Multimedia Data Cartridge

The MPEG-7 MDC is at the center of the metadata

life cycle because it must manage all the metadata

produced and deliver it to the consuming

elements. The MDC is an extension of an Oracle

database that can store, index, and query multimedia

metadata based on the MPEG-7 standard. It

currently consists of three main parts (see Figure 3,

next page). The core system consists of a multimedia

database schema based on MPEG-7, the Multimedia

Indexing Framework (MIF) supporting

query optimization, and a set of internal and external

libraries for incoming requests and queries.

The MDC has been implemented by a small

group of database programmers with experience

working with the Oracle DBMS kernel. They kept

the extensions to the Oracle database as modular

as possible. Part of these modules, mainly the

indexing framework, is in preparation of a

SourceForge project (http://sourceforge.net/

index.php), which CODAC plans to make available

to the public in Spring 2005.

MPEG-7-based database schema

The multimedia schema relies on the MPEG-7

standard to provide a complete multimedia metadata

schema for low-level descriptions (such as color, texture, and shape for images) and highlevel

descriptions (such as structural and semantic

descriptions) for all media types. We have mapped

the MPEG-7 descriptors, formulated as XML-types,

to object-relational tables to enable fine-grained

querying on these data. (A detailed explanation of

the mapping is available elsewhere.7)

Library support

A set of internal and external libraries are used

for incoming requests and queries. The set of

internal libraries is used as access points to the

core system and consists of InitLib, used for creating

new instances of the MDC data type;

InsertLib, which provides insert functionality of

MPEG-7 documents; DeleteLib, for deleting

MPEG-7 documents; UpdateLib, for updating

parts of stored MPEG-7 documents; and QueryLib,

for query services. Furthermore, external libraries

are used to offer application-specific services.

The services we described in the use case scenario

are VideoLib, for obtaining videos with

semantic search criteria, and AudioLib, for querying

with the humming functionality. Both external

libraries (VideoLib and AudioLib) rely on the

search functionality of the QueryLib, which is

basically a translation of search criteria to complex

SQL and XPATH statements on the schema tables.