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windytan / redsea

Command-line FM-RDS decoder with JSON output.
MIT License
390 stars 36 forks source link

Can't get it to decode anything #13

Closed niston closed 8 years ago

niston commented 8 years ago

Maybe the hardware (RPi B+) is not powerful enough?

pi@raspberrypi:~/redsea/src $ rtl_fm -M fm -f 88.2M -l 0 -A std -p 0 -s 228k -F 9 | ./redsea Found 1 device(s): 0: Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U OEM HWTUNER Rafael Micro R820T Tuner gain set to automatic. Tuned to 88656000 Hz. Oversampling input by: 8x. Oversampling output by: 1x. Buffer size: 4.49ms SAMPLERATE 1824000.017395 Sampling at 1824000 S/s. Output at 228000 Hz. buffer underrun!

...is all Im getting.

windytan commented 8 years ago

I haven't tested it on RPi yet, maybe soon. Thanks for the report.

kms commented 8 years ago

There are some recent optimizations. I'm running it successfully on an RPi2 now, the rtl_fm and redsea processes are using about 40% CPU each. Might still be a tad too slow for the RPi1, but one option could be to direct the output from rtl_fm to a file and then post-process with redsea. No idea if that makes sense for your use-case, though.

windytan commented 8 years ago

Works on RasPi 1 after recent optimizations. I also dropped the sampling rate from 228k -> 171k and added a tip in the readme about fast integer approximation in the FM decoder.