MPEG-4 Structured Audio is an
ISO/IEC standard for describing sound. It was published as subpart 5 of
MPEG-4 Part 3
MPEG-4 Part 3 or MPEG-4 Audio (formally ISO/IEC 14496-3) is the third part of the ISO/IEC MPEG-4 international standard developed by Moving Picture Experts Group. It specifies audio coding methods. The first version of ISO/IEC 14496-3 was publish ...
(
ISO
ISO is the most common abbreviation for the International Organization for Standardization.
ISO or Iso may also refer to: Business and finance
* Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007
* Iso ...
/
IEC 14496-3:1999) in 1999.
[ ]
It allows the transmission of synthetic music and sound effects at very low
bit rates (from 0.01 to 10 kbit/s), and the description of
parametric sound post-production for mixing multiple streams and adding
effects to audio scenes. It does not standardize a particular set of synthesis methods, but a method for describing synthesis methods.
The sound descriptions generate audio when compiled (or interpreted) by a compliant decoder. MPEG-4 Structured Audio consists of the following major elements:
*
Structured Audio Orchestra Language (SAOL), an audio
programming language
A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language.
The description of a programming ...
. SAOL is historically related to
Csound
Csound is a domain-specific computer programming language for audio programming. It is called Csound because it is written in C, as opposed to some of its predecessors.
It is free software, available under the LGPL-2.1-or-later.
Csound was o ...
and other so-called
Music-N languages. It was created by an
MIT Media Lab
The MIT Media Lab is a research laboratory at the Massachusetts Institute of Technology, growing out of MIT's Architecture Machine Group in the School of Architecture. Its research does not restrict to fixed academic disciplines, but draws from ...
grad student named
Eric Scheirer while he was studying under
Barry Vercoe during the 1990s.
* Structured Audio Score Language (SASL) - is used to describe the manner in which algorithms described in SAOL are used to produce sound.
* Structured Audio Sample Bank Format (SASBF) - allows for the transmission of banks of audio samples to be used in '
wavetable'
sample-based synthesis
Sample-based synthesis is a form of audio synthesis that can be contrasted to either subtractive synthesis or additive synthesis. The principal difference with sample-based synthesis is that the seed waveforms are sampled sounds or instruments ...
(based on
SoundFont
SoundFont is a brand name that collectively refers to a file format and associated technology that uses sample-based synthesis to play MIDI files. It was first used on the Sound Blaster AWE32 sound card for its General MIDI support.
SoundF ...
and
DownLoadable Sounds)
[
]
* A normative Structured Audio scheduler description - it is the supervisory
run-time element of the Structured Audio decoding process.
*
MIDI
MIDI (; Musical Instrument Digital Interface) is a technical standard that describes a communications protocol, digital interface, and electrical connectors that connect a wide variety of electronic musical instruments, computers, and ...
support - provides important backward-compatibility with existing content and authoring tools.
MPEG-4 Structured Audio was cited by CNN as one of the top-25 innovations to arise at the Media Laboratory.
See also
*
MPEG-4
References
External links
MPEG-4 Structured Audio Developer Tools*
tp://ftp.tnt.uni-hannover.de/pub/MPEG/audio/mpeg4/documents/w2203/w2203sa.pdf MPEG-4 Part 3 Subpart 5: Structured Audio, Final Committee Draft, N2203SA, 1998The MPEG-4 Structured Audio standard - Eric D. Scheirer, MIT Media LaboratoryOfficial MPEG web site MPEG-4
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