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 | ID3 Metadata for MP3, Version 2 |
| Description | Structured data chunk containing descriptive metadata about the file to which it is generally pre-pended, virtually always an MP3_FF (MP3 sound file). Referred to by its creators as an "informal standard" for a "container format," ID3v2 permits the identification of title, artist, date, genre, and more. See Notes for more information. Sub-versions are not separately described at this Web site at this time. The actual specifications are summarized in the Wikipedia article ID3 (consulted February 2007): • ID3v2.2: ". . . the first public version of ID3v2. . . . used three character frame identifiers rather than four (TT2 for the title instead of TIT2)." • ID3v2.3: ". . . expanded the frame identifier to four characters, and added a number of frames. A frame could contain multiple values, separated with a / character." • ID3v2.4: ". . . the latest version of the standard, dated November 1, 2000. Notably, it allows textual data to be encoded in UTF-8, which was a common practice in earlier tags despite the standard. It uses a null byte to separate multiple values, and so / can appear in text data again." Addenda to the ID3v2.3 and ID3v2.4 standards have been published: In addition, has been provided by the following "addenda": • ID3 Chapter (CHAP) and Table of Contents (CTOC) for single-file podcasts, talking books, and the like that contain multiple tracks, stories, or other distinct audio entries, compatible with ID3v2.3 and ID3v2.4 tags. (2005) • ID3 Accessibility Addendum ID3 metadata accessible to the visually impaired via a new Audiotext (ATXT) frame type, compatible with ID3v2.3 and ID3v2.4 tags. The addition of ATXT frames to an ID3 tag will allow compatible players to provide an audible description of the ID3 metadata. (2006) |
| Production phase | Generally used for final-state, end-user delivery. |
| Relationship to other formats | |
| Subtype of | ID3, ID3 Metadata for MP3 |
| Used by | MP3_FF, MP3 file format |
| LC experience or existing holdings | See ID3 |
| LC preference | See ID3 |
| Disclosure | Fully documented. Developed by Martin Nilsson and colleagues; see ID3.org web site. |
| Documentation | Documentation and specifications for all subversions and addenda at the ID3.org developer's page. |
| Adoption | Very widely adopted for World Wide Web dissemination and playback on specialized devices. |
| Licensing and patent claims | None, except use of the copyrighted logo is licensed by Martin Nilsson at no cost. |
| Transparency | See ID3 |
| Self-documentation | See ID3 |
| External dependencies | None |
| Technical protection considerations | None |
| Normal rendering for sound | Not applicable |
| Fidelity (support for high audio resolution) | Not applicable |
| Support for multiple sound channels | Not applicable |
| Support for downloadable or user-defined sounds, samples, and patches | Not applicable |
| Functionality beyond normal rendering for sound | Permits inclusion of binary elements like still images and can contain lyrics that may be music-synchronized for karaoke or other applications. Addenda listed in the Identification and description above permit the marking of chapters, tables of contents, and aids to accessibility. |
| Tag type | Value | Note |
| Filename Extension | Not applicable | |
| Internet Media Type | Not applicable | |
| Magic numbers | Not applicable | See 3DI marker information in Notes below. |
| General | ID3v2 binary content is structured as "frames" just like MP3_ENC (MP3 audio encoding). Each frame can contain up to 16 MB; the entire chunk can be as much as 256 MB. Version 2 supports Unicode, has an "unsynchronization scheme" to prevent incompatible players from attempting to play the ID3 chunk, and supports "enciphered" information. See also sub-version information in Identification and description above. When ID3 metadata is placed in a MP3_FF file, established conventions call for the use of the ID3 marker which consists of the string "3DI". For ID3v1, the marker is positioned 10 bytes preceding the metadata. For ID3v2 data, the marker is positioned in the first 3 bytes of the file when the metadata is pre-pended and 10 bytes from the end of a file when it is post-pended. |
| History |
URLs
• Developer's page at ID3.org (http://www.id3.org/Developer_Information)
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