11/01/1997 09:00 AM
Computer Science
Video-on-Demand (VOD) allows clients to view selected videos at any time, and it is essential for VOD servers to be run as efficiently as possible. Conventional VOD servers are not efficient; they dedicate a disk stream for each client, and this strategy quickly uses up all available streams. Other systems, such as batching, interval caching, and pyramid broadcasting, have been studied. These systems make more efficient use of the VOD server\'s disk streams. In this report we present a new VOD system called stream tapping. Stream tapping allows clients to aggressively \"tap\" into any disk streams on the VOD server that are reading data the client can use. This can be accomplished through the use of a small buffer -- as small as 115 MB for MPEG-1 encoding -- on the client\'s set-top box, and it can save over 80% of the disk bandwidth used by a conventional system. This report includes a description and analysis of the stream tapping system, and comparisons between it and other efficiency-improving systems.
