AN MBONE-BASED DISTANCE EDUCATION SYSTEM J. W. Wong, D. Evans Dept. of Computer Science University of Waterloo jwwong@bcr.uwaterloo.ca dfevans@bbcr.uwaterloo.ca N. Georganas, J. Brinskelle Dept. of Electrical Engineering University of Ottawa georganas@mcrlab.uottawa.ca jeff.brinskelle@entrust.com G. Neufeld, D. Makaroff Dept. of Computer Science University of British Columbia neufeld@cs.ubc.ca makaroff@cs.ubc.ca ABSTRACT Distributed multimedia communication has received a great deal of attention in recent years. Many systems have been developed to support multimedia conferencing to their users, delivering efficient use of available resources, sophisticated session control, and friendly user interfaces. In this paper we present a system that supports retrieval of stored multimedia documents and its integration into an audio/video conference. Our system is tailored to distance education. It features a flexible continuous media storage architecture, a robust yet simple synchronisation algorithm, media format independence, scalability, and the use of off-the-shelf software for conference participants. 1 Introduction The growing desire for multimedia communication and the popularity of the Internet have sparked a great deal of research into the delivery of time-sensitive data streams over IP-based networks. Technologies such as RealAudio [1] attempt to provide robust presentation of multimedia documents, while the MBone and multicast IP enable multimedia conferences where live audio and video are shared amongst the participants [2]. Tools that support conferencing are typically designed to deliver only live media. This works well for discussion sessions but is problematic for applications such as distance education. A lecturer may wish to use supplementary material, such as audio or video clips, to enhance his or her lecture. In this paper we present an application which includes extensions to the common MBone tools vic and vat to allow the inclusion of pre-recorded media streams in a MBone conference. These tools are integrated into the multimedia presentational technologies developed by the Canadian Institute for Telecommunications Research, which support the retrieval of documents stored in a multimedia database and quality of service negotiation [3]. A salient feature of our design is that extended software is not required at the machine of every user who wishes to take part in a distance education session. For student machines, off-the-shelf versions of vic and vat are used to transmit live audio and to receive audio and video from anyone in the conference. Only the lecturer machine requires the extended software because of the need to transmit pre-recorded documents. This paper is organised as follows. Section 2 describes our distance education application and its requirements. Section 3 discusses sources of time-sensitive data streams and examines some of the issues inherent in their delivery. Section 4 provides details on how the various modules within our presentational system are integrated with the MBone tools. Section 5 presents some preliminary observations about the complete system and Section 6 contains our conclusions and a discussion of some open issues. 2 Application Architecture and Requirements The distance education application under consideration involves a single lecturer and a group of students. Students are able to see and hear the lecturer, and are able to transmit audio as allowed by the lecturer. Students at any location may take part in the lecture provided that they have the necessary network connectivity and the lecturer’s permission. Lectures are often more valuable and interesting if they are augmented by supplementary information, which may take the form of pictures, audio recordings, video clips, and so on. In essence, any multimedia document may be used to enhance the lecture. To this end the system should support, alongside the conferencing facilities, a document storage and retrieval system. This system can act as a library. Facilities should be provided to search for and retrieve documents and to view them on a user workstation. Facilities should also be provided to allow a lecturer to include the contents of selected documents in his or her broadcast.