[Freeswitch-users] VAD and CN question

[Tamas]

Hello,

I've talked about CNG, VAD with Anthony and Brian already but I still
have a mess in it and don't really know how it works.

Could anybody explain the practical side of these magic options?

1. What does suppress_cng=true do exactly? (yep, I know it suppresses
CNG, but what does this mean? Won't send out the CN/8000 rtpmap in SDP?)

2. What do VAD settings do in sofia profile? I've read
http://wiki.freeswitch.org/wiki/Sofia.conf.xml

   <!-- <param name="vad" value="in"/> -->
   <!-- <param name="vad" value="out"/> -->
   <!-- <param name="vad" value="both"/> -->

What do these options do in practice? Can FS detect silence (e.g. no
RTP?) and than what can it do with?

3. I found undocumented options rtp_enable_vad_in, rtp_enable_vad_out
for sofia which might be the per call settings for point 2. ? If this is
correct, what will this do?
            <action application="set" data="rtp_enable_vad_in=true"/>
            <action application="set" data="rtp_enable_vad_out=true"/>
           <action application="bridge" data="sofia/....."/>

4. What will FS do when one side of the bridge supports CN but the other
doesn't?
E.g. softphone->FS->GW (sends CN packets)
the softphone does not support CN
Would it be possible to turn on comfort noise generation in FS for the
side which cannot handle CN?

5. Is it possible to let FS detect silence and on one leg send CN
packets insted of RTP?
E.g. softphone->FS->GW (sends  CN packets)
the softphone does not support CN, but for saving bandwidth it would be
good to have silence detection and in case of silence FS lets send CN
instead of RTP.

Sorry for my dump questions, I would like to understand the whole picture.

I would like to add the clarification to FS wiki to lets other have less
troubles (with endpoints on one side supporting VAD/CNG and endpoints on
other side not supporting VAD/CNG, e.g. CallWeaver)

Thanks in advance!

Regards,
    Tamas