How to find BPM of non-rhymic but regular sounds

nobody · Joined: Mar 09, 2008 Posts: 1687 Location: Not here

Anyone know a good way (other than hit-and-miss) of finding the tempo of a track? I have an audio track that does not have a beat, but it does have a definite repeating pattern. It was recorded from a hybrid synth with no MIDI clock or sync. The LFO that generated the rise-and-fall pattern of the sound has an arbitrary range that means nothing to any other instrument. I'd like to find the BPM so I can set my Sonar project to that BPM.

Antimon · Posted: Sat Feb 06, 2010 4:34 pm Post subject:

Turn on Sonar's metronome (or if there is no metronome, make a simple drum track). Play it simultaneously as your BPM-unknown track and tweak the tempo. It should be pretty obvious at first if it should go up or down, and when you start getting close it's just a matter of checking if Sonar or the other track starts racing ahead, and tweaking the BPM up by single units until your as close as you can get. If you can have fractional BPM you may get it spot on, but if you don't, and the synth that made the track is some kind of non-discrete control, chances are that you won't be satisfied with the result ever - you might get it fine in the middle but lose sync at the start and end.

Sorry if this is obvious and crude in the extreme, but I have struggled with this some myself and honestly don't know any better way - unless you're willing to buy Ableton Live (in Live you'd get the workstation's BPM as close as possible, and then you would time-stretch the unkown-BPM track to get it just right - you could try the free download if you want to check it out). I would love to see if anyone has a better trick.

/Stefan

nobody · Joined: Mar 09, 2008 Posts: 1687 Location: Not here

Sonar time-stretches, too. I actually did what you suggested and I'm happy with the result, even though it's not spot-on. It really doesn't matter for THIS particular composition because the hard rhythm doesn't come in until later.

I think the Akai AX80 has analog components and digital controls, and it's old, so there's probably a bit of drift you really can't control. Not that I'd necessarily want to!

Antimon · Posted: Sat Feb 06, 2010 5:59 pm Post subject:

Ah of course. For some reason I often think that Live does everything and other programs do nothing - been using it exclusively for too long I guess. Glad you got it working.

/Stefan