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/*
Copyright (C) 2005-2009 Michel de Boer <michel@twinklephone.com>
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 2 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 <https://www.gnu.org/licenses/>.
*/
#include "freq_gen.h"
#include <iostream>
#include <cassert>
#include <cmath>
#include "rtp_telephone_event.h"
#define PI 3.141592653589793
t_freq_gen::t_freq_gen(vector<uint16> frequencies, int8 db_level) {
assert(frequencies.size() > 0);
assert(db_level <= 0);
_frequencies = frequencies;
// dB = 20 * log(amplitude / 32768)
// 32767 is used below as +32768 does not fit in 16 bits
_amplitude = int16(pow(10.0, db_level / 20.0) * 32767 / _frequencies.size());
}
t_freq_gen::t_freq_gen(t_dtmf_ev dtmf, int8 db_level) : _frequencies(2)
{
assert(db_level <= 0);
switch (dtmf) {
case TEL_EV_DTMF_1:
_frequencies[0] = 697;
_frequencies[1] = 1209;
break;
case TEL_EV_DTMF_2:
_frequencies[0] = 697;
_frequencies[1] = 1336;
break;
case TEL_EV_DTMF_3:
_frequencies[0] = 697;
_frequencies[1] = 1477;
break;
case TEL_EV_DTMF_A:
_frequencies[0] = 697;
_frequencies[1] = 1633;
break;
case TEL_EV_DTMF_4:
_frequencies[0] = 770;
_frequencies[1] = 1209;
break;
case TEL_EV_DTMF_5:
_frequencies[0] = 770;
_frequencies[1] = 1336;
break;
case TEL_EV_DTMF_6:
_frequencies[0] = 770;
_frequencies[1] = 1477;
break;
case TEL_EV_DTMF_B:
_frequencies[0] = 770;
_frequencies[1] = 1633;
break;
case TEL_EV_DTMF_7:
_frequencies[0] = 852;
_frequencies[1] = 1209;
break;
case TEL_EV_DTMF_8:
_frequencies[0] = 852;
_frequencies[1] = 1336;
break;
case TEL_EV_DTMF_9:
_frequencies[0] = 852;
_frequencies[1] = 1477;
break;
case TEL_EV_DTMF_C:
_frequencies[0] = 852;
_frequencies[1] = 1633;
break;
case TEL_EV_DTMF_STAR:
_frequencies[0] = 941;
_frequencies[1] = 1209;
break;
case TEL_EV_DTMF_0:
_frequencies[0] = 941;
_frequencies[1] = 1336;
break;
case TEL_EV_DTMF_POUND:
_frequencies[0] = 941;
_frequencies[1] = 1477;
break;
case TEL_EV_DTMF_D:
_frequencies[0] = 941;
_frequencies[1] = 1633;
break;
default:
assert(false);
_frequencies.clear();
}
// dB = 20 * log(amplitude / 32768)
// 32767 is used below as +32768 does not fit in 16 bits
_amplitude = int16(pow(10.0, db_level / 20.0) * 32767 / _frequencies.size());
}
int16 t_freq_gen::get_sample(uint32 ts_usec) const {
double freq_sum = 0.0;
for (vector<uint16>::const_iterator f = _frequencies.begin();
f != _frequencies.end(); f++)
{
freq_sum += sin(*f * 2.0 * PI * (double)ts_usec / 1000000.0);
}
return (int16)(_amplitude * freq_sum);
}
void t_freq_gen::get_samples(int16 *sample_buf, uint16 buf_len,
uint32 ts_start, double interval) const
{
for (uint16 i = 0; i < buf_len; i++) {
sample_buf[i] = get_sample(uint32(ts_start + interval * i));
}
}
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