MPEG-4 Structured Audio is an

ISO/IEC ISO/IEC JTC 1, entitled "Information technology", is a joint technical committee (JTC) of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). Its purpose is to develop, maintain and ...

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 publis ...

(

ISO The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Me ...

IEC The International Electrotechnical Commission (IEC; ) is an international standards organization that prepares and publishes international standards for all electrical, electronic and related technologies. IEC standards cover a vast range of ...

14496-3:1999) in 1999. It allows the transmission of synthetic music and sound effects at very low

bit rate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction ...

s (from 0.01 to 10 kbit/s), and the description of parametric sound

post-production Post-production, also known simply as post, is part of the process of filmmaking, video production, audio production, and photography. Post-production includes all stages of production occurring after principal photography or recording indivi ...

for mixing multiple streams and adding

effects Effect may refer to: * A result or change of something ** List of effects ** Cause and effect, an idiom describing causality Pharmacy and pharmacology * Drug effect, a change resulting from the administration of a drug ** Therapeutic effect, ...

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. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

. SAOL is historically related to

Csound Csound is a domain-specific computer programming language for audio programming. It is named Csound because it is written in the language C, in contrast to some of its predecessors. It is free and open-source software, released under the GNU Les ...

and other so-called

Music-N MUSIC-N refers to a family of computer music programs and programming languages descended from or influenced by MUSIC, a program written by Max Mathews in 1957 at Bell Labs. MUSIC was the first computer program for generating digital audio wavefor ...

languages. It was created by

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 MIT School of Architecture and Planning, School of Architecture. Its research does not restrict to fi ...

grad student 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 instrument ...

(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. SoundFon ...

and DownLoadable Sounds) * A normative Structured Audio scheduler description - it is the supervisory run-time element of the Structured Audio decoding process. *

MIDI Musical Instrument Digital Interface (; MIDI) is an American-Japanese technical standard that describes a communication protocol, digital interface, and electrical connectors that connect a wide variety of electronic musical instruments, ...

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.

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, 1998
The MPEG-4 Structured Audio standard - Eric D. Scheirer, MIT Media Laboratory

Official MPEG web site

MPEG-4 {{Multimedia-software-stub

See also

References

External links