asterisk/apps/app_waitforsilence.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * WaitForSilence Application by David C. Troy <dave@popvox.com>
 * Version 1.11 2006-06-29
 *
 * Mark Spencer <markster@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Wait for Silence
 *   - Waits for up to 'x' milliseconds of silence, 'y' times \n
 *   - WaitForSilence(500,2) will wait for 1/2 second of silence, twice \n
 *   - WaitForSilence(1000,1) will wait for 1 second of silence, once \n
 *   - WaitForSilence(300,3,10) will wait for 300ms of silence, 3 times, and return after 10sec \n
 *
 * \author David C. Troy <dave@popvox.com>
 *
 * \brief Wait For Noise
 * The same as Wait For Silence but listenes noise on the chennel that is above \n
 * the pre-configured silence threshold from dsp.conf
 *
 * \author Philipp Skadorov <skadorov@yahoo.com>
 *
 * \ingroup applications
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include "asterisk/file.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/dsp.h"
#include "asterisk/module.h"

static char *app_silence = "WaitForSilence";
static char *synopsis_silence = "Waits for a specified amount of silence";
static char *descrip_silence =
"  WaitForSilence(silencerequired[,iterations][,timeout]):\n"
"Wait for Silence: Waits for up to 'silencerequired' \n"
"milliseconds of silence, 'iterations' times or once if omitted.\n"
"An optional timeout specified the number of seconds to return\n"
"after, even if we do not receive the specified amount of silence.\n"
"Use 'timeout' with caution, as it may defeat the purpose of this\n"
"application, which is to wait indefinitely until silence is detected\n"
"on the line.  This is particularly useful for reverse-911-type\n"
"call broadcast applications where you need to wait for an answering\n"
"machine to complete its spiel before playing a message.\n"
"The timeout parameter is specified only to avoid an infinite loop in\n"
"cases where silence is never achieved.  Typically you will want to\n"
"include two or more calls to WaitForSilence when dealing with an answering\n"
"machine; first waiting for the spiel to finish, then waiting for the beep, etc.\n\n"
  "Examples:\n"
"  - WaitForSilence(500,2) will wait for 1/2 second of silence, twice\n"
"  - WaitForSilence(1000) will wait for 1 second of silence, once\n"
"  - WaitForSilence(300,3,10) will wait for 300ms silence, 3 times,\n"
"     and returns after 10 sec, even if silence is not detected\n\n"
"Sets the channel variable WAITSTATUS with to one of these values:\n"
"SILENCE - if exited with silence detected\n"
"TIMEOUT - if exited without silence detected after timeout\n";

static char *app_noise = "WaitForNoise";
static char *synopsis_noise = "Waits for a specified amount of noise";
static char *descrip_noise =
"WaitForNoise(noiserequired[,iterations][,timeout]) \n"
"Wait for Noise: The same as Wait for Silance but waits for noise that is above the threshold specified\n";

static int do_waiting(struct ast_channel *chan, int timereqd, time_t waitstart, int timeout, int wait_for_silence) {
	struct ast_frame *f;
	int dsptime = 0;
	int rfmt = 0;
	int res = 0;
	struct ast_dsp *sildet;	 /* silence detector dsp */
 	time_t now;

	/*Either silence or noise calc depending on wait_for_silence flag*/
	int (*ast_dsp_func)(struct ast_dsp*, struct ast_frame*, int*) =
				wait_for_silence ? ast_dsp_silence : ast_dsp_noise;

	rfmt = chan->readformat; /* Set to linear mode */
	res = ast_set_read_format(chan, AST_FORMAT_SLINEAR);
	if (res < 0) {
		ast_log(LOG_WARNING, "Unable to set channel to linear mode, giving up\n");
		return -1;
	}

	sildet = ast_dsp_new(); /* Create the silence detector */
	if (!sildet) {
		ast_log(LOG_WARNING, "Unable to create silence detector :(\n");
		return -1;
	}
	ast_dsp_set_threshold(sildet, ast_dsp_get_threshold_from_settings(THRESHOLD_SILENCE));

	/* Await silence... */
	f = NULL;
	for(;;) {
		/* Start with no silence received */
		dsptime = 0;

		res = ast_waitfor(chan, timereqd);

		/* Must have gotten a hangup; let's exit */
		if (res <= 0) {
			f = NULL;
			break;
		}
		
		/* We waited and got no frame; sounds like digital silence or a muted digital channel */
		if (!res) {
			dsptime = timereqd;
		} else {
			/* Looks like we did get a frame, so let's check it out */
			f = ast_read(chan);
			if (!f)
				break;
			if (f && f->frametype == AST_FRAME_VOICE) {
				ast_dsp_func(sildet, f, &dsptime);
				ast_frfree(f);
			}
		}

		if (wait_for_silence)
			ast_verb(6, "Got %dms silence < %dms required\n", dsptime, timereqd);
		else
			ast_verb(6, "Got %dms noise < %dms required\n", dsptime, timereqd);

		if (dsptime >= timereqd) {
			if (wait_for_silence)
				ast_verb(3, "Exiting with %dms silence >= %dms required\n", dsptime, timereqd);
			else
				ast_verb(3, "Exiting with %dms noise >= %dms required\n", dsptime, timereqd);
			/* Ended happily with silence */
			res = 1;
			pbx_builtin_setvar_helper(chan, "WAITSTATUS", wait_for_silence ? "SILENCE" : "NOISE");
			ast_debug(1, "WAITSTATUS was set to %s\n", wait_for_silence ? "SILENCE" : "NOISE");
			break;
		}

		if (timeout && (difftime(time(&now), waitstart) >= timeout)) {
			pbx_builtin_setvar_helper(chan, "WAITSTATUS", "TIMEOUT");
			ast_debug(1, "WAITSTATUS was set to TIMEOUT\n");
			res = 0;
			break;
		}
	}


	if (rfmt && ast_set_read_format(chan, rfmt)) {
		ast_log(LOG_WARNING, "Unable to restore format %s to channel '%s'\n", ast_getformatname(rfmt), chan->name);
	}
	ast_dsp_free(sildet);
	return res;
}

static int waitfor_exec(struct ast_channel *chan, void *data, int wait_for_silence)
{
	int res = 1;
	int timereqd = 1000;
	int timeout = 0;
	int iterations = 1, i;
	time_t waitstart;

	res = ast_answer(chan); /* Answer the channel */

	if (!data || ( (sscanf(data, "%d,%d,%d", &timereqd, &iterations, &timeout) != 3) &&
		(sscanf(data, "%d,%d", &timereqd, &iterations) != 2) &&
		(sscanf(data, "%d", &timereqd) != 1) ) ) {
		ast_log(LOG_WARNING, "Using default value of 1000ms, 1 iteration, no timeout\n");
	}

	ast_verb(3, "Waiting %d time(s) for %d ms silence with %d timeout\n", iterations, timereqd, timeout);

	time(&waitstart);
	res = 1;
	for (i=0; (i<iterations) && (res == 1); i++) {
		res = do_waiting(chan, timereqd, waitstart, timeout, wait_for_silence);
	}
	if (res > 0)
		res = 0;
	return res;
}

static int waitforsilence_exec(struct ast_channel *chan, void *data)
{
	return waitfor_exec(chan, data, 1);
}

static int waitfornoise_exec(struct ast_channel *chan, void *data)
{
	return waitfor_exec(chan, data, 0);
}

static int unload_module(void)
{
	int res;
	res = ast_unregister_application(app_silence);
	res |= ast_unregister_application(app_noise);

	return res;
}

static int load_module(void)
{
	int res;

	res = ast_register_application(app_silence, waitforsilence_exec, synopsis_silence, descrip_silence);
	res |= ast_register_application(app_noise, waitfornoise_exec, synopsis_noise, descrip_noise);
	return res;
}

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Wait For Silence");