||In order to enable transparent and augmented use of multimedia
resources across a wide range of networks and devices, the
forthcoming MPEG-21 standard aims at integrating the various
existing technologies for delivery and consumption of digital
content in a common multimedia framework. Digital Item Adaptation
is one of the core concepts of the framework that will support
the adaptation of multimedia resources to device capabilities,
underlying network characteristics, or the users preferences.
The scope of the standardization, however, is limited to the
definition of description tools and does not deal with the internals
of the adaptation process itself.
In this paper, we first discuss the requirements of the resource
adaptation component of an adaptation engine. These requirements
include, for instance, openness for the integration of external
multimedia transforming tools as well as intelligent decision
taking when determining the set of required adaptation steps.
We also present a prototype of a simple video resource adaptation
engine that completely relies on descriptions of the resource
itself (MPEG-7), the usage environment of the resource (MPEG-21),
as well as declarative descriptions of the transformation tools.
The prototype employs a knowledge-based engine for finding and
executing the needed adaptation sequences.