Sustainability of Digital Formats: Planning for Library of Congress Collections

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QuickTime Audio, MP3 Codec

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name QuickTime file with MP3 Encoding
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, QuickTime File Format
    Contains MP3_ENC, MPEG Layer III Audio Encoding

Local use Explanation of format description terms

LC experience or existing holdings None
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.

Sustainability factors Explanation of format description terms

Disclosure Fully documented. For wrapper, see QuickTime; for bitstream, see MP3_ENC.
    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.

Quality and functionality factors Explanation of format description terms

Sound
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.

File type signifiers and format identifiers Explanation of format description terms

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 specifically identified as of 2004-05-26; see QuickTime.
Apple Sound Codec four-character codes Hex: 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

Notes Explanation of format description terms

General  
History  

Format specifications Explanation of format description terms


Useful references

URLs

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.


Last Updated: 02/21/2017