Most likely it's encrypted which if you don't have the matching deciphering key means it's garbage. Check the pcap capture of the control channel but chances encryption was turned out.

On Wed, Jul 8, 2020 at 9:41 PM fe8769 <fe8769@gmail.com> wrote:

hello

in /tmp/ I have some .dat files like :

/tmp/gmr1_speech_928_1_309814.dat . I think it is voice extract from arfcn 928

I tried

./gmr1_ambe_decode /tmp/gmr1_speech_928_1_309814.dat

I have stout garbage

I tried to review code in gmr1_ambe_decode.c to understand but I'm too bad

is it the way it is working ?

Thanks again

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