Design And Realization Of Audio/Video Broadcasting And On Demand System Based On Streaming Media Technology

Currently, streaming media is a really prevalent muiti-media technology. Sent by an invariable velocity, media is able to render while arriving. Users need not download a large file with huge time overhead before enjoying it. It can save a large amount of time and space as streaming file constructed previously or live stream coded by live coder is tremendously less than original data.In recent years, teachers and teaching devices are insufficient with the fast improvement of college. With network, lots of men educated can break through restriction of education resource and teaching method and share them without time and space restriction. Also, they can arrange their study plan and progress according to their ability and schedule, realizing "individual education" that traditional education can not. Meanwhile, multi-media such as texts, pictures, graphs, audio and video is available for interaction, which inspires their study interests and enhances teaching quality. Because of the limit of bandwidth, streaming media is an optimal choice.Paper chooses application of streaming media technology in network teaching as research object. It accomplishes four works as follows:1. Go deep into the principle of streaming media technology, including its system constitution, technological principle, network protocol, play manner, file format and comparison of three platform which is popular currently;2. Research in details of various developing skills under Windows platform, including Media Control Interface, Audio Compression Manager, Video Compression Manager, VFW, DirectShow, WMP SDK and WinSock technologies;3. Present complete scheme of network audio/video broadcasting and on demand system;4. Research and implement six key modules: audio on demand, video on demand, video broadcasting, screen broadcasting, voice broadcasting and audio broadcasting;The key problem is realization of video and screen broadcasting. Video broadcasting adopts DirectShow technology and screen broadcasting-"interframe expect + color pixel varying + LZ77 compress". By this way, network packets reduce numerously but system also behaves well. After tests of theory and experiment, this design is proved to be feasible and efficient.