Reasearch Of Transparent White Board In Railway Multimedia Conference System Based On IP

The video conference system according with H.320 protocol which was introduced by Ministry of Railways has made great effect on railway production and transportation.It satisfied the requirements of railway video conference with high quality of video and audio.However,along with speeding up of railways and high-speed railway development in our country,the video and telephone conference system need many new requirements,such as remote assistance,rush to deal with emergencies,remote guidance in field works and so on.The conferences only have video and audio couldn't meet our requirements already, we need to increase the function of data communication.Video conference system has developed for more than 10 years in China. From the costly system of H.320 in early stage to the low cost system of H323, the technology and cost performance have greatly changed.At present,most small company and government ministries are building their own video conference systems.So we can forecast that after few years,the development and usage of video conference system will make quite great progress,especially the video conference system which is based on IP and H.323.Considering the special requirements of video conference system in railways,here discussed a multimedia network conference system architecture based on the mature H.323 international video conference standard,and emphasized to research one of the data applications upon this architecture--the design and realization of video white board.In order to build the multi-communication network platform which supports the multi-communication conference,this network conference architecture referenced many protocol standard models,including H.323,T120, RTP/RTCP,SIP.These protocols respectively provide channels for audio and video data,function of data communication,application as well as the function of multimedia support and conference management for the conference platform. Based on this platform,a network conference media white board is designed, you can mark on dynamic movies by using it.This white board program uses the components of NetMeeting for multi-communication channel.It was developed on Microsoft Company's Visual Studio.NET 2003 IDE and programmed by VC++ and C++ language.It has achieved the functions below:connecting conferences,binding the window which has been choiced,marking by more than one person at the same time,transparence and so on.