Video-On-Demand in Education

Sandie Hui

Interactivity in video distribution is increasing and new ideas for services are emerging all the time. In Video-on-Demand (VoD) services, the user can choose programs when he/she wants. ATM technology, efficient compression techniques, and other developments of telecommunications make it possible to offer such services as home shopping, games, distance learning and movies-on-demand, etc. The range of applications is too wide to have everything covered in this article. Hence, our discussion will focus mainly on the application of VoD in the educational sector. In the next few sections, issues on why VoD should be used and how it can be employed as a teaching tool will be discussed. The implementation plan will be proposed at the end of the article.

Why Use VoD?

VoD allows users to browse, query linked text and video databases, author video modules and play back the selected video over the network. This technology is likely to greatly enhance the availability of multimedia information to teachers and adds substantial value to the educational process. The benefits gained from using VoD include:

• Teaching material can be encoded and stored on media server, allowing simultaneous real-time access to the same piece of information for teaching in various locations.

• Information can be retrieved instantly from the media server at any time. No initial preparation such as moving the huge TV and VCR, pre-loading of the tape and connecting the audio/visual equipment is required.

• Seminars from other institutions, laboratory demonstration, training sessions and lectures etc. can be pre-recorded by the speaker or lecturer. These sources can be played back at any time during a class to supplement the classroom experience and open up the exposure of the students to a more diversified wealth of information.

• Forums or conferences held abroad could be recorded. Users can review at a later time, thus saving travelling time and expenses.

• VoD allows users to rewind and play back as if they are watching from videotape. This helps to facilitate better understanding of the taped material.

• Material used repetitively (e.g. orientation information) can be loaded on the server. This helps to ease manpower limitation in arranging guest speakers.

• With VoD, maintenance of physical videotapes becomes obsolete.

Applications of VoD

So far, we discussed the benefits obtainable from VoD. Some of the many applications of VoD in enhancing teaching will be suggested here.

"Conduct" Seminars/Lectures by Local Instructors

If the lecturer has to be away for any reason and if he/she does not want to reschedule the lecture, he/she can record it on tape first. The tape can be replayed at the time of the next lecture. To facilitate a Question & Answer period at the end of the "lecture", videoconferencing can act as a supporting tool to VoD. With the help of videoconferencing system, the students can visually discuss any questions and problems with the lecturer.

"Conduct" Forums/Conferences/Seminars from Other Institutions

With VoD, seminars from other institutions, laboratory demonstration, training sessions and lectures, etc. can be pre-recorded by the speaker or lecturer. These sources can implement industrial training and public education, supplementing the classroom experience. Students can schedule their own timetable, book a terminal and attend the course quietly by themselves. Forums or conferences held abroad could be recorded. The promise of VoD is to make scheduling of programs unnecessary. Users can schedule their own forum/conference/seminar time. They can come back any time and retrieve the selected tape material from the tape server. In the course if they miss anything, they can always rewind and play back as if they are watching from videotape.

"Conduct" Staff/Students Orientation or Similar Events

In general, there is orientation for new staff and students. The material required for the orientation might be video taped. Using VoD, they can watch the tape at their own scheduled time. Since the orientation may be repetitive, this helps to ease manpower limitation in arranging guest speakers.

Implementation of Video-on-Demand Service

The implementation of VoD is demonstrated in the diagram below.

Basically, video materials are captured on a workstation with a MPEG1/2 encoder installed. The encoded data is then transferred to the media server for storage and video streaming. A client machine, which can be a desktop computer, a portable laptop or a Sun workstation, issues command to the media server. Upon receiving the requests, the media server starts to stream out video data that is then played back on the client machine. Once received, the audio and video data are decoded and played.

In short, the media production and delivery is composed of 3 phases:

Phase 1 : Media encoding from tapes or other resources

Phase 2 : Uploading of encoded content to media server

Phase 3 : Delivery of media streams to client workstations upon request

Our Work …

As of today, a Sun MediaCenter with two UltraSparc CPUs has been installed as the video server. The MediaCenter is equipped with 79GB hard disk and capable of supporting 100-BaseT and ATM network. In the first phase, a MPEG1 encoder card will be acquired for capturing video. An MPEG2 encoder card will be considered in the latter stage. We aim to deploy the VoD service to the 18 lecture theatres in the near future. Eventually, it will be extended to all other classrooms and student/staff PC workstations in the University and Video-on-Demand is then within reach of everyone.

Computing Services Centre City University of Hong Kong ccnetcom@cityu.edu.hk