[asterisk-users] Loud pop at the end of messages causing level problems

[Eric Deutsch]

Hi everyone, I've set up a little Asterisk system with a Digium TDM400P and
everything works splendidly except for the messages callers leave. Every
message that a caller leaves is very faint. I've already set volgain=6.0 in
voicemail.conf, and that seems better, but to be at a good volume I estimate
I may need to go up to 40.0. Is that reasonable?

 

One interesting artifact is that at the end of every message, there is a
loud pop (I think I usually hear a faint click when the caller hangs up and
then I surmise that the loud pop is some sort of local connection ending.
If I do:

 

sox msg0004.WAV zz1.WAV stat

 

it always tells me that the volume correction should be 1.0000. I surmise
that the volume peak is triggering on this loud pop. In fact if I trim off
the pop with something like:

 

sox msg0004.WAV zz1.WAV trim 0 00:00:15 stat

 

Then it tells me that the volume gain should be between 7 and 12 depending
on the message.

 

So here are the questions:

 

1) Is there anything simple I can do to stop this loud pop at the end of
every message?

 

2) Failing that, is there a way that I can shell out to some post processing
on the message easily after it is left?

 

I assume that Asterisk already does some processing with sox; this is where
the volgain goes. Can I instead insert some logic like:

- trim the last half-second off the message

- Do a sox stat to determine the suggested gain

- Use sox to readjust the gain

I could script this up if I knew how Asterisk would call my script.

 

Or, perhaps there is another solution I am not considering.

 

Any help would be most appreciated.

 

Thanks,

Eric

 

 

 

 

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