Hello, Thanks for guys on IRC channel, now things around VAD/CNG are more clear for me. I've started a wiki documentation about the topic as there is no such page yet and I hope it will be a good startup: http://wiki.freeswitch.org/wiki/VAD_and_CNG I'm aware of that some parts might be inaccurate and even wrong, so bear with me, I just took the time to start document this part. I would like to ask the gurus (anthm, bkw, coppice, etc.) to review the page and correct my mistakes. Thanks! Regards, Tamas Tamas írta:
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