Ivan Ivanov wrote:
If you've ever heard the spkmodem output, please could you try to decode this stuff if its' easy for you, or at least to tell if it sounds OK or not?
It sounds somehow like I remember spkmodem, but the file is very low amplitude (too quiet) and I can't confirm whether the signal is the correct speed.
I've only received spkmodem successfully with the microphone right next to the speaker - moving the mic only a few cm lost signal.
Note that spkmodem-recv requires 48k s16le mono PCM.
I tried decoding, resampling and normalizing the ogg file without success so I suggest increasing amplitude at the source; move the mic closer to the speaker and use the parecord | spkmodem-recv command as documented in spkmodem-recv.c. Make sure to set your mic input volume to 0dB (and not higher!) so that you get the best possible signal, without attenuation.
//Peter