Filtering drums
  • Hi, very new to this forum and Audulus. And very much in awe of the potential but also the difficulties. Just wondering if anyone can point me in the right direction. I want to filter a drumkit into the different elements and have different outputs with different drum parts (don't even know if that's possible?). Do I use a filter, or can I find out the different frequencies and somehow only allow them through, ie using maths?
  • @Fitz, welcome! As far as I know, what you're describing is a pretty complex problem. Its known as "source separation".

    You can use filters to approximate the separation, but there's quite a bit of overlap between the drums in terms of frequencies. The snare's attack for example, might get up into the range of the cymbals. And if you have two toms that are similar, probably all bets are off.

    But maybe that's good enough? What are you planning to do with the individual parts?

    Another idea would be to build something in Audulus that will recognize each type of drum, and then trigger samples which you could individually mix (though sample playback is only in the Mac version, sigh). This might look like a filter followed by an envelope follower.

    - Taylor
  • Thanks for the reply Taylor,
    It's the last paragraph that sums up what I want to do. I realise that actual source separation with drums is really difficult, I've already tried with an eq, and although it can recognise some of the sounds in the end, after the eq it's pretty unrecognisable. But if it could trigger samples, as in sending a midi note? Or actual live triggering as in Drumagog? That sounded possible, given the kind of things that go on here. Would I discover the unique frequencies first, ie with individual samples, then put a kit together? And then convert to a midi note, or to a synth sound? Of course the tricky thing maybe to do this live, I'm guessing.
    Is there a plan for sample playback in ios?
    Thanks again
  • Live is actually much easier. The tricky thing is teasing out individual instruments from a single audio stream. It largely depends on your source material.
    In a live situation you can get an individual signal from each drum -- audio or a trigger.
    But to get an individual signal from each percussion instrument on a pre-recorded track? Audulus is probably not your best solution. It should be possible to derive triggers from frequency bands. But that's the closest you'll get. And because percussion instruments have wide bandwidths, it's pretty hard to differentiate between them.