  The "event" concept appears repeatedly when developing metadata models for
the description and management of multimedia content. During the typical life
cycle of multimedia content, events occur at many different levels - from the
events which happen during content creation (directing, acting, camera panning
and zooming) to the events which happen to the physical form (acquisition,
relocation, damage of film or video) to the digital conversion, reformatting,
editing and repackaging events, to the events which are depicted in the actual
content (political, news, sporting) to the usage, ownership and copyright
agreement events and even the metadata attribution events. Support is required
within both MPEG-7 and MPEG-21 for the clear and unambiguous description of all
of these event types which may occur at widely different levels of nesting and
granularity. In this paper we first describe an event-aware model (the ABC
model) which is capable of modeling and yet clearly differentiating between all
of these, often recursive and overlapping events. We then illustrate how this
model can be used as the foundation to facilitate semantic interoperability
between MPEG-7 and MPEG-21. By expressing the semantics of both MPEG-7 and
MPEG-21 metadata terms in RDF Schema (and some DAML+OIL extensions) and
attaching the MPEG-7 and MPEG-21 class and property hierarchies to the
appropriate top-level classes and properties of the ABC model, we are
essentially able to define a single distributed machine-understandable
ontology, which will enable interoperability of data and services across the
entire multimedia content delivery chain.
