UNIX for Advanced & Expert Users

ffmpeg supports g.726 but it requires a header -- raw won't do. So that's no help.

Someone wrote a headerless g.72x to WAV converter:

https://lists.libav.org/pipermail/ff...ry/018843.html

Thanks a lot. I have converted it, using this decoder. The solution seems a bit closer. I need to use this tool very carefully. I will let you know how it goes

Thanks again

This gets me something:

Code:

cat  ~/input.raw |
        ./decode-g72x -3 -R -l | 
        sox -r 8000 -b 16 -c 1 -e signed-integer -t raw - -t wav ~/input.wav

It sounds like a badly tuned radio, but you can detect speech and pauses! So it's probably 3-bit ADPCM input, but this might be cramming it through the wrong compander.

None of the other codecs in decode-g72x would even touch it. (I literally bruteforced all possible options...) The g.726 codecs give silence and clicks, the other g.72x codecs generate white noise.

So you are suggesting to use another codec for ADPCM 3bit?

I clearly distinguish the difference between pauses and voice but I cannot hear anything clearly.

I feel really close but I do not know how to continue

I don't really know. I'm not 100% certain this is even the right protocol yet. G.722 is also possible, [edit] or G.722.1, which has a 16-kilobit version -- or maybe something I haven't found yet. A telecom protocol expert might know where it's going wrong, or might not.

It must be the wrong codec... The manual for that program doesn't even mention the 24 kilobit codec.

It might be G.727, which is a minor variation on G.726