[pulseaudio] how to play audio on two network devices simultaneously

[nightfrost]

Does anyone know how one goes about configuring pulseaudio to play audio on two sinks simultaneously?

I found this (http://www.pulseaudio.org/wiki/FAQ#CanIusePulseAudiotoplaybackmusicontwosoundcard ssimultaneously) on the Pulseaudio FAQ:


Can I use PulseAudio to playback music on two sound cards simultaneously?

Yes! Use module-combine for that.

load-module module-oss-mmap device="/dev/dsp" sink_name=output0
load-module module-oss-mmap device="/dev/dsp1" sink_name=output1
load-module module-combine sink_name=combined master=output0 slaves=output1
set-sink-default combined

This will combine the two sinks output0 and output1 into a new sink combined. Every sample written to the latter will be forwarded to the former two. PulseAudio will make sure to adjust the sample rate of the slave device in case it deviates from the master device. You can have more than one slave sink attached to the combined sink, and hence combine even three and more sound cards.


So I guess it should be possible to tweak that to be valid for two sinks on different clients. However, I don't understand how to assign names to the devices, so I can use those names with the module-combine.

Here's the pulseaudio configuration on the local machine: http://dl.getdropbox.com/u/175461/pulse/default.pa.local
And here's the configuration on the other machine (which starts pulseaudio as a system service, FWIW): http://dl.getdropbox.com/u/175461/pulse/default.pa.remote

Thanks in advance!

[unimatrix]

I would VERY MUCH like to know this too. Subscribed.

[markbuntu]

You can use module combine or, if you just want simultaneous output to all output devices you can just open the pulseaudio device chooser and go to configure local sound server/simultaneous output and check the box.

[unimatrix]

How do I find the name of a network sink?

[kwaanens]

I'm also interested in finding out how I do this. Anyone?

[00arthuryu]

I too would also like to know
:popcorn:
Subscribed

[taphos]

To see the module names run pulse audio with the shell from the terminal

pulseaudio -C

Use this command to get the list of local sinks in the pa shell

list-sinks

module-combine is able to combine only local sinks, so you need to create a tunnel sink that will send sound from local pa server to the remote one

load-module module-tunnel-sink server=soundserver.local

Now combine sinks

load-module module-combine sink_name=combined slaves="tunnel.soundserver.local,alsa_output.pci_10de_26c_ sound_card_0"
replace "alsa_output.pci_10de_26c_sound_card_0" and "soundserver.local" with your own values

Have fun ;)

[unimatrix]

Thanks taphos, but I have some further questions.

First of all, you don't need to kill pulseaudio just to get into the command prompt. You can use pacmd.
For example:


pacmd list-sinks
pacmd load-module module-tunnel-sink server=soundserver.local
pacmd load-module module-combine sink_name=combined slaves="tunnel.soundserver.local,alsa_output.pci_10de_26c_ sound_card_0"



Second, where do I load these modules? On the remote client or on the machine that will play audio to the clients?
Also, what is soundserver.local anyway and where do I find out what my value is?

Thanks!

[taphos]

I didn't know about pacmd, thanks for the advice.

You load those modules on the machine which will send the sound stream (where you run your music player)


load-module module-tunnel-sink server=soundserver.local
load-module module-combine sink_name=combined slaves="tunnel.soundserver.local,alsa_output.pci_10de_26c_ sound_card_0"
set-default-sink combined


On the remote sound server (which will receive a sound stream) you need to enable tcp protocol, I do it via gui application "padevchooser"
Configure local server > Network access > Enable network access to local devices
Or this can also be done by loading modules (but I haven't tried it):


load-module module-native-protocol-tcp auth-anonymous=1
load-module module-esound-protocol-tcp auth-anonymous=1


The soundserver.local is the host name of the remote sound server where "soundserver" is the name of the machine, to get it run "hostname" command. You can use the IP address instead if you like (i.e. 192.168.0.2).

Btw. you can also transmit sound to remote servers by using RTP,
if "padevchooser" Configure local server > Multicast/RTP
see also http://pulseaudio.org/wiki/Modules#RTPSDPSAPTransport
If you got a wired network, you should use this better.
But it does not work for me as I am using wifi and it can not handle the RTP broadcast traffic for some reason, sound becomes very choppy.