[Freeswitch-dev] VAD, TALK and NOTALK events

[Rajeev Vats]

Hi,

I had been involved on VAD few years back, now I am in the management and
out of coding. But VAD still attracts me, keep me posted on the development.
We had used VAD for "AIR FORCE" whenever the PILOT want to speak to Operator
at nearest Control Tower.

Thanks in advance

Regards

Rajeev Vats

 

From: freeswitch-dev-bounces at lists.freeswitch.org
[mailto:freeswitch-dev-bounces at lists.freeswitch.org] On Behalf Of KMTDBOURSE
Sent: Saturday, February 16, 2008 8:18 AM vats
To: freeswitch-dev at lists.freeswitch.org
Subject: Re: [Freeswitch-dev] VAD, TALK and NOTALK events

 

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



At 15:09 15/02/2008, Anthony Minessale wrote:



The algorithm used is not so great and could stand to be replaced
by a better one if we get the chance.

basically we decode the audio to signed linear 16bit samples
for each packet we receive and iterate the samples and add up the
absolute values then compute the average and compare it to the 
acceptable level considered "talking" then we use a counter to make
sure it's in the same state several times in a row before actually
changing the status of the channel to talking or not talking.


A real vad algorithm would also be able to filter out the voice from
the background noise and judge the energy based only on that.

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