interpreter/preprocessor/faust-0.9.47mr3/examples/lowboost.dsp

   1 declare name            "lowboost";
   2 declare version         "1.0";
   3 declare author          "Grame";
   4 declare license         "BSD";
   5 declare copyright       "(c)GRAME 2006";
   6
   7 //------------------------------------------------------------------
   8 //      DAFX, Digital Audio Effects (Wiley ed.)
   9 //      chapter 2       : filters
  10 //      section 2.3 : Equalizers
  11 //      page 53         : second order shelving filter design
  12 //------------------------------------------------------------------
  13
  14 import("music.lib");
  15
  16
  17 //------------------- low-frequency shelving boost (table 2.3) --------------------
  18
  19 V0(g)                   = pow(10,g/20.0);
  20 K(fc)                   = tan(PI*fc/SR);
  21 square(x)               = x*x;
  22 denom(fc)               = 1 + sqrt(2)*K(fc) + square(K(fc));
  23
  24 lfboost(fc, g)  = TF2(  (1 + sqrt(2*V0(g))*K(fc) + V0(g)*square(K(fc))) / denom(fc),
  25                                                  2 * (V0(g)*square(K(fc)) - 1) / denom(fc),
  26                                                 (1 - sqrt(2*V0(g))*K(fc) + V0(g)*square(K(fc))) / denom(fc),
  27                                                  2 * (square(K(fc)) - 1) / denom(fc),
  28                                                 (1 - sqrt(2)*K(fc) + square(K(fc))) / denom(fc)
  29                                          );
  30
  31
  32 //------------------------------ User Interface -----------------------------------
  33
  34 freq                            = hslider("[1]freq [unit:Hz][style:knob]", 1000, 20, 20000, 0.1);
  35 gain                            = hslider("[2]gain [unit:dB][style:knob]", 0, -20, 20, 0.1);
  36
  37
  38 //----------------------------------- Process -------------------------------------
  39
  40 process                         = vgroup("low-freq shelving boost", lfboost(freq,gain));
  41