[pulseaudio-discuss] Headless "Speaker Server" Configuration

Justin Chudgar justin at justinzane.com
Sun Jan 27 17:59:08 PST 2013

I'll takea look at the source for module-combine-sink. I've been
building some speakers and in the process discovered the vast extent of
the audio and acoustics world. One of the things that I discovered in
the DIY-audio world is that there is a significant use for digital
crossover, notch filtering and per-channel level balancing.

Of course, the typical way to do this is the traditional one -- using
inductors, resistors and capacitors in the speaker cabinet. But, being a
digital geek, it occurs to me that it would be very nice to do all this
in the sound server since everything I listen to ends up going through

While the vast majority of computer users probably use the built-in or
off-the-shelf  speakers that they got with their computers, I've come
across numerous individuals who are doing surround sound with two or
more pairs of mismatched commercial computer speakers. In this, much
more common, case, the ability to apply ladspa filters to individual
channels/channel-pairs would allow much better quality sound.

My point being that just as treating audio as atomic streams within the
sound server is a vast improvement over the single-app access to a
hardware sound card, treating audio streams as bundles of atomic
channels is also an improvement. Whether it is to achieve some audio
geek fantasy setup or just to enable someone to get their old Logitech
speakers to work well with the ones in their laptop, the ability to
route and filter channels independently is critical.

I'm a pretty crappy programmer and a newbie to the world of audio
processing, so please take my thoughts with a large shaker of salt. And,
thanks for the continuous improvements to pulse.

Justin Chudgar  |  Weed, CA 96094  |  530 921 0738 | http://www.justinzane.com/

On 01/26/2013 09:02 PM, Tanu Kaskinen wrote:
> On Sat, 2013-01-26 at 16:16 -0800, Justin Chudgar wrote:
>> I've been looking at the docs on system mode and am confused about how
>> to setup a headless speaker server. I have a very large room wired with
>> in-wall ethernet, but not audio. I would prefer to use an old headless
>> PC as a "speaker server" -- a sink for the rear-left and rear-right
>> channels instead of having to run lots of heavy gauge speaker wire.
> I don't think this is currently possible. You'd need module-combine-sink
> for combining the front and the rear speakers, but module-combine-sink
> doesn't support selecting some channels for one output and some other
> channels for another output.
> Even if module-combine-sink supported such splitting (it shouldn't be
> hard to implement, if you feel like contributing patches), there would
> still probably be issues with timing. I'd imagine that good surround
> experience would require very good synchronization, and I don't think
> module-combine-sink provides that. (It does provide some
> synchronization, but from what I've heard, it's far from perfect.)
>> Using Ubuntu server as a base, I've been trying to get pulseaudio to
>> work as a system instance and have thoroughly failed. Could someone
>> please help with configuration advice.
> Some details about what you've tried and what errors you're getting
> would be useful (if you still want to run pulseaudio in the system mode,
> given what I said above).

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