[Freeswitch-users] .wav vs .gsm file sizes for recording calls.

[David Ponzone]

Wes,

it's because you are confusing 2 things.
GSM is a codec, so it's a sound format.
WAVE is a kind of container (like MKV) that can contain various codecs.
In your case, you probably did a mistake using sox (it's not an easy tool), so you ended up with a wav which is still GSM audio inside.

You have to tell sox which exact output format you want.
AFAIR, you have to use the -s option (for signed linear).

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Le 24/06/2011 à 23:26, Wes a écrit :

> In my tests, if I record a call in .wav format, a 10 second file is 
> about 177,000 bytes, while a 10 second .gsm file is 17,000 bytes.
> 
> I  then used sox to convert the .gsm file to a .wav file, and it stayed 
> at around 17,000 bytes.  So, is the default recording format for .wav 
> using a higher sample rate? vs the default conversion format for the sox 
> tool?
> 
> checking the file type using "file" I see that the larger one is:
> RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, mono 8000 Hz
> 
> and the wav created by sox via the default conversion from .gsm is:
> RIFF (little-endian) data, WAVE audio, GSM 6.10, mono 8000 Hz
> 
> So apparently the larger wav file is 16 bit... how are these recording 
> parameters controlled?  Can I set it to record directly into the smaller 
> wav format? Or will I have to run sox on every file...
> 
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