[asterisk-users] MixMonitor inserting extra 20ms packets of silence (1.4.43)

Johan Wilfer lists at jttech.se
Mon Sep 10 12:32:21 CDT 2012

2012-09-10 18:13, Tony Mountifield skrev:
> I'm trying to diagnose potential causes of an issue with MixMonitor in 1.4.43
> (I doubt it's very version-specific). I won't have hands on the kit until the
> end of the week, but I have listened to some recordings. It doesn't happen on
> every call - only sometimes.
> Basically, it is a call from one SIP phone extension to another, and the
> dialplan sets up MixMonitor on the calling channel before doing the Dial.
> The call sounds fine to both parties in the call, but when listening back to
> the recording, the speech is slowed down and broken - a bit like a robot or
> dalek voice. Examining the recorded audio in Goldwave I can see that every 20ms
> (the size of a SIP packet), an extra 20ms of silence is being inserted in the
> recording file. This happens most of the time, punctuated by occasional bursts
> of clear audio before it starts happening again.
> Has anyone seen this kind of thing before? Better still, seen it and solved it?
> The "SIP phones" are actually Soundwin ATAs.
> There is no zaptel or dahdi timing source in the system.
> Are there any known issues with MixMonitor that could cause this behaviour?
> Any pointers would be appreciated - thanks!
> Tony

Maybe a I'm reaching here but.. I had some very strange issues with 
broken quality with Monitor and a NFS mount. This was 1.4, but several 
years ago. I ended up not using NFS in the end.

Johan Wilfer

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