View source for Audio Interchange File Format

{{Short description|File format family}}
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{{more citations needed|date=January 2016}}
{{Infobox file format
| name                   = Audio Interchange File Format <br>(AIFF)
| icon                   = 
| logo                   = 
| screenshot             = 
| caption                = 
| extension              = .aiff<br />.aif<br />.aifc
| mime                   = audio/x-aiff<br />audio/aiff
| type code              = AIFF, AIFC
| uniform type           = public.aiff-audio<br />public.aifc-audio
| magic                  = 
| owner                  = [[Apple Inc.|Apple]]
| released               = {{start date and age|1988|01|21|df=yes}}<ref name="aiff-spec">{{citation |url=https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/AIFF/Docs/AIFF-1.3.pdf |title=Audio Interchange File Format, A Standard for Sampled Sound Files, Version 1.3 |author=Apple Computer, Inc. |date=1989-01-04 |access-date=2010-03-21}}</ref><!-- {{Start date|YYYY|dd|mm|df=yes}} -->
| latest release version = 1.3
| latest release date    = {{Start date and age|1989|01|04}}<!-- {{Start date and age|YYYY|dd|mm|df=yes}} --><br />AIFF-C / {{Start date and age|1991|07|df=yes}}<ref name="aiff-spec2">{{cite web |url=https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/AIFF/AIFF.html |title=Audio File Format Specifications - AIFF / AIFF-C Specifications |author=P. Kabal |publisher=McGill University |date=2005-03-15 |access-date=2010-03-21}}</ref>
| genre                  = [[Audio file format]], [[container format (digital)|container format]]
| container for          = 
| contained by           = 
| extended from          = [[Interchange File Format|IFF (File format)]]
| extended to            = 
| standard               = 
| free                   = 
| url                    = 
}}

'''Audio Interchange File Format''' ('''AIFF''') is an [[audio file format]] standard used for storing [[sound]] data for [[personal computer]]s and other electronic audio devices. The format was developed by [[Apple Inc.|Apple Inc]]. in 1988 based on [[Electronic Arts]]' [[Interchange File Format]] (IFF, widely used on [[Amiga]] systems) and is most commonly used on [[Macintosh|Apple Macintosh]] computer systems.

The [[digital audio|audio data]] in most AIFF files is uncompressed [[pulse-code modulation]] (PCM). This type of AIFF file uses much more disk space than [[lossy]] formats like [[MP3]]—about 10 MB for one minute of stereo audio at a sample rate of 44.1&nbsp;kHz and a bit depth of 16 bits. There is also a compressed variant of AIFF known as '''AIFF-C''' or '''AIFC''', with various defined compression codecs.

In addition to audio data, AIFF can include [[Loop (music)|loop]] point data and the musical note of a [[sampling (music)|sample]], for use by hardware samplers and musical applications.

The file extension for the standard AIFF format is <code>.aiff</code> or <code>.aif</code>. For the compressed format the preferred suffix is <code>.aifc</code>, but audio applications supporting the format also allow <code>.aiff</code> or <code>.aif</code>.

==AIFF on macOS==
{{Original research|section|date=March 2009}}

With the development of the OS X operating system now known as [[macOS]], Apple created a new type of AIFF which is, in effect, an alternative [[little-endian]] byte order format.<ref>{{Cite web |date=2008-10-29 |title=Speech Synthesis Manager - OS X Manual |url=https://developer.apple.com/mac/library/documentation/Darwin/Reference/ManPages/man1/say.1.html |url-status=dead |archive-url=https://web.archive.org/web/20091128075236/https://developer.apple.com/mac/library/documentation/Darwin/Reference/ManPages/man1/say.1.html |archive-date=2009-11-28 |website=Apple}}</ref><ref>{{Cite web |date=2008-11-13 |title=Supported Audio File and Data Formats in Mac OS X |url=https://developer.apple.com/iphone/library/documentation/musicaudio/Conceptual/CoreAudioOverview/SupportedAudioFormatsMacOSX/SupportedAudioFormatsMacOSX.html |url-status=dead |archive-url=https://web.archive.org/web/20090523155253/https://developer.apple.com/iphone/library/documentation/musicaudio/Conceptual/CoreAudioOverview/SupportedAudioFormatsMacOSX/SupportedAudioFormatsMacOSX.html |archive-date=2009-05-23 |website=Apple}}</ref>

Because the AIFF architecture has no provision for alternative byte order, Apple used the existing AIFF-C compression architecture, and created a "pseudo-compressed" codec called '''sowt''' ('''twos''' spelled backwards). The only difference between a standard AIFF file and an AIFF-C/sowt file is the byte order; there is no compression involved at all.<ref name="RF04">{{cite web |date=1995-05-01 |title=Technical Q&A QTMRF04: QuickTime Sound |url=https://developer.apple.com/library/archive/qa/qtmrf/qtmrf04.html |url-status=live |archive-url=https://web.archive.org/web/20220705133320/https://developer.apple.com/library/archive/qa/qtmrf/qtmrf04.html |archive-date=2022-07-05 |access-date=2009-11-09 |website=Apple |publisher=}}</ref>

Apple uses this new little-endian AIFF type as its standard on macOS. When a file is imported to or exported from [[iTunes]] in "AIFF" format, it is actually AIFF-C/sowt that is being used. When audio from an audio CD is imported by dragging to the macOS Desktop, the resulting file is also an AIFF-C/sowt. In all cases, Apple refers to the files simply as "AIFF", and uses the <code>.aiff</code> extension.

For the vast majority of users this technical situation is completely unnoticeable and irrelevant. The sound quality of standard AIFF and AIFF-C/sowt are identical, and the data can be converted back and forth without loss. Users of older audio applications, however, may find that an AIFF-C/sowt file will not play, or will prompt the user to convert the format on opening, or will play as static.

All traditional AIFF and AIFF-C files continue to work normally on macOS, and many third-party audio applications as well as hardware continue to use the standard AIFF big-endian byte order.

==AIFF Apple Loops==
Apple has also created another recent extension to the AIFF format in the form of Apple Loops<ref>{{cite web |title=Logic Studio - Plug-ins & Sounds |url=https://www.apple.com/logic-pro/plugins-and-sounds/ |url-status=live |archive-url=https://web.archive.org/web/20130720011337/http://www.apple.com/logic-pro/plugins-and-sounds |archive-date=2013-07-20 |access-date=2010-04-30 |website=Apple |publisher=}}</ref> used by [[GarageBand]] and [[Logic Pro]], which allows the inclusion of data for pitch and tempo shifting by an application in the more common variety, and [[MIDI]]-sequence data and references to GarageBand playback instruments in another variety.

Apple Loops use either the <code>.aiff</code> (or <code>.aif</code>) or <code>.caf</code> extension regardless of type.

==Data format==
An AIFF file is divided into a number of chunks.<ref>{{Cite web |last=Kabal |first=Peter |date=2017-09-20 |title=Audio File Format Specifications |url=https://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/AIFF/AIFF.html |url-status=live |archive-url=https://web.archive.org/web/20220724201945/https://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/AIFF/AIFF.html |archive-date=2022-07-24 |website=MMSP Lab, ECE, McGill University}}</ref> Each chunk is identified by a ''chunk ID'' more broadly referred to as [[FourCC]].

Types of chunks found in AIFF files:

* Common Chunk (required)
* Sound Data Chunk (required)
* Marker Chunk
* Instrument Chunk
* Comment Chunk
* Name Chunk
* Author Chunk
* Copyright Chunk
* Annotation Chunk
* Audio Recording Chunk
* MIDI Data Chunk
* Application Chunk
* [[ID3]] Chunk

==Metadata==
AIFF files can store [[metadata]] in Name, Author, Comment, Annotation, and Copyright chunks. An [[ID3v2 tag]] chunk can also be embedded in AIFF files, as well as an Application Chunk with [[Extensible Metadata Platform]] (XMP) data in it.<ref>{{cite web |date=November 18, 2013 |title=AIFF Tagging |url=http://aifftagging.blogspot.com |url-status=live |archive-url=https://web.archive.org/web/20220407031344/https://aifftagging.blogspot.com/ |archive-date=2022-04-07}}</ref>

==Common compression types==
AIFF supports only uncompressed PCM data. AIFF-C also supports compressed audio formats, which can be specified in the "COMM" chunk. The compression type is "NONE" for PCM audio data. The compression type is accompanied by a printable name. Common compression types and names include, but are not limited to:

{| class="wikitable sortable"
|+AIFF-C common compression types<ref name="aiff-spec" /><ref>{{cite web |url=http://shoko.calarts.edu/~tre/AIFFC/comptype.html |title=AIFF-C Compression Types and Names |author=Tom Erbe |year=1999 |access-date=2010-03-21 |archive-url=https://web.archive.org/web/20060620002145/http://shoko.calarts.edu/~tre/AIFFC/comptype.html |archive-date=2006-06-20}}</ref><ref>{{cite web |date=2005-05-09 |title=AIFF-hul Module |url=http://hul.harvard.edu/jhove/aiff-hul.html |url-status=dead |archive-url=https://web.archive.org/web/20100629090032/http://hul.harvard.edu/jhove/aiff-hul.html |archive-date=2010-06-29 |access-date=2010-03-21 |website=JSTOR/Harvard Object Validation Environment}}</ref>
|-
! Compression type
! Compression name
! Data
! Source
|-
| NONE
| not compressed
| PCM, big-endian
| Apple Inc.
|-
| sowt
| not compressed
| PCM, little-endian
| Apple Inc.
|-
| fl32
| 32-bit [[floating point]]
| [[IEEE]] 32-bit float
| Apple Inc.
|-
| fl64
| 64-bit floating point
| IEEE 64-bit float
| Apple Inc.
|-
| alaw
| ALaw 2:1
| 8-bit ITU-T [[G.711]] [[A-law]]
| Apple Inc.
|-
| ulaw
| μLaw 2:1
| 8-bit ITU-T G.711 [[μ-law]]
| Apple Inc.
|-
| ALAW
| [[CCITT]] G.711 A-law
| 8-bit ITU-T G.711 A-law (64&nbsp;kbit/s)
| SGI
|-
| ULAW
| CCITT G.711 u-law
| 8-bit ITU-T G.711 μ-law (64&nbsp;kbit/s)
| SGI
|-
| FL32
| Float 32
| IEEE 32-bit float
| SoundHack & Csound
|-
| ADP4
| 4:1 Intel/[[Digital Video Interactive|DVI]] [[ADPCM]]
| 
| Stéphane Tavenard (Audio Convert/Player) [[AmigaOS]]
|-
| ima4
| [[Interactive Multimedia Association|IMA]] 4:1
| 
| 
|-
| ACE2
| ACE 2-to-1
| 
| Apple IIGS ACE (Audio Compression/Expansion)
|-
| ACE8
| ACE 8-to-3
| 
| 
|-
| DWVW
| Delta with variable word width
| 
| TX16W Typhoon
|-
| MAC3
| MACE 3-to-1
| 
| Apple Inc.
|-
| MAC6
| MACE 6-to-1
| 
| Apple Inc.
|-
| Qclp
| [[Qualcomm]] PureVoice
| 
| Qualcomm
|-
| QDMC
| [[QDesign]] Music
| 
| QDesign
|-
| rt24
| RT24 50:1
| 
| Voxware
|-
| rt29
| RT29 50:1
| 
| Voxware
|-
| SDX2
| Square-Root-Delta
| Big-endian
| 3DO (Panasonic) / Mac (Apple)
|}

==See also==
* [[Apple Lossless]] (ALAC)
* [[FLAC]]
* [[WAV]]
* [[Resource Interchange File Format|RIFF]], the [[little-endian]] format corresponding to [[Interchange File Format|IFF]]
* [[OSType]]
* [[FourCC]]

==References==
{{Reflist}}

==External links==
*[https://web.archive.org/web/20071219035740/http://www.cnpbagwell.com/aiff-c.txt Audio Interchange File Format AIFF-C – Draft 08/26/91 – Apple Computer, Inc.] – (archive.org backup)
*[https://web.archive.org/web/20171118222232/http://www-mmsp.ece.mcgill.ca/documents/audioformats/aiff/aiff.html AIFF / AIFC Sound File Specifications – Draft 17/11/17] – (archive.org backup)

{{Compression formats}}
{{Authority control}}

[[Category:Audio file formats]]
[[Category:Digital container formats]]
[[Category:Apple Inc. software]]