Research And Implementation Of Video Conferencing System

Video conferencing has now made a rapid development in practical, and has played an important role in the military, economic, cultural and other fields, and its function has developed it from a original and simple video-conferencing capabilities to the progressive development of the distance education system, remote monitoring system, remote medical system, and many other integrated services. Therefore, the video conferencing technology is bounded to enter a new stage of development. Proposed by the ITU, the standard H.323 video conferencing is now a widely followed standard. Compared to some other standard, the achieved standard based on H.323 has better system stability, interoperability, and economy.First, this thesis studies the H.323 protocol standard and video conferencing system architecture based on H.323 protocol, focusing on analyzing protocol stack, physical, communication process, conference control and management modules in the system in detail. In the thesis, openH.323 protocol library files that support the H.323 protocol and multi-point video conferencing are analyzed, and the overall and detailed design is made that based on the related ITU-T H.323 multi-point video conferencing system modules. Finally, the project has implemented a available video conferencing system that meets the H.323 protocol standard, and is able to achieve real-time LAN signaling session interaction and data transmission between the terminal. The system adopts a centralized architecture and regard C/S model as the implementation model, to provide users with comprehensive, intuitive, convenient and practical features, and user interface.In the project, basic video and audio conferencing system is implemented, and the system has also made improvements in three areas:First, Dynamic Key Loging module is added in the system. The basic principle of realization of Dynamic Key Loging module is generating and distributing dynamic key at the server side, and clients login system according to the key after receiving it. So in this way, security for people to login system is improved. Second, the encrypted communications module is added in the system. RSA data encryption technology is adopted to transmit encrypted data in the system to further enhance the system security of information transfer, and make sure that chat security is more secure. In addition, this module also has played a digital signature role, which can prevent information from tampering, repudiating and make client authentication in transmission. Third, Short Message Service module is added in the system. This module is implemented based on the SMS cat technology, and it has made an important extension in video conferencing system. This module allows mobile phone users to send and receive cell phone message to join the video conference, which greatly facilitate the users.Finally, the thesis has summarized all the work, and prospected the future of video conferencing systems.