Embed album art in MP3 file

Interesting question. I did a bit of Googling and discovered that Album Art can be embedded in ID3 tags which are appended to the end of an image (as per this link). The most appropriate size is probably 300x300 pixels as a JPEG, and there are a number of pieces of software which can edit ID3 tags and insert this information for you.

Googling "id3 tag editor" will provide a plethora of software options to modify ID3 tags. I've never used it, but http://id3tageditor.com/ claims to do what you need.

Both programs you mentioned already do this. However, once you upload the file somewhere else, you cannot prevent the server from removing album art again, if it decides so.

Also, ID3 tags are a finicky beast, and it could be that the server doesn't recognize the specific format you're trying to use:

• Try different image formats – JPEG vs. PNG;

• Use iTunes or foobar2000 to convert the ID3 tags between different versions (e.g. iTunes writes ID3v2.4, but quite a few tools only support v2.3);

• Use mp3Diags to make sure the ID3 tags aren't corrupted (though note that it sometimes gives false positives for v2.4).