Preferred image format?

Is there a preferred image format that is maximally compatible with all/most tag formats? How about image dimensions? Thanks!



Format: JPG, but PNG support is good.
Size: I embed 500px images.


Thanks! I've noticed that I can't attach cover art to OGG files. Is this a limitation of the format? Cover art tags are not listed here, otherwise I would already know the answer:


Cover art for ogg has just been added: /t/455/1

Super! I'll get to work immediately!