Setting Up AirPlay (with XLR Output)

This is a process I've done several times before, but as I'm sitting down to yet again setup a Raspberry Pi to host an AirPlay service, I figured it was time to write down the process.

The GitHub Repo

First off, this project is really easy thanks to Shairport-Sync by Mike Brad on GitHub, so much thanks to him. The first step, as always, is update the Pi and install the necessary libraries and clones the repository:

sudo apt update && sudo apt upgrade

sudo apt-get install autoconf automake avahi-daemon build-essential git libasound2-dev libavahi-client-dev libconfig-dev libdaemon-dev libpopt-dev libssl-dev libtool xmltoman

git clone https://github.com/mikebrady/shairport-sync.git

Next, open that new directory and build the service:

cd shairport-sync

autoreconf -i -f

./configure --with-alsa --with-avahi --with-ssl=openssl --with-systemd --with-metadata

make

sudo make install

Once that is installed, the service can be enabled (so it starts on bootup) and started:

sudo systemctl enable shairport-sync

sudo systemctl start shairport-sync

Setting Up the XLR Board

ls /boot/overlays/ | grep iqaudio ## identify the correct name for the board

sudo nano /boot/firmware/config.txt

dtoverlay=iqaudio-dac ## Or whatever the name was from listing overlaps

sudo reboot

Before Shairport-Sync can be configured to use the XLR DAC, the Pi needs to be configured to recognize it. The first step is to figure out how the iqAudio board is identified by the Pi. Then put that in the config file.

After adding the `dtoverlay` line, reboot the Pi and run `aplay -l` to list the identified soundcards.

Configure Shairport-Sync to Use the DAC

To find the proper name for Shairport-Sync, run:

aplay -l

This will list all the available soundcards on the Pi. Specifically, I got a line like this:

card 1: Pro [RPi DAC Pro], device 0: Raspberry Pi DAC Pro HiFi pcm512x-hifi-0 [Raspberry Pi DAC Pro HiFi pcm512x-hifi-0]

Using the information from that line, the config file can be updated using this format: 

hw:CARD=<card_name>,DEV=<device_number>

Open the config file for Shairport-Sync:

sudo nano /usr/local/etc/shairport-sync.conf

Find the block for ALSA, and update it with the information for the DAC:  

alsa =

{

    output_device = "hw:CARD=Pro,DEV=0";  // Correct ALSA device name

    mixer_control_name = "Digital";  // ALSA mixer for volume control (this might need to be PCM

    mixer_control_index = 0;

    output_rate = 44100;  // AirPlay default sample rate

    output_format = "S24_LE";  // 24-bit format, fully supported by the DAC

    disable_synchronization = "no";

    period_size = 1024;

    buffer_size = 6615;

    use_mmap_if_available = "yes";

    use_hardware_mute_if_available = "yes";

    maximum_stall_time = 0.200;

    use_precision_timing = "auto";

    disable_standby_mode = "always";

    disable_standby_mode_silence_threshold = 0.020;

    disable_standby_mode_silence_scan_interval = 0.002;

};

After saving those changes, restart the service:

sudo systemctl restart shairport-sync

That should, in theory, output any AirPlay sound through the XLR board. It took me a few tries originally to figure out the proper name for the DAC, but once the config file was setup, Shairport-Sync worked great.