1 Definition of Scope
This International Standard defines a Multimedia Content Description Interface, specifying a series of interfaces
from system to application level to allow disparate systems to interchange information about multimedia content. It
describes the architecture for systems, a language for extensions and specific applications, description tools in the
audio and visual domains, as well as tools that are not specific to audio-visual domains. As a whole, this
International Standard encompassing all of the aforementioned components is known as “MPEG-7.” MPEG-7 is
divided into eight parts (as defined in the Foreword).
This part of the MPEG-7 Standard (Part 4: Audio) specifies description tools that pertain to multimedia in the audio
domain. See below for further details of application.
This part of the MPEG-7 Standard is intended to be implemented in conjunction with other parts of the standard. In
particular, MPEG-7 Part 4: Audio assumes knowledge of Part 2: Description Definition Language (DDL) in its
normative syntactic definitions of Descriptors and Description Schemes. This part of the standard also has
dependencies upon clauses in Part 5: Multimedia Description Schemes, namely many of the fundamental
Description Schemes that extend the basic type capabilities of the DDL.
MPEG-7 is an extensible standard. The method to extend the standard beyond the Description Schemes provided
in the standard is to define new ones in the DDL, and to make those DSs available with the instantiated
descriptions. Further details are available in Part 2. To avoid duplicate functionality with other parts of the standard,
the DDL is the only extension facility provided.
2 Fields of application
MPEG-7 Part 4: Audio is applicable to all forms of audio content. The encoding format or medium of the said audio
is not limited in any way, and may include audio held in an analogue medium such as magnetic tape or optical film.
The content of the audio is not limited within or without music, speech, sound effects, soundtracks, or any mixtures
thereof.
The tools listed in this part of the International Standard are applicable to both audio in isolation and to audio
associated with video.
The specific tools provided within the Audio portion of the standard are designed to work in conjunction with the
Multimedia Description Schemes that apply to both audio and video. Because of the “toolbox” nature of the
standard, the most appropriate tools from the different parts of the standard may be mixed, within the constraints of
the DDL.
The MPEG-7 Audio tools are applicable to two general areas: low-level audio description, in the case of the Audio
Framework (clause 5), and application-driven description, in the case of the High Level Tools (clause 6).
The Audio Framework tools are applicable to general audio, without regard to the specific content carried by the
encoded signal. The Scalable Series provides general capabilities for multi-level sampled data. The Audio
Description Framework defines specific descriptors for use with the Scalable Series or with Audio Segments, which
has properties inherited from the general Segment described in the Multimedia Description Schemes part of the
standard. The Silence Descriptor works with the Segment descriptor, and is applicable across all possible audio
signals.
The high level description tools are applicable to specific types of content within audio. The specific domains are
well documented within the introduction to each sub-clause. The audio domains encompassed by the various
MPEG-7 Audio tools are speech, sound effects, musical instruments, melodies within music and general audio
recognition. These specialised tools may be employed in conjunction with the other tools within the standard.