[Freeswitch-dev] VAD, TALK and NOTALK events

[KMTDBOURSE]

         Know that

(OSLEC)

pretty well. Wanna test new algorithms but need wav data. Echo Cancel 
is also still under research process, VAD is part of a good echo 
canceller as it freezes the algo processing in case of double-talk. 
Generally a modified Geigel algo or energy based algo are used.

          I have new algorithms and want to test them. Unfortunately, 
I don't have enough data, there are out there very expensive 
databases such as (AURORA...) but don't think they are really 
suitable for my tests.

Zelda



At 01:55 19/02/2008, you wrote:
>KMTDBOURSE wrote:
> > Hi,
> >
> >   Thanks a lot for describing the vad algo it seems rather a basic
> > algo and I am surprised it is not more sophisticated. I hear also from
> > speex users (must be same algo?)  that the vad algo is very poor and
> > should be improved. That is what I am doing, try to improve vad and
> > echo cancellation algorithms. I would appreciate a link where I can
> > find data files (audio) to download on which I can perform tests. Of
> > course I will feedback the freeswitch community in case of improvment.
> >
> > best
> >
> > Zelda
>There is a pretty good free echo canceller at www.rowetel.com, although
>FreeSwitch can't directly use it as it is GPL software. It does,
>however, mean that free and open workable algorithms for robust EC do exist.
>
>VAD is different. It is still a research topic. You can see this from
>the way the VAD algorithms in things like G.729 have been revised over
>the codec's lifetime, as further research has been done. The algorithms
>G.729 and AMR use are encumbered by patents, otherwise cloning them
>would be excellent start. VAD for speech recognition is relatively
>straightforward. When you can buffer the audio, and look forwards and
>backwards in time, it become much easier to identify the start and end
>of voice bursts. It becomes hard when you can only look back in a low
>latency scenario.
>
>Steve
>
>
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