Basic question: smooth envelope follower


    Mar 25 2010 | 10:59 am
    I have an incoming audio signal like a voice or an instrument and want to let it control external effects, finally by sending out MIDI from Max. But I don't only need the signal strength, I want to smoothen the signal and apply compression, expansion, delay and so on. The result should look as if you would follow a singing voice with a fader.
    I think what I try to explain is called a controllable envelope follower. But not for single waves, rather for longer periods of an audio signal, let's say up to one second.
    Currently I am struggling with the very first step, smoothing the signal. I tried [average~], [degrade~], [sah~] and [adsr~] in several combinations but all of them were still to sensitive. Maybe a compressor could do the trick. Using the output of the levelmeter would also be an option but attack/release is not enough control.
    I hope this explanation was clear. So far I've learned yet I should first tame the signal, then convert to numbers and process the rest afterwards. Although, I do not like mathematical orgies. Is there another approach to extract data from an audio signal in a less sensitive way?

    • Mar 25 2010 | 11:12 am
      Have you looked at [rampsmooth~] and [slide~]?
    • Mar 25 2010 | 11:34 am
      if you are on Max 5.1 or above, you should take a look at:
      Max5 > patches > m4l-patches > Tools resources > M4L.envfol~.maxpat
      great starter example.
    • Mar 25 2010 | 12:06 pm
      @goodparleyandorfing
      I tried [slide~] but it got re-triggered without getting the chance to slide. Maybe I was doing something wrong.
      @ pid
      Thanks very much for pointing me to M4L.envfol~.maxpat
      This is what I basically need, there is a lot to explore and I can continue with that.
    • Mar 26 2010 | 1:42 am
      Or maybe what you really want to do is to study the MSP Compression tutorials - a lot to learn from them.
    • Mar 26 2010 | 4:58 am
      Here is the patch that I use for envelope following...
    • Mar 26 2010 | 8:15 am
      Here's my envelope follower abstraction:
    • Aug 23 2012 | 3:06 pm
      Thx Steven. Beautiful :)