fm95/README.md

fm95

FM95 is a audio processor for FM, it does:

• Pre-Emphasis
• Stereo
• Polar Stereo
• SCA

Supports these inputs:

• Audio (via Pulse)
• MPX (via Pulse)
• RDS (via Pulse, expects unmodulated RDS, stereo, left channel on 57 KHz, right on 66.5)
• SCA (via Pulse)

and one output:

• MPX (via Pulse)

How to compile?

To compile you need cmake and libpulse-dev, if you have those then do these commands:

mkdir build
cd build
cmake ..
make

Done!

CPU Usage?

Should run completly fine on a pi 5, right now with the preemp, on a pi 3b, its 20%

Recommendations

use a lpf, for example swh-plugins's lowpass_iir, for example:

pactl load-module module-null-sink sink_name=FM_Audio rate=48000 # this goes to fm95
pactl load-module module-ladspa-sink sink_name=FM_Audio_lpf sink_master=FM_Audio plugin=lowpass_iir_1891 label=lowpass_iir control=15000,6 rate=48000 # use 4 poles minimum
pactl load-module module-loopback source=radio_audio.monitor sink=FM_Audio_lpf rate=48000 # from the apps to the filter