[Freeswitch-users] Transcoding to GSM using SOX

Brian Wood bwood-lists at jacosoft.com
Mon Nov 3 19:01:42 PST 2008

I'm trying to transcode a .wav to a .gsm using SOX v14.0.1. What I get 
is a completely garbled when using playback in FreeSWITCH. I have 
verified that at least one other application (Quicktime Player) can in 
fact play the resulting .gsm file.

I have tried the following:

    sox william.wav -t gsm william.gsm
    sox william.wav -t gsm -r 8000 william.gsm resample -ql
    sox william.wav -t gsm -r 8000 -c1 william.gsm resample -ql

And I am playing the file using:

    originate sofia/internal/1000 at 

Other formats such as uLaw and aLaw (-t ul and -t al, respectively) seem 
to work fine.

Does anyone know of a set of parameters for SOX that will make this work?

At the end of the day, I just want it to work, so if anyone can 
recommend any other known/good command line tools to encode GSM that 
would be fine too.

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