Providing scalable on-demand interactive video service by means of multicasting and client buffering

True-VOD provides an interactive on-demand (i.e., virtually zero start-up delay) video service by allocating each user a dedicated stream. Such a streaming technique, however, cannot scale up to accommodate a large number of users. A more scalable solution is to use multicasting and client buffering. In this paper, we propose a client-initiated (client-pull) on-demand scheme in which short unicast streams are used to "merge" users onto the existing multicast streams by means of pre-buffering. The scheme is observed to trade-off some bandwidth with lower buffer requirement as compared with a previously proposed scheme. We then propose and analyze a server-initiated (server-push) scheme for on-demand interactive applications. The scheme is shown to offer a service level similar to true-VOD with substantially (many times) lower bandwidth, even with high user interactivity (e.g., averaged ten VCR commands/viewing).