This tool is not maintained anymore. I made a better one and it can be cloned from here: https://github.com/cubehub/demod
Simple command line application for doing AM or FM demodulation. Uses unix pipes for data transfer. Takes raw IQ data as input and outputs demodulated audio.
From this blog post can be read why such project/fork exists.
git clone https://github.com/andresv/demod.git
cd demod/src
mkdir build
cd build
cmake ../
make
make install
Demodulate and listen audio from FM station IQ data recording
cat fm_radio_r2.iq | demod -mod WBFM -bandwidth 170000 -maxf 75000 -inrate 230400 -outrate 48000 | play -t raw -r 48k -e signed-integer -b 16 -c 2 -V1 -
Notice that fm_radio_r2.iq is recorded using following command
rtl_fm -f 103.4M -M raw -s 230400 fm_radio_r2.iq
Demodulate FSK9600 raw IQ data recording and pipe output to multimon-ng for packet decoding
sox -t wav FSK9600raw_rf.wav -esigned-integer -b16 -r 1024000 -t raw - | demod -mod NBFM -maxf 3500 -inputtype i16 -inrate 1024000 -outrate 48000 -channels 1 -squaredoutput | multimon-ng -t raw -a FSK9600 /dev/stdin
Notice that here modified multimon-ng is used that supports 48000 sps input stream for fsk9600 decoder. Read here why multimon-ng must be modified instead of converting demod output to native 22050 format.