What is ID3

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Revision as of 22:45, 1 April 2012 by Darvinia (talk | contribs) (ID3v1, ID3v2, ID3v2 2.2 2.3 2.4 etc - What's that all about?)
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What is ID3?

An audio file has additional information that describes it. Usually that is at least an artist and a title. But there could be more: recording date, track number on a CD, the CD or collection that particular piece belongs to. Maybe even an image file that shows the cover or some additional information about how to play the file. That kind of information is often called metadata as well.

With plain .wav files you have the option of storing that information in an external file. So whenever the Wave file is copied, the additional information is lost.

To avoid that, the ID3 standard was created. It defines a way of adding the information directly to the MP3 file. Almost every hardware or software player is aware of the ID3 information and knows how to use it.

Why should you use it?

  • Simple answer: Using MP3 files with ID3 tags is a lot easier than using files without it.
  • Longer answer: Assuming only a few of the possible fields are set (say, Artist, Title, Album and Track Number), then a player will use that information to:
a. Sort files according to the information in the tags, so the parts of an audio book will be played in order :)
b. Display what you are listening to right now, and help you find other tracks
c. Group files belonging together (since they are on the same album or are part of the same audio book)

Further possible uses would be: automatic database creation (since the information is already present in the file); search for specific information like artist, title, year recorded, author and so on.

How does it work?

An ID3 tag is just an additional data block in the file. Most software MP3 Players allow the user to create and edit that information. At least Winamp, iTunes, xmms, and rhythmbox do. There are also specialised programs to edit the MP3 tags. Click here for a list of freeware ID3 tag editors. It's also possible to use the Explorer in Windows XP, or the QuickTime Player. You can find out on this page how to use these, and other, programs.

The tag itself is divided into separate fields with pre-defined names. The most important ones are:

  • Artist
  • Title
  • Album
  • Comment

However there are a lot more. Technically the tag can exist without any of the tags containing an value. Nevertheless it is advisable to fill in at least the Artist, Title and Album fields. If you leave out the "Track Number" field you should choose titles that will be sorted properly, because if the Track Number is not there, players sort by Title. Note that they don't recognize numbers but sort alphabetically. Therefore the titles chapter_8, chapter_9, chapter_10 will be sorted incorrectly:

  • chapter_10
  • chapter_8
  • chapter_9

Whereas chapter_08, chapter_09, chapter_10 will be sorted correctly as:

  • chapter_08
  • chapter_09
  • chapter_10

Therefore if you expect more than 9 files you should reserve two characters for the number, if you expect more than 99 you should reserve three and so on, and fill unused places with zeros.

The exact way of editing that information depends on the software you use, however usually you will be offered that option by right-clicking on any title in the playlist and selecting some option like "File Info".

ID3v1, ID3v2, ID3v2 2.2 2.3 2.4 etc - What's that all about?

When the MP3 file format was still young, computers were slow and storage space scarce, a very simple way of storing metadata was developed - this was the ID3v1 standard. Within that scheme, the size of the tag as well as the number, names and sizes of the possible fields were fixed. The maximum length for an entry in the Title, Artist of Album fields for example was 32 characters. For some uses, that is too short (e.g. "The portrait of the artist as a young man" already has 41 characters).

Therefore ID3v2 was developed, which is more flexible and allows for more or less arbitrary lengths of fields (there is a limit, but it is very high). The "new" ID3v2 has been around for quite some time as well, therefore most players handle it very well. Consequently, unless you have a special reason not to do so, you should choose to use ID3v2. The additional version numbers to the ID3v2 (2.2,2.3) are of less importance. They mainly add specified fields. However, ID3v2.4 tags are not recognized by many media players/taggers/encoders and Windows media applications so we recommend using ID3v2.3 for your tags.

How do I add or edit the ID3 tag in my software?

Glad you asked.

We have explanations of how to use a variety of programs to edit ID3 tags.