MPEG-4 Structured Audio explained

MPEG-4 Structured Audio is an ISO/IEC standard for describing sound. It was published as subpart 5 of MPEG-4 Part 3 (ISO/IEC 14496-3:1999) in 1999.^{[1] [2] [3]}

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. SAOL is historically related to Csound and other so-called Music-N languages. It was created by MIT Media Lab 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 (based on SoundFont and DownLoadable Sounds)^[4]
• A normative Structured Audio scheduler description - it is the supervisory run-time element of the Structured Audio decoding process.
• MIDI 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.^[5]

See also

• MPEG-4

External links

• MPEG-4 Structured Audio Developer Tools
• [ftp://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
• https://irudiotsrent.com/tics-tecnologia-de-la-comunicacion/

Notes and References

1. Web site: ISO/IEC 14496-3:1999 - Information technology -- Coding of audio-visual objects -- Part 3: Audio . ISO . ISO . 1999 . 2009-10-06. International Organization for Standardization .
2. Web site: MPEG Audio FAQ Version 9 - MPEG-4 . D. Thom, H. Purnhagen, and the MPEG Audio Subgroup . chiariglione.org . October 1998 . 2009-10-06 . https://web.archive.org/web/20090926231123/http://www.chiariglione.org/mpeg/faq/mp4-aud/mp4-aud.htm . 2009-09-26 . dead .
3. Web site: The MPEG-4 Audio Standard: Overview and Applications . Heiko Purnhagen . Heiko Purnhagen . 2001-06-01 . 2009-10-07.
4. Scheirer . Eric D. . Ray . Lee . Algorithmic and Wavetable Synthesis in the MPEG-4 Multimedia Standard . Audio Engineering Society Convention 105, 1998 . 1998 . 2.2 Wavetable synthesis with SASBF: The SASBF wavetable-bank format had a somewhat complex history of development. The original specification was contributed by E-Mu Systems and was based on their “SoundFont” format [15]. After integration of this component in the MPEG-4 reference software was complete, the MIDI Manufacturers Association (MMA) approached MPEG requesting that MPEG-4 SASBF be compatible with their “Downloaded Sounds” format [13]. E-Mu agreed that this compatibility was desirable, and so a new format was negotiated and designed collaboratively by all parties. . 10.1.1.35.2773 .
5. News: THE BIG I: MIT Media Lab Turns 25 . CNN.