interpreter/preprocessor/faust-0.9.47mr3/tools/faust2pd/examples/synth/chimes.syn

   1
   2 /* A simple "chimes" patch, using a bank of resonz filters (cf. Steiglitz, DSP
   3    Primer, pp. 89f.). */
   4
   5 declare name "chimes -- chimes synth using a bank of resonz filters";
   6 declare author "Albert Graef";
   7 declare version "2.0";
   8
   9 import("music.lib");
  10
  11 /* Control variables: */
  12
  13 // master volume, pan
  14 vol             = hslider("vol", 0.5, 0, 10, 0.01);             // %
  15 pan             = hslider("pan", 0.5, 0, 1, 0.01);              // %
  16
  17 // excitator and resonator parameters
  18
  19 // excitator decay time [sec]
  20 xdecay          = nentry("decay", 0.01, 0, 1, 0.001);
  21
  22 // resonator #0
  23 hrm0            = nentry("harmonic0", 1, 0, 50, 0.001);         // harmonic
  24 amp0            = nentry("amplitude0", 0.167, 0, 1, 0.001);     // amplitude
  25 decay0          = nentry("decay0", 3.693, 0, 10, 0.001);        // decay time
  26 rq0             = nentry("rq0", 0.002, 0, 1, 0.0001);           // filter 1/Q
  27 // resonator #1
  28 hrm1            = nentry("harmonic1", 3.007, 0, 50, 0.001);     // harmonic
  29 amp1            = nentry("amplitude1", 0.083, 0, 1, 0.001);     // amplitude
  30 decay1          = nentry("decay1", 2.248, 0, 10, 0.001);        // decay time
  31 rq1             = nentry("rq1", 0.002, 0, 1, 0.0001);           // filter 1/Q
  32 // resonator #2
  33 hrm2            = nentry("harmonic2", 4.968, 0, 50, 0.001);     // harmonic
  34 amp2            = nentry("amplitude2", 0.087, 0, 1, 0.001);     // amplitude
  35 decay2          = nentry("decay2", 2.828, 0, 10, 0.001);        // decay time
  36 rq2             = nentry("rq2", 0.002, 0, 1, 0.0001);           // filter 1/Q
  37 // resonator #3
  38 hrm3            = nentry("harmonic3", 8.994, 0, 50, 0.001);     // harmonic
  39 amp3            = nentry("amplitude3", 0.053, 0, 1, 0.001);     // amplitude
  40 decay3          = nentry("decay3", 3.364, 0, 10, 0.001);        // decay time
  41 rq3             = nentry("rq3", 0.002, 0, 1, 0.0001);           // filter 1/Q
  42 // resonator #4
  43 hrm4            = nentry("harmonic4", 12.006, 0, 50, 0.001);    // harmonic
  44 amp4            = nentry("amplitude4", 0.053, 0, 1, 0.001);     // amplitude
  45 decay4          = nentry("decay4", 2.488, 0, 10, 0.001);        // decay time
  46 rq4             = nentry("rq4", 0.002, 0, 1, 0.0001);           // filter 1/Q
  47
  48 // frequency, gain, gate
  49 freq            = nentry("freq", 440, 20, 20000, 1);            // Hz
  50 gain            = nentry("gain", 1, 0, 10, 0.01);               // %
  51 gate            = button("gate");                               // 0/1
  52
  53 /* Definition of the resonz filter. This is basically a biquad filter with
  54    pairs of poles near the desired resonance frequency and zeroes at -1 and
  55    +1. See Steiglitz for details. */
  56
  57 resonz(R,freq)  = f : (+ ~ g)
  58 with {
  59         f(x)    = a*(x-x');             // feedforward function (two zeros)
  60         g(y)    = 2*R*c*y - R*R*y';     // feedback function (two poles)
  61         w       = 2*PI*freq/SR;         // freq in rad per sample period
  62         c       = 2*R/(1+R*R)*cos(w);   // cosine of pole angle
  63         s       = sqrt (1-c*c);         // sine of pole angle
  64         a       = (1-R*R)*s;            // factor to normalize resonance
  65 };
  66
  67 /* The excitator, a short burst of noise. */
  68
  69 excitator(t)    = t : hgroup("1-excitator", adsr(0, xdecay, 0, 0) : *(noise));
  70
  71 /* Bank of 5 resonators. */
  72
  73 resonator(f,t,i,hrm,amp,decay,rq)
  74                 = (f,t,_) : hgroup("2-resonator-%i", g)
  75 with {
  76         g(f,t)  = resonz(R,h)*(amp*b*env)
  77         with {
  78                 h       = hrm*f;        // harmonic
  79                 B       = rq*f/SR;      // bandwidth, as fraction of sample rate
  80                 R       = 1-PI*B;       // resonance (pole radius)
  81                 b       = 1/(2*B);      // boost factor = Nyquist/bandwidth
  82                 env     = adsr(0, decay, 0, 0, t);      // envelop
  83         };
  84 };
  85
  86 resonators(f,t) = resonator(f,t,0,hrm0,amp0,decay0,rq0)
  87                 + resonator(f,t,1,hrm1,amp1,decay1,rq1)
  88                 + resonator(f,t,2,hrm2,amp2,decay2,rq2)
  89                 + resonator(f,t,3,hrm3,amp3,decay3,rq3)
  90                 + resonator(f,t,4,hrm4,amp4,decay4,rq4);
  91
  92 /* The synth. */
  93
  94 process         = excitator(gate)*gain <: resonators(freq, gate)
  95                 : vgroup("3-master", *(vol) : panner(pan));