The installation and setup of Shairport Sync is straightforward on recent Linux distributions. Issues can occasionally arise caused by problems elsewhere in the system, typically WiFi reception and/or the WiFi adapter settings, the network, the router, firewall settings or some more esoteric audio interfaces.
In this brief document will be listed some problems and some solutions, some provided by other users.
- Before starting, ensure that your software is up-to-date. This document always refers to the most recent version of Shairport Sync -- see here for information about the most recent release.
- If you have set
interpolationin thegeneralsection of the configuration file to tosoxr, comment it out or set it toautoorbasicas thesoxrsetting can cause lower-powered devices to bog down at critical times, e.g. see this report. - Ensure the volume setting of your output device is set to some reasonable value and ensure it is not muted. For ALSA devices, the
alsamixercommand-line tool is very good for this. For other sound systems, please consult the relevant documentation.
If the audio from your Shairport Sync device is delayed slightly by comparison with audio from other devices, it may be that the output device being fed by Shairport Sync is introducing a delay while it processes the audio. If your output device include any digital processing component, it probably delays the audio while it processing occurs.
For instance, if your output device is a HDMI-connected device such as a TV or an AV Receiver, it will almost certainly delay audio by anything up to several hundred milliseconds.
The fix for this is to ask Shairport Sync to provide the audio to the output device slightly ahead of time, so that by the time the output device has processed it, the audio emerges at exactly the right time. The setting to look for is in the general section of the Shairport Sync configuration file and is called audio_backend_latency_offset_in_seconds. By default it is 0.0 seconds.
For example, if your output device is delaying audio by 100 milliseconds (0.1 seconds), set the audio_backend_latency_offset_in_seconds to -0.1, so that audio is provided to your output device 0.1 seconds early. Remember to uncomment the line by removing the initial // and then restart Shairport Sync (or reboot the device) for the changed setting to take effect.
Check Throughput
You can check WiFi throughput using, for example, https://thepi.io/how-to-use-your-raspberry-pi-to-monitor-broadband-speed/
Problem
Shairport Sync is installed and running, but sometimes it disappears from the network, and sometimes it suffers from long dropouts.
Possible Cause
This can be caused by lots of things, but one of them is that the WiFi adapter may be set to run in a low-power or power-saving mode. If it's not busy, then after a while it goes into a low-power mode. This is bad as the device needs to be always connected to the network to provide the AirPlay service. You need to turn off power-saving mode. How you do this varies with platform and with WiFi adapter – internet search is your friend. Here, for instance, is the command for the C.H.I.P. from Next Thing Co, which has built in WiFi and Linux and has the iw command installed:
iw dev wlan0 set power_save off
Here is the command sequence for a Raspberry Pi 3, which has built-in WiFi:
sudo iwconfig wlan0 power off
Alternatively, (also for the Raspberry Pi), add the following line:
wireless-power off
to the file /etc/network/interfaces.
Here is another option, suggested by davidhq in #653:
$ sudo nano /etc/network/if-up.d/off-power-manager
Type:
#!/bin/sh
/sbin/iwconfig wlan0 power off
Then:
sudo chmod +x /etc/network/if-up.d/off-power-manager
There are some more details in some the closed issues on this repository.
To see the AirPlay service Shairport Sync provides, your devices must be on the same subnet as Shairport Sync. If, say, a device such as an iPhone is on a VPN and Shairport Sync is not, or vice-versa, then even though the devices might be physically on the same network, they are effectively on separate networks due to the VPN and the AirPlay service will not be accessible to the device. So, when you are troubleshooting, look out for VPN issues.
For an example of what it can take to track down a bad WiFi situation – in this case, a faulty WiFi adapter – please look at this report.
Problem
You can play from other devices but not from your Windows PC.
Possible Solution
Allow network discovery. This setting creates a private type network and enables Windows to access the ports and protocols necessary to use Shairport Sync.
Problem
You have installed Shairport Sync successfully, the daemon is running, you can see it from your remote terminal but you are unable to play a song.
Before you change anything to your configuration
-
Type the following command:
sudo ufw disable -
Try to launch a song from your remote device on the Shairport-sync one, if this works, proceed to the next step and follow the ones described below, in the solution section.
-
Enable UFW through the following command:
sudo ufw enable
Solution
You have to allow connections to your Shairport Sync device from remote devices. To do so, after re-enabling UFW (see last step of the previous section), enter the following commands in shell:
sudo ufw allow from 192.168.1.1/16 to any port 3689 proto tcp
sudo ufw allow from 192.168.1.1/16 to any port 5353
sudo ufw allow from 192.168.1.1/16 to any port 5000:5005 proto tcp
sudo ufw allow from 192.168.1.1/16 to any port 6000:6005 proto udp
sudo ufw allow from 192.168.1.1/16 to any port 35000:65535 proto udp
You may have to change the IP addresses range depending on your own local network settings.
You can check UFW config by typing sudo ufw status in shell. Please make sure that UFW is active, especially if you have deactivated it previously for testing purpose.
Run your song from your remote device. Enjoy !
This refers to slower machines, such as the Raspberry Pi Zero or the original (single core) Raspberry Pi, running a recent Linux that uses systemd.
Problem
Having compiled Shairport Sync properly using the README guide, and having completed the make install step, and having enabled startup on reboot using $ sudo systemctl enable shairport-sync, Shairport Sync will start manually upon entering $sudo systemctl enable shairport-sync, but it will not start automatically after a reboot.
Possible Cause
On lower-powered machines, such as the Raspberry Pi Zero or the original (single core) Raspberry Pi, particularly with a USB sound card, it may be that the sound system is not ready when Shairport Sync is automatically started. The result is that Shairport Sync cannot see the device it needs and shuts down.
Possible Solution
A good solution is to delay the automatic startup of Shairport Sync by a few seconds using the systemd timer mechanism:
Create a file called shairport-sync.timer and place it alongside shairport-sync.service in /lib/systemd/system. The file should contain the following:
[Unit]
Description=Shairport Sync AirPlay receiver
[Timer]
OnBootSec=10s
Unit=shairport-sync.service
[Install]
WantedBy=multi-user.target
You need to disable the shairport-sync service because the timer is calling the service, and you need to enable the shairport-sync timer:
# systemctl disable shairport-sync
# systemctl start shairport-sync.timer
# systemctl enable shairport-sync.timer
See also #179, with thanks to @maumi and others.
Alternative Solution
- Edit Shairport Sync service file
sudo nano /lib/systemd/system/shairport-sync.service - Update the service section to include the line
ExecStartPre=/bin/sleep 5
Example:
[Service]
ExecStartPre=/bin/sleep 5
ExecStart=/usr/local/bin/shairport-sync
User=pi
Group=pi
Problem When using a USB DAC on a Raspberry Pi audio plays fine through other methods (such as through mpd, mopidy, mplayer or aplay) but when streamed to Shairport Sync regular dropouts or stutters are heard.
Possible Cause There is a suspicion (although this is not 100% confirmed) that this is a fun latency/timing issue related to a combination of
- The Raspberry Pi's ethernet itself being a USB device resulting in shared bandwidth/interrupts with USB DACs
- Shairport Sync continually checking the latency of the USB DAC to maintain synchronisation of audio
- Quirky USB DACs (already known to be problematic on the Raspberry Pi more info available here For more discussion on this issue see issue 167 or read on for the quick fix!
Possible Solution To get nice smooth audio first check the details of your USB DAC by either using 'aplay -l' which will give you output something like this:
**** List of PLAYBACK Hardware Devices ****
card 0: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 0: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: MP3 [Sound Blaster MP3+], device 0: USB Audio [USB Audio]
Subdevices: 0/1
Subdevice #0: subdevice #0
or look at your existing '/etc/asound.conf' file, which may look something like this
pcm.!default {
type hw
card 1
}
ctl.!default {
type hw
card 1
}
The important information you want is the card number which in this case is 1.
Now modify your 'etc/asound.conf' file (or create one if it doesn't exist) using the following template substituting the 'pcm "hw:1"' and 'card 1' sections with the card number of your device
pcm.!default {
type plug
slave.pcm {
type dmix
ipc_key 1024
slave {
pcm "hw:1"
rate 48000 # this line is only needed for USB DACs which only support 48khz
period_time 0
period_size 1920
buffer_size 19200
}
}
}
ctl.!default {
type hw
card 1
}
This sets the default alsa audio device to be the USB DAC via a dmixer plugin (which can be used by multiple applications at once) using a modified period and buffer size and optionally mix to 48khz.
This will then be used by default by Shairport-Sync and any other applications using alsa.
Note that some distributions (such as Volumio 2) don't use an asound.conf file by default, they instead specify the hardware details directly in '/etc/mpd.conf' files so some more in-depth modification is needed to override this.
(Note: not tested by Mike B.)
**Problem **
Audio may seem to pause or drop for several seconds. iOS devices may regularly disconnect altogether and display an error message. This may be caused by a combination of factors listed above such as slow WiFi or limited resources on the device running Shairport Sync.
**Possible Solution **
If none of the above steps completely remove the issue, try increasing the audio backend buffer setting in the backend section of shairport-sync.conf. (This section may vary depending on the value of the "output_backend" setting.)
For example:
audio_backend_buffer_desired_length = 19845;
Is triple the default for the ALSA backend and effectively solves the above issue with a Pi Zero on a busy network.