asterisk users - Feb 2011 - Call Recording audio file quality query

Hi

We're getting requests coming in for higher quality audio in our call
recordings. We currently use MixMonitor and everything is being saved in
it's native 8000Hz, 16 bit wav format.

I have seen information on using Monitor and specifying a conversion to
mp3 when the call ends and the 2 channels get mixed but surely the 2
channels are already saved as 16bit 8000Hz wav files so the quality is
lost already?

Is there any way of making high quality recordings of call content?

We're currently using asterisk 1.4 and soon upgrading to 1.8

Thanks in Advance

Ish
-- 
Ishfaq Malik
Software Developer
PackNet Ltd

Office:   0161 660 3062

On Tue, Feb 8, 2011 at 5:09 AM, Ishfaq Malik <ish at pack-net.co.uk>
wrote:
> Hi
>
> We're getting requests coming in for higher quality audio in our call
> recordings. We currently use MixMonitor and everything is being saved in
> it's native 8000Hz, 16 bit wav format.
>
> I have seen information on using Monitor and specifying a conversion to
> mp3 when the call ends and the 2 channels get mixed but surely the 2
> channels are already saved as 16bit 8000Hz wav files so the quality is
> lost already?
>
> Is there any way of making high quality recordings of call content?
>
>
Have you ever heard of the saying "You can't polish a turd" ?

It doesn't matter if you have an app capable of recording 196Khz 24bit
recordings (or capable of upsampling to that sample rate)...if the call
itself is native at 8Khz 16bit, you'd just be making a bigger recording file
with no literal improvement in quality.

You can't create more samples of audio from nothing. it's like taking a
new
box of, say, 50 paperclips... Now, go get an empty box that says it
contained 250 paperclips when it was purchased... Now, throw all 50
paperclips from the little box into the big box marked 250..now, imagine
REALLY REALLY hard that you think you can perceive about 5 more paperclips
somewhere all mixed up in the jumble...(Extrapolation)....

that, my friend, is an over simplified metaphor, but in essence it's close
enough to get the point across..

Sorry bud :( If you don't believe me, I can refer you to my old audio
production school ;-D )

Slainte!
the Mick
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> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com [mailto:asterisk-users-
> bounces at lists.digium.com] On Behalf Of Ishfaq Malik
> Sent: Tuesday, February 08, 2011 6:10 AM
> To: asterisk-users at lists.digium.com
> Subject: [asterisk-users] Call Recording audio file quality query
> 
> Hi
> 
> We're getting requests coming in for higher quality audio in our call
> recordings. We currently use MixMonitor and everything is being saved
> in
> it's native 8000Hz, 16 bit wav format.
> 
> I have seen information on using Monitor and specifying a conversion to
> mp3 when the call ends and the 2 channels get mixed but surely the 2
> channels are already saved as 16bit 8000Hz wav files so the quality is
> lost already?
> 
> Is there any way of making high quality recordings of call content?
> 
> We're currently using asterisk 1.4 and soon upgrading to 1.8
> 
> Thanks in Advance
> 
> 
Switch everything to ulaw/alaw codecs, and stop using highly compressed
codecs

As for 16bit, 8khz, that is as high as your going to get in the telephone
world.