| The development of Internet technologies provides a new means for passing knowledge from pedagogs to learners. It includes abundant learning resources, information retrieval and query tools, all kinds of communication tools, which supports learners to acquire knowledge on his own or by working together. The concept of lifelong learning all gradually established causes a direct result of a huge user groups for education network.Instant communication technology and streaming media technology based on P2P solve the choke point of C/S and B/S models successfully, and become hot issues of research and application in Internet technology.This makes it possible and essencial to build a personalized multimedia platform for distance interactive teaching and learning.Distance education platform of "Founder Messenger" is a distance education system using hybrid P2P communication structure based on Internet, providing instant communications, audio and video exchanges, the sharing of resources and teaching management. It facilitates teachers, students and parents to immediate communicate, and now already be promoted in the primary and secondary schools. However, the teching fuction of the system can be realized only through text and video exchanges without real-time couseware teaching, and use the technical architecture of VFW which will eliminate. From the above analysis, it requires a good solution to multimedia teaching.This paper enhances the teaching function of "Founder Messenger ".It ameliorates the performance of audio and video using Diretshow framework, adds simultaneous courseware teaching and whiteboard tomake the system improves grately.This paper's structure is as follows. Firstly,related technologies and research background are introduced. Secondly,the resolution of system and key models' design are analyzed aiming at using limited network bandwidth as possible to meet the quality of the user's communication requirements,including DirectShow framework of real-time audio and video chatting, MP3 and MPEG-4 audio and video coding technologies,good packing and unpacking strategy in the use of the simplified RTP protocol, the adaptive rate control algorithm in accordance with changes of network bandwidth from the feedback of RTCP.Finally,the realization of the system is detailedly described, including collection, coding, transmission and playback of audio and video, the transmission,display and remote control of PPT courseware and the graphics' drawing, remote sharing control of whiteboard teaching.Meanwhile, synchronization problemof audio and video mixed with PPT courseware is solved, and the related technologies are studied for in-depth research.System Design and Implementation makes use of the current matural mainstream technologies. Although it costs low in hardware, it runs well on the distance education platform.The software is a new form of applying the multimedia technology with instant communication technologies to distance education system. |
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