, then improved the processing speed and reduced occupied bandwidth. Transmission of audio and video realized by RTP/RTCP protocol based on UDP, ensured real-time and continuity of flow transmission of the audio and video, avoided the packet loss and ensured sequential transmission. Finally, the system have been tested, under rate of 30 frames per second, image is fluent, reached lip phone synchronization, group meeting of six people probably occupied 300Kb/s terminal bandwidth. The contents of this thesis adapt to the development and update of science and technology, whether from the technical or economic perspective, development and research of this conference system has important significance, have certain practical value.