Philipp- > I have some problems with devices making use of VAD. When connected to an > asterisk server, comfort noise is not generated since asterisk does not > support this. On the other hand it is not possible to disable VAD on the > endpoints. > > My question is whether it is possible to utilize pjsip to parse the rtp > stream from the endpoints, watch for the rtp-packet with the cng marker bit > and add rtp packets with comfort noise until the endpoints start > transmitting again while forwarding the parsed stream to the asterisk. > > In this case G711.u codec ist used. If you're using basic G711 then there is no concept of comfort noise -- all RTP packets contain "sound" (voice, noise, silence, tone, etc). It's possible that your endpoints are using "G711 Appendix II" or other non-standard implementation that includes VAD and CNG. Do you know if that's the case? If so, then you may want to re-think because G711 II implementations are not common -- which could explain your compatibility issues with Asterisk. If you need VAD/CNG to reduce bandwidth then I might suggest using a popular / widely used codec (such as G729) that has supoprt for VAD/CNG. -Jeff
