metaflac [ options ] [ operations ] FLACfile ...
TYPE is optional; it is a number from one of:
1: 32x32 pixels 'file icon' (PNG only)
2: Other file icon
3: Cover (front)
4: Cover (back)
5: Leaflet page
6: Media (e.g. label side of CD)
7: Lead artist/lead performer/soloist
12: Lyricist/text writer
13: Recording Location
14: During recording
15: During performance
16: Movie/video screen capture
17: A bright coloured fish
19: Band/artist logotype
20: Publisher/Studio logotype
The default is 3 (front cover). There may only be one picture each of type 1 and 2 in a file.
MIME-TYPE is optional; if left blank, it will be detected from the file. For best compatibility with players, use pictures with MIME type image/jpeg or image/png. The MIME type can also be --> to mean that FILE is actually a URL to an image, though this use is discouraged.
DESCRIPTION is optional; the default is an empty string.
The next part specifies the resolution and color information. If the MIME-TYPE is image/jpeg, image/png, or image/gif, you can usually leave this empty and they can be detected from the file. Otherwise, you must specify the width in pixels, height in pixels, and color depth in bits-per-pixel. If the image has indexed colors you should also specify the number of colors used. When manually specified, it is not checked against the file for accuracy.
FILE is the path to the picture file to be imported, or the URL if MIME type is -->
For example, "|image/jpeg|||../cover.jpg" will embed the JPEG file at ../cover.jpg, defaulting to type 3 (front cover) and an empty description. The resolution and color info will be retrieved from the file itself.
The specification "4|-->|CD|320x300x24/173|http://blah.blah/backcover.tiff" will embed the given URL, with type 4 (back cover), description "CD", and a manually specified resolution of 320x300, 24 bits-per-pixel, and 173 colors. The file at the URL will not be fetched; the URL itself is stored in the PICTURE metadata block.
APPLICATION:abcd The APPLICATION block(s) whose textual repre- sentation of the 4-byte ID is "abcd" APPLICATION:0xXXXXXXXX The APPLICATION block(s) whose hexadecimal big- endian representation of the 4-byte ID is "0xXXXXXXXX". For the example "abcd" above the hexadecimal equivalalent is 0x61626364