#include <libteletone_detect.h>
#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include <time.h>
#include <fcntl.h>

Include dependency graph for libteletone_detect.c:

Macros
#define	LOW_ENG 10000000

#define	ZC 2

#define	teletone_goertzel_result(gs) (double)(((gs)->v3 * (gs)->v3 + (gs)->v2 * (gs)->v2 - (gs)->v2 * (gs)->v3 * (gs)->fac))

Functions
static void	goertzel_init (teletone_goertzel_state_t goertzel_state, teletone_detection_descriptor_t tdesc)

void	teletone_goertzel_update (teletone_goertzel_state_t *goertzel_state, int16_t sample_buffer[], int samples)
	Step through the Goertzel Algorithm for each sample in a buffer. More...

void	teletone_dtmf_detect_init (teletone_dtmf_detect_state_t *dtmf_detect_state, int sample_rate)
	Initilize a DTMF detection state object. More...

void	teletone_multi_tone_init (teletone_multi_tone_t mt, teletone_tone_map_t map)
	Initilize a multi-frequency tone detector. More...

int	teletone_multi_tone_detect (teletone_multi_tone_t *mt, int16_t sample_buffer[], int samples)
	Check a sample buffer for the presence of the mulit-frequency tone described by mt. More...

teletone_hit_type_t	teletone_dtmf_detect (teletone_dtmf_detect_state_t *dtmf_detect_state, int16_t sample_buffer[], int samples)
	Check a sample buffer for the presence of DTMF digits. More...

int	teletone_dtmf_get (teletone_dtmf_detect_state_t dtmf_detect_state, char buf, unsigned int *dur)
	retrieve any collected digits into a string buffer More...

Variables
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 float	dtmf_row [] = {697.0f, 770.0f, 852.0f, 941.0f}

static float	dtmf_col [] = {1209.0f, 1336.0f, 1477.0f, 1633.0f}

static char	dtmf_positions [] = "123A" "456B" "789C" "*0#D"

Macro Definition Documentation

#define LOW_ENG 10000000

Definition at line 103 of file libteletone_detect.c.

Referenced by teletone_dtmf_detect().

#define teletone_goertzel_result ( gs ) (double)(((gs)->v3 * (gs)->v3 + (gs)->v2 * (gs)->v2 - (gs)->v2 * (gs)->v3 * (gs)->fac))

Definition at line 137 of file libteletone_detect.c.

Referenced by teletone_dtmf_detect(), and teletone_multi_tone_detect().

#define ZC 2

Definition at line 104 of file libteletone_detect.c.

Referenced by teletone_dtmf_detect().

Function Documentation

static void goertzel_init	(	teletone_goertzel_state_t *	goertzel_state,
		teletone_detection_descriptor_t *	tdesc
	)

static

Definition at line 115 of file libteletone_detect.c.

References teletone_goertzel_state_t::fac, teletone_detection_descriptor_t::fac, teletone_goertzel_state_t::v2, and teletone_goertzel_state_t::v3.

Referenced by teletone_dtmf_detect(), teletone_dtmf_detect_init(), teletone_multi_tone_detect(), and teletone_multi_tone_init().

                                                                                                              {
         goertzel_state->v2 = goertzel_state->v3 = 0.0;
         goertzel_state->fac = tdesc->fac;
 }

teletone_hit_type_t teletone_dtmf_detect	(	teletone_dtmf_detect_state_t *	dtmf_detect_state,
		int16_t	sample_buffer[],
		int	samples
	)

Check a sample buffer for the presence of DTMF digits.

Parameters

dtmf_detect_state	the detection state object to check
sample_buffer	an array aof 16 bit signed linear samples
samples	the number of samples present in sample_buffer

Returns: true when DTMF was detected or false when it is not

Definition at line 307 of file libteletone_detect.c.

References BLOCK_LEN, DTMF_2ND_HARMONIC_COL, DTMF_2ND_HARMONIC_ROW, DTMF_NORMAL_TWIST, dtmf_positions, DTMF_RELATIVE_PEAK_COL, DTMF_RELATIVE_PEAK_ROW, DTMF_REVERSE_TWIST, DTMF_THRESHOLD, goertzel_init(), GRID_FACTOR, LOW_ENG, teletone_goertzel_result, TELETONE_MAX_DTMF_DIGITS, TT_HIT_BEGIN, TT_HIT_END, TT_HIT_MIDDLE, and ZC.

Referenced by inband_dtmf_callback().

 {
         float row_energy[GRID_FACTOR];
         float col_energy[GRID_FACTOR];
         float famp;
         float v1;
         int i;
         int j;
         int sample;
         int best_row;
         int best_col;
         char hit;
         int limit;
         teletone_hit_type_t r = 0;
 
         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 = (float)(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 = (float)(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 = (float)(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 = (float)(dtmf_detect_state->row_out2nd[x].fac*dtmf_detect_state->row_out2nd[x].v2 - v1 + famp);
                         }
 
                 }
 
                 if (dtmf_detect_state->zc > 0) {
                         if (dtmf_detect_state->energy < LOW_ENG && dtmf_detect_state->lenergy < LOW_ENG) {
                                 if (!--dtmf_detect_state->zc) {
                                         /* Reinitialise the detector for the next block */
                                         dtmf_detect_state->hit1 = dtmf_detect_state->hit2 = 0;
                                         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->dur -= samples;
                                         return TT_HIT_END;
                                 }
                         }
                         
                         dtmf_detect_state->dur += samples;
                         dtmf_detect_state->lenergy = dtmf_detect_state->energy;
                         dtmf_detect_state->energy = 0.0;
                         dtmf_detect_state->current_sample = 0;
                         return TT_HIT_MIDDLE;
                 } else if (dtmf_detect_state->digit) {
                         return TT_HIT_END;
                 }
                 
 
                 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 (! r && hit == dtmf_detect_state->hit3 && dtmf_detect_state->hit3 != dtmf_detect_state->hit2) {
                                         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->digit = hit;
                                         } else {
                                                 dtmf_detect_state->lost_digits++;
                                         }
                                         
                                         if (!dtmf_detect_state->zc) {
                                                 dtmf_detect_state->zc = ZC;
                                                 dtmf_detect_state->dur = 0;
                                                 r = TT_HIT_BEGIN;
                                                 break;
                                         }                                       
 
                                 }
                         }
                 }
 
                 dtmf_detect_state->hit1 = dtmf_detect_state->hit2;
                 dtmf_detect_state->hit2 = dtmf_detect_state->hit3;
                 dtmf_detect_state->hit3 = hit;
 
                 dtmf_detect_state->energy = 0.0;
                 dtmf_detect_state->current_sample = 0;
                 
         }
 
         return r;
 }

void teletone_dtmf_detect_init	(	teletone_dtmf_detect_state_t *	dtmf_detect_state,
		int	sample_rate
	)

Initilize a DTMF detection state object.

Parameters

dtmf_detect_state	the DTMF detection state to initilize
sample_rate	the desired sample rate

Definition at line 139 of file libteletone_detect.c.

References dtmf_col, dtmf_row, teletone_detection_descriptor_t::fac, goertzel_init(), GRID_FACTOR, and M_TWO_PI.

Referenced by switch_ivr_inband_dtmf_session().

 {
         int i;
         float theta;
 
         if (!sample_rate) {
                 sample_rate = 8000;
         }
 
         dtmf_detect_state->hit1 = dtmf_detect_state->hit2 = 0;
 
         for (i = 0;      i < GRID_FACTOR;  i++) {
                 theta = (float)(M_TWO_PI*(dtmf_row[i]/(float)sample_rate));
                 dtmf_detect_row[i].fac = (float)(2.0*cos(theta));
 
                 theta = (float)(M_TWO_PI*(dtmf_col[i]/(float)sample_rate));
                 dtmf_detect_col[i].fac = (float)(2.0*cos(theta));
         
                 theta = (float)(M_TWO_PI*(dtmf_row[i]*2.0/(float)sample_rate));
                 dtmf_detect_row_2nd[i].fac = (float)(2.0*cos(theta));
 
                 theta = (float)(M_TWO_PI*(dtmf_col[i]*2.0/(float)sample_rate));
                 dtmf_detect_col_2nd[i].fac = (float)(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->digit = 0;
         dtmf_detect_state->dur = 0;
 }

int teletone_dtmf_get	(	teletone_dtmf_detect_state_t *	dtmf_detect_state,
		char *	buf,
		unsigned int *	dur
	)

retrieve any collected digits into a string buffer

Parameters

dtmf_detect_state	the detection state object to check
buf	the string buffer to write to
max	the maximum length of buf

Returns: the number of characters written to buf

Definition at line 462 of file libteletone_detect.c.

Referenced by inband_dtmf_callback().

 {
         if (!dtmf_detect_state->digit) {
                 return 0;
         }
 
         *buf = dtmf_detect_state->digit;
 
         *dur = dtmf_detect_state->dur;
 
         if (!dtmf_detect_state->zc) {
                 dtmf_detect_state->dur = 0;
                 dtmf_detect_state->digit = 0;
         }
         
         return 1;
 }

void teletone_goertzel_update	(	teletone_goertzel_state_t *	goertzel_state,
		int16_t	sample_buffer[],
		int	samples
	)

Step through the Goertzel Algorithm for each sample in a buffer.

Parameters

goertzel_state	the goertzel state to step the samples through
sample_buffer	an array aof 16 bit signed linear samples
samples	the number of samples present in sample_buffer

Definition at line 120 of file libteletone_detect.c.

 {
         int i;
         float v1;
         
         for (i = 0;      i < samples;  i++) {
                 v1 = goertzel_state->v2;
                 goertzel_state->v2 = goertzel_state->v3;
                 goertzel_state->v3 = (float)(goertzel_state->fac*goertzel_state->v2 - v1 + sample_buffer[i]);
         }
 }

int teletone_multi_tone_detect	(	teletone_multi_tone_t *	mt,
		int16_t	sample_buffer[],
		int	samples
	)

Check a sample buffer for the presence of the mulit-frequency tone described by mt.

Parameters

mt	the multi-frequency tone descriptor
sample_buffer	an array aof 16 bit signed linear samples
samples	the number of samples present in sample_buffer

Returns: true when the tone was detected or false when it is not

Definition at line 217 of file libteletone_detect.c.

References goertzel_init(), teletone_goertzel_result, and TELETONE_MAX_TONES.

Referenced by tone_detect_callback().

 {
         int sample, limit = 0, j, x = 0;
         float v1, famp;
         float eng_sum = 0, eng_all[TELETONE_MAX_TONES] = {0.0};
         int gtest = 0, see_hit = 0;
 
         for (sample = 0;  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;
                 }
                 if (limit < 0 || limit > samples) {
                         limit = samples;
                 }
 
                 for (j = sample;  j < limit;  j++) {
                         famp = sample_buffer[j];
                         
                         mt->energy += famp*famp;
 
                         for(x = 0; x < TELETONE_MAX_TONES && x < mt->tone_count; x++) {
                                 v1 = mt->gs[x].v2;
                                 mt->gs[x].v2 = mt->gs[x].v3;
                                 mt->gs[x].v3 = (float)(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 = (float)(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 < TELETONE_MAX_TONES && x < mt->tone_count; x++) {
                         eng_all[x] = (float)(teletone_goertzel_result (&mt->gs[x]));
                         eng_sum += eng_all[x];
                 }
 
                 gtest = 0;
                 for(x = 0; x < TELETONE_MAX_TONES && x < mt->tone_count; x++) {
                         gtest += teletone_goertzel_result (&mt->gs2[x]) < eng_all[x] ? 1 : 0;
                 }
 
                 if ((gtest >= 2 || gtest == mt->tone_count) && 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 < TELETONE_MAX_TONES && 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;
 }

void teletone_multi_tone_init	(	teletone_multi_tone_t *	mt,
		teletone_tone_map_t *	map
	)

Initilize a multi-frequency tone detector.

Parameters

mt	the multi-frequency tone descriptor
map	a representation of the multi-frequency tone

Definition at line 177 of file libteletone_detect.c.

References goertzel_init(), M_TWO_PI, and TELETONE_MAX_TONES.

Referenced by switch_ivr_tone_detect_session().

 {
         float theta = 0;
         int x = 0;
 
         if (!mt->sample_rate) {
                 mt->sample_rate = 8000;
         }
 
         if (!mt->min_samples) {
                 mt->min_samples = 102;
         }
 
         mt->min_samples *= (mt->sample_rate / 8000);
 
         if (!mt->positive_factor) {
                 mt->positive_factor = 2;
         }
 
         if(!mt->negative_factor) {
                 mt->negative_factor = 10;
         }
 
         if (!mt->hit_factor) {
                 mt->hit_factor = 2;
         }
 
         for(x = 0; x < TELETONE_MAX_TONES; x++) {
                 if ((int) map->freqs[x] == 0) {
                         break;
                 }
                 mt->tone_count++;
                 theta = (float)(M_TWO_PI*(map->freqs[x]/(float)mt->sample_rate));
                 mt->tdd[x].fac = (float)(2.0 * cos(theta));
                 goertzel_init (&mt->gs[x], &mt->tdd[x]);
                 goertzel_init (&mt->gs2[x], &mt->tdd[x]);
         }
 
 }