Sustainability of Digital Formats
Planning for Library of Congress Collections
Sustainability of Digital Formats
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| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | Audio Interchange File Format (AIFF) |
| Description | File format for sound that wraps various sound bitstreams, ranging from uncompressed waveform to MIDI. Files with LCPM waveform data are the focus of this discussion. Compressed waveforms are wrapped by AIFF-C (or an earlier version sometimes referred to as AIFC), not documented at this web site. |
| Production phase | Used primarily as a initial- or middle-state format, including use as a master file for audio captured live digitally or reformatted from analog sources. |
| Relationship to other formats | |
| Subtype of | IFF, Electronic Arts Interchange File Format 1985 |
| Supertype of | AIFF_LPCM, AIFF with LPCM Audio |
| Supertype of | AIFF files containing other sound encodings not documented here |
| May contain | LPCM encoded audio |
| May contain | MIDI_SD MIDI sequence data |
| May contain | Other sound encodings, not documented here |
| LC experience or existing holdings | None |
| LC preference | General preference for recorded sound is WAVE_LCPM. |
| Disclosure | Fully documented. Developed by Apple Computer, Inc. |
| Documentation | AIFF and AIFF-C documentation produced by Apple and carrying no copyright notice is available from McGill University and other third parties. The principal document is titled Audio Interchange File Format (AIFF): A Standard for Samples Sound Files, Version 1.3 (Apple Computer, Inc) and it also forms Annex C to the CD-I IFF specification published by the American Interactive Media group. The compiler of this document was unable to locate the specifications at the Apple web site. |
| Adoption | Widely adopted among Apple users engaged in professional audio work; some adoption beyond, although most Windows users select WAVE, which is functionally equivalent. AIFF_LPCM is used as the master format by the Harvard University Library Digital Initiative audio reformatting activity. |
| Licensing and patent claims | None known to the compilers of this document. |
| Transparency | Wrapper is transparent. The transparency of the audio bitstreams is a function of the encoding used; for example, see LPCM. |
| Self-documentation | AIFF includes various chunks, each with a header that provides technical information; text chunks as defined from the supertype IFF format include name, author, copyright, and annotation. |
| External dependencies | None |
| Technical protection considerations | None known to the compilers of this document. |
| Normal rendering | Good support. |
| Fidelity (support for high audio resolution) | Excellent to good, depending upon encoding parameters selected. |
| Support for multiple sound channels | Mono, stereo, 3-channel, quad, and four and six channel surround sound are supported for waveform data, depending upon encoding; MIDI data may carry multi-channel information. [?] |
| Support for downloadable or user-defined sounds, samples, and patches | Not researched for this document |
| Functionality beyond normal rendering | Not applicable; added functionality may be associated with non-waveform data. |
| Tag type | Value | Note |
| Filename Extension | aif | Webopedia reports that ief is also used as an extension. |
| Macintosh file type | AIFF | |
| Internet Media Type |
audio/aiff audio/x-aiff sound/aiff audio/rmf audio/x-rmf audio/x-pn-aiff audio/x-gsm audio/x-midi audio/vnd.qcelp | From The File Extension Source. Note that encoding, e.g., gsm, midi and qcelp, is often a part of the MIME string. Internet Media Type for AIFF not found at http://www.iana.org/assignments/media-types/. |
| Magic numbers |
Hex: 46 4F 52 4D 00 ASCII: FORM | From The File Extension Source. |
| General | |
| History |
URLs
• McGill University page listing specification documents (http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/AIFF/AIFF.html)
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URLs
• AIFF by Paul Bourke of Australia (http://astronomy.swin.edu.au/~pbourke/dataformats/audio/)
• AIFF and AIFC format notes (http://sox.sourceforge.net/AudioFormats-11.html#ss11.1)
• The File Extension Source (http://filext/com/)
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