Hi nate_eagle
I just configured the ALSA loopback copy, and it worked out fine. These are the steps
Enable software mixer: Settings > Playback Options > Mixer
Check your soundcard name
aplay -l
Mine is sndrpihifiberry
card 2: sndrpihifiberry [snd_rpi_hifiberry_dac], device 0: HifiBerry DAC HiFi pcm5102a-hifi-0 [HifiBerry DAC HiFi pcm5102a-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
Edit /etc/asound.conf
nano /etc/asound.conf
remove what is there and add the following, but use your sound card name where mine appears
pcm.softvolume {
type plug
#slave.pcm "softvol"
slave.pcm "softvolume2"
}
pcm.softvol {
type softvol
slave {
pcm "plughw:sndrpihifiberry,0"
}
control {
name "SoftMaster"
card 1
device 0
}
max_dB 0.0
min_dB -50.0
resolution 100
}
pcm.softvolume2 {
type plug
slave.pcm {
type multi
slaves {
a { channels 2 pcm "softvol" } # the real device
b { channels 2 pcm "hw:Loopback,0" } # the loopback driver
}
bindings {
0 { slave a channel 0 }
1 { slave a channel 1 }
2 { slave b channel 0 }
3 { slave b channel 1 }
}
}
ttable [
[ 1 0 1 0 ] # left -> a.left, b.left
[ 0 1 0 1 ] # right -> a.right, b.right
]
}
Add the loopback device to load at boot. Edit the following file
sudo nano /etc/modules
Add the line
snd-aloop
Reboot!
Check the loopback device is loaded
aplay -l
You should see lines like
card 0: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
Subdevices: 7/8
Subdevice #0: subdevice #0
...
When you play audio you can now get a copy from plughw:Loopback,1
Using mpd_oled the command to use this copy is something like
sudo mpd_oled -o 6 -b 21 -g 1 -f 15 -c alsa,plughw:Loopback,1
Thats it!
Adrian.