[pulseaudio-discuss] Controlling where module-rtp-send sends multicast packets?

Matthew Patterson matt at v8zman.com
Thu Feb 14 22:23:03 PST 2008

Hello all,

I just discovered PulseAudio about 2 weeks ago and was struck by how 
applicable it could be in creating a whole home audio solution where 
each room can subscribe to the same or a different audio stream as 
another room. To create this I setup 4 mpd instances, each talking to a 
different rtp-send module. Then on the playback side there are 4 
rtp-recv modules that can connect to each of the multicast streams. I 
have all of this functioning and have written a small python app to 
configure the modules via the unix socket cli connection. All of this is 
implemented on one machine so I have the rtp-send modules looping back 
the data.

Now for my question: This implementation obviously spews a lot of 
multicast traffic onto my network. I didn't think this would be a 
problem, but my router/ap/switch seems to crap out when it gets hammered 
with all the traffic. Is there any way that I can specify which 
interface pulesaudio sends its multicast packets on? Or even more 
ideally, can I disable all outgoing multicast traffic and just have the 
local loopback happening?

I have attempted to configure the kernel routing tables on my ubuntu 
(7.10) install, but with no change. I still see all the multicast 
packets going out the interface (using ethereal on another machine to 

I have pulseaudio version 0.9.9 that I compiled myself.

Thank you to the authors of this awesome software package!


P.S. If anyone is interested in my little whole home audio project I am 
perfectly happy to share my rather hackish python/php code and maybe get 
a little help.

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