G723 codec and VAD support

[croberts2]

I'm finding with testing that only when codec G723ar53/63 is used does VAD work. When G723r53/63 is used, VAD does not work. Why is this??? VAD is on by default on Cisco gateways, so shouldn't it work with any codec??

[ssymes]

If you look at the spec for the AR versions of g723.1 one of the additions is inbuilt support of silence supression within the codec itself. This may be why you are seeing this behaviour

[croberts2]

If you could point me to the specs for that codec that would be helpful. In addition, during subsequent testing, it appears VAD DOES work sometimes w/ G723r53/63 (non-annex A). Another Cisco engineer has indicated that VAD will work w/ other than Annex A codec with "special configuration changes on VoIP gateway". I've asked them to clarify that for me. Do you (or anyone else on the forum) know of anything like this? All documentation links are greatly appreciated around this considering that CCO docs are limited and contridictary on this subject.

Thank you!

[msolak]

Hi,

hope this helps.

http://www.cisco.com/warp/public/788/voip/codec_complexity.html#code_com

Mehmet

[yraps]

You can always find this link usefull :

http://www.cisco.com/warp/public/788/pkt-voice-general/bwidth_consume.html