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2. Raspberry Pi Sound & Multiple Bluetooth Speaker Setup
If you have some USB or Bluetooth speakers you want to use this guide explains how to set them up using Raspberry Pi OS (based on Debian bookworm at the time of writing).
To my understanding PulseAudio is a higher framework built to manage ALSA which is the lowest level layer. Without PulseAudio for instance, you wouldn't be able to mix sounds from two applications to ALSA.
However PulseAudio can be a bit Frankenstein and PipeWire is built on top of both to manage the sound pipelines better. Many users want PulseAudio out of the map but I don't for now because it allows me two features I don't know how to migrate: (1) Combining sinks to play simultaneous sound on various speakers or (2) easily setup Bluetooth sound.
This guide explains how to setup Bluetooth devices and combine various of them to create a speaker group.
Since our app will run on Docker containers that will use PyAudio (PortAudio's Python bindings) to interact with the microphone and speakers we will have a bit of a challenge depending on whether the host running the container is Raspberry Pi OS or macOS. This is explained in Docker Container Sound.
Usually you should have the PulseAudio server running by default, check that with
ps -e | grep pulse and check if there is the server process. Note that you might have
PipeWire running (pipewire-pulse).
If not (in the case of older Raspberry Pi devices) you want to install PulseAudio as well as the package that allows PulseAudio to setup Bluetooth audio:
taconez@raspberrypi:~ $ sudo apt install pulseaudio pulseaudio-module-bluetooth
You will be playing with the various PulseAudio utils such as pactl, paplay, ... so
make sure the pulseaudio-utils are installed, which should be:
taconez@raspberrypi:~ $ sudo apt install pulseaudio-utils
Plug the USB speaker and you should see it listed to be used as an audio sink:
taconez@raspberrypi:~ $ pactl list sinks short
67 alsa_output.usb-Jieli_Technology_UACDemoV1.0_1120040808090721-01.analog-stereo PipeWire s16le 2ch 48000Hz SUSPENDED
69 alsa_output.platform-bcm2835_audio.stereo-fallback PipeWire s16le 2ch 48000Hz SUSPENDED
Connect your Bluetooth speakers by using bluetoothctl. This is an interactive process
which would need to be done manually on each Raspberry Pi. In the following example you
can see how to connect a bluetooth device JBL GO 2 with MAC F8:5C:7D:0F:6D:46:
taconez@raspberrypi:~ $ bluetoothctl
# Power on and start scanning until you find the JBL GO 2 you are looking for:
[bluetooth]# power on
[bluetooth]# scan on
[NEW] Device F8:5C:7D:0F:6D:46 JBL GO 2
# Scanning can be turned off:
[bluetooth]# scan off
[CHG] Controller DC:A6:32:50:10:F5 Discovering: no
Discovery stopped
# Pair, trust, and connect the device:
[bluetooth]# pair F8:5C:7D:0F:6D:46
Attempting to pair with F8:5C:7D:0F:6D:46
[CHG] Device F8:5C:7D:0F:6D:46 Connected: yes
[CHG] Device F8:5C:7D:0F:6D:46 Bonded: yes
[CHG] Device F8:5C:7D:0F:6D:46 UUIDs: 00001108-0000-1000-8000-00805f9b34fb
[CHG] Device F8:5C:7D:0F:6D:46 UUIDs: 0000110b-0000-1000-8000-00805f9b34fb
[CHG] Device F8:5C:7D:0F:6D:46 UUIDs: 0000110c-0000-1000-8000-00805f9b34fb
[CHG] Device F8:5C:7D:0F:6D:46 UUIDs: 0000110e-0000-1000-8000-00805f9b34fb
[CHG] Device F8:5C:7D:0F:6D:46 UUIDs: 0000111e-0000-1000-8000-00805f9b34fb
[CHG] Device F8:5C:7D:0F:6D:46 ServicesResolved: yes
[CHG] Device F8:5C:7D:0F:6D:46 Paired: yes
Pairing successful
[bluetooth]# trust F8:5C:7D:0F:6D:46
[CHG] Device F8:5C:7D:0F:6D:46 Trusted: yes
Changing F8:5C:7D:0F:6D:46 trust succeeded
[bluetooth]# connect F8:5C:7D:0F:6D:46
Attempting to connect to F8:5C:7D:0F:6D:46
[CHG] Device F8:5C:7D:0F:6D:46 Connected: yes
[NEW] Endpoint /org/bluez/hci0/dev_F8_5C_7D_0F_6D_46/sep1
[NEW] Transport /org/bluez/hci0/dev_F8_5C_7D_0F_6D_46/sep1/fd0
Connection successful
[CHG] Device F8:5C:7D:0F:6D:46 ServicesResolved: yes
[CHG] Transport /org/bluez/hci0/dev_F8_5C_7D_0F_6D_46/sep1/fd0 Volume: 0x003b (59)
[JBL GO 2]# exit
If you have problems connecting the Bluetooth speaker check the service's logs:
taconez@raspberrypi:~ $ journalctl -u bluetooth.service
For instance you might get:
[bluetooth]# connect F8:5C:7D:0F:6D:46
Attempting to connect to F8:5C:7D:0F:6D:46
Failed to connect: org.bluez.Error.Failed br-connection-profile-unavailable
[DEL] Device 6B:53:9D:87:E4:7A 6B-53-9D-87-E4-7A
[bluetooth]# exit
taconez@raspberrypi:~ $ journalctl -u bluetooth.service | tail -n 1
Nov 20 20:54:27 raspberrypi bluetoothd[682]: src/service.c:btd_service_connect() a2dp-sink profile connect failed for F8:5C:7D:0F:6D:46: Protocol not available
This error happened to me the first time I tried to connect the Bluetooth speaker after
having installed pulseaudio and pulseaudio-module-bluetooth. It got fixed after
rebooting!
taconez@raspberrypi:~ $ pactl list sinks short
67 alsa_output.usb-Jieli_Technology_UACDemoV1.0_1120040808090721-01.analog-stereo PipeWire s16le 2ch 48000Hz SUSPENDED
69 alsa_output.platform-bcm2835_audio.stereo-fallback PipeWire s16le 2ch 48000Hz SUSPENDED
80 bluez_output.F8_5C_7D_0F_6D_46.1 PipeWire s16le 2ch 48000Hz SUSPENDED
86 bluez_output.70_99_1C_51_36_1B.1 PipeWire s16le 2ch 48000Hz SUSPENDED
Try to play a sound to the new sink:
taconez@raspberrypi:~ $ pactl set-default-sink bluez_output.F8_5C_7D_0F_6D_46.1
taconez@raspberrypi:~ $ aplay /usr/share/sounds/alsa/Front_Center.wav # ALSA player
taconez@raspberrypi:~ $ paplay /usr/share/sounds/alsa/Front_center.wav # PulseAudio player
taconez@raspberrypi:~ $ pw-play /usr/share/sounds/alsa/Front_center.wav # PipeWire player
taconez@raspberrypi:~ $ speaker-test
Get sinks and get / set default sink (speaker output):
pactl list sinks short # Omit `short` for a more detailed output.
taconez@raspberrypi:~ $ pactl get-default-sink
taconez@raspberrypi:~ $ pactl set-default-sink <sink-name>
Get / set default source (microphone input):
pactl list sources short # Omit `short` for a more detailed output.
taconez@raspberrypi:~ $ pactl get-default-source
taconez@raspberrypi:~ $ pactl set-default-source <sink-name>
Note
Raspberry Pi 4 seemed to reconnect to the speakers upon rebooting, but not on
Raspberry Pi 3 B+, which uses an older bluetoothctl (5.66 vs 5.55).
If you want to reconnect the speaker after reboot, what worked with JBL GO 2 is to turn the speaker off and on. Then it autoconnects.
To be able to play a sound to two or more speakers you can create a combined sink:
# Combine all available sinks:
taconez@raspberrypi:~ $ pactl load-module module-combine-sink
536870913
# Now if you wished to unload that module: `pactl unload-module 536870913`.
# NOTE: You can pass arguments to the module-combine-sink arguments to select what
# devices you want to connect. To see the available sinks use `pactl list sinks short`.
#
# pactl load-module module-combine-sink sink_name=combined-sink sink_properties=device.description=Combined slaves=bluez_output.F8_5C_7D_0F_6D_46.1,bluez_output.70_99_1C_51_36_1B.1,alsa_output.usb-Jieli_Technology_UACDemoV1.0_1120040808090721-01.analog-stereo
#
Now check if it has been created:
taconez@raspberrypi:~ $ pactl list sinks short
67 alsa_output.usb-Jieli_Technology_UACDemoV1.0_1120040808090721-01.analog-stereo PipeWire s16le 2ch 48000Hz SUSPENDED
69 alsa_output.platform-bcm2835_audio.stereo-fallback PipeWire s16le 2ch 48000Hz SUSPENDED
80 bluez_output.F8_5C_7D_0F_6D_46.1 PipeWire s16le 2ch 48000Hz SUSPENDED
86 bluez_output.70_99_1C_51_36_1B.1 PipeWire s16le 2ch 48000Hz SUSPENDED
131 combined-sink PipeWire float32le 2ch 48000Hz SUSPENDED
Select it to be the default sink:
taconez@raspberrypi:~ $ pactl set-default-sink combined-sink
To play sound to it:
taconez@raspberrypi:~ $ speaker-test
If you restart the default sink might not be combined-sink anymore. You need to
persist that sink.
Depending on whether you have PipeWire available or not (in which case you would use PulseAudio directly) the steps change a bit.
You can check if PipeWire is installed by:
$ apt list --installed | grep pipewire
libpipewire-0.3-0/stable,now 0.3.65-3+rpt2 arm64 [installed,automatic]
libpipewire-0.3-common/stable,stable,now 0.3.65-3+rpt2 all [installed,automatic]
libpipewire-0.3-modules/stable,now 0.3.65-3+rpt2 arm64 [installed,automatic]
pipewire-bin/stable,now 0.3.65-3+rpt2 arm64 [installed,automatic]
pipewire-libcamera/stable,now 0.3.65-3+rpt2 arm64 [installed,automatic]
pipewire-pulse/stable,now 0.3.65-3+rpt2 arm64 [installed,automatic]
pipewire/stable,now 0.3.65-3+rpt2 arm64 [installed,automatic]
default.pa (PulseAudio Sound Server Startup Script) is what needs to be edited.
We can drop files in /etc/pulse/default.pa.d/ and they will be processed always, even
if we reboot.
Create /etc/pulse/default.pa.d/combine-sinks-and-set-default.pa with these contents:
load-module module-combine-sink
set-default-sink combined
To enable audio I/O from the Docker container into the host (Raspberry Pi) we need to
enable PulseAudio's module-native-protocol-tcp. To do that everytime we boot the
Raspberry Pi create /etc/pulse/default.pa.d/enable-tcp.pa with these contents:
load-module module-native-protocol-tcp
Now restart the pulse server:
systemctl --user restart pulseaudio.service
Create a ~/.config/pipewire/pipewire.conf.d/<name>.conf so PipeWire gets it by
default.
$ mkdir -p ~/.config/pipewire/pipewire.conf.d
$ touch ~/.config/pipewire/pipewire.conf.d/add-combined-sink.conf
Now use your editor to edit add-combined-sink.conf:
context.exec = [
{ path = "pactl" args = "load-module module-combine-sink" }
{ path = "pactl" args = "set-default-sink combined" }
]
Create another config ~/.config/pipewire/pipewire.conf.d/enable-tcp.conf:
# Sources:
#
# https://stackoverflow.com/a/39780130/2649699
# https://gist.github.com/janvda/e877ee01686697ceaaabae0f3f87da9c
# https://github.com/mviereck/x11docker/wiki/Container-sound:-ALSA-or-Pulseaudio
#
context.exec = [
{ path = "pactl" args = "load-module module-native-protocol-tcp" }
]
First we need to disable a feature called flat volumes on the PulseAudio daemon
(/etc/pulse/daemon.conf) that will mess with the rest of volumes when you change a
particular one.
flat-volumes scales the device-volume with the volume of the "loudest" application. For example, raising the VoIP call volume will raise the hardware volume and adjust the music-player volume so it stays where it was, without having to lower the volume of the music-player manually. Defaults to yes upstream, but to no within Arch. Note: The default behavior upstream can sometimes be confusing and some applications, unaware of this feature, can set their volume to 100% at startup, potentially blowing your speakers or your ears. This is why Arch defaults to the classic (ALSA) behavior by setting this to no.
...
flat-volumes = no
...
Then restart the service systemctl --user restart pulseaudio.service.
You can read the current audio volume level on each individual speaker as follows:
$ pactl get-sink-volume bluez_output.F8_5C_7D_0F_6D_46.1
Volume: front-left: 30446 / 46% / -19.98 dB, front-right: 30446 / 46% / -19.98 dB
balance 0.00
$ pactl set-sink-volume bluez_output.F8_5C_7D_0F_6D_46.1 100%
Do this with the rest of individual speakers:
$ pactl set-sink-volume alsa_output.usb-Jieli_Technology_UACDemoV1.0_1120040808090721-01.analog-stereo 100%
$ pactl set-sink-volume bluez_output.70_99_1C_51_36_1B.1 100%
Do it with the combined sink too if you want:
$ pactl set-sink-volume combined-sink 100%
If you reboot, even if the bluetooth speaker disconnects it seems to retain the volume
level set with the set-sink-volume command.