Abstract
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.