【作者】 张立涓；

【导师】 李志淮； 陈玉华；

【作者基本信息】 大连海事大学 ， 计算机应用技术， 2003， 硕士

【摘要】 网络教学被认为是构筑继续教育、终身教育和素质教育的重要手段，是“面向21世纪教育振兴行动计划”的重要举措，因而倍受国内外关注。其形式也多种多样，其中网络教室以其实时性、生动性和交互性，成为网络教学中最有效的一种方式。 本课题通过对网络教室中涉及到的多媒体信息特点的研究与分析，在Windows98／NT操作系统平台和校园网的环境中，实现了一个跨越局域网的网络教室。在多媒体数据传输方面，根据不同媒体信息的特性采用不同的压缩方式：对于图形信息采用基于语义的图形压缩；屏幕图像信息采用JPEG压缩；音频和视频采用Microsoft DirectX技术实现。在传输控制方面，多媒体信息传输采用IP多播UDP传输协议，设计并实现了在无连接的网络协议上的应用层传输控制协议，保证多媒体信息的完整性和同步性，建立了控制命令通道，控制命令信息传输采用TCP协议，从而既保证了控制命令的可靠传输，又提高了多媒体信息的传输性能。在强化教学功能方面，增加了包括电子白板，电子举手，网上影院，文件传输等实用功能，并对原有电子点名、锁定键盘鼠标等功能做了进一步的改进。在交互控制方面，进一步扩充了原有网络教学控制协议(NTCP)，实现了锁定，解锁，远程关机，重启等交互控制。更多还原

【Abstract】 Remote Education is considered as the most important method to build continual education.life education and diathesis education .It’s the most important measure of the plan of Build Up Education Action in 21th century .So more and more countries have paid attention to this field. Although there are many formats to implement Remote Education, Net Classroom has become the most effective method because of its real time capability, vitality, and interactive capability.In this thesis, we analysed the characteristic of multimedia information in net classroom, and implemented a Net Classroom Software based on Windows98/NT OS and the campus network of DLMU. In the multimedia data transmission part of this project, we take different transmission methods according to the characteristics of different multimedia information to deal with the multimedia data transmission .For the graph information , we take the method based on semantics. And the image information was disposed with JPEG arithmetic method to compress the data on the server, decompress the data to display it on the client .To video and audio data ,we take the method of Microsoft DirectX .In the part of transmission control ,we implemented the transmission of multimedia data by IP-Multicast method and UDP protocol .Moreover to assure the integrality and synchronization of the multimedia data, we designed and implemented application layer transfer control protocol above the connectionless lower network protocol. Further more we build the control command channel based on TCP protocol to assure the credibility transmission of the control command and approve the transmission performance of multimedia data .The education functions of this project include screen image broadcasting, electron roll calling, electron raising hands, net cinema, file transmission etc .In order to increase the interactive function, the Net-classroom Teaching Control Protocol (NTCP) was extended by locking, unlocking ,remote shutting down and remote restarting etc.更多还原