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The term multimedia makes reference to the union of different media
(e.g., audio, visual video and text), which are created, delivered and presented together.
There are a wide variety of formats, proposals and (de jure and de facto) standards to represent multimedia.
CAIN-21 is a multimedia adaptation engine that complies with
the representation schema proposed in the MPEG-21 framework
and it is not restrictive in adapting a specific kind of media.
In order to serve this purpose, CAIN-21 allows the integration of third-party pluggable
and reusable multimedia conversions referred as Component Adaptation Tools (CATs).
The adaptation capabilities of each CAT must be described by means of a CAT Capabilities description.
CAIN-21 is self-configurable, that is, based on these descriptions, it automatically decides
which CATs and parameters to execute in order to adapt specific media to the usage environment.
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The MPEG-21 standard comprises different parts with different objectives.
MPEG-21 Part-2 proposes the use of Digital Items (DIs) as containers that are
potentially capable of representing
every type of multimedia content along with its descriptors (metadata).
MPEG-21 Part-7 proposes the use of a
set of Description Tools that assist the adaptation of DIs.
These tools are referred as DIA Description Tools (Digital Item Adaptation DescriptionTools),
and its instances are referred as DIA Descriptions.
CAIN-21 makes use of these descriptions in order for the multimedia system to decide
which adaptation to perform and execute the adaptation.
The environment (terminals, networks,
users, and natural environment) is described using the UED Tool (Usage Environment Description Tool).
In addition, CAIN-21 has proposed the introduction of complementary Description Tools
in order to decide and perform the adaptation. Particularly,
(1) the ARC Tool (Adaptation Request Configuration Tool)
can be used to select the target terminal, network and user among those described in the UED Repository.
(2) The CAT Capabilities Tool (Component Adaptation Capabilities Tools) describes the adaptation capabilities
of the software modules (CATs) that are deployed into CAIN-21.
(3) The Properties Repository Tool gathers information in a compact way about
the XPath locations of the resources and metadata used to make decisions.
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