rtl_fm problem with capture audio

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Adam Nielsen a.nielsen at shikadi.net
Wed Nov 14 21:39:46 UTC 2012


> I use rtl_fm, check any options, but I can't listen any good sound :(
>
> For example: rtl_fm -f 10000000 -s 44100  - | mplayer - -quiet
> -rawaudio rate=8000:bitrate=44100 -demuxer rawaudio

-s means you are setting the RF bandwidth to 44.1kHz.  Maybe you meant -r to 
set the output sampling rate to 44.1k?

Either way your -rawaudio option is setting the input sampling rate to 8kHz, 
so the audio is going to sound like it has been slowed down.

You may want to add the "-l 0" option to rtl_fm to disable squelch while 
you're testing, just to see whether you are getting any audio at all.  If the 
signal isn't that strong the default squelch value will cause you to only hear 
silence.

Cheers,
Adam.





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