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Audio Interchange File Format (AIFF) is an audio file format
Audio file format
An audio file format is a file format for storing digital audio data on a computer system. This data can be stored uncompressed, or compressed to reduce the file size. It can be a raw bitstream, but it is usually a container format or an audio data format with defined storage layer.-Types of...

 standard used for storing sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

 data for personal computers and other electronic audio devices. The format was co-developed by Apple Computer
Apple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...

 in 1988 based on Electronic Arts
Electronic Arts
Electronic Arts, Inc. is a major American developer, marketer, publisher and distributor of video games. Founded and incorporated on May 28, 1982 by Trip Hawkins, the company was a pioneer of the early home computer games industry and was notable for promoting the designers and programmers...

' Interchange File Format
Interchange File Format
Interchange File Format , is a generic container file format originally introduced by the Electronic Arts company in 1985 in order to ease transfer of data between software produced by different companies....

 (IFF, widely used on Amiga
The Amiga is a family of personal computers that was sold by Commodore in the 1980s and 1990s. The first model was launched in 1985 as a high-end home computer and became popular for its graphical, audio and multi-tasking abilities...

 systems) and is most commonly used on Apple Macintosh computer systems.

The audio data in a standard AIFF file is uncompressed pulse-code modulation
Pulse-code modulation
Pulse-code modulation is a method used to digitally represent sampled analog signals. It is the standard form for digital audio in computers and various Blu-ray, Compact Disc and DVD formats, as well as other uses such as digital telephone systems...

 (PCM). There is also a compressed variant of AIFF known as AIFF-C or AIFC, with various defined compression codecs.

Standard AIFF is a leading format (along with SDII and WAV
Waveform Audio File Format , is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs...

) used by professional-level audio and video applications, and unlike the better-known lossy MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...

 format, it is non-compressed (which aids rapid streaming of multiple audio files from disk to the application), and lossless. Like any non-compressed, lossless format, it uses much more disk space than MP3—about 10MB for one minute of stereo audio at a sample rate of 44.1 kHz and a sample size of 16 bits. In addition to audio data, AIFF can include loop
Music loop
In electroacoustic music, a loop is a repeating section of sound material. Short sections of material can be repeated to create ostinato patterns...

 point data and the musical note of a sample
Sampling (music)
In music, sampling is the act of taking a portion, or sample, of one sound recording and reusing it as an instrument or a different sound recording of a song or piece. Sampling was originally developed by experimental musicians working with musique concrète and electroacoustic music, who physically...

, for use by hardware samplers and musical applications.

The file extension for the standard AIFF format is .aiff or .aif. For the compressed variants it is supposed to be .aifc, but .aiff or .aif are accepted as well by audio applications supporting the format.

AIFF on Mac OS X

With the development of the Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...

 operating system, Apple created a new type of AIFF which is, in effect, an alternative little-endian byte order format.

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.

Apple uses this new little-endian AIFF type as its standard on Mac OS X. When a file is imported to or exported from iTunes
iTunes is a media player computer program, used for playing, downloading, and organizing digital music and video files on desktop computers. It can also manage contents on iPod, iPhone, iPod Touch and iPad....

 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 Mac OS X 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 Mac OS X (including on the new Intel-based hardware), and many third-party audio applications as well as hardware continue to use the standard AIFF big-endian byte order.

Note: As of Mac OS X version 10.4.9, the system will sometimes incorrectly display the AIFC icon for files with the .aif extension, whether or not the actual file format is AIFF or AIFF-C. This can be verified by opening the files in a hex editor and checking the FORM chunk's form type. This can sometimes happen when exporting files from QuickTime
QuickTime is an extensible proprietary multimedia framework developed by Apple Inc., capable of handling various formats of digital video, picture, sound, panoramic images, and interactivity. The classic version of QuickTime is available for Windows XP and later, as well as Mac OS X Leopard and...

, and frequently happens when sending and receiving files between Windows and Mac computers or extracting files from an archive.

AIFF Apple Loops

Apple has also created another recent extension to the AIFF format in the form of Apple Loops used by GarageBand
GarageBand is a software application for Mac OS X and iOS that allows users to create music or podcasts. It is developed by Apple Inc. as a part of the iLife software package on Mac OS X.-Audio recording:...

 and Logic Audio, 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.

AppleLoops use the .aiff (or .aif) extension regardless of type.

Data format

An AIFF file is divided into a number of chunks. Each chunk is identified by a chunk ID more broadly referred to as FourCC
A FourCC is a sequence of four bytes used to uniquely identify data formats.The concept originated in the OSType scheme used in the Macintosh system software and was adopted for the Amiga/Electronic Arts Interchange File Format and derivatives...


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
    ID3 is a metadata container most often used in conjunction with the MP3 audio file format. It allows information such as the title, artist, album, track number, and other information about the file to be stored in the file itself....


AIFF-C common compression types

AIFF supports only uncompressed PCM data. AIFF-C also supports compression audio formats, that 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:
AIFF-C common compression types
Compression Type Compression Name Data Source
NONE not compressed PCM Apple Computer, Inc.
fl32 32-bit floating point
Floating point
In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...

IEEE 32-bit float Apple Computer, Inc.
fl64 64-bit floating point IEEE 64-bit float Apple Computer, Inc.
alaw ALaw 2:1 8-bit ITU-T G.711
G.711 is an ITU-T standard for audio companding. It is primarily used in telephony. The standard was released for usage in 1972. Its formal name is Pulse code modulation of voice frequencies. It is required standard in many technologies, for example in H.320 and H.323 specifications. It can also...

Apple Computer, Inc.
ulaw µLaw 2:1 8-bit ITU-T G.711 µ-law Apple Computer, 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
Digital Video Interactive
Digital Video Interactive was the first multimedia desktop video standard for IBM-compatible personal computers, developed around 1984 by Section 17 of The David Sarnoff Research Center Labs then a division of RCA. When General Electric purchased RCA in 1986, GE considered the DSRC redundant...

ima4 IMA
Interactive Multimedia Association
The Interactive Multimedia Association was an industry association which developed a set of audio algorithms. The most important is the ADPCM algorithm which is in use by Apple and Microsoft....

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 Computer, Inc.
MAC6 MACE 6-to-1 Apple Computer, Inc.
Qclp Qualcomm
Qualcomm is an American global telecommunication corporation that designs, manufactures and markets digital wireless telecommunications products and services based on its code division multiple access technology and other technologies. Headquartered in San Diego, CA, USA...

QDMC QDesign
QDesign is a music codec, originally known as LBpack, by Dmitry Shmunk. QDesign corporation bought the codec and hired the developer to create what would become the official audio compression in Apple Computer's QuickTime v3....

rt24 RT24 50:1 Voxware
rt29 RT29 50:1 Voxware

See also

  • Apple Lossless
    Apple Lossless
    Apple Lossless Apple Lossless Apple Lossless (also known as ALAC (Apple Lossless Audio Codec), or ALE (Apple Lossless Encoder) is an audio codec developed by Apple Inc. for lossless data compression of digital music. After initially being proprietary for many years, in late 2011 Apple open sourced...

  • FLAC
    FLAC is a codec which allows digital audio to be losslessly compressed such that file size is reduced without any information being lost...

  • WAV
    Waveform Audio File Format , is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs...

  • RIFF, the little-endian format corresponding to IFF
    Interchange File Format
    Interchange File Format , is a generic container file format originally introduced by the Electronic Arts company in 1985 in order to ease transfer of data between software produced by different companies....

  • OSType
    OSType is the name of a four-byte sequence commonly used as an identifier in Mac OS. While the bytes can have any value, they usually display figures characterized in software programs such as those utilized in ASCII or Mac OS Roman character sets.OSType values are used to identify file data...

  • FourCC
    A FourCC is a sequence of four bytes used to uniquely identify data formats.The concept originated in the OSType scheme used in the Macintosh system software and was adopted for the Amiga/Electronic Arts Interchange File Format and derivatives...

External links