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-rw-r--r--include/asterisk/dsp.h3
-rw-r--r--main/dsp.c147
-rw-r--r--res/res_fax.c65
3 files changed, 170 insertions, 45 deletions
diff --git a/include/asterisk/dsp.h b/include/asterisk/dsp.h
index 333415200..78c9a74ac 100644
--- a/include/asterisk/dsp.h
+++ b/include/asterisk/dsp.h
@@ -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
diff --git a/main/dsp.c b/main/dsp.c
index ee1891823..02cdc9d73 100644
--- a/main/dsp.c
+++ b/main/dsp.c
@@ -246,6 +246,20 @@ typedef struct
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
+{
goertzel_state_t row_out[4];
goertzel_state_t col_out[4];
int hits_to_begin; /* How many successive hits needed to consider begin of a digit */
@@ -391,6 +405,7 @@ struct ast_dsp {
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 @@ static void ast_tone_detect_init(tone_detect_state_t *s, int freq, int duration,
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)
@@ -513,6 +573,89 @@ static void ast_digit_detect_init(digit_detect_state_t *s, int mf, unsigned int
}
}
+/*! \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)
{
float tone_energy;
@@ -1441,6 +1584,10 @@ struct ast_frame *ast_dsp_process(struct ast_channel *chan, struct ast_dsp *dsp,
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)) {
diff --git a/res/res_fax.c b/res/res_fax.c
index 18f3fa133..31aede8a6 100644
--- a/res/res_fax.c
+++ b/res/res_fax.c
@@ -246,8 +246,6 @@ struct fax_gateway {
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 @@ struct fax_gateway {
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 @@ static int fax_logger_level = -1;
#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 @@ static struct fax_gateway *fax_gateway_new(struct ast_fax_session_details *detai
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 @@ static struct ast_frame *fax_gateway_request_t38(struct fax_gateway *gateway, st
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 @@ static struct ast_frame *fax_gateway_detect_ced(struct fax_gateway *gateway, str
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);
}
}
@@ -2593,9 +2582,6 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
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
* other channel appears to support T.38, we'll pass
@@ -2635,7 +2621,7 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
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 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
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 @@ static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct
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 @@ static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct
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 @@ static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct
}
/* 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 = {
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-27 14:54:22 +0000