[Asterisk-Users] TDM card and voicemail volume

[Rich Adamson]

> asterisk-users-bounces at lists.digium.com wrote on 06/28/2005 07:52:50 AM:
> 
> > I was able to raise the volume from inaudible to acceptable by
> > increasing the RxGain in zapata.conf by 5db.  I'd rather not go the
> > uncomressed wav route, as it will chew up storage in my email system. 
> 
> I know I'm way behind on reading this, but I thought I would follow up.
> 
> According to this message:
> 
>  
> http://lists.digium.com/pipermail/asterisk-users/2004-November/072990.html
> 
> the reason that uncompressed WAV files are louder is that the software 
> that saves the WAV file is amplifying the volume of the files by shifting 
> the data two bits to the left (or making it 4x louder).  It is in no way 
> "fixing" the underlying problem of the file being too quiet;  it is just 
> throwing away dynamic range in order to amplify the file.
> 
> Now that may not be a bad solution:  if you don't need the dynamic range, 
> but you *do* need the volume, so be it:  you would prefer the off-chance 
> of some clipping.  It *has* to be a better solution to using the rxgain 
> setting if you don't need to:  rxgain is going to affect echo for the 
> worse.  Also notice that the volume of these files is sufficient when they 
> are played back over the telephone:  it's only when you play them back via 
> a sound card that you have the volume problem.  So, you can't just 
> willy-nilly amplify everything.

I'd personally agree with every word above.

There is a work around coming that will help with the VM gain issue
while other work is in progress to identify the root cause.

Might see the work around today if you monitor the cvs changes. ;)

Rich