Sound and Bluetooth

The box plays through the sound output of the Raspberry Pi: the headphone jack, a USB speaker, HDMI, a sound card that sits on the header (sound cards), or Bluetooth. Sound goes through PipeWire, which current Raspberry Pi OS brings along.

Lauschkiste knows two outputs: the primary one, which must be there after every start (your speaker or sound card), and an optional secondary one for Bluetooth headphones or a Bluetooth speaker. In the web page you switch between them.

No sound?

Check on the box (log in with SSH, see Install):

wpctl status                                       # lists the outputs ("Sinks"), the starred one is the default
wpctl set-default <id>                             # make another one the default
alsamixer                                          # volume of the sound card (leave with Esc)
pw-play /usr/share/sounds/alsa/Front_Center.wav    # play a test sound

If the test sound works but Lauschkiste is silent, look at Settings → Playback and audio and at the volume limit. If even the test sound is silent, the problem is the sound card, not Lauschkiste.

Choosing the outputs

lauschctl setup audio

lists the outputs of the box and asks which one is primary and which one secondary. Outputs of sound cards are named after the card (for example “HiFiBerry DAC+”). Without this step the box uses the system’s default output.

Bluetooth headphones or speaker

Pair once, then register the device as the secondary output.

bluetoothctl

Put the headphones into pairing mode, then in bluetoothctl:

scan on          wait until your device shows up, note its address (C4:FB:20:63:C0:FE)
scan off
pair C4:FB:20:63:C0:FE
trust C4:FB:20:63:C0:FE
connect C4:FB:20:63:C0:FE
exit

If bluetoothctl complains about permissions, start it with sudo. After a few seconds wpctl status should list the device as an output (bluez_output...); test it with pw-play. If not, switch the headphones off and on. Then run lauschctl setup audio again and choose the headphones as the secondary output.

Bluetooth is on by default; do not answer yes to “also switch Bluetooth off” in lauschctl setup.

Buttons on Bluetooth headphones

The play, next, previous and volume buttons of headphones appear as input devices. To let the box react to them, set input.media_keys: true in the settings (off by default so a keyboard on a desktop computer does not take over). The buttons run the matching actions (pause, next, volume). Other keys and USB buttons are described in Buttons and knobs.

To change between the speaker and the headphones from a card or a button, use the action volume.toggle_output.

Volume

• The slider in the player sets the volume.
• volume.soft_max_volume (default 70) is the highest volume that can be set, a protection for ears. Change it in the web page under Settings → Playback and audio.
• volume.startup_volume (default 40) is the volume after a start.