[Asterisk-Dev] IAX2 Jitter Buffer questions
Andrew Kohlsmith
akohlsmith-asterisk at benshaw.com
Tue Jan 20 09:54:18 MST 2004
> This is going to be a kind of meandering email, it's mostly a brain dump
> of trying to understand what's going on. I have been trying to help fix
> a problem with my one asterisk server. Calls through Voicepulse are
> mostly fine but sometimes the jitter on my line causes the GSM call to
> sound like absolute shit.
Just an update and some data points
there is a call currently in progress. iax2 show channels shows the lag at
about 70-90ms, with ~20ms jitter. Jumps as high as 260ms jitter (with the
lag following).
Now I thought that with my maxexcessbuffer set to 250ms that I would
MAINTAIN 250ms of lag. This doesn't seem to be the case, or perhaps
chan_iax2's buggy and doesn't actually take that into account.
I entered "iax2 set jitter 100" and now my lag is pretty much locked at
136ms with jitter in the 20-90ms range (but sometimes jumping)
I'm waiting for the guy talking to get off the phone so I can ask him about
the quality but it would seem that my suspicions about maxexcessbuffer not
being taken into account are true.
I just tried "iax2 set jitter 200" and 250 but the lag hasn't moved at all.
In fact it got a little lower (128ms)...
Is there any definitive information on how to adjust these settings and how
to monitor their effect??
Regards,
Andrew
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