Hi everyone Im trying to follow a tutorial on generating truly random bits How To Generate Truly Random Bits This is the command from the tutorial but it does not work rec -c 1 -d /dev/dsp -r 8000 -t wav -s w - | ./noise-filter >bits I know i can record my mic input using rec -c 1 no.wav this is the command i tried using rec -c 1 -r 8000 -t wav -s noise.wav | ./noise-filter >bits but i get root@xxc:~/cc# rec -c 1 -r 8000 -t wav -s noise.wav - | ./noise-filter >bits rec WARN formats: can't set sample rate 8000; using 48000 rec FAIL sox: Input files must have the same sample-rate I have complied noise-filter noise-filter I think the tutorial is using an older version of SOX and REC I'm using sox: SoX v14.3.2 on Ubuntu 12.04 server Can someone please help me ?