I've created a patch to override the value of MIN_TIME in the vmd modules using a channel variable. In this way, it can be configured on a call by call basis. The channel variable is name "vmd_min_time". I didn't add the other detection parameters, but doing so would be straight forward. So, in our app, we can catch T-Mobile and the other problematic cell carriers beeps. I did this because in our app, we would rather have false positives than miss the start of recording on a voice mail system. This way, anyone using the VMD module can configure the vmd module to be as touchy or hard to trigger as they would like. I not sure how to implement it (at least in the vmd module code), but a way to make mod_vmd more robust to false positives, especially with short beeps would be to have it look for short silence immediately proceeding and/or following the beep. I've noticed that it tends to trigger on noise if there is tone in the noise, if for example I extend a syllable in a word or I have music on in the background. However on a voice mail system there will likely be a short near silence before the tone and an indefinite silence after it. In fact, background noise should be non-existent, except for line noise which should be Gaussian and not look like a structured tone. Looking for a beep + near silence after it for some period should eliminate many false positive where tones are embedded in other sounds (e.g. music or someone holding a vowel for longer than normal). Andrew Index: src/mod/applications/mod_vmd/mod_vmd.c =================================================================== --- src/mod/applications/mod_vmd/mod_vmd.c (revision 15668) +++ src/mod/applications/mod_vmd/mod_vmd.c (working copy) @@ -162,6 +162,8 @@ /*! A count of how long a distinct beep was detected * by the discreet energy separation algorithm. */ switch_size_t timestamp; + /*! The MIN_TIME to use for this call */ + int minTime; } vmd_session_info_t; static switch_bool_t process_data(vmd_session_info_t * vmd_info, switch_frame_t * frame); @@ -312,7 +314,7 @@ if (c < (POINTS - MAX_CHIRP)) { vmd_info->state = BEEP_NOT_DETECTED; - if (vmd_info->timestamp < MIN_TIME) { + if (vmd_info->timestamp < vmd_info->minTime) { break; } @@ -541,6 +543,7 @@ switch_channel_t *channel; vmd_session_info_t *vmd_info; int i; + const char *minTimeString; if (session == NULL) return; @@ -588,6 +591,14 @@ switch_channel_set_private(channel, "_vmd_", bug); + minTimeString = switch_channel_get_variable(channel, "vmd_min_time"); + if (minTimeString != 0) { + sscanf(minTimeString,"%d",&(vmd_info->minTime)); + } else { + vmd_info->minTime = MIN_TIME; + } + + switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_NOTICE, "MIN_TIME for call: %d\n",vmd_info->minTime); } /*! \brief Called when the module shuts down