adding Airplay to a Sonos with Raspberry Pi

I mostly like my Sonos system. The downsides: I had a controller die on me out of warranty; it’s a bit pricey; and it doesn’t have Airplay support. This last one, at least, turns out to be fixable, thanks to a few open source projects and the Raspberry Pi.

The ingredients:

• the Shairport project, for providing Airplay
• the SoCo project, for controlling the Sonos

This last one is important for making the Sonos start listening to its line-in when Airplay begins to be used.

Getting your Raspberry Pi on your wifi network is a bit of a pain. You’ll need to compile Shairport’s dependencies and install some modules from CPAN. SoCo’s setup.py doesn’t leave you with a working installation, but the codebase is fine if you use it directly.

With all the pieces in place, you just need a script like this to switch the Sonos:

import re, sys
from soco import SonosDiscovery, SoCo

def main():
sd = SonosDiscovery()
possible_matches = sd.get_speaker_ips()
speaker_info = {}
for ip in possible_matches:
s = SoCo(ip)
try:
speaker_info[ip] = s.get_speaker_info()
except Exception, e:
speaker_info[ip] = {}

for (ip, speaker) in speaker_info.items():
if re.search(sys.argv[1], speaker.get('zone_name', ''), re.I) is not None:
s = SoCo(ip)
s.switch_to_line_in()
s.play()

if __name__ == '__main__':
main()

and then to start the Shairport daemon like so:

perl /home/pi/sonos-airplay/shairport.pl -d -w /home/pi/sonos-airplay/shairport.pid -l 100 --apname="Sonos" --play_prog="/home/pi/.virtualenvs/sonos/bin/python /home/pi/sonos-airplay/set_line_in.py bedroom"

This will call the set_line_in.py script every time a new Airplay client connects.

For good measure, here’s the /etc/init.d/shairport startup file I’m using:

#!/bin/sh
# /etc/init.d/shairport
PIUSER='pi'
case "$1" in
start)
/home/pi/sonos-airplay/start_shairport.sh
echo "Starting Shairport Server for $PIUSER "
;;
stop)
kill `cat /home/pi/sonos-airplay/shairport.pid`
echo "Shairport Server stopped"
;;
*)
echo "Usage: /etc/init.d/shairport {start|stop}"
exit 1
;;
esac
exit 0

It all works pretty well! The only real downside is the volume: Airplay’s pretty quiet. I should be able to automate the volume adjustment on the Sonos — SoCo exposes that functionality as well, and Shairport can call scripts upon client disconnect, too, to reset the volume. But I haven’t had a chance to write that yet.

Anyway, if folks start wandering in from Google and find this useful or desirable, let me know. I could probably make this all a bit more reusable without a ton of trouble (distributing a Raspberry Pi filesystem image might be the easiest thing, really).

UPDATE: Hmm. Subsequent investigation of the Sonos’s line-in level adjustment capabilities reveals that the SoCo portion of this might be unnecessary: there is indeed some capacity for adjusting amplification on the line-in. Better still, there’s some sort of line-in activity detection! I think I might stick with my script anyway: I have a Sonos unit on the porch that’s usually powered off; I’ll probably just adjust the script’s logic to pipe the line-in to it if it’s activated. Still, for most users the Shairport stuff should be sufficient.