dsp.c User configuration of DTMF_NORMAL_TWIST and DTMF_REVERSE_TWIST values

Asterisk's DTMF Specifications are based on AT&T specs, which may not be compatible in other countries.

Various countries have different specifications for the maximum power level differences
between the DTMF low group and high group of frequencies.

Power level difference between frequencies for different Administrations/RPOAs
 NTT        = Max. 5 dB
 AT&T       = 4dB(reverse) to 8dB(normal)
 Danish     = Max. 6 dB
 Australian = Max. 10 dB
 Brazilian  = Max. 9 dB
 ETSI       = Max. 6 dB from ETSI ES 201 235-3 V1.3.1 (2006-03)

Now allow 4 variables to be individually configured in dsp.conf, with reasonable min/max of 2dB to 20dB.
Default is AT&T specifications

Add's the following variables to dsp.conf
;dtmf_normal_twist=6.31 
;dtmf_reverse_twist=2.51 
;relax_dtmf_normal_twist=6.31 
;relax_dtmf_reverse_twist=3.98 


(closes issue ASTERISK-20442)
Reported by: tbsky
Tested by: tbsky,alecdavis

alecdavis (license 585)

Review https://reviewboard.asterisk.org/r/2141/
........

Merged revisions 374384 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 374385 from http://svn.asterisk.org/svn/asterisk/branches/10
........

Merged revisions 374386 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@374387 65c4cc65-6c06-0410-ace0-fbb531ad65f3

3 files changed, 86 insertions, 6 deletions

diff --git a/CHANGES b/CHANGES
index 344f28f23..e062a3d69 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1551,6 +1551,8 @@ Miscellaneous
    rate changes during translation are now avoided unless absolutely necessary.
  * The addition of the res_stun_monitor module for monitoring and reacting to network
    changes while behind a NAT.
+ * The DTMF Normal and Reverse Twist acceptance values can be set in dsp.conf.
+   This allows support for any Administration. Default is AT&T values.
 
 CLI Changes
 -----------
diff --git a/configs/dsp.conf.sample b/configs/dsp.conf.sample
index 788b78cdb..95cb9796e 100644
--- a/configs/dsp.conf.sample
+++ b/configs/dsp.conf.sample
@@ -5,3 +5,34 @@
 ; to talking.  [default=256]
 ;
 ;silencethreshold=256
+
+; DTMF Reverse Twist and Normal Twist is the difference in power between the row and column energies.
+;
+; Normal Twist is where the Column energy is greater than the Row energy
+; Reverse Twist is where the Row energy is greater.
+;
+; Power level difference between frequencies for different Administrations/RPOAs
+;		Power Gain		equiv
+;		normal	reverse		dB's
+; AT&T(default) 6.31	2.51		8dB(normal), 4dB(reverse)
+; NTT		3.16	3.16		Max. 5dB
+; Danish	3.98	3.98		Max. 6dB
+; Australian	10.0	10.0		Max. 10dB
+; Brazilian	7.94	7.94		Max. 9dB
+; ETSI		3.98	3.98		Max. 6dB
+
+;previous version compatible AT&T values
+; RADIO_RELAX disabled, and relaxdtmf=no
+;		6.30	2.50		7.99dB(normal), 3.98dB(reverse)
+; RADIO_RELAX disabled, and relaxdtmf=yes
+;		6.30	4.00		7.99dB(normal), 6.02dB(reverse)
+; RADIO_RELAX enabled, and relaxdtmf=no
+;		6.30	2.50		7.99dB(normal), 3.984dB(reverse)
+; RADIO_RELAX enabled, and relaxdtmf=yes
+;		6.30	6.50		7.99dB(normal), 8.13dB(reverse)
+
+;If you don't know what these mean, don't change them.
+;dtmf_normal_twist=6.31
+;dtmf_reverse_twist=2.51
+;relax_dtmf_normal_twist=6.31
+;relax_dtmf_reverse_twist=3.98
diff --git a/main/dsp.c b/main/dsp.c
index 0645eab6f..3ff5f009d 100644
--- a/main/dsp.c
+++ b/main/dsp.c
@@ -146,7 +146,7 @@ enum gsamp_thresh {
 
 #define	MAX_DTMF_DIGITS		128
 
-/* Basic DTMF specs:
+/* Basic DTMF (AT&T) specs:
  *
  * Minimum tone on = 40ms
  * Minimum tone off = 50ms
@@ -161,12 +161,18 @@ enum gsamp_thresh {
 #define DTMF_THRESHOLD		8.0e7
 #define FAX_THRESHOLD		8.0e7
 #define FAX_2ND_HARMONIC	2.0     /* 4dB */
-#define DTMF_NORMAL_TWIST	6.3     /* 8dB */
+
+#define DEF_DTMF_NORMAL_TWIST		6.31	 /* 8.0dB */
+#define DEF_RELAX_DTMF_NORMAL_TWIST	6.31	 /* 8.0dB */
+
 #ifdef	RADIO_RELAX
-#define DTMF_REVERSE_TWIST          (relax ? 6.5 : 2.5)     /* 4dB normal */
+#define DEF_DTMF_REVERSE_TWIST		2.51	 /* 4.01dB */
+#define DEF_RELAX_DTMF_REVERSE_TWIST	6.61	 /* 8.2dB */
 #else
-#define DTMF_REVERSE_TWIST          (relax ? 4.0 : 2.5)     /* 4dB normal */
+#define DEF_DTMF_REVERSE_TWIST		2.51	 /* 4.01dB */
+#define DEF_RELAX_DTMF_REVERSE_TWIST	3.98	 /* 6.0dB */
 #endif
+
 #define DTMF_RELATIVE_PEAK_ROW	6.3     /* 8dB */
 #define DTMF_RELATIVE_PEAK_COL	6.3     /* 8dB */
 #define DTMF_2ND_HARMONIC_ROW       (relax ? 1.7 : 2.5)     /* 4dB normal */
@@ -297,6 +303,10 @@ static const float mf_tones[] = {
 static const char dtmf_positions[] = "123A" "456B" "789C" "*0#D";
 static const char bell_mf_positions[] = "1247C-358A--69*---0B----#";
 static int thresholds[THRESHOLD_MAX];
+static float dtmf_normal_twist;		/* AT&T = 8dB */
+static float dtmf_reverse_twist;	/* AT&T = 4dB */
+static float relax_dtmf_normal_twist;	/* AT&T = 8dB */
+static float relax_dtmf_reverse_twist;	/* AT&T = 6dB */
 
 static inline void goertzel_sample(goertzel_state_t *s, short sample)
 {
@@ -706,8 +716,8 @@ static int dtmf_detect(struct ast_dsp *dsp, digit_detect_state_t *s, int16_t amp
 		/* 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]) {
+		    col_energy[best_col] < row_energy[best_row] * (relax ? relax_dtmf_reverse_twist : dtmf_reverse_twist) &&
+		    row_energy[best_row] < col_energy[best_col] * (relax ? relax_dtmf_normal_twist : dtmf_normal_twist)) {
 			/* Relative peak test */
 			for (i = 0; i < 4; i++) {
 				if ((i != best_col &&
@@ -1828,12 +1838,17 @@ static int _dsp_init(int reload)
 	struct ast_variable *v;
 	struct ast_flags config_flags = { reload ? CONFIG_FLAG_FILEUNCHANGED : 0 };
 	int cfg_threshold;
+	float cfg_twist;
 
 	if ((cfg = ast_config_load2(CONFIG_FILE_NAME, "dsp", config_flags)) == CONFIG_STATUS_FILEUNCHANGED) {
 		return 0;
 	}
 
 	thresholds[THRESHOLD_SILENCE] = DEFAULT_SILENCE_THRESHOLD;
+	dtmf_normal_twist = DEF_DTMF_NORMAL_TWIST;
+	dtmf_reverse_twist = DEF_DTMF_REVERSE_TWIST;
+	relax_dtmf_normal_twist = DEF_RELAX_DTMF_NORMAL_TWIST;
+	relax_dtmf_reverse_twist = DEF_RELAX_DTMF_REVERSE_TWIST;
 
 	if (cfg == CONFIG_STATUS_FILEMISSING || cfg == CONFIG_STATUS_FILEINVALID) {
 		return 0;
@@ -1848,6 +1863,38 @@ static int _dsp_init(int reload)
 			} else {
 				thresholds[THRESHOLD_SILENCE] = cfg_threshold;
 			}
+		} else if (!strcasecmp(v->name, "dtmf_normal_twist")) {
+			if (sscanf(v->value, "%30f", &cfg_twist) < 1) {
+				ast_log(LOG_WARNING, "Unable to convert '%s' to a numeric value.\n", v->value);
+			} else if ((cfg_twist < 2.0) || (cfg_twist > 100.0)) {		/* < 3.0dB or > 20dB */
+				ast_log(LOG_WARNING, "Invalid dtmf_normal_twist value '%.2f' specified, using default of %.2f\n", cfg_twist, dtmf_normal_twist);
+			} else {
+				dtmf_normal_twist = cfg_twist;
+			}
+		} else if (!strcasecmp(v->name, "dtmf_reverse_twist")) {
+			if (sscanf(v->value, "%30f", &cfg_twist) < 1) {
+				ast_log(LOG_WARNING, "Unable to convert '%s' to a numeric value.\n", v->value);
+			} else if ((cfg_twist < 2.0) || (cfg_twist > 100.0)) {		/* < 3.0dB or > 20dB */
+				ast_log(LOG_WARNING, "Invalid dtmf_reverse_twist value '%.2f' specified, using default of %.2f\n", cfg_twist, dtmf_reverse_twist);
+			} else {
+				dtmf_reverse_twist = cfg_twist;
+			}
+		} else if (!strcasecmp(v->name, "relax_dtmf_normal_twist")) {
+			if (sscanf(v->value, "%30f", &cfg_twist) < 1) {
+				ast_log(LOG_WARNING, "Unable to convert '%s' to a numeric value.\n", v->value);
+			} else if ((cfg_twist < 2.0) || (cfg_twist > 100.0)) {		/* < 3.0dB or > 20dB */
+				ast_log(LOG_WARNING, "Invalid relax_dtmf_normal_twist value '%.2f' specified, using default of %.2f\n", cfg_twist, relax_dtmf_normal_twist);
+			} else {
+				relax_dtmf_normal_twist = cfg_twist;
+			}
+		} else if (!strcasecmp(v->name, "relax_dtmf_reverse_twist")) {
+			if (sscanf(v->value, "%30f", &cfg_twist) < 1) {
+				ast_log(LOG_WARNING, "Unable to convert '%s' to a numeric value.\n", v->value);
+			} else if ((cfg_twist < 2.0) || (cfg_twist > 100.0)) {		/* < 3.0dB or > 20dB */
+				ast_log(LOG_WARNING, "Invalid relax_dtmf_reverse_twist value '%.2f' specified, using default of %.2f\n", cfg_twist, relax_dtmf_reverse_twist);
+			} else {
+				relax_dtmf_reverse_twist = cfg_twist;
+			}
 		}
 	}
 	ast_config_destroy(cfg);