On Wed, 16 Feb 2005, Rich Adamson wrote: > > It's more than that, from what I know a *missing* RTP packet could be > > 'silence' (vad) or it could be 'network related' (jitter). * not seeing > > a packet doesn't always mean it was vad, it might mean your network had > > a split second (subsecond) hiccup that caused the packet to disappear - > > both 'look the same' to *. This is why someone had already mentioned > > the idea that the new jitter-buffer might handle this better/correctly.
VAD and lost packets do not look the same. When silence is detected the CN command is sent several times to ensure that it is not lost. A missing message should be interpreted as packet loss. CN is explicit. > Personal opinion (and everyone's got one) is that vad does not produce the > savings that one might expect. People are use to constantly talking (in > many cases full-duplex-style), room background noise, dog barking, etc, > etc, which reducees the impact. Vad may have some small value for > residential voip users where their bandwidth is a little on the too- > small side, but asterisk was not designed with the intent of putting a > pbx in every home. Silence supression and VAD is not very significant on a connection that carries only a single line. Most measurements I have seen in telecom litterature quotes a typical ratio of 40-60% silence for conversations. When you have several calls active at the same time the savings add up. It mostly affects big nodes with a lot of simultaneous calls. Peter _______________________________________________ Asterisk-Users mailing list [email protected] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
