The state of music file formats and album art
Different file formats support different music metadata abilities. When it comes to album art the support varies from no support at all to allowing a veritable gallery of art to be stored within each music file.
Here's a rundown of how the combination of file format and tag format support album art. There's an explanation for each column afterwards:
|Supported||Multi-art||Picture types||Descriptions||Link to file|
Whether embedded album art is supported at all.
Whether multiple different artworks may be embedded in the file.
Whether a descriptor of the artwork can be stored denoting the type of the artwork, for instance the front cover, back cover, sleeve notes etc.
Whether a plain text description of the artwork is allowed.
Link to file
Whether the artwork can be sourced from an external file.
Why it may not even matter(!)
All of this is simply documenting how artwork may be stored in files as per the format specification. As a music lover, this matters not a jot if your music player does not support these features. At the extreme end of things, your music player may not support artwork at all!
In reality, the differences are more subtle. iTunes, for instance, ignores the picture type field when reading or writing artwork, regardless of whether the file format supports it. It merely always chooses the first artwork found in a file, whether it's a back cover or whatever.
The lesson is: choose a powerful, flexible file format, but don't expect to be able to circumvent your music player's deficiencies.