Audio Interchange File Format: Difference between revisions

Revision as of 01:30, 17 May 2022

Revision as of 15:43, 31 October 2022

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{{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 Mac|url-status=dead OS X Reference Library]<|archive-url=https://web.archive.org/web/20091128075236/ref><ref>[https://developer.apple.com/iphonemac/library/documentation/musicaudioDarwin/ConceptualReference/CoreAudioOverviewManPages/SupportedAudioFormatsMacOSXman1/SupportedAudioFormatsMacOSXsay.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/mac/library/archive/qa/qtmrf/qtmrf04.html | publisherurl-status=Applelive |archive-url=https://web.archive.org/web/20220705133320/https://developer.apple.com/library/archive/qa/qtmrf/qtmrf04.html |archive-date=19952022-07-05-01 | 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 ".aiff" extension.

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==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/ |titleurl-status=Logic Studiolive |archive- Plugurl=https://web.archive.org/web/20130720011337/http://www.apple.com/logic-ins & Soundspro/plugins-and-sounds |publisherarchive-date=Apple2013-07-20 |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 .aiff (or .aif) or .caf extension regardless of type.

==Data format==

An AIFF file is divided into a number of chunks.<ref>[http{{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 Audio|url-status=live File|archive-url=https://web.archive.org/web/20220724201945/https://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/AIFF/AIFF.html Format|archive-date=2022-07-24 Specifications]|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:

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==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==

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{| 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 |title=JSTOR/Harvard Object Validation Environment - AIFF-hul Module |date=2005-05-09 |access-date=2010-03-21 |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