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  • /*
     * Asterisk -- A telephony toolkit for Linux.
     * 
     * Copyright (C) 1999-2004, Digium, Inc.
     *
     * Mark Spencer <markster@digium.com>
     *
     * Wait for Silence
     *   - Waits for up to 'x' milliseconds of silence, 'y' times
     *   - WaitForSilence(500,2) will wait for 1/2 second of silence, twice
     *   - WaitForSilence(1000,1) will wait for 1 second of silence, once
     *
     * WaitForSilence Application by David C. Troy <dave@popvox.com>
     * Version 1.00 2004-01-29
     *
     * This program is free software, distributed under the terms of
     * the GNU General Public License
     */
    
    #include <asterisk/file.h>
    #include <asterisk/logger.h>
    #include <asterisk/channel.h>
    #include <asterisk/pbx.h>
    #include <asterisk/dsp.h>
    #include <asterisk/module.h>
    #include <asterisk/options.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <string.h>
    #include <pthread.h>
    
    static char *tdesc = "Wait For Silence";
    static char *app = "WaitForSilence";
    static char *synopsis = "Waits for a specified amount of silence";
    static char *descrip = 
    "  WaitForSilence(x[|y]) Wait for Silence: Waits for up to 'x' \n"
    "milliseconds of silence, 'y' times or 1 if omitted\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";
    
    STANDARD_LOCAL_USER;
    
    LOCAL_USER_DECL;
    
    static int do_waiting(struct ast_channel *chan, int duration) {
    
    	struct ast_frame *f;
    	int totalsilence = 0;
    	int dspsilence = 0;
    	int gotsilence = 0; 
    	static int silencethreshold = 64;
    	int rfmt = 0;
    	int res = 0;
    	struct ast_dsp *sildet;	 /* silence detector dsp */
    
    	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 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, silencethreshold);
    
    	/* Await silence... */
    	f = NULL;
    	for(;;) {
    		res = ast_waitfor(chan, 2000);
    		if (!res) {
    			ast_log(LOG_WARNING, "One waitfor failed, trying another\n");
    			/* Try one more time in case of masq */
    			res = ast_waitfor(chan, 2000);
    			if (!res) {
    				ast_log(LOG_WARNING, "No audio available on %s??\n", chan->name);
    				res = -1;
    			}
    		}
    
    		if (res < 0) {
    			f = NULL;
    			break;
    		}
    		f = ast_read(chan);
    		if (!f)
    			break;
    		if (f->frametype == AST_FRAME_VOICE) {
    			dspsilence = 0;
    			ast_dsp_silence(sildet, f, &dspsilence);
    			if (dspsilence)
    				totalsilence = dspsilence;
    			else
    				totalsilence = 0;
    			/* ast_verbose(VERBOSE_PREFIX_3 "dspsilence: %d, totalsilence: %d\n", dspsilence, totalsilence); */
    
    			if (totalsilence >= duration) {
    				ast_verbose(VERBOSE_PREFIX_3 "exiting with %d silence > %d required\n", totalsilence, duration);
    				/* Ended happily with silence */
    				ast_frfree(f);
    				gotsilence = 1;
    				break;
    			}
    		}
    		ast_frfree(f);
    	}
    	ast_dsp_free(sildet);
    	return gotsilence;
    }
    
    static int waitforsilence_exec(struct ast_channel *chan, void *data)
    {
    	int res=1;
    	struct localuser *u;
    	int duration = 1000;
    	int iterations = 1, i;
    
    	res = ast_answer(chan); /* Answer the channel */
    
    	if (!data || ((sscanf(data, "%d|%d", &duration, &iterations) != 2) &&
    
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    		(sscanf(data, "%d", &duration) != 1))) {
    
    		ast_log(LOG_WARNING, "Using default value of 1000ms, 1 iteration\n");
    	}
    
    	ast_verbose(VERBOSE_PREFIX_3 "Waiting %d time(s) for %d ms silence\n", iterations, duration);
    	LOCAL_USER_ADD(u);
    	res = 1;
    	for ( i=0; (i<iterations) && (res == 1); i++) {
    		res = do_waiting(chan, duration);
    	}
    	LOCAL_USER_REMOVE(u);
    	if (res > 0)
    		res = 0;
    	return res;
    }
    
    int unload_module(void)
    {
    	STANDARD_HANGUP_LOCALUSERS;
    	return ast_unregister_application(app);
    }
    
    int load_module(void)
    {
    	return ast_register_application(app, waitforsilence_exec, synopsis, descrip);
    }
    
    char *description(void)
    {
    	return tdesc;
    }
    
    int usecount(void)
    {
    	int res;
    	STANDARD_USECOUNT(res);
    	return res;
    }
    
    char *key()
    {
    	return ASTERISK_GPL_KEY;
    }