Add comfort noise generation option

[GoogleCodeExporter]

Better yet add slider for level of cng.

Thanks.

Original issue reported on code.google.com by kro...@gmail.com on 14 Aug 2010 at 7:22

[GoogleCodeExporter]

CNG is an option available only in some codecs such as g729 (not sure it's 
available in pjsip, but should be available with speex too).
For now, it's probably automatically activated on codecs that support it (if 
not, should be). But there is not level concept on this point if think that it 
is just a yes/no option. 

So, I have to check which codec can support this, but not sure that if it is 
automatically activated an option is necessary (as far as I know when embedded 
in the codec it's always better to activate it since doesn't require so much 
extra bandwidth and provide a better comfort).

Original comment by r3gis...@gmail.com on 16 Aug 2010 at 10:06

[GoogleCodeExporter]

Not sure codec support is necessary.  One could pump out quiet static to the 
speaker when data is not being received with the relative volume configured in 
the preferences.

Thoughts?

Original comment by kro...@gmail.com on 16 Aug 2010 at 10:10

[GoogleCodeExporter]

My understanding of CNG is that no extra bandwidth is required as it is never 
transmitted.  The client plays static  (rather than sent from the other end) so 
that one can hear that the connection is still active when no data sent due to 
vad.

Original comment by kro...@gmail.com on 16 Aug 2010 at 10:13

[GoogleCodeExporter]

Well, after verification : CNG is linked to the codec capabilities. A CNG on 
CSipSimple side would consume an extra CPU time, I guess that's not really 
needed.
If you are using a codec that support CNG, it will produce a CNG on your side, 
else no (since that's not already coded in the codec and that if the remote 
party doesn't send any sound (VAD), on our side, for now there is no way in 
pjsip to generate some comfort noise if the codec doesn't support it. 

If pjsip guys add this option, I'll integrate it but it's not implemented on 
their side.

Original comment by r3gis...@gmail.com on 17 Oct 2010 at 11:03

• Changed state: Fixed