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How can I convert GSM sound files to G.729 format? I've used Sox in the past for transcoding sound files, but have not been able to find a way to transcode to G.729. Using Sox, I have found a way to convert GSM to WAV.

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ffmpeg says you can decode GSM to G.729 BIT (but not G.729 RAW). Not sure if that helps you or not. – sunk818 Nov 28 '14 at 6:47
up vote 1 down vote accepted

A free and easy way to convert proper sound files to G.729 is adding appropriate free G.729 codec binary to Asterisk and use 'convert' module.

You can follow these steps:

  1. Install Asterisk
  2. Follow the instructions and install the free G.729 codec for Asterisk
  3. And then issue this command to convert your 8k sampled gsm file to G.729:

asterisk -rx "file convert /path/to/your/file/inputfilename.gsm /path/to/your/file/outputfilename.g729"

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