ID3
ID3, or ID3 tag, is a metadata format, mainly used in MP3 audio files. It stores information such as the song title, artist, and album.
Although usually associated with MP3, an ID3 tag is a single self-contained blob of bytes, so it can theoretically be used in most any format that is designed to be extensible. For example, here is a WMA file with ID3 data.
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Format details
There are two major versions. ID3v1 defines a fixed-length data block that is always placed at the end of the file. ID3v2, which has very little in common with ID3v1, defines a block with variable-length frames and allows more flexibility and verbosity. ID3v2 data usually appears at the beginning of the file. It is possible, and common, for a file to have both ID3v1 and ID3v2 metadata.
As of 2017, there are three versions of ID3v2 to be aware of: v2.2.x, v2.3.x, and v2.4.x. These formats have some critical differences, and are definitely not compatible with each other.
Identification
For an MP3 file with an ID3v1 tag, ASCII "TAG" appears beginning 128 bytes from the end of the file.
An MP3 file with an ID3v2 tag usually begins with ASCII "ID3".
Alternatively, the signature "3DI" could appear 10 bytes from the end of the file, or 138 bytes from the end of the file if there is also an ID3v1 tag. This is much less likely.
There are other (rare) ways to use ID3v2, not covered by the above identification logic.
Specifications
- ID3.org Developer Information
- ID3v1
- ID3v2.2.0
- ID3v2.3.0: Plain text · HTML
- ID3v2.4.0: Main Structure · Native Frames
- ID3 tag version 2 (Another copy of v2.2.0)
- MPEG Audio Tag ID3v1
- Hydrogenaudio Knowledgebase: ID3v1
- Hydrogenaudio Knowledgebase: ID3v1.1
- Hydrogenaudio Knowledgebase: ID3v2
Software
[Ed. note: There are many utilities that can read and write ID3 tags, including Windows Explorer to some extent. We suggest searching the web.]
