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freeswitch/libs/libteletone/src/libteletone_detect.c

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/*
* libteletone
* Copyright (C) 2005/2006, Anthony Minessale II <anthmct@yahoo.com>
*
* Version: MPL 1.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is tone_detect.c - General telephony tone detection, and specific detection of DTMF.
*
*
* The Initial Developer of the Original Code is
* Stephen Underwood <steveu@coppice.org>
* Portions created by the Initial Developer are Copyright (C)
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* The the original interface designed by Steve Underwood was preserved to retain
*the optimizations when considering DTMF tones though the names were changed in the interest
* of namespace.
*
* Much less efficient expansion interface was added to allow for the detection of
* a single arbitrary tone combination which may also exceed 2 simultaneous tones.
* (controlled by compile time constant TELETONE_MAX_TONES)
*
* Copyright (C) 2006 Anthony Minessale II <anthmct@yahoo.com>
*
*
* libteletone_detect.c Tone Detection Code
*
*
*********************************************************************************
*
* Derived from tone_detect.c - General telephony tone detection, and specific
* detection of DTMF.
*
* Copyright (C) 2001 Steve Underwood <steveu@coppice.org>
*
* Despite my general liking of the GPL, I place this code in the
* public domain for the benefit of all mankind - even the slimy
* ones who might try to proprietize my work and use it to my
* detriment.
*/
#include <math.h>
#ifndef _MSC_VER
#include <stdint.h>
#endif
#include <string.h>
#include <stdio.h>
#include <time.h>
#include <fcntl.h>
#include <libteletone_detect.h>
static teletone_detection_descriptor_t dtmf_detect_row[GRID_FACTOR];
static teletone_detection_descriptor_t dtmf_detect_col[GRID_FACTOR];
static teletone_detection_descriptor_t dtmf_detect_row_2nd[GRID_FACTOR];
static teletone_detection_descriptor_t dtmf_detect_col_2nd[GRID_FACTOR];
static teletone_process_t dtmf_row[] = {697.0, 770.0, 852.0, 941.0};
static teletone_process_t dtmf_col[] = {1209.0, 1336.0, 1477.0, 1633.0};
static char dtmf_positions[] = "123A" "456B" "789C" "*0#D";
static void goertzel_init(teletone_goertzel_state_t *goertzel_state, teletone_detection_descriptor_t *tdesc) {
goertzel_state->v2 = goertzel_state->v3 = 0.0;
goertzel_state->fac = tdesc->fac;
}
void teletone_goertzel_update(teletone_goertzel_state_t *goertzel_state,
int16_t sample_buffer[],
int samples)
{
int i;
teletone_process_t v1;
for (i = 0; i < samples; i++) {
v1 = goertzel_state->v2;
goertzel_state->v2 = goertzel_state->v3;
goertzel_state->v3 = goertzel_state->fac*goertzel_state->v2 - v1 + sample_buffer[i];
}
}
teletone_process_t teletone_goertzel_result (teletone_goertzel_state_t *goertzel_state)
{
return goertzel_state->v3 * goertzel_state->v3 + goertzel_state->v2 * goertzel_state->v2 - goertzel_state->v2 * goertzel_state->v3 * goertzel_state->fac;
}
void teletone_dtmf_detect_init (teletone_dtmf_detect_state_t *dtmf_detect_state, int sample_rate)
{
int i;
teletone_process_t theta;
dtmf_detect_state->hit1 = dtmf_detect_state->hit2 = 0;
for (i = 0; i < GRID_FACTOR; i++) {
theta = M_TWO_PI*(dtmf_row[i]/(teletone_process_t)sample_rate);
dtmf_detect_row[i].fac = 2.0*cos(theta);
theta = M_TWO_PI*(dtmf_col[i]/(teletone_process_t)sample_rate);
dtmf_detect_col[i].fac = 2.0*cos(theta);
theta = M_TWO_PI*(dtmf_row[i]*2.0/(teletone_process_t)sample_rate);
dtmf_detect_row_2nd[i].fac = 2.0*cos(theta);
theta = M_TWO_PI*(dtmf_col[i]*2.0/(teletone_process_t)sample_rate);
dtmf_detect_col_2nd[i].fac = 2.0*cos(theta);
goertzel_init (&dtmf_detect_state->row_out[i], &dtmf_detect_row[i]);
goertzel_init (&dtmf_detect_state->col_out[i], &dtmf_detect_col[i]);
goertzel_init (&dtmf_detect_state->row_out2nd[i], &dtmf_detect_row_2nd[i]);
goertzel_init (&dtmf_detect_state->col_out2nd[i], &dtmf_detect_col_2nd[i]);
dtmf_detect_state->energy = 0.0;
}
dtmf_detect_state->current_sample = 0;
dtmf_detect_state->detected_digits = 0;
dtmf_detect_state->lost_digits = 0;
dtmf_detect_state->digits[0] = '\0';
dtmf_detect_state->mhit = 0;
}
void teletone_multi_tone_init(teletone_multi_tone_t *mt, teletone_tone_map_t *map)
{
teletone_process_t theta = 0;
int x = 0;
if(!mt->min_samples) {
mt->min_samples = 102;
}
if (!mt->positive_factor) {
mt->positive_factor = 2;
}
if(!mt->negative_factor) {
mt->negative_factor = 10;
}
if (!mt->hit_factor) {
mt->hit_factor = 2;
}
if (!mt->sample_rate) {
mt->sample_rate = 8000;
}
for(x = 0; x < TELETONE_MAX_TONES; x++) {
if ((int) map->freqs[x] == 0) {
break;
}
mt->tone_count++;
theta = M_TWO_PI*(map->freqs[x]/(teletone_process_t)mt->sample_rate);
mt->tdd[x].fac = 2.0 * cos(theta);
goertzel_init (&mt->gs[x], &mt->tdd[x]);
goertzel_init (&mt->gs2[x], &mt->tdd[x]);
}
}
int teletone_multi_tone_detect (teletone_multi_tone_t *mt,
int16_t sample_buffer[],
int samples)
{
int sample, limit, j, x = 0;
teletone_process_t v1, famp;
teletone_process_t eng_sum = 0, eng_all[TELETONE_MAX_TONES];
int gtest = 0, see_hit = 0;
for (sample = 0; sample < samples; sample = limit) {
mt->total_samples++;
if ((samples - sample) >= (mt->min_samples - mt->current_sample)) {
limit = sample + (mt->min_samples - mt->current_sample);
} else {
limit = samples;
}
for (j = sample; j < limit; j++) {
famp = sample_buffer[j];
mt->energy += famp*famp;
for(x = 0; x < mt->tone_count; x++) {
v1 = mt->gs[x].v2;
mt->gs[x].v2 = mt->gs[x].v3;
mt->gs[x].v3 = mt->gs[x].fac * mt->gs[x].v2 - v1 + famp;
v1 = mt->gs2[x].v2;
mt->gs2[x].v2 = mt->gs2[x].v3;
mt->gs2[x].v3 = mt->gs2[x].fac*mt->gs2[x].v2 - v1 + famp;
}
}
mt->current_sample += (limit - sample);
if (mt->current_sample < mt->min_samples) {
continue;
}
eng_sum = 0;
for(x = 0; x < mt->tone_count; x++) {
eng_all[x] = teletone_goertzel_result (&mt->gs[x]);
eng_sum += eng_all[x];
}
gtest = 0;
for(x = 0; x < mt->tone_count; x++) {
gtest += teletone_goertzel_result (&mt->gs2[x]) < eng_all[x] ? 1 : 0;
}
if (gtest >= 2 && eng_sum > 42.0 * mt->energy) {
if(mt->negatives) {
mt->negatives--;
}
mt->positives++;
if(mt->positives >= mt->positive_factor) {
mt->hits++;
}
if (mt->hits >= mt->hit_factor) {
see_hit++;
mt->positives = mt->negatives = mt->hits = 0;
}
} else {
mt->negatives++;
if(mt->positives) {
mt->positives--;
}
if(mt->negatives > mt->negative_factor) {
mt->positives = mt->hits = 0;
}
}
/* Reinitialise the detector for the next block */
for(x = 0; x < mt->tone_count; x++) {
goertzel_init (&mt->gs[x], &mt->tdd[x]);
goertzel_init (&mt->gs2[x], &mt->tdd[x]);
}
mt->energy = 0.0;
mt->current_sample = 0;
}
return see_hit;
}
int teletone_dtmf_detect (teletone_dtmf_detect_state_t *dtmf_detect_state,
int16_t sample_buffer[],
int samples)
{
teletone_process_t row_energy[GRID_FACTOR];
teletone_process_t col_energy[GRID_FACTOR];
teletone_process_t famp;
teletone_process_t v1;
int i;
int j;
int sample;
int best_row;
int best_col;
char hit;
int limit;
hit = 0;
for (sample = 0; sample < samples; sample = limit) {
/* BLOCK_LEN is optimised to meet the DTMF specs. */
if ((samples - sample) >= (BLOCK_LEN - dtmf_detect_state->current_sample)) {
limit = sample + (BLOCK_LEN - dtmf_detect_state->current_sample);
} else {
limit = samples;
}
for (j = sample; j < limit; j++) {
int x = 0;
famp = sample_buffer[j];
dtmf_detect_state->energy += famp*famp;
for(x = 0; x < GRID_FACTOR; x++) {
v1 = dtmf_detect_state->row_out[x].v2;
dtmf_detect_state->row_out[x].v2 = dtmf_detect_state->row_out[x].v3;
dtmf_detect_state->row_out[x].v3 = dtmf_detect_state->row_out[x].fac*dtmf_detect_state->row_out[x].v2 - v1 + famp;
v1 = dtmf_detect_state->col_out[x].v2;
dtmf_detect_state->col_out[x].v2 = dtmf_detect_state->col_out[x].v3;
dtmf_detect_state->col_out[x].v3 = dtmf_detect_state->col_out[x].fac*dtmf_detect_state->col_out[x].v2 - v1 + famp;
v1 = dtmf_detect_state->col_out2nd[x].v2;
dtmf_detect_state->col_out2nd[x].v2 = dtmf_detect_state->col_out2nd[x].v3;
dtmf_detect_state->col_out2nd[x].v3 = dtmf_detect_state->col_out2nd[x].fac*dtmf_detect_state->col_out2nd[x].v2 - v1 + famp;
v1 = dtmf_detect_state->row_out2nd[x].v2;
dtmf_detect_state->row_out2nd[x].v2 = dtmf_detect_state->row_out2nd[x].v3;
dtmf_detect_state->row_out2nd[x].v3 = dtmf_detect_state->row_out2nd[x].fac*dtmf_detect_state->row_out2nd[x].v2 - v1 + famp;
}
}
dtmf_detect_state->current_sample += (limit - sample);
if (dtmf_detect_state->current_sample < BLOCK_LEN) {
continue;
}
/* We are at the end of a DTMF detection block */
/* Find the peak row and the peak column */
row_energy[0] = teletone_goertzel_result (&dtmf_detect_state->row_out[0]);
col_energy[0] = teletone_goertzel_result (&dtmf_detect_state->col_out[0]);
for (best_row = best_col = 0, i = 1; i < GRID_FACTOR; i++) {
row_energy[i] = teletone_goertzel_result (&dtmf_detect_state->row_out[i]);
if (row_energy[i] > row_energy[best_row]) {
best_row = i;
}
col_energy[i] = teletone_goertzel_result (&dtmf_detect_state->col_out[i]);
if (col_energy[i] > col_energy[best_col]) {
best_col = i;
}
}
hit = 0;
/* Basic signal level test and the twist test */
if (row_energy[best_row] >= DTMF_THRESHOLD &&
col_energy[best_col] >= DTMF_THRESHOLD &&
col_energy[best_col] < row_energy[best_row]*DTMF_REVERSE_TWIST &&
col_energy[best_col]*DTMF_NORMAL_TWIST > row_energy[best_row]) {
/* Relative peak test */
for (i = 0; i < GRID_FACTOR; i++) {
if ((i != best_col && col_energy[i]*DTMF_RELATIVE_PEAK_COL > col_energy[best_col]) ||
(i != best_row && row_energy[i]*DTMF_RELATIVE_PEAK_ROW > row_energy[best_row])) {
break;
}
}
/* ... and second harmonic test */
if (i >= GRID_FACTOR && (row_energy[best_row] + col_energy[best_col]) > 42.0*dtmf_detect_state->energy &&
teletone_goertzel_result (&dtmf_detect_state->col_out2nd[best_col])*DTMF_2ND_HARMONIC_COL < col_energy[best_col] &&
teletone_goertzel_result (&dtmf_detect_state->row_out2nd[best_row])*DTMF_2ND_HARMONIC_ROW < row_energy[best_row]) {
hit = dtmf_positions[(best_row << 2) + best_col];
/* Look for two successive similar results */
/* The logic in the next test is:
We need two successive identical clean detects, with
something different preceeding it. This can work with
back to back differing digits. More importantly, it
can work with nasty phones that give a very wobbly start
to a digit. */
if (hit == dtmf_detect_state->hit3 && dtmf_detect_state->hit3 != dtmf_detect_state->hit2) {
dtmf_detect_state->mhit = hit;
dtmf_detect_state->digit_hits[(best_row << 2) + best_col]++;
dtmf_detect_state->detected_digits++;
if (dtmf_detect_state->current_digits < TELETONE_MAX_DTMF_DIGITS) {
dtmf_detect_state->digits[dtmf_detect_state->current_digits++] = hit;
dtmf_detect_state->digits[dtmf_detect_state->current_digits] = '\0';
}
else
{
dtmf_detect_state->lost_digits++;
}
}
}
}
dtmf_detect_state->hit1 = dtmf_detect_state->hit2;
dtmf_detect_state->hit2 = dtmf_detect_state->hit3;
dtmf_detect_state->hit3 = hit;
/* Reinitialise the detector for the next block */
for (i = 0; i < GRID_FACTOR; i++) {
goertzel_init (&dtmf_detect_state->row_out[i], &dtmf_detect_row[i]);
goertzel_init (&dtmf_detect_state->col_out[i], &dtmf_detect_col[i]);
goertzel_init (&dtmf_detect_state->row_out2nd[i], &dtmf_detect_row_2nd[i]);
goertzel_init (&dtmf_detect_state->col_out2nd[i], &dtmf_detect_col_2nd[i]);
}
dtmf_detect_state->energy = 0.0;
dtmf_detect_state->current_sample = 0;
}
if ((!dtmf_detect_state->mhit) || (dtmf_detect_state->mhit != hit)) {
dtmf_detect_state->mhit = 0;
return(0);
}
return (hit);
}
int teletone_dtmf_get (teletone_dtmf_detect_state_t *dtmf_detect_state,
char *buf,
int max)
{
if (max > dtmf_detect_state->current_digits) {
max = dtmf_detect_state->current_digits;
}
if (max > 0) {
memcpy (buf, dtmf_detect_state->digits, max);
memmove (dtmf_detect_state->digits, dtmf_detect_state->digits + max, dtmf_detect_state->current_digits - max);
dtmf_detect_state->current_digits -= max;
}
buf[max] = '\0';
return max;
}
/* For Emacs:
* Local Variables:
* mode:c
* indent-tabs-mode:nil
* tab-width:4
* c-basic-offset:4
* End:
* For VIM:
* vim:set softtabstop=4 shiftwidth=4 tabstop=4 expandtab:
*/
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