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.

There are two unrelated versions of ID3: ID3v1 and ID3v2.

Although ID3 is sometimes referred to as a ''standard'', the term applies only in the ''de facto'' sense, as no standardization body was involved in its creation nor has such an organization given it a formal approval status.

ID3v1

After the creation of the MP3 standard, there appeared a problem with storing data about the file. Standalone MP3s didn't have any special method of doing this. In 1996 Eric Kemp had the idea to add a small chunk of data to the audio file, thus solving the problem. The method, now known as ID3v1, quickly became the ''de facto'' standard for storing metadata in MP3s. The format was released by Damaged Cybernetics, an underground group that specialized in cracking console gaming systems. This format was first used to identify ROMs for the 8-bit Nintendo decrypted by the leader "MindRape", Donald Ray Moore, Jr., in 1996. There was no identifying information for any of the ROMS, thus an ID tagging system was created to make tracking easier. Eric and associates carried this over into mp3 files. This format was used for a number of file formats unknown at that time.

The ID3v1 tag occupies 128 bytes, beginning with the string ''TAG''. The tag was placed at the end of the file to maintain compatibility with older media players. Some players would play a small burst of static when they read the tag, but most ignored it, and almost all modern players will correctly skip it. This tag allows 30 bytes each for the title, artist, album, and a "comment", four bytes for the year, and a byte to identify the genre of the song from a predefined list of 80 values (Winamp later extended this list to 148 values).

One improvement to ID3v1 was made by Michael Mutschler in 1997. Since the comment field was too small to write anything useful, he decided to trim it by two bytes and use those two bytes to store the track number. Such tags are referred to as ID3v1.1.

Enhanced tag

The enhanced tag is an extra data block before an ID3v1 tag, which extends the title, artist and album fields by 60 bytes each, offers a freetext genre, a one-byte (values 0-5) speed and the start and stop time of the music in the MP3 file, e.g., for fading in. If none of the fields are used, it will be automatically omitted.

Programs supporting ID3v1 tags can read the enhanced tag, but writing may leave stale values in the extended block. The extended block is not an official standard, and is only supported by few programs, not including XMMS or Winamp.

Layout

Strings are either space- or zero-padded. Unset string entries are filled using an empty string.

ID3v1: 128 bytes

! Field	! Length	! Description
header	3	"TAG"
title	30	30 characters of the title
artist	30	30 characters of the artist name
album	30	30 characters of the album name
year	4	A four-digit year
comment	28 or 30	The comment.
zero-byte	1	If a track number is stored, this byte contains a binary 0.
track	1	The number of the track on the album, or 0. Invalid, if previous byte is not a binary 0.
genre	1	Index in a list of genres, or 255

Extended tag (placed before the ID3v1 tag): 227 bytes

! Field	! Length	! Description
header	4	"TAG+"
title	60	Next 60 characters of the title (90 characters total)
artist	60	Next 60 characters of the artist name
album	60	Next 60 characters of the album name
speed	1	0=unset, 1=slow, 2= medium, 3=fast, 4=hardcore
genre	30	A free-text field for the genre
start-time	6	the start of the music as mmm:ss
end-time	6	the end of the music as mmm:ss

ID3v2

In 1998, a new specification called ID3v2 was created. Although it bears the name ID3, it has little to no relation to ID3v1.

ID3v2 tags are of variable size, and usually occur at the start of the file, to aid streaming media. They consist of a number of ''frames'', each of which contains a piece of metadata. For example, the ''TIT2'' frame contains the title, and the ''WOAR'' frame contains the URL of the artist's website. Frames can be up to 16MB in length, while total tag size is limited to 256MB. The internationalization problem was solved by allowing the encoding of strings not only with ISO-8859-1, but also with UTF-16. Textual frames are marked with an encoding byte.

$00 – ISO-8859-1 (ASCII).
$01 – UCS-2 in ID3v2.2 and ID3v2.3, UTF-16 encoded Unicode with BOM.
$02 – UTF-16BE encoded Unicode without BOM in ID3v2.4 only.
$03 – UTF-8 encoded Unicode in ID3v2.4 only.

However, mojibake is still common when using local encoding instead of UTF-16. In particular, some japanese editors are known to use shift-jis code, which usually has disastrous effects : it will assuredly not work with any standard-compliant software regardless of local settings (since it is not supported by the standard), assuredly not work outside Japan (since shift-jis has very little support outside of Japan), and will not even work on all Japanese computers even with a specifically non-compliant reader (as it is software-dependent and settings-dependent).

In the latest ID3v2 specification there are 84 types of frame, and applications can also define their own types. There are standard frames for containing cover art, BPM, copyright and license, lyrics, and arbitrary text and URL data, as well as other things.

There are three versions of ID3v2. ID3v2.2 was the first public version of ID3v2. It used three character frame identifiers rather than four (''TT2'' for the title instead of ''TIT2''). Most of the common v2.3 and v2.4 frames have direct analogues in v2.2. Now this standard is considered obsolete.

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. This is the most widely used version of ID3v2 tags.

ID3v2.4 is the latest version published, 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, since it was not supported yet) because it has several noticeable advantages over UTF-16. It uses a null byte to separate multiple values, so the character "/" can appear in text data again. Another new feature allows the addition of a tag to the end of the file before other tags (like ID3v1).

Windows Explorer and Windows Media Player cannot handle ID3v2.4 tags in any version, up to and including Windows 7/Windows Media Player 12. Windows can understand ID3v2 up to and including version 2.3.

ID3v2 Chapters

The ID3v2 Chapter Addendum was published in December 2005 but is not widely supported as yet. It allows users to jump easily to specific locations or chapters within an audio file and can provide a synchronized slide show of images and titles during playback. Typical applications include Enhanced podcasts and it can be used in ID3v2.3 or ID3v2.4 tags.

ID3v2 Embedded Image Extension

The metadata can also contain images of the following types:

$00     Other
$01     32x32 pixels 'file icon' (PNG only)
$02     Other file icon
$03     Cover (front)
$04     Cover (back)
$05     Leaflet page
$06     Media (e.g. label side of CD)
$07     Lead artist/lead performer/soloist
$08     Artist/performer
$09     Conductor
$0A     Band/Orchestra
$0B     Composer
$0C     Lyricist/text writer
$0D     Recording Location
$0E     During recording
$0F     During performance
$10     Movie/video screen capture
$11     A bright coloured fish [sic]
$12     Illustration
$13     Band/artist logotype
$14     Publisher/Studio logotype

ID3v2 Frame Specification (Version 2.3)

AENC Audio encryption APIC Attached picture

COMM Comments COMR Commercial frame

ENCR Encryption method registration EQUA Equalization (replaced by EQU2 in v2.4) ETCO Event timing codes

GEOB General encapsulated object GRID Group identification registration

IPLS Involved people list (replaced by TMCL and TIPL in v2.4)

LINK Linked information

MCDI Music CD identifier MLLT MPEG location lookup table

OWNE Ownership frame

PRIV Private frame PCNT Play counter POPM Popularimeter POSS Position synchronisation frame

RBUF Recommended buffer size RVAD Relative volume adjustment (replaced by RVA2 in v2.4) RVRB Reverb

SYLT Synchronized lyric/text SYTC Synchronized tempo codes

TALB Album/Movie/Show title TBPM BPM (beats per minute) TCOM Composer TCON Content type TCOP Copyright message TDAT Date (replaced by TDRC in v2.4) TDLY Playlist delay TENC Encoded by TEXT Lyricist/Text writer TFLT File type TIME Time (replaced by TDRC in v2.4) TIT1 Content group description TIT2 Title/songname/content description TIT3 Subtitle/Description refinement TKEY Initial key TLAN Language(s) TLEN Length TMED Media type TOAL Original album/movie/show title TOFN Original filename TOLY Original lyricist(s)/text writer(s) TOPE Original artist(s)/performer(s) TORY Original release year (replaced by TDOR in v2.4) TOWN File owner/licensee TPE1 Lead performer(s)/Soloist(s) TPE2 Band/orchestra/accompaniment TPE3 Conductor/performer refinement TPE4 Interpreted, remixed, or otherwise modified by TPOS Part of a set TPUB Publisher TRCK Track number/Position in set TRDA Recording dates (replaced by TDRC in v2.4) TRSN Internet radio station name TRSO Internet radio station owner TSIZ Size (deprecated in v2.4) TSRC ISRC (international standard recording code) TSSE Software/Hardware and settings used for encoding TYER Year (replaced by TDRC in v2.4) TXXX User defined text information frame

UFID Unique file identifier USER Terms of use USLT Unsynchronized lyric/text transcription

WCOM Commercial information WCOP Copyright/Legal information WOAF Official audio file webpage WOAR Official artist/performer webpage WOAS Official audio source webpage WORS Official internet radio station homepage WPAY Payment WPUB Publishers official webpage WXXX User defined URL link frame

Multiple values in v2.3 tags

The version 2.3 of the standard prescribes that some fields can contain multiple values separated by the "/" character. The fields that can contain multiple values are:

TPE1 TCOM TEXT TOLY TOPE

ID3v2 Frame Specification (Version 2.4 - delta respect to 2.3)

EQUA replaced by the EQU2 frame IPLS replaced by the two frames TMCL and TIPL RVAD replaced by the RVA2 frame TDAT replaced by the TDRC frame TIME replaced by the TDRC frame TORY replaced by the TDOR frame TRDA replaced by the TDRC frame TYER replaced by the TDRC frame TSIZ deprecated.

New frames ASPI Audio seek point index EQU2 Equalisation RVA2 Relative volume adjustment SEEK Seek frame SIGN Signature frame TDEN Encoding time TDOR Original release time TDRC Recording time TDRL Release time TDTG Tagging time TIPL Involved people list TMCL Musician credits list TMOO Mood TPRO Produced notice TSOA Album sort order TSOP Performer sort order TSOT Title sort order TSST Set subtitle

Multiple values in v2.4 tags

Version 2.4 of the specification prescribes that the text fields (all the fields starting with a T except TXXX) can contain multiple values separated by a null character. The null character is the one represented by the termination code for the character encoding used.

Editing ID3 tags

ID3 tags may be edited in a variety of ways. On some platforms the file's properties may be edited by viewing extended information in the file manager. Additionally most audio players allow editing single or groups of files. Editing groups of files is often referred to as "batch tagging". There are also specialized applications, called taggers, which concentrate specifically on editing the tags and related tasks. These often offer advanced features such as advanced batch tagging or editing based on regular expressions.

Implementation in non-mp3s and alternatives

ID3 tags were designed with MP3 in mind, so they would work without problems with MP3 and MP3Pro files. However, the tagsets are an independent part of the MP3 file and should be usable elsewhere. In practice, the only other format which widely uses ID3v2 tags is AIFF, where the tag is stored inside an IFF chunk named "ID3". The same could be accomplished in WAV, but isn't. The only tagging system in wide usage for WAV is the Broadcast Wave Format, stored as a RIFF chunk. Windows media ASF files (WMA, WMV) have their own tagging formats but also supports ID3 Tags embedded as attributes. MP4 also allows the embedding of an ID3 tag, and this is widely supported, especially in Apple's iTunes, which uses MP4 standards in its audio and video file formats. Other container-based formats use their own tagging formats. An example of this is Ogg, which uses Vorbis comments. Adding ID3 tags to these would break the container structure. Earlier versions of Winamp such as 2.xx have been proven able to add ID3v1 and ID3v2 tags to MP1 and MP2 files.

See also

APEv2 tag

CD-Text

Vorbis comment

References

External links

Official site for ID3, including the format specifications

List of genres in ID3v1

ID3v1 Specification

ID3 TAG and Enhanced TAG specification

TagLib

Category:Computer file formats Category:Metadata

ca:ID3 cs:ID3 tag de:ID3-Tag es:ID3 fr:ID3 ko:ID3 it:Tag ID3 nl:ID3 (tag) ja:ID3タグ pl:ID3 pt:ID3 ru:ID3 (метаданные) sk:ID3 tag fi:ID3 uk:ID3 zh:ID3