The Study And Implementation Of Technologies Correlated With Video Transmitting In The Network Conference System

Desktop videoconference system is a production combining with computer technology, communication technology and network technology. It will apply more and more broadly in modern society with the rapid development of Internet/Intranet. This thesis discusses the design and implement of technologies correlated with video transmitting in the ITU-T H.323 video conference system , the schemes in this thesis has operated successfully in the project of "Network Multimedia Video Conference System" imbursed by Ministry of Communications.This thesis is divided into five parts .In the first part, we brief the development of video conference, and then discuss the video transmission through IP network from the aspects of characteristics, transmission methods and quality. Subsequently, we introduce the background of this thesis, the meaning of the study and the author's task in the project. The second part study the tactics of transmitting video data through IP networks, including QoS control tactics, multicast tactics , the scalable video coding and layered transmission, as well as the real time transmission protocol (RTP) and the real time transmission control protocol (RTCP). The third part design and implement a scheme of controllable multi-image technology in the network video conference system based on the video transmission theory, by which the user can choose display mode and number of terminal images according to network environment. It is an extension to the video function in the network video conference system. The fourth part design and implement a scheme of recording and playing in the network video conference system, which make the system be "Caching Conference System". In the last part part ,the summarization and prospect are given.