ABSTRACT
The MPEG-21 standard defines a framework for the interoperable
delivery and consumption of multimedia content. Within this
framework the adaptation of content plays a vital role in order
to support a variety of terminals and to overcome the
limitations of the heterogeneous access networks. In most cases
the multimedia content can be adapted by applying different
adaptation operations that result in certain characteristics of
the content. Therefore, an instance within the framework has to
decide which adaptation operations have to be performed to achieve
a satisfactory result. This process is known as adaptation
decision-taking and makes extensive use of metadata describing
the possible adaptation operations, the usage environment of the
consumer, and constraints concerning the adaptation. Based on this
metadata a mathematical optimization problem can be formulated and
its solution yields the optimal parameters for the adaptation
operations. However, the metadata is represented in XML resulting
in a verbose and inefficient encoding. In this paper, an
architecture for an Adaptation Decision-Taking Engine (ADTE) is
introduced. The ADTE operates both on XML metadata and on metadata
encoded with MPEG's Binary Format for Metadata (BiM) enabling an
efficient metadata processing by separating the problem extraction
from the actual optimization step. Furthermore, several
optimization algorithms which are suitable for scalable multimedia
formats are reviewed and extended where it was appropriate.

Keywords: Adaptation Decision-Taking, MPEG-21, Digital Item
Adaptation, Binary Format for Metadata (BiM)