Very cool. I had this same idea (and of course secretly hoped I was the first to have thought of it, but that's rarely the case) just the other day, as I found myself having to re-encode a bunch of FLAC files purchased at HDtracks.com to M4A, since Spotify for some absurd reason doesn't support FLAC. It's straightforward enough with ffmpeg, but it's yet another annoying step required before you can listen to the music.