Audio Interchange File Format (
AIFF) is an
audio file formatAn audio file format is a file format for storing audio data on a computer system. It can be a raw bitstream, but it is usually a container format or an audio data format with defined storage layer....
standard used for storing
soundSound is a travelling wave which 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.- Perception of sound...
data for personal computers and other electronic audio devices. The format was co-developed by
Apple ComputerApple Inc. is an American multinational corporation that designs and manufactures consumer electronics and computer software products. The company's best-known hardware products include Macintosh computers, the iPod and the iPhone...
in 1988 based on
Electronic ArtsElectronic Arts is an international 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 responsible...
'
Interchange File FormatInterchange File Format , is a generic 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
AmigaThe Amiga was a family of personal computers originally developed by Amiga Corporation. Development on the Amiga began in 1982 with Jay Miner as the principal hardware designer. Commodore International bought Amiga Corporation and introduced the machine to the market in 1985...
systems) and is most commonly used on Apple Macintosh computer systems.
The audio data in a standard AIFF file is uncompressed
pulse-code modulationPulse-code modulation is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a numeric code. PCM has been used in digital telephone systems and 1980s-era electronic musical keyboards...
(PCM).
Audio Interchange File Format (
AIFF) is an
audio file formatAn audio file format is a file format for storing audio data on a computer system. It can be a raw bitstream, but it is usually a container format or an audio data format with defined storage layer....
standard used for storing
soundSound is a travelling wave which 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.- Perception of sound...
data for personal computers and other electronic audio devices. The format was co-developed by
Apple ComputerApple Inc. is an American multinational corporation that designs and manufactures consumer electronics and computer software products. The company's best-known hardware products include Macintosh computers, the iPod and the iPhone...
in 1988 based on
Electronic ArtsElectronic Arts is an international 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 responsible...
'
Interchange File FormatInterchange File Format , is a generic 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
AmigaThe Amiga was a family of personal computers originally developed by Amiga Corporation. Development on the Amiga began in 1982 with Jay Miner as the principal hardware designer. Commodore International bought Amiga Corporation and introduced the machine to the market in 1985...
systems) and is most commonly used on Apple Macintosh computer systems.
The audio data in a standard AIFF file is uncompressed
pulse-code modulationPulse-code modulation is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a numeric code. PCM has been used in digital telephone systems and 1980s-era electronic musical keyboards...
(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
WAVWAV , short for Waveform audio format, also known as Audio for Windows, is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs. It is an application of the RIFF bitstream format method for storing data in “chunks”, and thus is also close to the 8SVX and the AIFF...
) used by professional-level audio and video applications, and unlike the better-known lossy
MP3MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression. It is a common audio format for consumer audio storage, as well as a de facto standard of digital audio compression for the transfer and playback of music on...
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
loopA loop is generally something that closes back on itself such as a circle. The closing can appear in time or in space. It can be a cycle or ball but not a square.-Science and technology:*Loop , a quasigroup with an identity element...
point data and the musical note of a
sampleIn 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. This is typically done with a sampler, which can be a piece of hardware or a computer program on a digital computer. Sampling is also...
, 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 XMac OS X is a line of computer operating systems developed, marketed, and sold by Apple Inc., and 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-endianLittle-endian may refer to:* Endianness, the byte ordering in memory used to represent some kind of data in computing.* One of two competing philosophical viewpoints among the people of Lilliput from the book Gulliver's Travels by Jonathan Swift. According to this viewpoint, eggs should be broken...
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. 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
iTunesiTunes is a proprietary digital media player application, used for playing and organizing digital music and video files. The program is also an interface to manage the contents on Apple's popular iPod digital media players as well as the iPhone...
in "AIFF" format, it is actually AIFF-C/sowt that is being used. When audio from an audio CD disc 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.
What meaning
sowt may have as an acronym or abbreviation does not appear to be documented, but it is probably the reverse of "twos", the big-endian designation for twos-complement format.
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
QuickTimeQuickTime is a multimedia framework developed by Apple Inc., capable of handling various formats of digital video, media clips, sound, text, animation, music, and interactive panoramic images. It is available for Mac OS classic , Mac OS X and Microsoft Windows operating systems...
, 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
GarageBandGarageBand is a software application that allows users to create music or podcasts. It is developed by Apple Inc., and is included in all shipments of iLife.-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
FourCCA 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....
Chunk
See also
- Apple Lossless
Apple Lossless is an audio codec developed by Apple Inc. for lossless data compression of digital music....
- FLAC
Free Lossless Audio Codec is a file format for lossless audio data compression. During compression, FLAC does not lose quality from the audio stream, as lossy compression formats such as MP3, AAC, and Vorbis do. Josh Coalson is the primary author of FLAC.FLAC reduces bandwidth and storage...
- WAV
WAV , short for Waveform audio format, also known as Audio for Windows, is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs. It is an application of the RIFF bitstream format method for storing data in “chunks”, and thus is also close to the 8SVX and the AIFF...
- RIFF
- 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 are usually characters from the ASCII or Mac OS Roman character sets....
- 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