Improve T.38 gateway V.21 preamble detection.

This commit removes the V.21 preamble detection code previously added to the
generic DSP implementation in Asterisk, and instead enhances the res_fax module
to be able to utilize V.21 preamble detection functionality made available by
FAX technology modules. This commit also adds such support to res_fax_spandsp,
which uses the Spandsp modem tone detection code to do the V.21 preamble
detection.

There should be no functional change here, other than much more reliable V.21
preamble detection (and thus T.38 gateway initiation).
........

Merged revisions 349248 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@349249 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 82 insertions, 3 deletions

diff --git a/res/res_fax_spandsp.c b/res/res_fax_spandsp.c
index 81711bb40..7f4fbfc67 100644
--- a/res/res_fax_spandsp.c
+++ b/res/res_fax_spandsp.c
@@ -80,6 +80,9 @@ static int spandsp_fax_switch_to_t38(struct ast_fax_session *s);
 static int spandsp_fax_gateway_start(struct ast_fax_session *s);
 static int spandsp_fax_gateway_process(struct ast_fax_session *s, const struct ast_frame *f);
 static void spandsp_fax_gateway_cleanup(struct ast_fax_session *s);
+static int spandsp_v21_detect(struct ast_fax_session *s, const struct ast_frame *f);
+static void spandsp_v21_cleanup(struct ast_fax_session *s);
+static void spandsp_v21_tone(void *data, int code, int level, int delay);
 
 static char *spandsp_fax_cli_show_capabilities(int fd);
 static char *spandsp_fax_cli_show_session(struct ast_fax_session *s, int fd);
@@ -98,7 +101,9 @@ static struct ast_fax_tech spandsp_fax_tech = {
 	 */
 	.version = "pre-20090220",
 #endif
-	.caps = AST_FAX_TECH_AUDIO | AST_FAX_TECH_T38 | AST_FAX_TECH_SEND | AST_FAX_TECH_RECEIVE | AST_FAX_TECH_GATEWAY,
+	.caps = AST_FAX_TECH_AUDIO | AST_FAX_TECH_T38 | AST_FAX_TECH_SEND
+		| AST_FAX_TECH_RECEIVE | AST_FAX_TECH_GATEWAY
+		| AST_FAX_TECH_V21_DETECT,
 	.new_session = spandsp_fax_new,
 	.destroy_session = spandsp_fax_destroy,
 	.read = spandsp_fax_read,
@@ -150,8 +155,12 @@ struct spandsp_pvt {
 
 	struct ast_timer *timer;
 	AST_LIST_HEAD(frame_queue, ast_frame) read_frames;
+
+	int v21_detected;
+	modem_connect_tones_rx_state_t *tone_state;
 };
 
+static int spandsp_v21_new(struct spandsp_pvt *p);
 static void session_destroy(struct spandsp_pvt *p);
 static int t38_tx_packet_handler(t38_core_state_t *t38_core_state, void *data, const uint8_t *buf, int len, int count);
 static void t30_phase_e_handler(t30_state_t *t30_state, void *data, int completion_code);
@@ -450,6 +459,20 @@ static void set_ecm(t30_state_t *t30_state, struct ast_fax_session_details *deta
 	t30_set_supported_compressions(t30_state, T30_SUPPORT_T4_1D_COMPRESSION | T30_SUPPORT_T4_2D_COMPRESSION | T30_SUPPORT_T6_COMPRESSION);
 }
 
+static int spandsp_v21_new(struct spandsp_pvt *p)
+{
+	/* XXX Here we use MODEM_CONNECT_TONES_FAX_CED_OR_PREAMBLE even though
+	 * we don't care about CED tones. Using MODEM_CONNECT_TONES_PREAMBLE
+	 * doesn't seem to work right all the time.
+	 */
+	p->tone_state = modem_connect_tones_rx_init(NULL, MODEM_CONNECT_TONES_FAX_CED_OR_PREAMBLE, spandsp_v21_tone, p);
+	if (!p->tone_state) {
+		return -1;
+	}
+
+	return 0;
+}
+
 /*! \brief create an instance of the spandsp tech_pvt for a fax session */
 static void *spandsp_fax_new(struct ast_fax_session *s, struct ast_fax_tech_token *token)
 {
@@ -461,6 +484,15 @@ static void *spandsp_fax_new(struct ast_fax_session *s, struct ast_fax_tech_toke
 		goto e_return;
 	}
 
+	if (s->details->caps & AST_FAX_TECH_V21_DETECT) {
+		if (spandsp_v21_new(p)) {
+			ast_log(LOG_ERROR, "Cannot initialize the spandsp private v21 technology structure.\n");
+			goto e_return;
+		}
+		s->state = AST_FAX_STATE_ACTIVE;
+		return p;
+	}
+
 	if (s->details->caps & AST_FAX_TECH_GATEWAY) {
 		s->state = AST_FAX_STATE_INITIALIZED;
 		return p;
@@ -513,6 +545,11 @@ e_return:
 	return NULL;
 }
 
+static void spandsp_v21_cleanup(struct ast_fax_session *s) {
+	struct spandsp_pvt *p = s->tech_pvt;
+	modem_connect_tones_rx_free(p->tone_state);
+}
+
 /*! \brief Destroy a spandsp fax session.
  */
 static void spandsp_fax_destroy(struct ast_fax_session *s)
@@ -521,6 +558,8 @@ static void spandsp_fax_destroy(struct ast_fax_session *s)
 
 	if (s->details->caps & AST_FAX_TECH_GATEWAY) {
 		spandsp_fax_gateway_cleanup(s);
+	} else if (s->details->caps & AST_FAX_TECH_V21_DETECT) {
+		spandsp_v21_cleanup(s);
 	} else {
 		session_destroy(p);
 	}
@@ -571,6 +610,36 @@ static struct ast_frame *spandsp_fax_read(struct ast_fax_session *s)
 	return &ast_null_frame;
 }
 
+static void spandsp_v21_tone(void *data, int code, int level, int delay)
+{
+	struct spandsp_pvt *p = data;
+
+	if (code == MODEM_CONNECT_TONES_FAX_PREAMBLE) {
+		p->v21_detected = 1;
+	}
+}
+
+static int spandsp_v21_detect(struct ast_fax_session *s, const struct ast_frame *f) {
+	struct spandsp_pvt *p = s->tech_pvt;
+
+	if (p->v21_detected) {
+		return 0;
+	}
+
+	/*invalid frame*/
+	if (!f->data.ptr || !f->datalen) {
+		return -1;
+	}
+
+	modem_connect_tones_rx(p->tone_state, f->data.ptr, f->samples);
+
+	if (p->v21_detected) {
+		s->details->option.v21_detected = 1;
+	}
+
+	return 0;
+}
+
 /*! \brief Write a frame to the spandsp fax stack.
  * \param s a fax session
  * \param f the frame to write
@@ -585,6 +654,10 @@ static int spandsp_fax_write(struct ast_fax_session *s, const struct ast_frame *
 {
 	struct spandsp_pvt *p = s->tech_pvt;
 
+	if (s->details->caps & AST_FAX_TECH_V21_DETECT) {
+		return spandsp_v21_detect(s, f);
+	}
+
 	if (s->details->caps & AST_FAX_TECH_GATEWAY) {
 		return spandsp_fax_gateway_process(s, f);
 	}
@@ -906,10 +979,10 @@ static char *spandsp_fax_cli_show_capabilities(int fd)
 /*! \brief */
 static char *spandsp_fax_cli_show_session(struct ast_fax_session *s, int fd)
 {
-	struct spandsp_pvt *p = s->tech_pvt;
-
 	ao2_lock(s);
 	if (s->details->caps & AST_FAX_TECH_GATEWAY) {
+		struct spandsp_pvt *p = s->tech_pvt;
+
 		ast_cli(fd, "%-22s : %d\n", "session", s->id);
 		ast_cli(fd, "%-22s : %s\n", "operation", "Gateway");
 		ast_cli(fd, "%-22s : %s\n", "state", ast_fax_state_to_str(s->state));
@@ -920,7 +993,13 @@ static char *spandsp_fax_cli_show_session(struct ast_fax_session *s, int fd)
 			ast_cli(fd, "%-22s : %d\n", "Data Rate", stats.bit_rate);
 			ast_cli(fd, "%-22s : %d\n", "Page Number", stats.pages_transferred + 1);
 		}
+	} else if (s->details->caps & AST_FAX_TECH_V21_DETECT) {
+		ast_cli(fd, "%-22s : %d\n", "session", s->id);
+		ast_cli(fd, "%-22s : %s\n", "operation", "V.21 Detect");
+		ast_cli(fd, "%-22s : %s\n", "state", ast_fax_state_to_str(s->state));
 	} else {
+		struct spandsp_pvt *p = s->tech_pvt;
+
 		ast_cli(fd, "%-22s : %d\n", "session", s->id);
 		ast_cli(fd, "%-22s : %s\n", "operation", (s->details->caps & AST_FAX_TECH_RECEIVE) ? "Receive" : "Transmit");
 		ast_cli(fd, "%-22s : %s\n", "state", ast_fax_state_to_str(s->state));