Caching of Interactive Branching Video in MPEG-4
Simen Rekkedal · 2004
The goal is to investigate the minimum amount of knowledge needed by a proxy server for consistent caching of interactive multimedia scenes encoded in MPEG-4 systems. We limit the interactive multimedia scenes to be of the type branching video. The caching scheme proposed is a specialization of partial caching. The extent of a branching video is the number of alternative branches available to the user at a branching point. The proposed caching scheme is extent domain caching. It works by limiting the number of alternative branches stored in the cache. Cache misses are served from the source server to provide a service transparent for the users. An implementation with test runs is provided. In the implementation the interactivity is limited to building blocks of complete ES. For content with several alternative scenes within a single ES, a different approach is needed. The proxy have to construct ad hoc objects from the AUs that constitute the alternative scenes. These ad hoc objects should be identifiable and have defined boundaries. Caching replacement decisions are then made on the ad hoc objects, and not on the complete ES. Identities can be constructed from the sequence number of the AUs and the ES id. The boundaries can be found by analysing where the users shift playback point.