Study And Realization For Video Conferencing Systems Basing On H323

With the development of multi-media computer technology and the communication technology, people are not satisfied with simple voice and characters communication, hoping to incorporate multi-media communication which assembles pronunciation, characters and image in whole, video conferencing system is the one of this new communication means.With the development of Internet and the coding technology as well as multi-media application, the multi-media data, especially video data, is ample. In order to satisfy the requirement of transmission bandwidth and gain the high-quality video images under low rates, the video signal must be compressed tenderly in order to remove the data redundancy, which is a key problem of H.323 video conferencing system.How to improve the MCU video buffer and MCU stability to make sure that the MCU could deal with more terminal of video conferencing system; What's more, video picture capturing and displaying images are key factors which affect quality of video conferencing system; For all above problems, a video conferencing system based on OpenH323 is designed with the current development trend. There are some main points as following about the study of this paper:1,This paper presents the principle and method of video conferencing system, H323 agreements characteristic, OpenH323 Project, and introduces the main designing ideas, as well as realization method which is developing the key technologies of video conferencing system.2,Applying QT as system interface developing platform based on the source code, This paper compiles H. 264 coding into DLL on the VC++ 6.0 platform and embeds H.323 into video conferencing system, which improves video images and image data compression and error correction, and it also has important significance on making high-quality video stream become reality which is transferred under low bandwidth's condition.3,Improving stored-and-transmit ability of MCU, and increasing Endpoints of video conferencing system By using soft exchange.4,Due to the advantages of DirectX technology, this system applies DirectShow into image capture in order to reduce video Catching time and make the video image more fluent.5,Finally, perfecting the ActiveX control of video conferencing system basing on OpenH323 and gives testing result on system ActiveX control.