PICTURE is block type 6. It holds a picture, usually the cover, and a stream may have several.
Layout
Lengths and numbers are big-endian, 32 bits each.
| Bytes | Field | Meaning |
|---|---|---|
| 4 | Picture type | See below |
| 4 | MIME type length | |
| n | MIME type | ASCII, such as image/png; --> means the data is a link |
| 4 | Description length | |
| n | Description | UTF-8 |
| 4 | Width | In pixels |
| 4 | Height | In pixels |
| 4 | Colour depth | Bits per pixel |
| 4 | Indexed colours | The number of colours for an indexed picture, otherwise 0 |
| 4 | Data length | |
| n | Data | The picture file, or the link |
Width, height, depth and colour count are for choosing among pictures without decoding them; they do not affect how a picture is decoded, and 0 is used when they are not known.
When the MIME type is -->, the data is a URI, absolute or relative.
Readers should ask before following a link outside the file’s folder or to a remote
address, must cope if it is missing, and may refuse.
Picture types
| Value | Type |
|---|---|
| 0 | Other |
| 1 | PNG file icon of 32×32 pixels. At most one |
| 2 | General file icon. At most one |
| 3 | Front cover |
| 4 | Back cover |
| 5 | Liner notes page |
| 6 | Media label, such as a CD’s |
| 7 | Lead artist, lead performer or soloist |
| 8 | Artist or performer |
| 9 | Conductor |
| 10 | Band or orchestra |
| 11 | Composer |
| 12 | Lyricist or text writer |
| 13 | Recording location |
| 14 | During recording |
| 15 | During performance |
| 16 | Movie or video screen capture |
| 17 | A bright coloured fish, a value carried over from ID3v2 |
| 18 | Illustration |
| 19 | Band or artist logotype |
| 20 | Publisher or studio logotype |
Other values are reserved. Type 1 must be a PNG.