On-demand access to remote multimedia content via the Internet is becoming increasingly popular. Applications like Video on Demand and News on Demand are increasingly based on structured multimedia presentations, which give users more options and freedom to interact with the content than just VCR-like operations. For example, authors provide multiple choices for parts of the presentation and the user can select the most interesting one. Distributing such presentations in hierarchical distribution systems comprised of origin server and proxies can lead to new challenges for proxies since entire presentations are large but only smalls parts of them are actually consumed by each user. We have analyzed this problem for interactive presentations encoded in MPEG-4 and found that we can use the internal structure of MPEG-4 objects to improve performance in a distribution system based on proxy caching.
Carsten Griwodz, Frank T. Johnsen, Simen Rekkedal,