src/ptclib/dtmf.cxx

   1 /*
   2  * ----------------------------------------------------------------------------
   3  * "THE BEER-WARE LICENSE" (Revision 42):
   4  * <phk@FreeBSD.org> wrote this file.  As long as you retain this notice you
   5  * can do whatever you want with this stuff. If we meet some day, and you think
   6  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
   7  * ----------------------------------------------------------------------------
   8  *
   9  * Extract DTMF signals from 16 bit PCM audio
  10  *
  11  * Originally written by Poul-Henning Kamp <phk@freebsd.org>
  12  * Made into a C++ class by Roger Hardiman <roger@freebsd.org>, January 2002
  13  *
  14  * $Log$
  15  * Revision 1.18  2007/07/19 08:10:32  csoutheren
  16  * Add detection of CNG
  17  *
  18  * Revision 1.17  2006/12/13 04:56:03  csoutheren
  19  * Applied 1613270 - fixed for dtmfEncoder
  20  * Thanks to Frederic Heem
  21  *
  22  * Revision 1.16  2006/11/11 15:23:37  hfriederich
  23  * Use correct GetSize() to avoid allocation problems
  24  *
  25  * Revision 1.15  2006/10/25 08:18:22  rjongbloed
  26  * Major upgrade of tone generation subsystem.
  27  *
  28  * Revision 1.14  2005/11/30 12:47:41  csoutheren
  29  * Removed tabs, reformatted some code, and changed tags for Doxygen
  30  *
  31  * Revision 1.13  2005/01/25 06:35:27  csoutheren
  32  * Removed warnings under MSVC
  33  *
  34  * Revision 1.12  2004/11/17 10:13:14  csoutheren
  35  * Fixed compilation with gcc 4.0.0
  36  *
  37  * Revision 1.11  2004/09/09 23:50:49  csoutheren
  38  * Fixed problem with duplicate definition of sinetab causing problems
  39  *
  40  * Revision 1.10  2004/09/09 05:23:38  dereksmithies
  41  * Add utility function to report on dtmf characters used.
  42  *
  43  * Revision 1.9  2004/09/09 04:22:46  csoutheren
  44  * Added sine table for DTMF encoder
  45  *
  46  * Revision 1.8  2004/09/09 04:00:01  csoutheren
  47  * Added DTMF encoding functions
  48  *
  49  * Revision 1.7  2003/03/17 07:39:25  robertj
  50  * Fixed possible invalid value causing DTMF detector to crash.
  51  *
  52  * Revision 1.6  2002/02/20 02:59:34  yurik
  53  * Added end of line to trace statement
  54  *
  55  * Revision 1.5  2002/02/12 10:21:56  rogerh
  56  * Stop sending '?' when a bad DTMF tone is detected.
  57  *
  58  * Revision 1.4  2002/01/24 11:14:45  rogerh
  59  * Back out robert's change. It did not work (no sign extending)
  60  * and replace it with a better solution which should be happy on both big
  61  * endian and little endian systems.
  62  *
  63  * Revision 1.3  2002/01/24 10:40:17  rogerh
  64  * Add version log
  65  *
  66  *
  67  */
  68
  69 #ifdef __GNUC__
  70 #pragma implementation "dtmf.h"
  71 #endif
  72
  73 #include <ptlib.h>
  74 #include <ptclib/dtmf.h>
  75
  76 #include <math.h>
  77
  78 /* Integer math scaling factor */
  79 #define FSC (1<<12)
  80
  81 /* This is the Q of the filter (pole radius) */
  82 #define POLRAD .99
  83
  84 #define P2 ((int)(POLRAD*POLRAD*FSC))
  85
  86
  87
  88 PDTMFDecoder::PDTMFDecoder()
  89 {
  90   // Initialise the class
  91   int i,kk;
  92   for (kk = 0; kk < NumTones; kk++) {
  93     y[kk] = h[kk] = k[kk] = 0;
  94   }
  95
  96   nn = 0;
  97   ia = 0;
  98   so = 0;
  99
 100   for (i = 0; i < 256; i++) {
 101     key[i] = '?';
 102   }
 103
 104   /* We encode the tones in 8 bits, translate those to symbol */
 105   key[0x11] = '1'; key[0x12] = '4'; key[0x14] = '7'; key[0x18] = '*';
 106   key[0x21] = '2'; key[0x22] = '5'; key[0x24] = '8'; key[0x28] = '0';
 107   key[0x41] = '3'; key[0x42] = '6'; key[0x44] = '9'; key[0x48] = '#';
 108   key[0x81] = 'A'; key[0x82] = 'B'; key[0x84] = 'C'; key[0x88] = 'D';
 109
 110   /* The frequencies we're trying to detect */
 111   /* These are precalculated to save processing power */
 112   /* static int dtmf[9] = {697, 770, 852, 941, 1209, 1336, 1477, 1633, 1100}; */
 113   /* p1[kk] = (-cos(2 * 3.141592 * dtmf[kk] / 8000.0) * FSC) */
 114   p1[0] = -3497; p1[1] = -3369; p1[2] = -3212; p1[3] = -3027;
 115   p1[4] = -2384; p1[5] = -2040; p1[6] = -1635; p1[7] = -1164;
 116   p1[9] = -2660;
 117 }
 118
 119
 120 PString PDTMFDecoder::Decode(const short * sampleData, PINDEX numSamples)
 121 {
 122   int x;
 123   int s, kk;
 124   int c, d, f, n;
 125
 126   PString keyString;
 127
 128   PINDEX pos;
 129   for (pos = 0; pos < numSamples; pos++) {
 130
 131     /* Read (and scale) the next 16 bit sample */
 132     x = ((int)(*sampleData++)) / (32768/FSC);
 133
 134     /* Input amplitude */
 135     if (x > 0)
 136       ia += (x - ia) / 128;
 137     else
 138       ia += (-x - ia) / 128;
 139
 140     /* For each tone */
 141     s = 0;
 142     for(kk = 0; kk < NumTones; kk++) {
 143
 144       /* Turn the crank */
 145       c = (P2 * (x - k[kk])) / FSC;
 146       d = x + c;
 147       f = (p1[kk] * (d - h[kk])) / FSC;
 148       n = x - k[kk] - c;
 149       k[kk] = h[kk] + f;
 150       h[kk] = f + d;
 151
 152       /* Detect and Average */
 153       if (n > 0)
 154         y[kk] += (n - y[kk]) / 64;
 155       else
 156         y[kk] += (-n - y[kk]) / 64;
 157
 158       /* Threshold */
 159       if (y[kk] > FSC/10 && y[kk] > ia) {
 160         if (kk < 8)
 161           s |= 1 << kk;
 162         else if (kk == 8)
 163           s = 0x100;
 164       }
 165     }
 166
 167     /* Hysteresis and noise supressor */
 168     if (s != so) {
 169       nn = 0;
 170       so = s;
 171     } else if (nn++ == 520) {
 172       if (s < 256) {
 173         if (key[s] != '?') {
 174           PTRACE(3,"DTMF\tDetected '" << key[s] << "' in PCM-16 stream");
 175           keyString += key[s];
 176         }
 177       }
 178       else if (s == 0x100) {
 179         PTRACE(3,"DTMF\tDetected CNG in PCM-16 stream");
 180         keyString += 'X';
 181       }
 182     }
 183   }
 184   return keyString;
 185 }
 186
 187 ////////////////////////////////////////////////////////////////////////////////////////////
 188
 189 static int sine(int angle)
 190 {
 191   static int sinArray[PTones::MaxFrequency] = {
 192     0,0,1,2,3,3,4,5,6,7,7,8,9,10,10,11,12,13,14,14,15,16,17,18,18,19,20,21,21,22,
 193     23,24,25,25,26,27,28,29,29,30,31,32,32,33,34,35,36,36,37,38,39,40,40,41,42,43,43,44,45,46,
 194     47,47,48,49,50,51,51,52,53,54,54,55,56,57,58,58,59,60,61,62,62,63,64,65,65,66,67,68,69,69,
 195     70,71,72,72,73,74,75,76,76,77,78,79,80,80,81,82,83,83,84,85,86,87,87,88,89,90,90,91,92,93,
 196     94,94,95,96,97,98,98,99,100,101,101,102,103,104,105,105,106,107,108,108,109,110,111,112,112,113,114,115,115,116,
 197     117,118,119,119,120,121,122,122,123,124,125,126,126,127,128,129,130,130,131,132,133,133,134,135,136,137,137,138,139,140,
 198     140,141,142,143,144,144,145,146,147,147,148,149,150,151,151,152,153,154,154,155,156,157,157,158,159,160,161,161,162,163,
 199     164,164,165,166,167,168,168,169,170,171,171,172,173,174,175,175,176,177,178,178,179,180,181,181,182,183,184,185,185,186,
 200     187,188,188,189,190,191,192,192,193,194,195,195,196,197,198,198,199,200,201,202,202,203,204,205,205,206,207,208,208,209,
 201     210,211,212,212,213,214,215,215,216,217,218,218,219,220,221,221,222,223,224,225,225,226,227,228,228,229,230,231,231,232,
 202     233,234,234,235,236,237,238,238,239,240,241,241,242,243,244,244,245,246,247,247,248,249,250,250,251,252,253,254,254,255,
 203     256,257,257,258,259,260,260,261,262,263,263,264,265,266,266,267,268,269,269,270,271,272,272,273,274,275,275,276,277,278,
 204     278,279,280,281,282,282,283,284,285,285,286,287,288,288,289,290,291,291,292,293,294,294,295,296,297,297,298,299,300,300,
 205     301,302,303,303,304,305,306,306,307,308,309,309,310,311,312,312,313,314,314,315,316,317,317,318,319,320,320,321,322,323,
 206     323,324,325,326,326,327,328,329,329,330,331,332,332,333,334,335,335,336,337,337,338,339,340,340,341,342,343,343,344,345,
 207     346,346,347,348,349,349,350,351,352,352,353,354,354,355,356,357,357,358,359,360,360,361,362,363,363,364,365,365,366,367,
 208     368,368,369,370,371,371,372,373,373,374,375,376,376,377,378,379,379,380,381,381,382,383,384,384,385,386,387,387,388,389,
 209     389,390,391,392,392,393,394,394,395,396,397,397,398,399,400,400,401,402,402,403,404,405,405,406,407,407,408,409,410,410,
 210     411,412,412,413,414,415,415,416,417,417,418,419,420,420,421,422,422,423,424,425,425,426,427,427,428,429,430,430,431,432,
 211     432,433,434,434,435,436,437,437,438,439,439,440,441,442,442,443,444,444,445,446,446,447,448,449,449,450,451,451,452,453,
 212     453,454,455,456,456,457,458,458,459,460,460,461,462,463,463,464,465,465,466,467,467,468,469,470,470,471,472,472,473,474,
 213     474,475,476,476,477,478,478,479,480,481,481,482,483,483,484,485,485,486,487,487,488,489,489,490,491,492,492,493,494,494,
 214     495,496,496,497,498,498,499,500,500,501,502,502,503,504,504,505,506,507,507,508,509,509,510,511,511,512,513,513,514,515,
 215     515,516,517,517,518,519,519,520,521,521,522,523,523,524,525,525,526,527,527,528,529,529,530,531,531,532,533,533,534,535,
 216     535,536,537,537,538,539,539,540,541,541,542,543,543,544,545,545,546,547,547,548,549,549,550,550,551,552,552,553,554,554,
 217     555,556,556,557,558,558,559,560,560,561,562,562,563,564,564,565,565,566,567,567,568,569,569,570,571,571,572,573,573,574,
 218     575,575,576,576,577,578,578,579,580,580,581,582,582,583,583,584,585,585,586,587,587,588,589,589,590,590,591,592,592,593,
 219     594,594,595,596,596,597,597,598,599,599,600,601,601,602,602,603,604,604,605,606,606,607,607,608,609,609,610,611,611,612,
 220     612,613,614,614,615,616,616,617,617,618,619,619,620,620,621,622,622,623,624,624,625,625,626,627,627,628,628,629,630,630,
 221     631,631,632,633,633,634,635,635,636,636,637,638,638,639,639,640,641,641,642,642,643,644,644,645,645,646,647,647,648,648,
 222     649,650,650,651,651,652,653,653,654,654,655,655,656,657,657,658,658,659,660,660,661,661,662,663,663,664,664,665,666,666,
 223     667,667,668,668,669,670,670,671,671,672,673,673,674,674,675,675,676,677,677,678,678,679,679,680,681,681,682,682,683,683,
 224     684,685,685,686,686,687,687,688,689,689,690,690,691,691,692,693,693,694,694,695,695,696,697,697,698,698,699,699,700,700,
 225     701,702,702,703,703,704,704,705,705,706,707,707,708,708,709,709,710,710,711,712,712,713,713,714,714,715,715,716,717,717,
 226     718,718,719,719,720,720,721,721,722,723,723,724,724,725,725,726,726,727,727,728,728,729,730,730,731,731,732,732,733,733,
 227     734,734,735,735,736,736,737,738,738,739,739,740,740,741,741,742,742,743,743,744,744,745,745,746,746,747,748,748,749,749,
 228     750,750,751,751,752,752,753,753,754,754,755,755,756,756,757,757,758,758,759,759,760,760,761,761,762,762,763,763,764,764,
 229     765,765,766,766,767,768,768,769,769,770,770,771,771,772,772,773,773,774,774,774,775,775,776,776,777,777,778,778,779,779,
 230     780,780,781,781,782,782,783,783,784,784,785,785,786,786,787,787,788,788,789,789,790,790,791,791,792,792,793,793,793,794,
 231     794,795,795,796,796,797,797,798,798,799,799,800,800,801,801,802,802,802,803,803,804,804,805,805,806,806,807,807,808,808,
 232     809,809,809,810,810,811,811,812,812,813,813,814,814,814,815,815,816,816,817,817,818,818,819,819,819,820,820,821,821,822,
 233     822,823,823,823,824,824,825,825,826,826,827,827,827,828,828,829,829,830,830,831,831,831,832,832,833,833,834,834,834,835,
 234     835,836,836,837,837,837,838,838,839,839,840,840,840,841,841,842,842,843,843,843,844,844,845,845,846,846,846,847,847,848,
 235     848,848,849,849,850,850,850,851,851,852,852,853,853,853,854,854,855,855,855,856,856,857,857,857,858,858,859,859,859,860,
 236     860,861,861,861,862,862,863,863,863,864,864,865,865,865,866,866,867,867,867,868,868,869,869,869,870,870,870,871,871,872,
 237     872,872,873,873,874,874,874,875,875,875,876,876,877,877,877,878,878,878,879,879,880,880,880,881,881,881,882,882,883,883,
 238     883,884,884,884,885,885,885,886,886,887,887,887,888,888,888,889,889,889,890,890,891,891,891,892,892,892,893,893,893,894,
 239     894,894,895,895,895,896,896,896,897,897,898,898,898,899,899,899,900,900,900,901,901,901,902,902,902,903,903,903,904,904,
 240     904,905,905,905,906,906,906,907,907,907,908,908,908,909,909,909,910,910,910,911,911,911,912,912,912,913,913,913,913,914,
 241     914,914,915,915,915,916,916,916,917,917,917,918,918,918,918,919,919,919,920,920,920,921,921,921,922,922,922,922,923,923,
 242     923,924,924,924,925,925,925,925,926,926,926,927,927,927,928,928,928,928,929,929,929,930,930,930,930,931,931,931,932,932,
 243     932,932,933,933,933,934,934,934,934,935,935,935,935,936,936,936,937,937,937,937,938,938,938,939,939,939,939,940,940,940,
 244     940,941,941,941,941,942,942,942,942,943,943,943,944,944,944,944,945,945,945,945,946,946,946,946,947,947,947,947,948,948,
 245     948,948,949,949,949,949,950,950,950,950,951,951,951,951,952,952,952,952,952,953,953,953,953,954,954,954,954,955,955,955,
 246     955,956,956,956,956,956,957,957,957,957,958,958,958,958,958,959,959,959,959,960,960,960,960,960,961,961,961,961,962,962,
 247     962,962,962,963,963,963,963,963,964,964,964,964,964,965,965,965,965,965,966,966,966,966,967,967,967,967,967,967,968,968,
 248     968,968,968,969,969,969,969,969,970,970,970,970,970,971,971,971,971,971,972,972,972,972,972,972,973,973,973,973,973,973,
 249     974,974,974,974,974,975,975,975,975,975,975,976,976,976,976,976,976,977,977,977,977,977,977,978,978,978,978,978,978,979,
 250     979,979,979,979,979,980,980,980,980,980,980,980,981,981,981,981,981,981,981,982,982,982,982,982,982,983,983,983,983,983,
 251     983,983,984,984,984,984,984,984,984,984,985,985,985,985,985,985,985,986,986,986,986,986,986,986,986,987,987,987,987,987,
 252     987,987,987,988,988,988,988,988,988,988,988,989,989,989,989,989,989,989,989,989,990,990,990,990,990,990,990,990,990,990,
 253     991,991,991,991,991,991,991,991,991,992,992,992,992,992,992,992,992,992,992,992,993,993,993,993,993,993,993,993,993,993,
 254     993,994,994,994,994,994,994,994,994,994,994,994,994,995,995,995,995,995,995,995,995,995,995,995,995,995,995,996,996,996,
 255     996,996,996,996,996,996,996,996,996,996,996,996,997,997,997,997,997,997,997,997,997,997,997,997,997,997,997,997,997,997,
 256     998,998,998,998,998,998,998,998,998,998,998,998,998,998,998,998,998,998,998,998,998,998,998,998,999,999,999,999,999,999,
 257     999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,
 258     999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999
 259   };
 260
 261   int quadrant = angle / PTones::MaxFrequency;
 262   int offset   = angle % PTones::MaxFrequency;
 263
 264   switch (quadrant) {
 265     case 0:
 266       return sinArray[offset];
 267     case 1:
 268       return sinArray[PTones::MaxFrequency-1-offset];
 269     case 2:
 270       return -sinArray[offset];
 271     default:
 272       return -sinArray[PTones::MaxFrequency-1-offset];
 273   }
 274 }
 275
 276
 277 ////////////////////////////////////////////////////////////////////////
 278
 279
 280 PTones::PTones(unsigned volume):
 281   PShortArray(),
 282   masterVolume(volume),
 283   lastOperation(0),
 284   lastFrequency1(0),
 285   lastFrequency2(0),
 286   angle1(0),
 287   angle2(0)
 288 {
 289 }
 290
 291
 292 PTones::PTones(const PString & descriptor, unsigned volume)
 293   : masterVolume(volume)
 294 {
 295   if (!Generate(descriptor)) {
 296     PTRACE(1,"DTMF\tCannot encode tone \"" << descriptor << '"');
 297   }
 298 }
 299
 300
 301 bool PTones::Generate(const PString & descriptor)
 302 {
 303   PStringArray toneChunks = descriptor.Tokenise('/');
 304   if (toneChunks.IsEmpty())
 305     return false;
 306
 307   for (PINDEX chunk = 0; chunk < toneChunks.GetSize(); chunk++) {
 308     // split frequency and cadence
 309     PINDEX pos = toneChunks[chunk].Find(':');
 310     if (pos == P_MAX_INDEX)
 311       return false;
 312
 313     PString frequencyStr = toneChunks[chunk].Left(pos).Trim();
 314     PString cadenceStr = toneChunks[chunk].Mid(pos+1).Trim();
 315
 316     if (cadenceStr.IsEmpty())
 317       return false;
 318
 319     // Do we have a volume?
 320     unsigned volume = 100;
 321     if ((pos = frequencyStr.Find('%')) != P_MAX_INDEX) {
 322         volume = frequencyStr.Left(pos).AsUnsigned();
 323         if (volume < 1 || volume > 100)
 324           return false;
 325         frequencyStr.Delete(0, pos+1);
 326     }
 327
 328     if (frequencyStr.IsEmpty())
 329       return false;
 330
 331     // Parse the frequencies
 332     unsigned frequency1, frequency2;
 333     char operation;
 334     if ((pos =  frequencyStr.FindOneOf("+-x")) != P_MAX_INDEX) {
 335       frequency1 = frequencyStr.Left(pos).AsUnsigned();
 336       frequency2 = frequencyStr.Mid(pos+1).AsUnsigned();
 337       operation = frequencyStr[pos];
 338     }
 339     else {
 340       frequency1 = frequency2 = frequencyStr.AsUnsigned();
 341       operation = '-';
 342     }
 343
 344     // Parse the cadence
 345     double duration = cadenceStr.AsReal();
 346
 347     // First one
 348     if (!Generate(operation, frequency1, frequency2, (unsigned)(duration*1000), volume))
 349       return false;
 350
 351     char originalOperation = operation;
 352     operation = ' ';
 353
 354     pos = 0;
 355     while ((pos = cadenceStr.Find('-', pos)) != P_MAX_INDEX) {
 356       duration = cadenceStr.Mid(++pos).AsReal();
 357       if (duration < 0 || duration > 60)
 358         return false;
 359
 360       if (!Generate(operation, frequency1, frequency2, (unsigned)(duration*1000), volume))
 361         return false;
 362
 363       // Alternate between the tone and silence
 364       operation = operation == ' ' ? originalOperation : ' ';
 365     }
 366   }
 367
 368   return true;
 369 }
 370
 371
 372 bool PTones::Generate(char operation, unsigned frequency1, unsigned frequency2, unsigned milliseconds, unsigned volume)
 373 {
 374   if (lastOperation  != operation  ||
 375       lastFrequency1 != frequency1 ||
 376       lastFrequency2 != frequency2) {
 377     lastOperation  = operation;
 378     lastFrequency1 = frequency1;
 379     lastFrequency2 = frequency2;
 380
 381     angle1 = 0;
 382     angle2 = 0;
 383   }
 384
 385   switch (operation) {
 386     case '+':
 387       return Juxtapose(frequency1, frequency2, milliseconds, volume);
 388
 389     case 'x':
 390       return Modulate(frequency1, frequency2, milliseconds, volume);
 391
 392     case '-':
 393       return PureTone(frequency1, milliseconds, volume);
 394
 395     case ' ':
 396       return Silence(milliseconds);
 397   }
 398
 399   return false;
 400 }
 401
 402
 403 bool PTones::Juxtapose(unsigned frequency1, unsigned frequency2, unsigned milliseconds, unsigned volume)
 404 {
 405   if (frequency1 < MinFrequency || frequency1 > MaxFrequency ||
 406       frequency2 < MinFrequency || frequency2 > MaxFrequency)
 407     return false;
 408
 409   // TODO this gived 8000 samples for 100 ms !!!
 410   //unsigned samples = CalcSamples(milliseconds, frequency1, frequency2);
 411   unsigned samples = milliseconds * SampleRate / 1000;
 412   while (samples-- > 0) {
 413     int a1 = sine(angle1);
 414     int a2 = sine(angle2);
 415
 416     AddSample((a1 + a2) / 2, volume);
 417
 418     angle1 += frequency1;
 419     if (angle1 >= SampleRate)
 420       angle1 -= SampleRate;
 421
 422     angle2 += frequency2;
 423     if (angle2 >= SampleRate)
 424       angle2 -= SampleRate;
 425   }
 426   return true;
 427 }
 428
 429
 430 bool PTones::Modulate(unsigned frequency1, unsigned modulator, unsigned milliseconds, unsigned volume)
 431 {
 432   if (frequency1 < MinFrequency || frequency1 > MaxFrequency || modulator < MinModulation || modulator >= frequency1/2)
 433     return false;
 434
 435   unsigned samples = CalcSamples(milliseconds, frequency1, modulator);
 436
 437   while (samples-- > 0) {
 438     int a1 = sine(angle1);   // -999 to 999
 439     int a2 = sine(angle2);   // -999 to 999
 440
 441     AddSample((a1 * (a2 + SineScale)) / SineScale / 2, volume);
 442
 443     angle1 += frequency1;
 444     if (angle1 >= SampleRate)
 445       angle1 -= SampleRate;
 446
 447     angle2 += modulator;
 448     if (angle2 >= SampleRate)
 449       angle2 -= SampleRate;
 450   }
 451   return true;
 452 }
 453
 454
 455 bool PTones::PureTone(unsigned frequency1, unsigned milliseconds, unsigned volume)
 456 {
 457   if (frequency1 < MinFrequency || frequency1 > MaxFrequency)
 458     return false;
 459
 460   unsigned samples = CalcSamples(milliseconds, frequency1);
 461   while (samples-- > 0) {
 462     AddSample(sine(angle1), volume);
 463
 464     angle1 += frequency1;
 465     if (angle1 >= SampleRate)
 466       angle1 -= SampleRate;
 467   }
 468   return true;
 469 }
 470
 471
 472 bool PTones::Silence(unsigned milliseconds)
 473 {
 474   unsigned samples = milliseconds * SampleRate/1000;
 475   while (samples-- > 0)
 476     AddSample(0, 0);
 477   return true;
 478 }
 479
 480
 481 unsigned PTones::CalcSamples(unsigned ms, unsigned f1, unsigned f2)
 482 {
 483   // firstly, find the minimum time to repeat the waveform
 484   unsigned v1 = 1;
 485   unsigned v2 = 1;
 486
 487   if (f2 > 0)
 488   {
 489       while (v1*f2 != v2*f1) {
 490         if (v1*f2 < v2*f1)
 491           v1++;
 492         else
 493           v2++;
 494       }
 495   }
 496
 497   // v1 repetitions of f1 == v2 repetitions of f2
 498   //cout << v1 << " cycles of " << f1 << "hz = " << v2 << " samples of " << f2 << "hz" << endl;
 499
 500   // now find the number of times we need to repeat this to match the sampling rate
 501   unsigned n1 = 1;
 502   unsigned n2 = 1;
 503   while (n1*SampleRate*v1 != n2*f1) {
 504     if (n1*SampleRate*v1 < n2*f1)
 505       n1++;
 506     else
 507       n2++;
 508   }
 509
 510   // v1 repetitions of t == v2 repetitions sample frequency
 511   //cout << n1*v1 << " cycles at " << f1 << "hz = "
 512   //     << n1*v2 << " cycles at " << f2 << "hz = "
 513   //     << n2    << " samples at " << SampleRate << "hz" << endl;
 514
 515   // Make sure we round up the number of milliseconds to even multiple of cycles
 516   return ms == 0 ? n2 : ((ms * SampleRate/1000 + n2 - 1)/n2*n2);
 517 }
 518
 519
 520 void PTones::AddSample(int sample, unsigned volume)
 521 {
 522   // Sample added is value from -1000 to 1000, rescale to short range -32767 to +32767
 523   PINDEX length = GetSize();
 524   SetSize(length + 1);
 525   sample *= volume;
 526   sample *= masterVolume;
 527   sample /= SineScale*100*100/SHRT_MAX;
 528   SetAt(length, (short)sample);
 529 }
 530
 531
 532 ////////////////////////////////////////////////////////////////////////
 533
 534 PDTMFEncoder::PDTMFEncoder(const char * dtmf, unsigned milliseconds) :
 535    PTones()
 536 {
 537     AddTone(dtmf, milliseconds);
 538 }
 539
 540 PDTMFEncoder::PDTMFEncoder(char digit, unsigned milliseconds) :
 541    PTones()
 542 {
 543   AddTone(digit, milliseconds);
 544 }
 545
 546 void PDTMFEncoder::AddTone(const char * str, unsigned milliseconds)
 547 {
 548   if (str == NULL)
 549       return;
 550
 551   while (*str != '\0')
 552     AddTone(*str++, milliseconds);
 553 }
 554
 555
 556 void PDTMFEncoder::AddTone(char digit, unsigned milliseconds)
 557 {
 558     // DTMF frequencies as per http://www.commlinx.com.au/DTMF_frequencies.htm
 559
 560     static unsigned const dtmfFreqs[16][2] = {
 561       { 941,1336 },  // 0
 562       { 697,1209 },  // 1
 563       { 697,1336 },  // 2
 564       { 697,1477 },  // 3
 565       { 770,1209 },  // 4
 566       { 770,1336 },  // 5
 567       { 770,1477 },  // 6
 568       { 852,1209 },  // 7
 569       { 852,1336 },  // 8
 570       { 852,1477 },  // 9
 571       { 697,1633 },  // A
 572       { 770,1633 },  // B
 573       { 852,1633 },  // C
 574       { 941,1633 },  // D
 575       { 941,1209 },  // *
 576       { 941,1477 }   // #
 577     };
 578
 579   digit = (char)toupper(digit);
 580   PINDEX index;
 581   if ('0' <= digit && digit <= '9')
 582     index = digit - '0';
 583   else if ('A' <= digit && digit <= 'D')
 584     index = digit + 10 - 'A';
 585   else if (digit == '*')
 586     index = 14;
 587   else if (digit == '#')
 588     index = 15;
 589   else
 590     return;
 591
 592   Generate('+', dtmfFreqs[index][0], dtmfFreqs[index][1], milliseconds);
 593 }
 594
 595
 596 void PDTMFEncoder::AddTone(double f1, double f2, unsigned milliseconds)
 597 {
 598   if (f1 > 0 && f1 < MaxFrequency && f2 > 0 && f2 < MaxFrequency){
 599     Generate('+', (unsigned)f1, (unsigned)f2, milliseconds);
 600   } else {
 601     PAssertAlways(PInvalidParameter);
 602   }
 603 }
 604
 605
 606 char PDTMFEncoder::DtmfChar(PINDEX i)
 607 {
 608   PAssert(i < 16, "Only 16 dtmf symbols. Index too large");
 609
 610   static char dtmfSymbols[16] = { '0','1','2','3','4','5','6','7','8','9','A','B','C','D','*','#' };
 611   return dtmfSymbols[i];
 612 }
 613
 614
 615 ////////////////////////////////////////////////////////////////////////////