Reply to Beat Meter

I have seen this done in at least one youtube video and I don't know if they were using Traktor so I don't know if it's even possible. Essentially they mapped the top row of say an APC20/40 or a launchpad tohave the first light light up with say beat 1 and then in time it would move to button/light 2,3,4,5 etc.. I can't find the video to show you I wish I had saved it. If anyone has any idea about what I'm talking about let me know. It would be a fun little project for my intro to computers class. I have nothing else to do in there except troll the community s. :P