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Audio Interchange File Format

{{Short description|File format family}}

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{{Infobox file format

| name = Audio Interchange File Format
(AIFF)

| icon =

| logo =

| screenshot =

| caption =

| extension = .aiff
.aif
.aifc

| mime = audio/x-aiff
audio/aiff

| type code = AIFF, AIFC

| uniform type = public.aiff-audio
public.aifc-audio

| magic =

| owner = Apple

| released = {{start date and age|1988|01|21|df=yes}}{{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}}

| latest release version = 1.3

| latest release date = {{Start date and age|1989|01|04}}
AIFF-C / {{Start date and age|1991|07|df=yes}}{{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}}

| genre = Audio file format, container format

| container for =

| contained by =

| extended from = 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 computers and other electronic audio devices. The format was developed by Apple Inc. in 1988 based on Electronic Arts' Interchange File Format (IFF, widely used on Amiga systems) and is most commonly used on Apple Macintosh computer systems.

The 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 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 point data and the musical note of a sample, for use by hardware samplers and musical applications.

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

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.{{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}}{{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}}

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.{{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=}}

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.

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{{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=}} 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.{{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}} 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.{{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}}

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{{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}}{{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}}

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 kbit/s)

| SGI

ULAW

| CCITT G.711 u-law

| 8-bit ITU-T G.711 μ-law (64 kbit/s)

| SGI

FL32

| Float 32

| IEEE 32-bit float

| SoundHack & Csound

ADP4

| 4:1 Intel/DVI ADPCM

|

| Stéphane Tavenard (Audio Convert/Player) AmigaOS

ima4

| 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

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