[pulseaudio-discuss] Sending audio from source to multiple sinks dynamically

[Timothy J Massey]

Hello!

I am trying to build your typical multi-room audio server.  I would like 
to have a single computer with e.g. 4 copies of MPD as 4 sources, and e.g. 
8 USB soundcards, creating 8 sinks.  I would like users to be able to 
select, independently, for each of the sinks the source that it is 
using--without disturbing any of the other sinks.  A single source could 
be played back by any number of sinks independently of each other, and 
each source would be able to select from any of the available sources, 
regardless of who else is using it as well.

>From what I can tell, with PA you can pick only which (single) sink a 
source is connected to.  If you pick a new sink for the source, it is 
removed from whatever sink it was using before.  And AFAICT, if you want 
to have a source play via more than one sink, the only way to do this is 
to create a virtual sink that is a combination of more than one sink.  Is 
this correct?  It's not really practical to create a virtual sink for each 
of the possible combinations of e.g. 8 different sinks...

I'm looking for a more flexible structure.  I would like to be able to 
connect a sink to a source, and leave whatever other sinks that might 
already be playing from that source *alone*.  For example, if I'm 
listening to MPD#1 in the living room, and I start moving between the 
living room and the kitchen, I want to be able to select MPD#1 in the 
kitchen *and* leave it undisturbed in the living room.  Then, if someone 
moves into the living room and switches it to MPD#2, I want my playback in 
the kitchen undisturbed.

What I'm describing is a very typical bus setup that any higher-end 
multi-zone audio (or mixing board) would support.  Each output can 
independently connect to one of a number of available sources without 
affecting any of the other output channels.  The sources don't care which 
channels (if any) are connecting to them, and the sinks don't care what 
the other channels are doing.

I apologize in advance if this is a FAQ:  I'm very willing to RTFM--just 
please tell me which FM to R!  :)  I am open to any suggestions how I 
might be able to accomplish this, including both different Linux 
distributions and different sound management layers (i.e. would Jack be 
better for this?).

Thank you,

Tim Massey