dsp.c has silence detection that works quite well for detecting end-of-voice silence. It is used to allow only a certain amount of silence at the end of voicemails, for instance. See app_voicemail2.c on how to use it, specifically the function play_and_record(). Note that the silence threshold (how sensitive you are to silence) is read in from the voicemail.conf file.
Since the silence detection stuff has a nice public API, you can use it for any app you write. See app_skel.c for a basic "shell", and follow something like app_voicemail2.c. Read in the acceptable values for threshold and so forth from a configuration file (there is a nice Asterisk API for this, also), and you're set. For your purposes (playing a file after detecting silence in a remote voice stream), such an app should be quite simple. Christian On Friday 03 October 2003 10:25, Brad Waite wrote: > Steve, > > I don't have any real experience in DSP methodologies, although I have > picked up on the high-level theories in my research. However, I am *very* > strong-willed in the "Where there's a will, there's a way" category. :) > > Here's my current thought: > > Sphinx is an open source STT library that can work in real-time > (specifically sphinx2). Could we not pipe the called party's audio into it > and then look for a given period of time with no text output? > > I also found this site, > http://www.cs.wpi.edu/~claypool/courses/525-S01/projects/proj1/ where a > prof's got a project for students that fits perfectly with what I'd like to > do. He mentions Rabiner and Sambur's algorithm (from 1975) for detecting > isolated speech endpoints. > > Brad > > Steve Underwood wrote: > > Hi Brad, > > > > If you want to detect that a sound is voice, rather than something else, > > it isn't easy. There is information around on the Internet about > > methods, but I have never tried them and don't know how well they work. > > Unless you have some understanding of DSP I wouldn't bother trying. On > > the other hand, if you do have some DSP expertise it might be a fun > > thing to try. > > > > Regards, > > Steve > > > > Brad Waite wrote: > >> Does anyone know if there's public voice detection algorithms > >> available? I've scoured the net for the last hour or so, and I can't > >> come up with anything except a few proprietary or embedded solutions. > >> > >> I know dsp.c uses goertzel algorithms for DTMF detection, but how does > >> one detect voice? > >> > >> I dunno, maybe detecting voice isn't the way to go. I want to begin > >> playback of a file after a phone/answering machine has answered. > > > > _______________________________________________ > > Asterisk-Users mailing list > > [EMAIL PROTECTED] > > http://lists.digium.com/mailman/listinfo/asterisk-users > > _______________________________________________ > Asterisk-Users mailing list > [EMAIL PROTECTED] > http://lists.digium.com/mailman/listinfo/asterisk-users _______________________________________________ Asterisk-Users mailing list [EMAIL PROTECTED] http://lists.digium.com/mailman/listinfo/asterisk-users
