[asterisk-users] RE: Playback 0.5% Too Fast?

[David Brazier]

Just checked my figures, and I mean 0.5%-0.7%.  Anyway, it is the
resulting
clicks that are the problem.  

Any help still appreciated.

David

-----Original Message-----
From: David Brazier 
Sent: 13 March 2007 00:33
To: asterisk-users at lists.digium.com
Subject: Playback 5% Too Fast?

Hi All

I have a problem with IVR scripts which consist mainly of Playback of
audio
files, driven from an AGI application.  There are clicks every few
seconds
or more frequently that is audible on the remote end (PSTN), but not on
the
Asterisk recording of the call.  If I record the remote end and compare
it
to the local recording, it appears to be about 5%-7% too fast - i.e. if
I
synchronise the starts, the remote end finishes sooner.  I can find
points
in the remote recording where parts of the waveform have been missed
out,
leading to jumps in the waveform, which correspond to the audible
clicks.
These "jumps" seem like dropped packets, and I'm deducing that Asterisk
is
sending data slightly too fast (i.e. more frequently than 50x160 sample
per
second) for the remote end, which has to drop data to keep up.  

This is a VoIP-only set up - no Zap hardware.  Thinking this was a
timing
issue, I have installed Zaptel to get ztdummy, which is loaded OK, but
that
hasn't made any difference.  I have tried it with different VoIP
providers
and observed the same problem.


Behaviour has persisted from 1.2 to 1.4 and now 1.4.1.  CentOS 4.4
(2.6.9
kernel), Dell 1950.

Any ideas how to progress?  Is this a timing issue or am I wide of the
mark?

Thanks for any help

David