[asterisk-users] Playback 5% Too Fast?

Cosmin Prund cosmin at adicomsoft.ro
Wed Mar 14 06:52:25 MST 2007


I've had similar behavior on my own IVR. I moved my sound files to a ram 
disk and all pops and ticks stopped!

David Brazier wrote:
> 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
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