| Distance education live-cast system was the foundation of modern distance education. The data of teachers'screen ,video and audio could collected by it and broadcasted to remote client after compressed. Realized remote real-time classroom. How to improve the collection efficiency of streaming media data and transmission in a more effective way was a urgent problems to solve in designing distance education system.At present, the domestic market has some distance learning broadcast systems. PowerCreater was the mature products which based on Client/Server(C/S). Highly Streaming Media data collection efficiency was PowerCreater's feature. But because of it based on C/S, lower quality of service was easy led by system performance bottleneck when the number of users increases,The solution which based on peer-to-peer network was an effective way to support more users as possible and make full use of the server capacity. Accordingly, a distance learning broadcast system which based on P2P was realized and the media data was transmitted in the form of P2P. Because each server is no longer a need for direct delivery of client data, thereby the pressure of server was reduced, and the number of users online was increased. From another side, the cost of hardware was reduced for the system which based on P2P require lower network bandwidth and server capacity.The method of capturing screen which in virtual display driver can grasp the changed image data on screen ,and the collection efficiency of the data was improved by use the method. The screen data was compressed by using the JPEG compression algorithm. The video data and the audio data was compressed by using MPEG-4 compression algorithm. The data need to transmit was reduced after been compressed.The test of the system shows that the system for the efficient collection of data streaming media. Meanwhile it is a effective solution based on C/S system performance falling when the number of users to increase. |
