A few years ago, I recall having an ALAC track that would not play in JRemote due to its embedded album art.
In my case I don’t recall if the issue was caused by the art being JPG or PNG. However I can say that it was definitely caused by the byte size of the embedded image; to be specific the original image byte size was in the hundreds of kBytes and that failed to play in JRemote, whereas if it was replaced by an image sized in the tens of kBytes it worked fine.
As far as I recall this size issue was specific to playing on JRemote, and both versions of the file playing just fine when played in MC natively. And also working fine in iTunes. EDIT: and — tellingly — also working fine when playing transcoded to JRemote.
The JRiver guys, and I, never really found the exact cause of my problem, and if you know the work around, you can — well — work around it. However my suspicion is that it is either a) something to do with the way that JRemote parses the M4A “boxes” that contain the album art — perhaps an integer wrap around on say 256kBytes (or 512k etc.), or alternatively b) a buffer size problem in that JRemote has to skip over too much RAM in order to get to the part of the buffer where the music stream “box” is located.
