[asterisk-commits] mnicholson: trunk r327769 - in /trunk: include/asterisk/ main/ res/

SVN commits to the Asterisk project asterisk-commits at lists.digium.com
Tue Jul 12 10:23:27 CDT 2011


Author: mnicholson
Date: Tue Jul 12 10:23:24 2011
New Revision: 327769

URL: http://svnview.digium.com/svn/asterisk?view=rev&rev=327769
Log:
do v21 detection instead of CED detection for the fax gateway

Modified:
    trunk/include/asterisk/dsp.h
    trunk/main/dsp.c
    trunk/res/res_fax.c

Modified: trunk/include/asterisk/dsp.h
URL: http://svnview.digium.com/svn/asterisk/trunk/include/asterisk/dsp.h?view=diff&rev=327769&r1=327768&r2=327769
==============================================================================
--- trunk/include/asterisk/dsp.h (original)
+++ trunk/include/asterisk/dsp.h Tue Jul 12 10:23:24 2011
@@ -45,7 +45,8 @@
 
 #define DSP_FAXMODE_DETECT_CNG	(1 << 0)
 #define DSP_FAXMODE_DETECT_CED	(1 << 1)
-#define DSP_FAXMODE_DETECT_ALL	(DSP_FAXMODE_DETECT_CNG | DSP_FAXMODE_DETECT_CED)
+#define DSP_FAXMODE_DETECT_V21	(1 << 2)
+#define DSP_FAXMODE_DETECT_ALL	(DSP_FAXMODE_DETECT_CNG | DSP_FAXMODE_DETECT_CED | DSP_FAXMODE_DETECT_V21)
 
 #define DSP_TONE_STATE_SILENCE  0
 #define DSP_TONE_STATE_RINGING  1

Modified: trunk/main/dsp.c
URL: http://svnview.digium.com/svn/asterisk/trunk/main/dsp.c?view=diff&rev=327769&r1=327768&r2=327769
==============================================================================
--- trunk/main/dsp.c (original)
+++ trunk/main/dsp.c Tue Jul 12 10:23:24 2011
@@ -243,6 +243,20 @@
 	int last_hit;		/* Indicates if the last processed block was a hit */
 
 } tone_detect_state_t;
+
+typedef struct
+{
+	int block_size;
+	goertzel_state_t tone;
+	float energy;		/* Accumulated energy of the current block */
+	int samples_pending;	/* Samples remain to complete the current block */
+
+	float threshold;	/* Energy of the tone relative to energy from all other signals to consider a hit */
+
+	int hit_count;
+	int miss_count;
+
+} v21_detect_state_t;
 
 typedef struct
 {
@@ -391,6 +405,7 @@
 	digit_detect_state_t digit_state;
 	tone_detect_state_t cng_tone_state;
 	tone_detect_state_t ced_tone_state;
+	v21_detect_state_t v21_state;
 };
 
 static void mute_fragment(struct ast_dsp *dsp, fragment_t *fragment)
@@ -463,10 +478,55 @@
 	ast_debug(1, "Setup tone %d Hz, %d ms, block_size=%d, hits_required=%d\n", freq, duration, s->block_size, s->hits_required);
 }
 
+static void ast_v21_detect_init(v21_detect_state_t *s, unsigned int sample_rate)
+{
+	float x;
+	int periods_in_block;
+
+	/* If we want to remove tone, it is important to have block size not
+	   to exceed frame size. Otherwise by the moment tone is detected it is too late
+	   to squelch it from previous frames. Block size is 20ms at the given sample rate.*/
+	s->block_size = (20 * sample_rate) / 1000;
+
+	periods_in_block = s->block_size * 1850 / sample_rate;
+
+	/* Make sure we will have at least 5 periods at target frequency for analisys.
+	   This may make block larger than expected packet and will make squelching impossible
+	   but at least we will be detecting the tone */
+	if (periods_in_block < 5)
+		periods_in_block = 5;
+
+	/* Now calculate final block size. It will contain integer number of periods */
+	s->block_size = periods_in_block * sample_rate / 1850;
+
+	goertzel_init(&s->tone, 1850.0, s->block_size, sample_rate);
+
+	s->samples_pending = s->block_size;
+	s->hit_count = 0;
+	s->miss_count = 0;
+	s->energy = 0.0;
+
+	/* We want tone energy to be amp decibels above the rest of the signal (the noise).
+	   According to Parseval's theorem the energy computed in time domain equals to energy
+	   computed in frequency domain. So subtracting energy in the frequency domain (Goertzel result)
+	   from the energy in the time domain we will get energy of the remaining signal (without the tone
+	   we are detecting). We will be checking that
+		10*log(Ew / (Et - Ew)) > amp
+	   Calculate threshold so that we will be actually checking
+		Ew > Et * threshold
+	*/
+
+	x = pow(10.0, 16 / 10.0);
+	s->threshold = x / (x + 1);
+
+	ast_debug(1, "Setup v21 detector, block_size=%d\n", s->block_size);
+}
+
 static void ast_fax_detect_init(struct ast_dsp *s)
 {
 	ast_tone_detect_init(&s->cng_tone_state, FAX_TONE_CNG_FREQ, FAX_TONE_CNG_DURATION, FAX_TONE_CNG_DB, s->sample_rate);
 	ast_tone_detect_init(&s->ced_tone_state, FAX_TONE_CED_FREQ, FAX_TONE_CED_DURATION, FAX_TONE_CED_DB, s->sample_rate);
+	ast_v21_detect_init(&s->v21_state, s->sample_rate);
 }
 
 static void ast_dtmf_detect_init (dtmf_detect_state_t *s, unsigned int sample_rate)
@@ -511,6 +571,89 @@
 	} else {
 		ast_dtmf_detect_init(&s->td.dtmf, sample_rate);
 	}
+}
+
+/*! \brief Detect a v21 preamble.
+ * This code is derived from the tone_detect code and detects a pattern of 1850
+ * Hz tone found in a v21 preamble.
+ */
+static int v21_detect(struct ast_dsp *dsp, v21_detect_state_t *s, int16_t *amp, int samples)
+{
+	float tone_energy;
+	int i;
+	int hit = 0;
+	int limit;
+	int res = 0;
+	int16_t *ptr;
+	int start, end;
+
+	for (start = 0;  start < samples;  start = end) {
+		/* Process in blocks. */
+		limit = samples - start;
+		if (limit > s->samples_pending) {
+			limit = s->samples_pending;
+		}
+		end = start + limit;
+
+		for (i = limit, ptr = amp ; i > 0; i--, ptr++) {
+			/* signed 32 bit int should be enough to suqare any possible signed 16 bit value */
+			s->energy += (int32_t) *ptr * (int32_t) *ptr;
+
+			goertzel_sample(&s->tone, *ptr);
+		}
+
+		s->samples_pending -= limit;
+
+		if (s->samples_pending) {
+			/* Finished incomplete (last) block */
+			break;
+		}
+
+		tone_energy = goertzel_result(&s->tone);
+
+		/* Scale to make comparable */
+		tone_energy *= 2.0;
+		s->energy *= s->block_size;
+
+		ast_debug(10, "v21 1850 Ew=%.2E, Et=%.2E, s/n=%10.2f\n", tone_energy, s->energy, tone_energy / (s->energy - tone_energy));
+
+		hit = 0;
+		if (tone_energy > s->energy * s->threshold) {
+			ast_debug(10, "Hit! count=%d; miss_count=%d\n", s->hit_count, s->miss_count);
+			hit = 1;
+		}
+
+		if (hit) {
+			if (s->hit_count == 0 || s->miss_count == 3) {
+				s->hit_count++;
+			} else {
+				s->hit_count = 0;
+			}
+
+			s->miss_count = 0;
+		} else {
+			s->miss_count++;
+			if (s->miss_count > 3) {
+				s->hit_count = 0;
+			}
+		}
+
+		if (s->hit_count == 4) {
+			ast_debug(1, "v21 preamble detected\n");
+			res = 1;
+		}
+
+		/* Reinitialise the detector for the next block */
+		goertzel_reset(&s->tone);
+
+		/* Advance to the next block */
+		s->energy = 0.0;
+		s->samples_pending = s->block_size;
+
+		amp += limit;
+	}
+
+	return res;
 }
 
 static int tone_detect(struct ast_dsp *dsp, tone_detect_state_t *s, int16_t *amp, int samples)
@@ -1441,6 +1584,10 @@
 		if ((dsp->faxmode & DSP_FAXMODE_DETECT_CED) && tone_detect(dsp, &dsp->ced_tone_state, shortdata, len)) {
 			fax_digit = 'e';
 		}
+
+		if ((dsp->faxmode & DSP_FAXMODE_DETECT_V21) && v21_detect(dsp, &dsp->v21_state, shortdata, len)) {
+			fax_digit = 'g';
+		}
 	}
 
 	if (dsp->features & (DSP_FEATURE_DIGIT_DETECT | DSP_FEATURE_BUSY_DETECT)) {

Modified: trunk/res/res_fax.c
URL: http://svnview.digium.com/svn/asterisk/trunk/res/res_fax.c?view=diff&rev=327769&r1=327768&r2=327769
==============================================================================
--- trunk/res/res_fax.c (original)
+++ trunk/res/res_fax.c Tue Jul 12 10:23:24 2011
@@ -246,8 +246,6 @@
 	struct ast_fax_tech_token *token;
 	/*! \brief the start of our timeout counter */
 	struct timeval timeout_start;
-	/*! \brief the start of our ced timeout */
-	struct timeval ced_timeout_start;
 	/*! \brief DSP Processor */
 	struct ast_dsp *chan_dsp;
 	struct ast_dsp *peer_dsp;
@@ -255,8 +253,8 @@
 	int framehook;
 	/*! \brief bridged */
 	int bridged:1;
-	/*! \brief 1 if the ced tone came from chan, 0 if it came from peer */
-	int ced_chan:1;
+	/*! \brief 1 if a v21 preamble has been detected */
+	int detected_v21:1;
 	/*! \brief a flag to track the state of our negotiation */
 	enum ast_t38_state t38_state;
 	/*! \brief original audio formats */
@@ -273,7 +271,6 @@
 
 #define RES_FAX_TIMEOUT 10000
 #define FAX_GATEWAY_TIMEOUT RES_FAX_TIMEOUT
-#define FAX_GATEWAY_CED_TIMEOUT 3000
 
 /*! \brief The faxregistry is used to manage information and statistics for all FAX sessions. */
 static struct {
@@ -2412,10 +2409,10 @@
 	gateway->framehook = -1;
 
 	ast_dsp_set_features(gateway->chan_dsp, DSP_FEATURE_FAX_DETECT);
-	ast_dsp_set_faxmode(gateway->chan_dsp, DSP_FAXMODE_DETECT_CED);
+	ast_dsp_set_faxmode(gateway->chan_dsp, DSP_FAXMODE_DETECT_V21);
 
 	ast_dsp_set_features(gateway->peer_dsp, DSP_FEATURE_FAX_DETECT);
-	ast_dsp_set_faxmode(gateway->peer_dsp, DSP_FAXMODE_DETECT_CED);
+	ast_dsp_set_faxmode(gateway->peer_dsp, DSP_FAXMODE_DETECT_V21);
 
 	details->caps = AST_FAX_TECH_GATEWAY;
 	if (!(gateway->s = fax_session_reserve(details, &gateway->token))) {
@@ -2503,21 +2500,17 @@
 	gateway->t38_state = T38_STATE_NEGOTIATING;
 	gateway->timeout_start = ast_tvnow();
 
-	gateway->ced_timeout_start.tv_sec = 0;
-	gateway->ced_timeout_start.tv_usec = 0;
-
 	ast_debug(1, "requesting T.38 for gateway session for %s\n", chan->name);
 	return fp;
 }
 
-static struct ast_frame *fax_gateway_detect_ced(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_channel *peer, struct ast_channel *active, struct ast_frame *f)
+static struct ast_frame *fax_gateway_detect_v21(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_channel *peer, struct ast_channel *active, struct ast_frame *f)
 {
 	struct ast_frame *dfr = ast_frdup(f);
 	struct ast_dsp *active_dsp = (active == chan) ? gateway->chan_dsp : gateway->peer_dsp;
 	struct ast_channel *other = (active == chan) ? peer : chan;
 
-	/* if we have already detected a CED tone, don't waste time here */
-	if (!ast_tvzero(gateway->ced_timeout_start)) {
+	if (gateway->detected_v21) {
 		return f;
 	}
 
@@ -2529,17 +2522,13 @@
 		return f;
 	}
 
-	if (dfr->frametype == AST_FRAME_DTMF && dfr->subclass.integer == 'e') {
+	if (dfr->frametype == AST_FRAME_DTMF && dfr->subclass.integer == 'g') {
+		gateway->detected_v21 = 1;
 		if (ast_channel_get_t38_state(other) == T38_STATE_UNKNOWN) {
-			if (ast_channel_get_t38_state(active) == T38_STATE_UNKNOWN) {
-				gateway->ced_timeout_start = ast_tvnow();
-				gateway->ced_chan = (active == chan);
-				ast_debug(1, "detected CED tone from %s; will schedule T.38 request on %s\n", active->name, other->name);
-			} else {
-				return fax_gateway_request_t38(gateway, chan, f);
-			}
+			ast_debug(1, "detected v21 preamble from %s\n", active->name);
+			return fax_gateway_request_t38(gateway, chan, f);
 		} else {
-			ast_debug(1, "detected CED tone on %s, but %s does not support T.38 for T.38 gateway session\n", active->name, other->name);
+			ast_debug(1, "detected v21 preamble on %s, but %s does not support T.38 for T.38 gateway session\n", active->name, other->name);
 		}
 	}
 
@@ -2592,9 +2581,6 @@
 
 	if (control_params->request_response == AST_T38_REQUEST_NEGOTIATE) {
 		enum ast_t38_state state = ast_channel_get_t38_state(other);
-
-		gateway->ced_timeout_start.tv_sec = 0;
-		gateway->ced_timeout_start.tv_usec = 0;
 
 		if (state == T38_STATE_UNKNOWN) {
 			/* we detected a request to negotiate T.38 and the
@@ -2635,7 +2621,7 @@
 			return &ast_null_frame;
 		} else if (gateway->t38_state == T38_STATE_NEGOTIATING) {
 			/* we got a request to negotiate T.38 after we already
-			 * sent one to the other party based on CED tone
+			 * sent one to the other party based on v21 preamble
 			 * detection. We'll just pretend we passed this request
 			 * through in the first place. */
 
@@ -2643,12 +2629,12 @@
 			gateway->t38_state = T38_STATE_UNKNOWN;
 			gateway->timeout_start = ast_tvnow();
 
-			ast_debug(1, "%s is attempting to negotiate T.38 after we already sent a negotiation request based on CED detection\n", active->name);
+			ast_debug(1, "%s is attempting to negotiate T.38 after we already sent a negotiation request based on v21 preamble detection\n", active->name);
 			ao2_ref(details, -1);
 			return &ast_null_frame;
 		} else if (gateway->t38_state == T38_STATE_NEGOTIATED) {
 			/* we got a request to negotiate T.38 after we already
-			 * sent one to the other party based on CED tone
+			 * sent one to the other party based on v21 preamble
 			 * detection and received a response. We need to
 			 * respond to this and shut down the gateway. */
 
@@ -2869,7 +2855,8 @@
 
 		gateway->timeout_start = ast_tvnow();
 
-		/* we are bridged, change r/w formats to SLIN for CED detection and T.30 */
+		/* we are bridged, change r/w formats to SLIN for v21 preamble
+		 * detection and T.30 */
 		ast_format_copy(&gateway->chan_read_format, &chan->readformat);
 		ast_format_copy(&gateway->chan_write_format, &chan->readformat);
 
@@ -2944,20 +2931,10 @@
 		return fax_gateway_detect_t38(gateway, chan, peer, active, f);
 	}
 
-	/* handle the ced timeout delay */
-	if (!ast_tvzero(gateway->ced_timeout_start)) {
-		if (ast_tvdiff_ms(ast_tvnow(), gateway->ced_timeout_start) > FAX_GATEWAY_CED_TIMEOUT) {
-			if (gateway->ced_chan && chan == active) {
-				return fax_gateway_request_t38(gateway, chan, f);
-			} else if (!gateway->ced_chan && peer == active) {
-				return fax_gateway_request_t38(gateway, chan, f);
-			}
-		}
-	} else if (gateway->t38_state == T38_STATE_UNAVAILABLE && f->frametype == AST_FRAME_VOICE) {
-		/* not in gateway mode and have not detected CED yet, listen
-		 * for CED */
-		/* XXX this should detect a v21 preamble instead of CED */
-		return fax_gateway_detect_ced(gateway, chan, peer, active, f);
+	if (!gateway->detected_v21 && gateway->t38_state == T38_STATE_UNAVAILABLE && f->frametype == AST_FRAME_VOICE) {
+		/* not in gateway mode and have not detected v21 yet, listen
+		 * for v21 */
+		return fax_gateway_detect_v21(gateway, chan, peer, active, f);
 	}
 
 	/* in gateway mode, gateway some packets */
@@ -2981,7 +2958,7 @@
 	}
 
 	/* force silence on the line if T.38 negotiation might be taking place */
-	if (!ast_tvzero(gateway->ced_timeout_start) || (gateway->t38_state != T38_STATE_UNAVAILABLE && gateway->t38_state != T38_STATE_REJECTED)) {
+	if (gateway->t38_state != T38_STATE_UNAVAILABLE && gateway->t38_state != T38_STATE_REJECTED) {
 		if (f->frametype == AST_FRAME_VOICE && f->subclass.format.id == AST_FORMAT_SLINEAR) {
 			short silence_buf[f->samples];
 			struct ast_frame silence_frame = {




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