Research On The Process Of Digital Media Production And Broadcast In Distance Learning Website

Along with the development of modern information technology, distance learning website becomes a new kind of education platform. Courses are sent to students out of campus with real-time and non real-time transmission of audio and video by technology of computer and network. At present, the user scale of each distance learning website grows rapidly. All aspects of teaching content production and broadcast are facing many new problems. For example, when a large number of teaching contents need to be captured, the reliability of capture progress is not satisfactory. Besides, the phenomenon of delay and non-synchronization exists when various parts of education course content playback. Otherwise, teaching course content can not be effectively protected. Finally, the widespread users are not all able to obtain satisfactory access speed when studying course content from website. All above restrict the further development of the website.This article bases on the project practice of teaching content production and broadcast in a distance learning website. Content capture programs, postproduction coding schemes, content protection programs and content distribution programs are proposed to meet the requirements of content production and broadcast. Not only the bandwidth resources of distance learning website are made better use of, but also the learner's experience is improved and the interests of content providers are effectively protected.Firstly, the main requirements and current shortcomings of teaching content capture process are analyzed in this paper, and new efficient design of streaming media capture program is proposed to enhance the real-time capture process reliability of teaching demonstration on computer. Fault-tolerant redundancy is introduced to the new design in order to avoid capture failures caused by dropped frames, as well as system crashes, or misuse. Besides, the capture process is also designed to meet the requirements of virtual teaching scene presentation, live teaching process with real-time display of subtitles, virtual digital blackboard function, and so on.Secondly, by analyzing the main post-production requirements of teaching content, this paper points out that the common solution such as combined video stream can solve the synchronize of multi-channel video content playback. But it is still difficult to solve the problem of playback delay. By researching encoding parameters combination tests of streaming media and analyzing the tests conclusions, this paper obtain ideal encoding parameters combination when dynamic changes of video images are large or small, and the teaching contents are voice-based audio or not. With the premise of clear and smooth of video and audio content, the new streaming media content encoding programs solve to minimize media file size, the bandwidth load of streaming media server and client-side CPU load and bandwidth, when viewing the courses from website. New postproduction coding schemes prevent users from the problem of playback delay.In addition, this paper analyzes the main requirements of digital course content protection, and compares advantages and disadvantages of other content protection solutions, such as digital fingerprint and so on. Therefore, the content protection design based on DRM technology for distance education service is proposed to meet the website development and prevent online streaming media contents from unauthorized use. The commercial interests of distance education website are also protected by controlling the number of authorized computers, play times, playback time, or playback validity.Finally, by analyzing the major requirements of content distribution process, this paper points out that the content delivery network (CDN) technology is able to allow users to access the nearest server nodes by cache servers and mirror servers acceleration. However, in the process of dynamic content acceleration with data centralized model, there exists conflict between real-time updates and data caching. That is to say, if the performance needs to be improved, the data caching must exist on CDN node servers. But dynamic contents are unable to update in real time. Therefore, with the website structure of centralized data storage, a new network architecture based on the content delivery network (CDN) technology is proposed to solve the cross-ISP access problems. By using the new content distribution solution, users from China Telecom and China Unicom can obtain a relatively better access speed when visiting the website.