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 | QuickTime file with MP3 Encoding |
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| Description | Bitstream encoding and file format designed for efficient distribution of sound files over moderate bandwidth connections, e.g., Apple's iTunes music service; QTA_MP3 may be used at higher data rates for better fidelity. |
| Production phase | Generally used for final-state, end-user delivery. |
| Relationship to other formats | |
| Subtype of | QuickTime, |
| Contains | MP3_ENC, bitstream encoding |
| LC experience or existing holdings | None |
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| LC preference | The Broadcast WAVE format (either version, WAVE_BWF_1 or WAVE_BWF_2), wrapping LPCM, is preferred as the archival master format for mono and stereo audio when reformatting analog sound recordings. |
| Disclosure | Fully documented. For wrapper, see QuickTime; for bitstream, see MP3_ENC. |
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| Documentation | See QuickTime and MP3_ENC. |
| Adoption | Used by the Apple iTunes music distribution service; may be in diminished production or discontinued as AAC receives wider use. See also QuickTime and MP3_ENC. |
| Licensing and patents | See QuickTime. |
| Transparency | See QuickTime and MP3_ENC. |
| Self-documentation | See QuickTime. |
| External dependencies | Files from iTunes can be played on an iPod device and as many as five computers authorized by the enduser's agreement; see About Music Store Authorization and Deauthorization. |
| Technical protection considerations | Files from iTunes can be played by endusers who use the required Apple ID and Password. The Apple iTunes FairPlay system to protect content is the subject of a Green Paper from the Digital Media research initiative at the Berkman Center of Harvard Law School. See also QuickTime. |
| Sound | |
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| Normal rendering | Good support. |
| Fidelity (high audio resolution) | See MP3_ENC. |
| Multiple channels | See MP3_ENC. |
| Support for user-defined sounds, samples, and patches | See MP3_ENC. |
| Functionality beyond normal rendering | See MP3_ENC. |
| Tag | Value | Note |
|---|---|---|
| Filename extension | mp3 |
Reported by an iTunes user; files said to be protected according to iTunes policies. |
| Internet Media Type | See note. | None specific identified as of 2004-05-26; see QuickTime. |
| Apple Sound Codec four-character codes | 0x6D73055 |
Four-character code (as Hex) identifying the MP3 audio codec (CBR only, pre-QT4.1), from QuickTime File Format, p. 103 or p. 109.1 |
| Apple Sound Codec four-character codes | .mp3 |
Four-character code identifying the MP3 audio codec (CBR and VBR, QT4.1 and later), from QuickTime File Format, p. 103 or p. 109.1 |
| General | |
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| History |
1There seem to have been at least two printings of the specification carrying the same date. These were not systematically compared by the compiler of this Web page. Pagination varies between these two printings.
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