In short here it is:
Now everything one by one:
- docker run --rm -ti - run non-persistent docker and prepare it as interactive (shell) run
- --device=.... make local sound devices available in container. This feature is quite new in docker, so make sure you have recent version (mine is 1.8)
- -p 4713:4713 set up port forwarding between host and container to make pulse server available to clients
- rpi-deb-pulse is my docker image built from armbuild/debian by running system upgrade and install pulseaudio
- /bin/bash -c "..." is command to run inside container, more on this below
- groupadd --gid $(...) alsadev create a group inside container named alsadev and having same id as group of /dev/snd/controlC0 device. We need this to allow pulse to access native alsa devices.
- $(ls -l /dev/snd/controlC0 | cut -d' ' -f4 | xargs getent group | cut -d: -f3) this subshell is executed on host, not in container and prints group id of /dev/snd/controlC0
- gpasswd -a pulse alsadev adds user pulse to our new group alsadev
- pulseaudio ... run pulseaudio
- -L 'module-alsa-sink device=hw:0,0' explicitly load alsa sink and specify which output to use
- -L 'module-native-protocol-tcp auth-ip-acl=10.2.0.0/24' load tcp protocol listener and (optionally) configure ip-acl to only accept connections from given subnet
How to then use it to play sound remotely (client):
- pactl load-module module-tunnel-sink server=10.2.0.1
- in pavucontrol on Playback tab select desired sink for a stream
Things to improve:
- list of devices may be replaced with another subshell to not specify each dev manually
- add systemd unit to start container automatically
- tune pulseaudio since sound over tcp tunnel is worse then playing locally
Why was this done :)
I have a Raspberry Pi 2 acting as a wireless router and i didn't wont to install pulse into host system. And i was just curious about whether this will work :)
