Add DTMF coder to common part

pull/1/head
Andreas Eversberg 7 years ago
parent 3bee5e728a
commit 4ab1cd5026
  1. 1
      src/common/Makefile.am
  2. 118
      src/common/dtmf.c
  3. 14
      src/common/dtmf.h

@ -10,6 +10,7 @@ libcommon_a_SOURCES = \
../common/jitter.c \
../common/loss.c \
../common/filter.c \
../common/dtmf.c \
../common/samplerate.c \
../common/call.c \
../common/freiton.c \

@ -0,0 +1,118 @@
/* DTMF coder
*
* (C) 2016 by Andreas Eversberg <jolly@eversberg.eu>
* All Rights Reserved
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdint.h>
#include <string.h>
#include <math.h>
#include "dtmf.h"
#define PI M_PI
#define TX_PEAK_DTMF 7000 /* single dtmf tone peak (note this is half to total peak) */
#define DTMF_DURATION 0.100 /* duration in seconds */
int dsp_sine_dtmf[256];
void dtmf_init(dtmf_t *dtmf, int samplerate)
{
int i;
memset(dtmf, 0, sizeof(*dtmf));
dtmf->samplerate = samplerate;
dtmf->max = (int)((double)samplerate * DTMF_DURATION + 0.5);
// FIXME: do this globally and not per instance */
for (i = 0; i < 256; i++)
dsp_sine_dtmf[i] = (int)(sin((double)i / 256.0 * 2.0 * PI) * TX_PEAK_DTMF);
}
/* set dtmf tone */
void dtmf_set_tone(dtmf_t *dtmf, char tone)
{
double f1, f2;
switch(tone) {
case '1': f1 = 697.0; f2 = 1209.0; break;
case '2': f1 = 697.0; f2 = 1336.0; break;
case '3': f1 = 697.0; f2 = 1477.0; break;
case'a':case 'A': f1 = 697.0; f2 = 1633.0; break;
case '4': f1 = 770.0; f2 = 1209.0; break;
case '5': f1 = 770.0; f2 = 1336.0; break;
case '6': f1 = 770.0; f2 = 1477.0; break;
case'b':case 'B': f1 = 770.0; f2 = 1633.0; break;
case '7': f1 = 852.0; f2 = 1209.0; break;
case '8': f1 = 852.0; f2 = 1336.0; break;
case '9': f1 = 852.0; f2 = 1477.0; break;
case'c':case 'C': f1 = 852.0; f2 = 1633.0; break;
case '*': f1 = 941.0; f2 = 1209.0; break;
case '0': f1 = 941.0; f2 = 1336.0; break;
case '#': f1 = 941.0; f2 = 1477.0; break;
case'd':case 'D': f1 = 941.0; f2 = 1633.0; break;
default:
dtmf->tone = 0;
return;
}
dtmf->tone = tone;
dtmf->pos = 0;
dtmf->phaseshift256[0] = 256.0 / ((double)dtmf->samplerate / f1);
dtmf->phaseshift256[1] = 256.0 / ((double)dtmf->samplerate / f2);
}
/* Generate audio stream from DTMF tone. Keep phase for next call of function. */
void dtmf_tone(dtmf_t *dtmf, int16_t *samples, int length)
{
double *phaseshift, *phase;
int i, pos, max;
/* use silence, if no tone */
if (!dtmf->tone) {
memset(samples, 0, length * sizeof(*samples));
return;
}
phaseshift = dtmf->phaseshift256;
phase = dtmf->phase256;
pos = dtmf->pos;
max = dtmf->max;
for (i = 0; i < length; i++) {
*samples++ = dsp_sine_dtmf[((uint8_t)phase[0]) & 0xff]
+ dsp_sine_dtmf[((uint8_t)phase[1]) & 0xff];
phase[0] += phaseshift[0];
if (phase[0] >= 256)
phase[0] -= 256;
phase[1] += phaseshift[1];
if (phase[1] >= 256)
phase[1] -= 256;
/* tone ends */
if (++pos == max) {
dtmf->tone = 0;
break;
}
}
length -= i;
dtmf->pos = pos;
/* if tone ends, fill rest with silence */
if (length)
memset(samples, 0, length * sizeof(*samples));
}

@ -0,0 +1,14 @@
typedef struct dtmf {
int samplerate; /* samplerate */
char tone; /* current tone to be played */
int pos; /* sample counter for tone */
int max; /* max number of samples for tone duration */
double phaseshift256[2]; /* how much the phase of sine wave changes per sample */
double phase256[2]; /* current phase */
} dtmf_t;
void dtmf_init(dtmf_t *dtmf, int samplerate);
void dtmf_set_tone(dtmf_t *dtmf, char tone);
void dtmf_tone(dtmf_t *dtmf, int16_t *samples, int length);
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