Bathroom Smart Speaker Part 2 – AirPlay to Bluetooth Speaker via Raspberry Pi

In part 1 I wrote on how to create a smart speaker supporting Spotify Connect using a Raspberry Pi and a Bluetooth speaker. Since writing that post I started using Apple Music and wanted to enjoy simultaneous streaming of music to multiple speakers in my house. I wanted my bathroom speaker, which became smart by supporting Spotify Connect, to also be able to play Apple Music.

Apple Music casting uses AirPlay for casting audio between devices. It can be used to cast any sound from Apple devices, even when using Spotify, watching YouTube or having a phone call.

In order to add this capability to your smart speaker from the previous post - we’re going to use shairport-sync, which is an open-source audio player supporting AirPlay 1 (and AirPlay 2 partially, at the time of writing this post). The instructions in this post are partially based on this GitHub comment by bedrin.

Steps

Installing shairport-sync

Execute the following commands from to install the most recent version of shairport-sync:

sudo apt-get update
sudo apt-get install build-essential git xmltoman autoconf automake libtool libpopt-dev libconfig-dev libasound2-dev avahi-daemon libavahi-client-dev libssl-dev libsoxr-dev
git clone https://github.com/mikebrady/shairport-sync.git
cd shairport-sync
autoreconf -fi
./configure --sysconfdir=/etc --with-alsa --with-soxr --with-avahi --with-ssl=openssl --with-systemd
make
sudo make install

Giving shairport-sync Bluetooth Permissions

shairport-sync needs permissions to play sound over Bluetooth. Run these commands to add shairport-sync’s user (and pi for testing purposes) to the Bluetooth UNIX group which will permit it to play audio:

sudo adduser pi bluetooth
sudo adduser shairport-sync bluetooth

Adding Additional ALSA Device

In the previous post we edited /etc/asound.conf to point to the Bluetooth speaker as the default device. shairport-sync requires a named device, so we’ll create another ALSA device alongside the default one to also map to the Bluetooth speaker.

Open /etc/asound.conf and copy the MAC address you filled after defaults.bluealsa.device (should be at line 4 in quotation marks). Replace the content of /etc/asound.conf with the following, while replacing <UE Boom Bluetooth MAC> with the MAC address you found in line 4:

pcm.!default "bluealsa"
ctl.!default "bluealsa"
defaults.bluealsa.interface "hci0"
defaults.bluealsa.device "<UE Boom Bluetooth MAC>"
defaults.bluealsa.profile "a2dp"

pcm.bathroom_bt {
 type plug
  slave {
    pcm {
      type bluealsa
      device "<UE Boom Bluetooth MAC>"
      profile "a2dp"
    }
  }
  hint {
    show on
    description "Bathroom BT"
  }
}

In the above configuration I named this device “bathroom_bt” (line 7) with the description “Bathroom BT”. You can replace this to fit your scenario, but make sure to replace it in the below shairport-sync configuration as well.

shairport-sync Configuration

Now that the ALSA device is configured - we should configure shairport-sync to use this device as the sound output device. Replace the content of /etc/shairport-sync.conf with the following:

general =
{
	name = "Bathroom Speaker";
};

sessioncontrol =
{
	allow_session_interruption = "yes";
};

alsa =
{
	output_device = "bathroom_bt";
};

The name parameter under general (line 3) will be the displayed AirPlay name, set it to a suitable value. If you changed the name of the ALSA device (in /etc/asound.conf at line 7) change it under output_device at line 13 as well.

Disable WiFi Power Management

Raspberry Pi’s WiFi can sometimes goes into power-saving mode, which can cause audio drops and glitches when acting as an AirPlay server. We can disable the WiFi power management by editing /etc/rc.local and adding the following line right before exit 0 (if you followed my previous post - this should be at line 19):

iwconfig wlan0 power off

After adding this line, your /etc/rc.local should look like this:

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

# Print the IP address
_IP=$(hostname -I) || true
if [ "$_IP" ]; then
  printf "My IP address is %s\n" "$_IP"
fi

iwconfig wlan0 power off

exit 0

Enable shairport-sync Service

Finalize your setup by enabling the shairport-sync service and performing a system reboot to load all the new configurations:

sudo systemctl enable shairport-sync
sudo reboot