app_waitforsilence.c

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/*
 * 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
 *
 * \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
 */
 
/*** MODULEINFO
    <support_level>extended</support_level>
 ***/
 
#include "asterisk.h"
 
#include "asterisk/app.h"
#include "asterisk/file.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/dsp.h"
#include "asterisk/module.h"
#include "asterisk/format_cache.h"
 
/*** DOCUMENTATION
    <application name="WaitForSilence" language="en_US">
        <synopsis>
            Waits for a specified amount of silence.
        </synopsis>
        <syntax>
            <parameter name="silencerequired">
                <para>If not specified, defaults to <literal>1000</literal> milliseconds.</para>
            </parameter>
            <parameter name="iterations">
                <para>If not specified, defaults to <literal>1</literal>.</para>
            </parameter>
            <parameter name="timeout">
                <para>Is specified only to avoid an infinite loop in cases where silence is never achieved.</para>
            </parameter>
        </syntax>
        <description>
            <para>Waits for up to <replaceable>silencerequired</replaceable> milliseconds of silence,
            <replaceable>iterations</replaceable> times. An optional <replaceable>timeout</replaceable>
            specified the number of seconds to return after, even if we do not receive the specified amount of silence.
            Use <replaceable>timeout</replaceable> with caution, as it may defeat the purpose of this application, which
            is to wait indefinitely until silence is detected on the line. This is particularly useful for reverse-911-type
            call broadcast applications where you need to wait for an answering machine to complete its spiel before
            playing a message.</para>
            <para>Typically you will want to include two or more calls to WaitForSilence when dealing with an answering
            machine; first waiting for the spiel to finish, then waiting for the beep, etc.</para>
            <example title="Wait for half a second of silence, twice">
            same => n,WaitForSilence(500,2)
            </example>
            <example title="Wait for one second of silence, once">
            same => n,WaitForSilence(1000)
            </example>
            <example title="Wait for 300 ms of silence, 3 times, and returns after 10 seconds, even if no silence detected">
            same => n,WaitForSilence(300,3,10)
            </example>
            <para>Sets the channel variable <variable>WAITSTATUS</variable> to one of these values:</para>
            <variablelist>
                <variable name="WAITSTATUS">
                    <value name="SILENCE">
                        if exited with silence detected.
                    </value>
                    <value name="TIMEOUT">
                        if exited without silence detected after timeout.
                    </value>
                </variable>
            </variablelist>
        </description>
        <see-also>
            <ref type="application">WaitForNoise</ref>
        </see-also>
    </application>
    <application name="WaitForNoise" language="en_US">
        <synopsis>
            Waits for a specified amount of noise.
        </synopsis>
        <syntax>
            <parameter name="noiserequired">
                <para>If not specified, defaults to <literal>1000</literal> milliseconds.</para>
            </parameter>
            <parameter name="iterations">
                <para>If not specified, defaults to <literal>1</literal>.</para>
            </parameter>
            <parameter name="timeout">
                <para>Is specified only to avoid an infinite loop in cases where silence is never achieved.</para>
            </parameter>
        </syntax>
        <description>
            <para>Waits for up to <replaceable>noiserequired</replaceable> milliseconds of noise,
            <replaceable>iterations</replaceable> times. An optional <replaceable>timeout</replaceable>
            specified the number of seconds to return after, even if we do not receive the specified amount of noise.
            Use <replaceable>timeout</replaceable> with caution, as it may defeat the purpose of this application, which
            is to wait indefinitely until noise is detected on the line.</para>
        </description>
        <see-also>
            <ref type="application">WaitForSilence</ref>
        </see-also>
    </application>
 ***/
 
static char *app_silence = "WaitForSilence";
static char *app_noise = "WaitForNoise";
 
struct wait_type {
    const char *name;
    const char *status;
    int stop_on_frame_timeout;
    int (*func)(struct ast_dsp *, struct ast_frame *, int *);
};
 
static const struct wait_type wait_for_silence = {
    .name = "silence",
    .status = "SILENCE",
    .stop_on_frame_timeout = 1,
    .func = ast_dsp_silence,
};
 
static const struct wait_type wait_for_noise = {
    .name = "noise",
    .status = "NOISE",
    .stop_on_frame_timeout = 0,
    .func = ast_dsp_noise,
};
 
static int do_waiting(struct ast_channel *chan, int timereqd, time_t waitstart, int timeout, const struct wait_type *wait_for)
{
    RAII_VAR(struct ast_format *, rfmt, NULL, ao2_cleanup);
    int res;
    struct ast_dsp *sildet;
 
    rfmt = ao2_bump(ast_channel_readformat(chan));
    if ((res = ast_set_read_format(chan, ast_format_slin)) < 0) {
        ast_log(LOG_WARNING, "Unable to set channel to linear mode, giving up\n");
        return -1;
    }
 
    /* Create the silence detector */
    if (!(sildet = ast_dsp_new())) {
        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));
 
    for (;;) {
        int dsptime = 0;
 
        res = ast_waitfor(chan, timereqd);
 
        /* Must have gotten a hangup; let's exit */
        if (res < 0) {
            pbx_builtin_setvar_helper(chan, "WAITSTATUS", "HANGUP");
            break;
        }
 
        /* We waited and got no frame; sounds like digital silence or a muted digital channel */
        if (res == 0) {
            if (wait_for->stop_on_frame_timeout) {
                dsptime = timereqd;
            }
        } else {
            /* Looks like we did get a frame, so let's check it out */
            struct ast_frame *f = ast_read(chan);
            if (!f) {
                pbx_builtin_setvar_helper(chan, "WAITSTATUS", "HANGUP");
                break;
            }
            if (f->frametype == AST_FRAME_VOICE) {
                wait_for->func(sildet, f, &dsptime);
            }
            ast_frfree(f);
        }
 
        ast_debug(1, "Got %dms of %s < %dms required\n", dsptime, wait_for->name, timereqd);
 
        if (dsptime >= timereqd) {
            ast_verb(3, "Exiting with %dms of %s >= %dms required\n", dsptime, wait_for->name, timereqd);
            pbx_builtin_setvar_helper(chan, "WAITSTATUS", wait_for->status);
            ast_debug(1, "WAITSTATUS was set to %s\n", wait_for->status);
            res = 1;
            break;
        }
 
        if (timeout && difftime(time(NULL), 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_format_get_name(rfmt), ast_channel_name(chan));
    }
 
    ast_dsp_free(sildet);
    return res;
}
 
static int waitfor_exec(struct ast_channel *chan, const char *data, const struct wait_type *wait_for)
{
    int res = 1;
    int timereqd = 1000;
    int timeout = 0;
    int iterations = 1, i;
    time_t waitstart;
    char *parse;
    struct ast_silence_generator *silgen = NULL;
 
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(timereqd);
        AST_APP_ARG(iterations);
        AST_APP_ARG(timeout);
    );
 
    parse = ast_strdupa(data);
    AST_STANDARD_APP_ARGS(args, parse);
 
    if (!ast_strlen_zero(args.timereqd)) {
        if (sscanf(args.timereqd, "%30d", &timereqd) != 1 || timereqd < 0) {
            ast_log(LOG_ERROR, "Argument '%srequired' must be an integer greater than or equal to zero.\n",
                    wait_for->name);
            return -1;
        }
    }
 
    if (!ast_strlen_zero(args.iterations)) {
        if (sscanf(args.iterations, "%30d", &iterations) != 1 || iterations < 1) {
            ast_log(LOG_ERROR, "Argument 'iterations' must be an integer greater than 0.\n");
            return -1;
        }
    }
 
    if (!ast_strlen_zero(args.timeout)) {
        if (sscanf(args.timeout, "%30d", &timeout) != 1 || timeout < 0) {
            ast_log(LOG_ERROR, "Argument 'timeout' must be an integer greater than or equal to zero.\n");
            return -1;
        }
    }
 
    if (ast_channel_state(chan) != AST_STATE_UP) {
        ast_answer(chan); /* Answer the channel */
    }
 
    ast_verb(3, "Waiting %d time(s) for %dms of %s with %ds timeout\n",
             iterations, timereqd, wait_for->name, timeout);
 
    if (ast_opt_transmit_silence) {
        silgen = ast_channel_start_silence_generator(chan);
    }
 
    time(&waitstart);
    for (i = 0; i < iterations && res == 1; i++) {
        res = do_waiting(chan, timereqd, waitstart, timeout, wait_for);
    }
 
    if (silgen) {
        ast_channel_stop_silence_generator(chan, silgen);
    }
 
    return res > 0 ? 0 : res;
}
 
static int waitforsilence_exec(struct ast_channel *chan, const char *data)
{
    return waitfor_exec(chan, data, &wait_for_silence);
}
 
static int waitfornoise_exec(struct ast_channel *chan, const char *data)
{
    return waitfor_exec(chan, data, &wait_for_noise);
}
 
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_xml(app_silence, waitforsilence_exec);
    res |= ast_register_application_xml(app_noise, waitfornoise_exec);
    return res;
}
 
AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "Wait For Silence/Noise");