Yes, you can use it independently by using speex_preprocess(). This function can do noise removal, AGC, and VAD. I've been using it to do all three and it usually works very well. There can be a train going by outside, producing lots of sound that makes it through the noise filter, and yet the VAD knows it's not speech. However, sometimes the VAD seems to get into a bad state and will either always indicate speech (even when the input is very nearly silent) or rarely indicate it such that the person has to shout to be heard. When this happens, it never recovers, and I have to destroy and recreate the state to fix it. I don't know what could be wrong... it probably works fine for everyone else... Also, be aware that there are probabilities that can be tweaked to alter the sensitivity of the VAD, as described in this post to the list awhile ago: At 06:37 AM 5/18/2004, Steve Kann wrote:>I don't seem to get that; I suppose you've already changed the thresholds >to make things more sensitive though: > >This is what I have now in iaxclient; the first number is the "initial" >probability to go from not speech -> speech. The second is to go from >speech -> not speech. [the difference implements hysteresis]. > >/* if (st->speech_prob> .35 || (st->last_speech < 20 && >st->speech_prob>.1)) */ > if (st->speech_prob> .30 || (st->last_speech < 20 && > st->speech_prob>.07))Might be helpful for you. Tom Joachim Boomberschloss <boomberschloss@yahoo.com> wrote:> > Hello, > > I am wondering whether Speex's voice activity > detection mechanism can be used independently of > encoding and decoding speech, and how reliable it is > in general. I need this kind of functionality for a > project I am working on, and I was wondering if Speex > provides it in a ready-to-use fashion, or if it > requires modification of the source code. If so, I > would be glad to consider doing this work for the > benefit of others with some guidance (depending on > complexity and usefulness). > > Thanks, > > Joe.
Thanks Tom and Steve. Your replies make me quite happy. It is strange that this information is not available anywhere other than this list! Joe ;) --- Tom Grandgent <tgrand@canvaslink.com> wrote:> Yes, you can use it independently by using > speex_preprocess(). > This function can do noise removal, AGC, and VAD. > I've been > using it to do all three and it usually works very > well. There > can be a train going by outside, producing lots of > sound that > makes it through the noise filter, and yet the VAD > knows it's > not speech. > > However, sometimes the VAD seems to get into a bad > state and > will either always indicate speech (even when the > input is > very nearly silent) or rarely indicate it such that > the person > has to shout to be heard. When this happens, it > never recovers, > and I have to destroy and recreate the state to fix > it. I don't > know what could be wrong... it probably works fine > for everyone > else... > > Also, be aware that there are probabilities that can > be tweaked > to alter the sensitivity of the VAD, as described in > this post > to the list awhile ago: > > At 06:37 AM 5/18/2004, Steve Kann wrote: > >I don't seem to get that; I suppose you've already > changed the thresholds > >to make things more sensitive though: > > > >This is what I have now in iaxclient; the first > number is the "initial" > >probability to go from not speech -> speech. The > second is to go from > >speech -> not speech. [the difference implements > hysteresis]. > > > >/* if (st->speech_prob> .35 || > (st->last_speech < 20 && > >st->speech_prob>.1)) */ > > if (st->speech_prob> .30 || (st->last_speech > < 20 && > > st->speech_prob>.07)) > > Might be helpful for you. > > Tom > > Joachim Boomberschloss <boomberschloss@yahoo.com> > wrote: > > > > Hello, > > > > I am wondering whether Speex's voice activity > > detection mechanism can be used independently of > > encoding and decoding speech, and how reliable it > is > > in general. I need this kind of functionality for > a > > project I am working on, and I was wondering if > Speex > > provides it in a ready-to-use fashion, or if it > > requires modification of the source code. If so, I > > would be glad to consider doing this work for the > > benefit of others with some guidance (depending on > > complexity and usefulness). > > > > Thanks, > > > > Joe. > >__________________________________ Do you Yahoo!? All your favorites on one personal page – Try My Yahoo! http://my.yahoo.com