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 pr ...

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 The International Electrotechnical Commission (IEC; in French: ''Commission électrotechnique internationale'') is an international standards organization that prepares and publishes international standards for all electrical, electronic and r ...

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 w ...

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

post-production Post-production 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 individual program segments. The ...

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, a ...

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 Structured Audio Orchestra Language (SAOL) is an imperative, MUSIC-N programming language designed for describing virtual instruments, processing digital audio, and applying sound effects. It was published as subpart 5 of MPEG-4 Part 3 (ISO/IEC ...

(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 or ...

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 The given name Eric, Erich, Erikk, Erik, Erick, or Eirik is derived from the Old Norse name ''Eiríkr'' (or ''Eríkr'' in Old East Norse due to monophthongization). The first element, ''ei-'' may be derived from the older Proto-Norse ''* ain ...

while he was studying under

Barry Vercoe Barry Lloyd Vercoe (born 1937) is a New Zealand-born computer scientist and composer. He is best known as the inventor of Csound, a music synthesis language with wide usage among computer music composers. SAOL, the underlying language for th ...

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 i ...

(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 DLS format (from Downloadable Sound) is any of the standardized file formats for digital musical instrument sound banks (collections of virtual musical instrument programs). The DLS standards also include detailed specifications for how MIDI pro ...

) * 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 re ...

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