Linear smoother

linSmooth.dsp

import("stdfaust.lib");

// slewRate: a slew rate limiter
// - rate: maximum variation allowed in the time frame of a second (positive)
slewRate(rate) = next with {
  next(x) = y letrec {
    'y = y+step(rate/ma.SR,x-y);
  }
  with {
    step(r, dy) = abs(dy) : min(r) : *(ba.if(dy>0,1,-1));
  };
};

// linSmooth: a linear smoother
// - t: time to converge to the final value
linSmooth(t) = next with {
  next(x) = y letrec {
    'y = x : slewRate(r);
    'r = ba.if(rch, abs((y-x)/dt), r);
  }
  letrec {
    'dt = ba.if(rch, t, max(0,dt-1.0/ma.SR));
  }
  with {
    rch = (x!=x')|(t!=t');
  };
};

process = (value : linSmooth(smoothTime)),
          (value : si.smooth(ba.tau2pole(smoothTime/6.91)))
with {
  value = hslider("[1] value", 0.0, -1.0, 1.0, 0.001);
  smoothTime = hslider("[2] smooth time (ms)", 100, 0, 500, 1) : *(1e-3);
};