it's suposed to be (kinda) on the music (and it's approximate, the music is on 120bpm, and I've set a 1sec timer to synch the start on it, bimut not sure if the music loop exactly so there can be a shift if yoy play a too long)
But I didn't take the time to mach the up beat, it can happen on the up or the down depending on when you bet ^^"