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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Hi,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>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.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Thanks in advance<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Regards<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Rajeev Vats<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
freeswitch-dev-bounces@lists.freeswitch.org
[mailto:freeswitch-dev-bounces@lists.freeswitch.org] <b>On Behalf Of </b>KMTDBOURSE<br>
<b>Sent:</b> Saturday, February 16, 2008 8:18 AM vats<br>
<b>To:</b> freeswitch-dev@lists.freeswitch.org<br>
<b>Subject:</b> Re: [Freeswitch-dev] VAD, TALK and NOTALK events<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='color:blue'>Hi,<br>
<br>
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.<br>
<br>
best<br>
<br>
Zelda<br>
<br>
<br>
<br>
</span>At 15:09 15/02/2008, Anthony Minessale wrote:<br>
<br>
<o:p></o:p></p>
<p class=MsoNormal>The algorithm used is not so great and could stand to be
replaced<br>
by a better one if we get the chance.<br>
<br>
basically we decode the audio to signed linear 16bit samples<br>
for each packet we receive and iterate the samples and add up the<br>
absolute values then compute the average and compare it to the <br>
acceptable level considered "talking" then we use a counter to make<br>
sure it's in the same state several times in a row before actually<br>
changing the status of the channel to talking or not talking.<br>
<br>
<br>
A real vad algorithm would also be able to filter out the voice from<br>
the background noise and judge the energy based only on that.<o:p></o:p></p>
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