When you say a bluetooth device connected as the input to the SB X4, what do you exactly mean?
Are you talking about a bluetooth DAC or SPDIF output device that you would connect directly to the X4 input? If so you would use the X4 as your CamillaDSP capture device like in your current configuration.
If you mean using something like bluez-alsa (
https://github.com/arkq/bluez-alsa) you could use one side of the ALSA loopback as bluez-alsa playback (Loopback,1) and the other side as CamillaDSP capture device (Loopback,0). At one point I had instructions for this in my tutorial but have removed them, see below for reference, but note I haven't tried them in a few years.
First install blue-alsa-utils.
Rich (BB code):
sudo apt install bluez-alsa-utils
Modify bluealsa service to use a2dp-sink profile.
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sudo nano /lib/systemd/system/bluez-alsa.service
Add bolded text to "ExecStart".
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ExecStart=/usr/bin/bluealsa $OPTIONS -p a2dp-sink
Reboot RPi.
Run bluetoothctl to pair your device.
Once you are in bluetoothctl setup pairing agent and make RPi discoverable.
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default-agent
discoverable on
Pair your device and say yes to all prompts.
Make your device trusted so that the RPi will accept connections in the future and exit bluetoothctl. XX:XX:XX:XX:XX:XX is the MAC address of your device, when you pair your device you should see this listed in the bluetoothctl output.
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trust XX:XX:XX:XX:XX:XX
exit
Setup service to run bluealsa-aplay playing to the ALSA loopback. You will need to change "ExecStart" line to reflect your device MAC address.
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sudo nano /lib/systemd/system/bluealsa-aplay.service
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[Unit]
After=syslog.target
StartLimitIntervalSec=10
StartLimitBurst=10
[Service]
Type=simple
ExecStart=bluealsa-aplay XX:XX:XX:XX:XX:XX -D plughw:Loopback,1
Restart=always
RestartSec=1
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=bluealsa-aplay
User=root
Group=root
[Install]
WantedBy=multi-user.target
Enable service and reboot RPi.
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sudo systemctl enable bluealsa-aplay
sudo reboot
CamillaDSP also now has bluetooth capture device functionality which could be used without the loopback (
https://github.com/HEnquist/camilladsp#bluealsa) but I haven't tried it.
You would only use the USB gadget as your CamillaDSP capture device if you had some sort of bluetooth device that acted as a USB host. Basically the gadget appears to the USB host as a USB audio device and CamillaDSP runs between the gadget capture device and your DAC.
Based on the output you provided earlier, this is how I assume the channels are assigned.
0: FL
1: FR
2: FC
3: LFE
4: RL
5: RR
6: SL
7: SR
Michael
