interpretor/preprocessor/faust-0.9.47mr3/tools/faust2pd/examples/seqdemo/karplusplus.dsp

   1
   2 declare name "karplusplus -- Karplus-Strong + Fuzz";
   3 declare author "Yann Orlarey, Albert Graef";
   4 declare version "1.0";
   5
   6 import("music.lib");
   7
   8 // control variables
   9
  10 // master volume and pan
  11 vol     = hslider("vol", 0.3, 0, 10, 0.01);     // %
  12 pan     = hslider("pan", 0.5, 0, 1, 0.01);      // %
  13
  14 // excitator and resonator parameters
  15 size    = hslider("samples", 512, 1, 1024, 1);  // #samples
  16 dtime   = hslider("decay time", 4, 0, 10, 0.01);// -60db decay time
  17
  18 // fuzz parameters
  19 drive   = hslider("drive", 0, 0, 50, 0.1);      // overdrive factor
  20 res     = hslider("res", 0, 0, 20, 0.1);        // filter resonance
  21 tone    = hslider("tone", 20, 1, 20, 0.1);      // filter cutoff harmonic
  22 level   = hslider("level", 1, 0, 10, 0.01);     // output gain (%)
  23
  24 // voice parameters
  25 freq    = nentry("freq", 440, 20, 20000, 1);    // Hz
  26 gain    = nentry("gain", 1, 0, 10, 0.01);       // %
  27 gate    = button("gate");                       // 0/1
  28
  29 /* The excitator: */
  30
  31 upfront(x)      = (x-x') > 0.0;
  32 decay(n,x)      = x - (x>0)/n;
  33 release(n)      = + ~ decay(n);
  34 trigger(n)      = upfront : release(n) : >(0.0) : +(leak);
  35 leak            = 1.0/65536.0; // avoid denormals on Pentium
  36 excitator       = trigger(size);
  37
  38 /* The resonator: */
  39
  40 average(x)      = (x+x')/2;
  41 att(d,t)        = 1-1/pow(db2linear(60), d/(SR*t));
  42 comb(d,a)       = (+ : fdelay(4096, d-1.5)) ~ (average : *(1.0-a));
  43 resonator(d)    = comb(d,att(d,dtime));
  44
  45 /* DC blocker (see http://ccrma.stanford.edu/~jos/filters/DC_Blocker.html): */
  46
  47 dcblocker(x)    = (x-x') : (+ ~ *(0.995));
  48
  49 // resonant lowpass
  50
  51 // This is a tweaked Butterworth filter by David Werner and Patrice Tarrabia,
  52 // see http://www.musicdsp.org and http://www.experimentalscene.com for
  53 // details.
  54
  55 // res = resonance in dB above DC gain
  56 // freq = cutoff frequency
  57
  58 lowpass(res,freq)       = f : (+ ~ g) : *(a)
  59 with {
  60         f(x)    = a0*x+a1*x'+a2*x'';
  61         g(y)    = 0-b1*y-b2*y';
  62         a       = 1/db2linear(0.5*res);
  63
  64         c       = 1.0/tan(PI*(freq/SR));
  65         c2      = c*c;
  66         r       = 1/db2linear(2.0*res);
  67         q       = sqrt(2.0)*r;
  68         a0      = 1.0/(1.0+(q*c)+(c2));
  69         a1      = 2.0*a0;
  70         a2      = a0;
  71         b1      = 2.0*a0*(1.0-c2);
  72         b2      = a0*(1.0-q*c+c2);
  73 };
  74
  75 /* Fuzz effect. */
  76
  77 clip(x)         = f*x+1-f with { f = abs(drive*x)<=1; };
  78 fuzz(freq)      = clip : lowpass(res,tone*freq) : *(level);
  79
  80 /* Karplus-Strong string synthesizer: */
  81
  82 process = vgroup("1-excitator", noise*gain : *(gate : excitator))
  83         : vgroup("2-resonator", resonator(SR/freq)) : dcblocker
  84         : vgroup("3-fuzz", fuzz(freq))
  85         : vgroup("4-master", *(vol) : panner(pan));