interpretor/faust-0.9.47mr3/architecture/maxmsp.lib

   1 /************************************************************************
   2  ************************************************************************
   3         FAUST library file
   4         Copyright (C) 2003-2011 GRAME, Centre National de Creation Musicale
   5     ---------------------------------------------------------------------
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU Lesser General Public License as
   8         published by the Free Software Foundation; either version 2.1 of the
   9         License, or (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU Lesser General Public License for more details.
  15
  16     You should have received a copy of the GNU Lesser General Public
  17         License along with the GNU C Library; if not, write to the Free
  18         Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19         02111-1307 USA.
  20  ************************************************************************
  21  ************************************************************************/
  22
  23 declare name "MaxMSP compatibility Library";
  24 declare author "GRAME";
  25 declare copyright "GRAME";
  26 declare version "1.0";
  27 declare license "LGPL";
  28
  29 import("music.lib");
  30
  31
  32 atodb = db2lin;
  33
  34 //-------------------------------------------------------------------------
  35 //
  36 // Implementation of MaxMSP filtercoeff
  37 //
  38 //              from : Cookbook formulae for audio EQ biquad filter coefficients
  39 //        by : Robert Bristow-Johnson  <rbj@audioimagination.com>
  40 //       URL : http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt
  41 //
  42 //-------------------------------------------------------------------------
  43
  44 filtercoeff(f0, dBgain, Q) = environment
  45 {
  46         //----------------------------------------
  47         // biquad coeffs for various filters
  48         // usage : filtercoeff(f0, dBgain, Q).LPF
  49         //----------------------------------------
  50
  51                 LPF = rbjcoef( a0, a1, a2, b0, b1, b2 )
  52                                 with {
  53                                     b0 =  (1 - cos(w0))/2;
  54                                     b1 =   1 - cos(w0);
  55                                     b2 =  (1 - cos(w0))/2;
  56                                     a0 =   1 + alpha;
  57                                     a1 =  -2*cos(w0);
  58                                     a2 =   1 - alpha;
  59                                 };
  60
  61                 HPF = rbjcoef( a0, a1, a2, b0, b1, b2 )
  62                                 with {
  63                                     b0 =  (1 + cos(w0))/2;
  64                                     b1 = -1 - cos(w0);
  65                                     b2 =  (1 + cos(w0))/2;
  66                                     a0 =   1 + alpha;
  67                                     a1 =  -2*cos(w0);
  68                                     a2 =   1 - alpha;
  69                                 };
  70
  71                 BPF = rbjcoef( a0, a1, a2, b0, b1, b2 ) // constant 0 dB peak gain
  72                                 with {
  73                                     b0 =   alpha;
  74                                     b1 =   0;
  75                                     b2 =  -alpha;
  76                                     a0 =   1 + alpha;
  77                                     a1 =  -2*cos(w0);
  78                                     a2 =   1 - alpha;
  79                                 };
  80
  81           notch = rbjcoef( a0, a1, a2, b0, b1, b2 )
  82                                 with {
  83                                     b0 =   1;
  84                                     b1 =  -2*cos(w0);
  85                                     b2 =   1;
  86                                     a0 =   1 + alpha;
  87                                     a1 =  -2*cos(w0);
  88                                     a2 =   1 - alpha;
  89                                 };
  90
  91                 APF = rbjcoef( a0, a1, a2, b0, b1, b2 )
  92                                 with {
  93                                     b0 =   1 - alpha;
  94                                     b1 =  -2*cos(w0);
  95                                     b2 =   1 + alpha;
  96                                     a0 =   1 + alpha;
  97                                     a1 =  -2*cos(w0);
  98                                     a2 =   1 - alpha;
  99                                 };
 100
 101   peakingEQ     = rbjcoef( a0, a1, a2, b0, b1, b2 )
 102                                 with {
 103                         b0 =   1 + alpha*A;
 104                         b1 =  -2*cos(w0);
 105                         b2 =   1 - alpha*A;
 106                         a0 =   1 + alpha/A;
 107                         a1 =  -2*cos(w0);
 108                         a2 =   1 - alpha/A;
 109                                 };
 110
 111   peakNotch     = rbjcoef( a0, a1, a2, b0, b1, b2 )
 112                                 with {
 113                         b0 =   1 + alpha*G;
 114                         b1 =  -2*cos(w0);
 115                         b2 =   1 - alpha*G;
 116                         a0 =   1 + alpha/G;
 117                         a1 =  -2*cos(w0);
 118                         a2 =   1 - alpha/G;
 119                                 };
 120
 121    lowShelf = rbjcoef( a0, a1, a2, b0, b1, b2 )
 122                                 with {
 123                         b0 =    A*( (A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha );
 124                         b1 =  2*A*( (A-1) - (A+1)*cos(w0)                   );
 125                         b2 =    A*( (A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha );
 126                         a0 =        (A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha;
 127                         a1 =   -2*( (A-1) + (A+1)*cos(w0)                   );
 128                         a2 =        (A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha;
 129                                 };
 130
 131   highShelf     = rbjcoef( a0, a1, a2, b0, b1, b2 )
 132                                 with {
 133                                     b0 =    A*( (A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha );
 134                                     b1 = -2*A*( (A-1) + (A+1)*cos(w0)                   );
 135                                     b2 =    A*( (A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha );
 136                                     a0 =        (A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha;
 137                                     a1 =    2*( (A-1) - (A+1)*cos(w0)                   );
 138                                     a2 =        (A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha;
 139                                 };
 140
 141         // --------------------- implementation ------------------------------
 142
 143         // convert rbj coeffs to biquad coeffs
 144         rbjcoef(a0,a1,a2,b0,b1,b2) = (b0/a0, b1/a0, b2/a0,-a1/a0,-a2/a0);
 145
 146         // common values
 147 //      alpha   = sin(w0)/(2*Q);
 148 //      w0              = 2*PI*f0/Fs;
 149         alpha   = sin(w0)/(2*max(0.001,Q));
 150         w0              = 2*PI*max(0,f0)/Fs;
 151         Fs              = SR;
 152         A               = 10^(dBgain/40);                       // (for peaking and shelving EQ filters only)
 153         G               = sqrt(max(0.00001, dBgain));   // When gain is a linear values (i.e. not in dB)
 154 };
 155
 156
 157 //-------------------------------------------------------------------------
 158 // Implementation of MaxMSP biquad~
 159 // y[n] = a0 * x[n] + a1 * x[n-1] + a2 * x[n-2] + b1 * y[n-1] + b2 * y[n-2]
 160 //-------------------------------------------------------------------------
 161
 162 biquad(x,a0,a1,a2,b1,b2) = x : conv3(a0, a1, a2) : + ~ conv2(b1, b2)
 163         with {
 164                 conv2(c0,c1,x) = c0*x+c1*x';
 165                 conv3(c0,c1,c2,x) = c0*x+c1*x'+c2*x'';
 166         };
 167
 168
 169 //-------------------------------------------------------------------------
 170 //
 171 // Filters using filtercoeff and biquad
 172 //
 173 //-------------------------------------------------------------------------
 174
 175
 176 // Low Pass Filter
 177 LPF(x, f0, gain, Q)             = x , filtercoeff(f0,gain,Q).LPF : biquad;
 178
 179 // High Pass Filter
 180 HPF(x, f0, gain, Q)             = x , filtercoeff(f0,gain,Q).HPF : biquad;
 181
 182 // Band Pass Filter
 183 BPF(x, f0, gain, Q)             = x , filtercoeff(f0,gain,Q).BPF : biquad;
 184
 185 // notch Filter
 186 notch(x, f0, gain, Q)           = x , filtercoeff(f0,gain,Q).notch : biquad;
 187
 188 // All Pass Filter
 189 APF(x, f0, gain, Q)             = x , filtercoeff(f0,gain,Q).APF : biquad;
 190
 191 // ????
 192 peakingEQ(x, f0, gain, Q)       = x , filtercoeff(f0,gain,Q).peakingEQ : biquad;
 193
 194 // Max peakNotch is like peakingEQ but with a linear gain
 195 peakNotch(x, f0, gain, Q)       = x , filtercoeff(f0,gain,Q).peakNotch : biquad;
 196
 197 // ????
 198 lowShelf(x, f0, gain, Q)        = x , filtercoeff(f0,gain,Q).lowShelf : biquad;
 199
 200 // ????
 201 highShelf(x, f0, gain, Q)       = x , filtercoeff(f0,gain,Q).highShelf : biquad;
 202
 203
 204
 205
 206 //-------------------------------------------------------------------------
 207 // Implementation of Max/MSP line~. Generate signal ramp or envelope
 208 //
 209 // USAGE : line(value, time)
 210 //      value : the desired output value
 211 //      time  : the interpolation time to reach this value (in milliseconds)
 212 //
 213 // NOTE : the interpolation process is restarted every time the desired
 214 // output value changes. The interpolation time is sampled only then.
 215 //-------------------------------------------------------------------------
 216
 217 line (value, time) = state ~ ( _ , _ ) : ! , _
 218         with {
 219                 state (t , c) = nt , if( nt <= 0 , value , c + (value - c) / nt)
 220                 with {
 221                         nt = if( value != value' , samples, t - 1) ;
 222                         samples = time * SR / 1000.0 ;
 223                 } ;
 224         } ;
 225
 226