filter_parameters.cpp

   1 /*
   2   ZynAddSubFX - a software synthesizer
   3
   4   FilterParams.C - Parameters for filter
   5   Copyright (C) 2002-2005 Nasca Octavian Paul
   6   Author: Nasca Octavian Paul
   7
   8   This program is free software; you can redistribute it and/or modify
   9   it under the terms of version 2 of the GNU General Public License
  10   as published by the Free Software Foundation.
  11
  12   This program is distributed in the hope that it will be useful,
  13   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15   GNU General Public License (version 2) for more details.
  16
  17   You should have received a copy of the GNU General Public License (version 2)
  18   along with this program; if not, write to the Free Software Foundation,
  19   Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  20
  21 */
  22
  23 #include <math.h>
  24
  25 #include "globals.h"
  26 #include "filter_parameters.h"
  27
  28 void FilterParams::init(
  29   float sample_rate,
  30   unsigned char Ptype_,
  31   unsigned char Pfreq_,
  32   unsigned  char Pq_)
  33 {
  34   m_sample_rate = sample_rate;
  35
  36   Dtype=Ptype_;
  37   Dfreq=Pfreq_;
  38   Dq=Pq_;
  39
  40   defaults();
  41 }
  42
  43 void FilterParams::defaults(){
  44   Ptype=Dtype;
  45   Pfreq=Dfreq;
  46   Pq=Dq;
  47
  48   m_additional_stages = 0;
  49   m_frequency_tracking = 0;
  50   m_gain = 0;
  51   m_category = ZYN_FILTER_TYPE_ANALOG;
  52
  53   Pnumformants=3;
  54   Pformantslowness=64;
  55   for (int j=0;j<FF_MAX_VOWELS;j++){
  56     defaults(j);
  57   };
  58
  59   Psequencesize=3;
  60   for (int i=0;i<FF_MAX_SEQUENCE;i++) Psequence[i].nvowel=i%FF_MAX_VOWELS;
  61
  62   Psequencestretch=40;
  63   Psequencereversed=0;
  64   Pcenterfreq=64;//1 kHz
  65   Poctavesfreq=64;
  66   Pvowelclearness=64;
  67 };
  68
  69 void FilterParams::defaults(int n){
  70   int j=n;
  71   for (int i=0;i<FF_MAX_FORMANTS;i++){
  72     Pvowels[j].formants[i].freq=(int)(RND*127.0);//some random freqs
  73     Pvowels[j].formants[i].q=64;
  74     Pvowels[j].formants[i].amp=127;
  75   };
  76 };
  77
  78 /*
  79  * Parameter control
  80  */
  81 REALTYPE FilterParams::getfreq(){
  82   return((Pfreq/64.0-1.0)*5.0);
  83 };
  84
  85 REALTYPE FilterParams::getq(){
  86   return(exp(pow((REALTYPE) Pq/127.0,2)*log(1000.0))-0.9);
  87 };
  88 REALTYPE FilterParams::getfreqtracking(REALTYPE notefreq)
  89 {
  90   return log(notefreq / 440.0) * m_frequency_tracking / LOG_2;
  91 };
  92
  93 /*
  94  * Get the center frequency of the formant's graph
  95  */
  96 REALTYPE FilterParams::getcenterfreq(){
  97   return(10000.0*pow(10,-(1.0-Pcenterfreq/127.0)*2.0));
  98 };
  99
 100 /*
 101  * Get the number of octave that the formant functions applies to
 102  */
 103 REALTYPE FilterParams::getoctavesfreq(){
 104   return(0.25+10.0*Poctavesfreq/127.0);
 105 };
 106
 107 /*
 108  * Get the frequency from x, where x is [0..1]
 109  */
 110 REALTYPE FilterParams::getfreqx(REALTYPE x){
 111   if (x>1.0) x=1.0;
 112   REALTYPE octf=pow(2.0,getoctavesfreq());
 113   return(getcenterfreq()/sqrt(octf)*pow(octf,x));
 114 };
 115
 116 /*
 117  * Get the x coordinate from frequency (used by the UI)
 118  */
 119 REALTYPE FilterParams::getfreqpos(REALTYPE freq){
 120   return((log(freq)-log(getfreqx(0.0)))/log(2.0)/getoctavesfreq());
 121 };
 122
 123
 124 /*
 125  * Get the freq. response of the formant filter
 126  */
 127 void FilterParams::formantfilterH(int nvowel,int nfreqs,REALTYPE *freqs)
 128 {
 129   REALTYPE c[3],d[3];
 130   REALTYPE filter_freq,filter_q,filter_amp;
 131   REALTYPE omega,sn,cs,alpha;
 132
 133   for (int i=0;i<nfreqs;i++) freqs[i]=0.0;
 134
 135   //for each formant...
 136   for (int nformant=0;nformant<Pnumformants;nformant++)
 137   {
 138     //compute formant parameters(frequency,amplitude,etc.)
 139     filter_freq=getformantfreq(Pvowels[nvowel].formants[nformant].freq);
 140     filter_q=getformantq(Pvowels[nvowel].formants[nformant].q)*getq();
 141
 142     if (m_additional_stages > 0)
 143     {
 144       filter_q = (filter_q > 1.0 ? pow(filter_q, 1.0 / (m_additional_stages + 1)) : filter_q);
 145     }
 146
 147     filter_amp=getformantamp(Pvowels[nvowel].formants[nformant].amp);
 148
 149
 150     if (filter_freq <= (m_sample_rate / 2 - 100.0))
 151     {
 152       omega = 2 * PI * filter_freq / m_sample_rate;
 153       sn=sin(omega);
 154       cs=cos(omega);
 155       alpha=sn/(2*filter_q);
 156       REALTYPE tmp=1+alpha;
 157       c[0]=alpha/tmp*sqrt(filter_q+1);
 158       c[1]=0;
 159       c[2]=-alpha/tmp*sqrt(filter_q+1);
 160       d[1]=-2*cs/tmp*(-1);
 161       d[2]=(1-alpha)/tmp*(-1);
 162     }
 163     else
 164     {
 165       continue;
 166     }
 167
 168     for (int i=0;i<nfreqs;i++) {
 169       REALTYPE freq=getfreqx(i/(REALTYPE) nfreqs);
 170
 171       if (freq > m_sample_rate / 2)
 172       {
 173         for (int tmp = i ; tmp < nfreqs ; tmp++)
 174         {
 175           freqs[tmp] = 0.0;
 176         }
 177
 178         break;
 179       }
 180
 181       REALTYPE fr = freq / m_sample_rate * PI * 2.0;
 182       REALTYPE x=c[0],y=0.0;
 183       for (int n=1;n<3;n++){
 184         x+=cos(n*fr)*c[n];
 185         y-=sin(n*fr)*c[n];
 186       };
 187       REALTYPE h=x*x+y*y;
 188       x=1.0;y=0.0;
 189       for (int n=1;n<3;n++){
 190         x-=cos(n*fr)*d[n];
 191         y+=sin(n*fr)*d[n];
 192       };
 193       h=h/(x*x+y*y);
 194
 195       freqs[i] += pow(h, (m_additional_stages + 1.0) / 2.0) * filter_amp;
 196     };
 197   };
 198   for (int i=0;i<nfreqs;i++) {
 199     if (freqs[i]>0.000000001) freqs[i]=rap2dB(freqs[i]) + m_gain;
 200     else freqs[i]=-90.0;
 201   };
 202
 203 };
 204
 205 /*
 206  * Transforms a parameter to the real value
 207  */
 208 REALTYPE FilterParams::getformantfreq(unsigned char freq){
 209   REALTYPE result=getfreqx(freq/127.0);
 210   return(result);
 211 };
 212
 213 REALTYPE FilterParams::getformantamp(unsigned char amp){
 214   REALTYPE result=pow(0.1,(1.0-amp/127.0)*4.0);
 215   return(result);
 216 };
 217
 218 REALTYPE FilterParams::getformantq(unsigned char q){
 219   //temp
 220   REALTYPE result=pow(25.0,(q-32.0)/64.0);
 221   return(result);
 222 };