Crossfading between two synchronised audio loops

Hi there,

Relatively new to Max msp here! I was wondering if anyone has come up with (or can think of) a means by which to have two audio loops of equal an length looping in sync, and then have them crossfade from one to another when a bang is triggered? I have a patch wherein the frame differences from a live webcam feed gives me a floating decimal value, where when it's "<" than a certain value nothing happens, but when it's ">" it crossfades into the other audio clip... The purpose of which being that with a certain amount of movement on the camera feed you can uncover a clean and undistorted version of the same audio clip whilst both play as a loop.

If anyone has any pointers I would really be appreciative, cheers!