Answering machine detection. More...

#include "asterisk.h"
#include "asterisk/module.h"
#include "asterisk/lock.h"
#include "asterisk/channel.h"
#include "asterisk/dsp.h"
#include "asterisk/pbx.h"
#include "asterisk/config.h"
#include "asterisk/app.h"

Include dependency graph for app_amd.c:

Go to the source code of this file.

Defines
#define	STATE_IN_SILENCE 2
#define	STATE_IN_WORD 1
Functions
static void	__reg_module (void)
static void	__unreg_module (void)
static int	amd_exec (struct ast_channel chan, const char data)
static void	isAnsweringMachine (struct ast_channel chan, const char data)
static int	load_config (int reload)
static int	load_module (void)
static int	reload (void)
static int	unload_module (void)
Variables
static struct ast_module_info	__mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "Answering Machine Detection Application" , .key = "This paragraph is copyright (c) 2006 by Digium, Inc. \In order for your module to load, it must return this \key via a function called \"key\". Any code which \includes this paragraph must be licensed under the GNU \General Public License version 2 or later (at your \option). In addition to Digium's general reservations \of rights, Digium expressly reserves the right to \allow other parties to license this paragraph under \different terms. Any use of Digium, Inc. trademarks or \logos (including \"Asterisk\" or \"Digium\") without \express written permission of Digium, Inc. is prohibited.\n" , .buildopt_sum = AST_BUILDOPT_SUM, .load = load_module, .unload = unload_module, .reload = reload, }
static const char	app [] = "AMD"
static struct ast_module_info *	ast_module_info = &__mod_info
static int	dfltAfterGreetingSilence = 800
static int	dfltBetweenWordsSilence = 50
static int	dfltGreeting = 1500
static int	dfltInitialSilence = 2500
static int	dfltMaximumNumberOfWords = 3
static int	dfltMaximumWordLength = 5000
static int	dfltMaxWaitTimeForFrame = 50
static int	dfltMinimumWordLength = 100
static int	dfltSilenceThreshold = 256
static int	dfltTotalAnalysisTime = 5000

Detailed Description

Answering machine detection.

Author:: Claude Klimos (claude.klimos@aheeva.com)

Definition in file app_amd.c.

Define Documentation

#define STATE_IN_SILENCE 2

Definition at line 133 of file app_amd.c.

Referenced by isAnsweringMachine().

#define STATE_IN_WORD 1

Definition at line 132 of file app_amd.c.

Referenced by isAnsweringMachine().

Function Documentation

static void __reg_module ( void ) [static]

Definition at line 510 of file app_amd.c.

static void __unreg_module ( void ) [static]

Definition at line 510 of file app_amd.c.

static int amd_exec	(	struct ast_channel *	chan,
		const char *	data
	)		`[static]`

Definition at line 414 of file app_amd.c.

References isAnsweringMachine().

Referenced by load_module().

{
   isAnsweringMachine(chan, data);

   return 0;
}

static void isAnsweringMachine	(	struct ast_channel *	chan,
		const char *	data
	)		`[static]`

Definition at line 149 of file app_amd.c.

References args, AST_APP_ARG, ast_channel_caller(), ast_channel_name(), ast_channel_readformat(), ast_channel_redirecting(), ast_codec_get_samples(), ast_debug, AST_DECLARE_APP_ARGS, ast_dsp_free(), ast_dsp_new(), ast_dsp_set_threshold(), ast_dsp_silence(), ast_format_clear(), ast_format_copy(), AST_FORMAT_SLINEAR, AST_FRAME_CNG, AST_FRAME_NULL, AST_FRAME_VOICE, ast_frfree, ast_getformatname(), ast_log(), ast_read(), ast_set_read_format(), ast_set_read_format_by_id(), AST_STANDARD_APP_ARGS, ast_strlen_zero(), ast_verb, ast_waitfor(), DEFAULT_SAMPLES_PER_MS, dfltAfterGreetingSilence, dfltBetweenWordsSilence, dfltGreeting, dfltInitialSilence, dfltMaximumNumberOfWords, dfltMaximumWordLength, dfltMaxWaitTimeForFrame, dfltMinimumWordLength, dfltSilenceThreshold, dfltTotalAnalysisTime, f, ast_frame::frametype, ast_format::id, LOG_WARNING, parse(), pbx_builtin_setvar_helper(), S_COR, STATE_IN_SILENCE, and STATE_IN_WORD.

Referenced by amd_exec().

{
   int res = 0;
   struct ast_frame *f = NULL;
   struct ast_dsp *silenceDetector = NULL;
   int dspsilence = 0, framelength = 0;
   struct ast_format readFormat;
   int inInitialSilence = 1;
   int inGreeting = 0;
   int voiceDuration = 0;
   int silenceDuration = 0;
   int iTotalTime = 0;
   int iWordsCount = 0;
   int currentState = STATE_IN_WORD;
   int consecutiveVoiceDuration = 0;
   char amdCause[256] = "", amdStatus[256] = "";
   char *parse = ast_strdupa(data);

   /* Lets set the initial values of the variables that will control the algorithm.
      The initial values are the default ones. If they are passed as arguments
      when invoking the application, then the default values will be overwritten
      by the ones passed as parameters. */
   int initialSilence       = dfltInitialSilence;
   int greeting             = dfltGreeting;
   int afterGreetingSilence = dfltAfterGreetingSilence;
   int totalAnalysisTime    = dfltTotalAnalysisTime;
   int minimumWordLength    = dfltMinimumWordLength;
   int betweenWordsSilence  = dfltBetweenWordsSilence;
   int maximumNumberOfWords = dfltMaximumNumberOfWords;
   int silenceThreshold     = dfltSilenceThreshold;
   int maximumWordLength    = dfltMaximumWordLength;
   int maxWaitTimeForFrame  = dfltMaxWaitTimeForFrame;

   AST_DECLARE_APP_ARGS(args,
      AST_APP_ARG(argInitialSilence);
      AST_APP_ARG(argGreeting);
      AST_APP_ARG(argAfterGreetingSilence);
      AST_APP_ARG(argTotalAnalysisTime);
      AST_APP_ARG(argMinimumWordLength);
      AST_APP_ARG(argBetweenWordsSilence);
      AST_APP_ARG(argMaximumNumberOfWords);
      AST_APP_ARG(argSilenceThreshold);
      AST_APP_ARG(argMaximumWordLength);
   );

   ast_format_clear(&readFormat);
   ast_verb(3, "AMD: %s %s %s (Fmt: %s)\n", ast_channel_name(chan),
      S_COR(ast_channel_caller(chan)->ani.number.valid, ast_channel_caller(chan)->ani.number.str, "(N/A)"),
      S_COR(ast_channel_redirecting(chan)->from.number.valid, ast_channel_redirecting(chan)->from.number.str, "(N/A)"),
      ast_getformatname(ast_channel_readformat(chan)));

   /* Lets parse the arguments. */
   if (!ast_strlen_zero(parse)) {
      /* Some arguments have been passed. Lets parse them and overwrite the defaults. */
      AST_STANDARD_APP_ARGS(args, parse);
      if (!ast_strlen_zero(args.argInitialSilence))
         initialSilence = atoi(args.argInitialSilence);
      if (!ast_strlen_zero(args.argGreeting))
         greeting = atoi(args.argGreeting);
      if (!ast_strlen_zero(args.argAfterGreetingSilence))
         afterGreetingSilence = atoi(args.argAfterGreetingSilence);
      if (!ast_strlen_zero(args.argTotalAnalysisTime))
         totalAnalysisTime = atoi(args.argTotalAnalysisTime);
      if (!ast_strlen_zero(args.argMinimumWordLength))
         minimumWordLength = atoi(args.argMinimumWordLength);
      if (!ast_strlen_zero(args.argBetweenWordsSilence))
         betweenWordsSilence = atoi(args.argBetweenWordsSilence);
      if (!ast_strlen_zero(args.argMaximumNumberOfWords))
         maximumNumberOfWords = atoi(args.argMaximumNumberOfWords);
      if (!ast_strlen_zero(args.argSilenceThreshold))
         silenceThreshold = atoi(args.argSilenceThreshold);
      if (!ast_strlen_zero(args.argMaximumWordLength))
         maximumWordLength = atoi(args.argMaximumWordLength);
   } else {
      ast_debug(1, "AMD using the default parameters.\n");
   }

   /* Find lowest ms value, that will be max wait time for a frame */
   if (maxWaitTimeForFrame > initialSilence)
      maxWaitTimeForFrame = initialSilence;
   if (maxWaitTimeForFrame > greeting)
      maxWaitTimeForFrame = greeting;
   if (maxWaitTimeForFrame > afterGreetingSilence)
      maxWaitTimeForFrame = afterGreetingSilence;
   if (maxWaitTimeForFrame > totalAnalysisTime)
      maxWaitTimeForFrame = totalAnalysisTime;
   if (maxWaitTimeForFrame > minimumWordLength)
      maxWaitTimeForFrame = minimumWordLength;
   if (maxWaitTimeForFrame > betweenWordsSilence)
      maxWaitTimeForFrame = betweenWordsSilence;

   /* Now we're ready to roll! */
   ast_verb(3, "AMD: initialSilence [%d] greeting [%d] afterGreetingSilence [%d] "
      "totalAnalysisTime [%d] minimumWordLength [%d] betweenWordsSilence [%d] maximumNumberOfWords [%d] silenceThreshold [%d] maximumWordLength [%d] \n",
            initialSilence, greeting, afterGreetingSilence, totalAnalysisTime,
            minimumWordLength, betweenWordsSilence, maximumNumberOfWords, silenceThreshold, maximumWordLength);

   /* Set read format to signed linear so we get signed linear frames in */
   ast_format_copy(&readFormat, ast_channel_readformat(chan));
   if (ast_set_read_format_by_id(chan, AST_FORMAT_SLINEAR) < 0 ) {
      ast_log(LOG_WARNING, "AMD: Channel [%s]. Unable to set to linear mode, giving up\n", ast_channel_name(chan));
      pbx_builtin_setvar_helper(chan , "AMDSTATUS", "");
      pbx_builtin_setvar_helper(chan , "AMDCAUSE", "");
      return;
   }

   /* Create a new DSP that will detect the silence */
   if (!(silenceDetector = ast_dsp_new())) {
      ast_log(LOG_WARNING, "AMD: Channel [%s]. Unable to create silence detector :(\n", ast_channel_name(chan));
      pbx_builtin_setvar_helper(chan , "AMDSTATUS", "");
      pbx_builtin_setvar_helper(chan , "AMDCAUSE", "");
      return;
   }

   /* Set silence threshold to specified value */
   ast_dsp_set_threshold(silenceDetector, silenceThreshold);

   /* Now we go into a loop waiting for frames from the channel */
   while ((res = ast_waitfor(chan, 2 * maxWaitTimeForFrame)) > -1) {

      /* If we fail to read in a frame, that means they hung up */
      if (!(f = ast_read(chan))) {
         ast_verb(3, "AMD: Channel [%s]. HANGUP\n", ast_channel_name(chan));
         ast_debug(1, "Got hangup\n");
         strcpy(amdStatus, "HANGUP");
         res = 1;
         break;
      }

      if (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_NULL || f->frametype == AST_FRAME_CNG) {
         /* If the total time exceeds the analysis time then give up as we are not too sure */
         if (f->frametype == AST_FRAME_VOICE) {
            framelength = (ast_codec_get_samples(f) / DEFAULT_SAMPLES_PER_MS);
         } else {
            framelength = 2 * maxWaitTimeForFrame;
         }

         iTotalTime += framelength;
         if (iTotalTime >= totalAnalysisTime) {
            ast_verb(3, "AMD: Channel [%s]. Too long...\n", ast_channel_name(chan));
            ast_frfree(f);
            strcpy(amdStatus , "NOTSURE");
            sprintf(amdCause , "TOOLONG-%d", iTotalTime);
            break;
         }

         /* Feed the frame of audio into the silence detector and see if we get a result */
         if (f->frametype != AST_FRAME_VOICE)
            dspsilence += 2 * maxWaitTimeForFrame;
         else {
            dspsilence = 0;
            ast_dsp_silence(silenceDetector, f, &dspsilence);
         }

         if (dspsilence > 0) {
            silenceDuration = dspsilence;
            
            if (silenceDuration >= betweenWordsSilence) {
               if (currentState != STATE_IN_SILENCE ) {
                  ast_verb(3, "AMD: Channel [%s]. Changed state to STATE_IN_SILENCE\n", ast_channel_name(chan));
               }
               /* Find words less than word duration */
               if (consecutiveVoiceDuration < minimumWordLength && consecutiveVoiceDuration > 0){
                  ast_verb(3, "AMD: Channel [%s]. Short Word Duration: %d\n", ast_channel_name(chan), consecutiveVoiceDuration);
               }
               currentState  = STATE_IN_SILENCE;
               consecutiveVoiceDuration = 0;
            }

            if (inInitialSilence == 1  && silenceDuration >= initialSilence) {
               ast_verb(3, "AMD: Channel [%s]. ANSWERING MACHINE: silenceDuration:%d initialSilence:%d\n",
                  ast_channel_name(chan), silenceDuration, initialSilence);
               ast_frfree(f);
               strcpy(amdStatus , "MACHINE");
               sprintf(amdCause , "INITIALSILENCE-%d-%d", silenceDuration, initialSilence);
               res = 1;
               break;
            }
            
            if (silenceDuration >= afterGreetingSilence  &&  inGreeting == 1) {
               ast_verb(3, "AMD: Channel [%s]. HUMAN: silenceDuration:%d afterGreetingSilence:%d\n",
                  ast_channel_name(chan), silenceDuration, afterGreetingSilence);
               ast_frfree(f);
               strcpy(amdStatus , "HUMAN");
               sprintf(amdCause , "HUMAN-%d-%d", silenceDuration, afterGreetingSilence);
               res = 1;
               break;
            }
            
         } else {
            consecutiveVoiceDuration += framelength;
            voiceDuration += framelength;

            /* If I have enough consecutive voice to say that I am in a Word, I can only increment the
               number of words if my previous state was Silence, which means that I moved into a word. */
            if (consecutiveVoiceDuration >= minimumWordLength && currentState == STATE_IN_SILENCE) {
               iWordsCount++;
               ast_verb(3, "AMD: Channel [%s]. Word detected. iWordsCount:%d\n", ast_channel_name(chan), iWordsCount);
               currentState = STATE_IN_WORD;
            }
            if (consecutiveVoiceDuration >= maximumWordLength){
               ast_verb(3, "AMD: Channel [%s]. Maximum Word Length detected. [%d]\n", ast_channel_name(chan), consecutiveVoiceDuration);
               ast_frfree(f);
               strcpy(amdStatus , "MACHINE");
               sprintf(amdCause , "MAXWORDLENGTH-%d", consecutiveVoiceDuration);
               break;
            }
            if (iWordsCount >= maximumNumberOfWords) {
               ast_verb(3, "AMD: Channel [%s]. ANSWERING MACHINE: iWordsCount:%d\n", ast_channel_name(chan), iWordsCount);
               ast_frfree(f);
               strcpy(amdStatus , "MACHINE");
               sprintf(amdCause , "MAXWORDS-%d-%d", iWordsCount, maximumNumberOfWords);
               res = 1;
               break;
            }

            if (inGreeting == 1 && voiceDuration >= greeting) {
               ast_verb(3, "AMD: Channel [%s]. ANSWERING MACHINE: voiceDuration:%d greeting:%d\n", ast_channel_name(chan), voiceDuration, greeting);
               ast_frfree(f);
               strcpy(amdStatus , "MACHINE");
               sprintf(amdCause , "LONGGREETING-%d-%d", voiceDuration, greeting);
               res = 1;
               break;
            }

            if (voiceDuration >= minimumWordLength ) {
               if (silenceDuration > 0)
                  ast_verb(3, "AMD: Channel [%s]. Detected Talk, previous silence duration: %d\n", ast_channel_name(chan), silenceDuration);
               silenceDuration = 0;
            }
            if (consecutiveVoiceDuration >= minimumWordLength && inGreeting == 0) {
               /* Only go in here once to change the greeting flag when we detect the 1st word */
               if (silenceDuration > 0)
                  ast_verb(3, "AMD: Channel [%s]. Before Greeting Time:  silenceDuration: %d voiceDuration: %d\n", ast_channel_name(chan), silenceDuration, voiceDuration);
               inInitialSilence = 0;
               inGreeting = 1;
            }
            
         }
      }
      ast_frfree(f);
   }
   
   if (!res) {
      /* It took too long to get a frame back. Giving up. */
      ast_verb(3, "AMD: Channel [%s]. Too long...\n", ast_channel_name(chan));
      strcpy(amdStatus , "NOTSURE");
      sprintf(amdCause , "TOOLONG-%d", iTotalTime);
   }

   /* Set the status and cause on the channel */
   pbx_builtin_setvar_helper(chan , "AMDSTATUS" , amdStatus);
   pbx_builtin_setvar_helper(chan , "AMDCAUSE" , amdCause);

   /* Restore channel read format */
   if (readFormat.id && ast_set_read_format(chan, &readFormat))
      ast_log(LOG_WARNING, "AMD: Unable to restore read format on '%s'\n", ast_channel_name(chan));

   /* Free the DSP used to detect silence */
   ast_dsp_free(silenceDetector);

   return;
}

static int load_config ( int reload ) [static]

Definition at line 421 of file app_amd.c.

References ast_category_browse(), ast_config_destroy(), ast_config_load, ast_dsp_get_threshold_from_settings(), ast_log(), ast_variable_browse(), ast_verb, CONFIG_FLAG_FILEUNCHANGED, CONFIG_STATUS_FILEINVALID, CONFIG_STATUS_FILEUNCHANGED, ast_variable::lineno, LOG_ERROR, LOG_WARNING, ast_variable::name, ast_variable::next, THRESHOLD_SILENCE, ast_variable::value, and var.

Referenced by load_module(), and reload().

{
   struct ast_config *cfg = NULL;
   char *cat = NULL;
   struct ast_variable *var = NULL;
   struct ast_flags config_flags = { reload ? CONFIG_FLAG_FILEUNCHANGED : 0 };

   dfltSilenceThreshold = ast_dsp_get_threshold_from_settings(THRESHOLD_SILENCE);

   if (!(cfg = ast_config_load("amd.conf", config_flags))) {
      ast_log(LOG_ERROR, "Configuration file amd.conf missing.\n");
      return -1;
   } else if (cfg == CONFIG_STATUS_FILEUNCHANGED) {
      return 0;
   } else if (cfg == CONFIG_STATUS_FILEINVALID) {
      ast_log(LOG_ERROR, "Config file amd.conf is in an invalid format.  Aborting.\n");
      return -1;
   }

   cat = ast_category_browse(cfg, NULL);

   while (cat) {
      if (!strcasecmp(cat, "general") ) {
         var = ast_variable_browse(cfg, cat);
         while (var) {
            if (!strcasecmp(var->name, "initial_silence")) {
               dfltInitialSilence = atoi(var->value);
            } else if (!strcasecmp(var->name, "greeting")) {
               dfltGreeting = atoi(var->value);
            } else if (!strcasecmp(var->name, "after_greeting_silence")) {
               dfltAfterGreetingSilence = atoi(var->value);
            } else if (!strcasecmp(var->name, "silence_threshold")) {
               dfltSilenceThreshold = atoi(var->value);
            } else if (!strcasecmp(var->name, "total_analysis_time")) {
               dfltTotalAnalysisTime = atoi(var->value);
            } else if (!strcasecmp(var->name, "min_word_length")) {
               dfltMinimumWordLength = atoi(var->value);
            } else if (!strcasecmp(var->name, "between_words_silence")) {
               dfltBetweenWordsSilence = atoi(var->value);
            } else if (!strcasecmp(var->name, "maximum_number_of_words")) {
               dfltMaximumNumberOfWords = atoi(var->value);
            } else if (!strcasecmp(var->name, "maximum_word_length")) {
               dfltMaximumWordLength = atoi(var->value);

            } else {
               ast_log(LOG_WARNING, "%s: Cat:%s. Unknown keyword %s at line %d of amd.conf\n",
                  app, cat, var->name, var->lineno);
            }
            var = var->next;
         }
      }
      cat = ast_category_browse(cfg, cat);
   }

   ast_config_destroy(cfg);

   ast_verb(3, "AMD defaults: initialSilence [%d] greeting [%d] afterGreetingSilence [%d] "
      "totalAnalysisTime [%d] minimumWordLength [%d] betweenWordsSilence [%d] maximumNumberOfWords [%d] silenceThreshold [%d] maximumWordLength [%d]\n",
      dfltInitialSilence, dfltGreeting, dfltAfterGreetingSilence, dfltTotalAnalysisTime,
      dfltMinimumWordLength, dfltBetweenWordsSilence, dfltMaximumNumberOfWords, dfltSilenceThreshold, dfltMaximumWordLength);

   return 0;
}

static int load_module ( void ) [static]

Definition at line 490 of file app_amd.c.

References amd_exec(), AST_MODULE_LOAD_DECLINE, AST_MODULE_LOAD_FAILURE, AST_MODULE_LOAD_SUCCESS, ast_register_application_xml, and load_config().

{
   if (load_config(0))
      return AST_MODULE_LOAD_DECLINE;
   if (ast_register_application_xml(app, amd_exec))
      return AST_MODULE_LOAD_FAILURE;
   return AST_MODULE_LOAD_SUCCESS;
}

static int reload ( void ) [static]

Definition at line 499 of file app_amd.c.

References AST_MODULE_LOAD_DECLINE, AST_MODULE_LOAD_SUCCESS, and load_config().

{
   if (load_config(1))
      return AST_MODULE_LOAD_DECLINE;
   return AST_MODULE_LOAD_SUCCESS;
}

static int unload_module ( void ) [static]

Definition at line 485 of file app_amd.c.

References ast_unregister_application().

{
   return ast_unregister_application(app);
}

Variable Documentation

struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "Answering Machine Detection Application" , .key = "This paragraph is copyright (c) 2006 by Digium, Inc. \In order for your module to load, it must return this \key via a function called \"key\". Any code which \includes this paragraph must be licensed under the GNU \General Public License version 2 or later (at your \option). In addition to Digium's general reservations \of rights, Digium expressly reserves the right to \allow other parties to license this paragraph under \different terms. Any use of Digium, Inc. trademarks or \logos (including \"Asterisk\" or \"Digium\") without \express written permission of Digium, Inc. is prohibited.\n" , .buildopt_sum = AST_BUILDOPT_SUM, .load = load_module, .unload = unload_module, .reload = reload, } [static]

Definition at line 510 of file app_amd.c.

const char app[] = "AMD" [static]

Definition at line 130 of file app_amd.c.

struct ast_module_info* ast_module_info = &__mod_info [static]

Definition at line 510 of file app_amd.c.

int dfltAfterGreetingSilence = 800 [static]

Definition at line 138 of file app_amd.c.

Referenced by isAnsweringMachine().

int dfltBetweenWordsSilence = 50 [static]

Definition at line 141 of file app_amd.c.

Referenced by isAnsweringMachine().

int dfltGreeting = 1500 [static]