[pulseaudio-discuss] Moving sources and sinks

Lennart Poettering lennart at poettering.net
Mon May 5 17:42:05 PDT 2008

On Fri, 02.05.08 10:20, Nick Thompson (rextanka at comcast.net) wrote:

> OK so I figured out the error of my ways, but I have to say this list is 
> pretty unresponsive in helping the community so I have to ask myself "is 
> pulse is a sensible choice for audio development today"?   Particularly 
> since there is little in the way of useful setup documentation for actually 
> using the library on a programatic way, the error messages from the library 
> and utilities are not particularly helpful and so on.

Yes, our documentation is not perfect. Nothing is perfect. But
complaining about Free Software like this doesn't really make you any
friends in the community, you know? This is not how Free Software

Our resources are not infinite. Actually they are very much finite,
it's only me who works on PA full-time. All other contributors do it
in their spare time or supply only patches from time to time.

Also, coling and tanuk and others do a very good job with responding
on this mailing list (and I am very thankful for what they are
doing. Thanks, dudes!). I am not constantly monitoring this
list. However, I try my best to respond to every single post that is
left unanswered, from time to time. So please be patient, eventually
most people should get an answer from me, even if it might take a while,
like this reply did. 

In short: we're not your support monkeys! Thank you very much.

> What I need to be able to do is route audio around.  I suspect write a 
> module for pulse that will look at the alsa stream class and based on that 
> use the input index to set the sick for that stream.  It would be nice to 
> have a feature whereby I can rout all output sent to a particular sink, to 
> another sink.  I guess what I'd like to do is be able to create virtual 
> devices whose output can be changed on the fly.  So for example I could 
> define an mp3 output that I can switch between headphone output and speaker 
> output depending on a system setting.  Or between one speaker output and 
> another.  If pulse has a means to do this already I'd appreciate someone 
> pointing me in the direction that can help.

Something like this has been asked for before.

In the glitch-free branch in SVN you'll find a "proplist" feature that
allows you to attach all kinds of meta information to streams, sinks,
sources, clients. One of the reasons to add this is to allow
implementation of policy routing like you suggest.

> It seems ALSA will do most of this and the ALSA list seems to be a lot more 
> active, so maybe I was mistaken in thinking that Pulse would really be a 
> useful addition to our audio stack, particularly since on an embedded 
> system it consume disproportionate resources for the benefit it
> provides.

Oh come on, dude. You make it sound like I should feel bad because you
won't use my software. I am not sure in what strange a world you
live. You should be thankful that the Free Software people allow you
to use your software for free -- no the other way around. And for
fuck's sake, if there's something that the software you are interested
in lacks, then please stop complaining and supply a patch. That is how
free software works.

Also, if you don't need PA, then don't use it. Nobody forces
you. Especially in embedded space you should really know if you need
something before you add it to your stack. I am happy for every
complaint I get less from people with no clue about open source like you.

> Also where is the mixer implemented and how is it controlled.  Or is the 
> mixer just a dumb "you have 3 streams coming in and I will make them one" 
> type deal.  In other words is there bussing or output switching in the 
> mixer.  If not, is this planned?

I am not sure I get what exactly you are asking for. But yes, PA mixes
audio. Surpised? 

> Anyway, in case this helps anyone else, the sources that are listed by 
> list-sources are not really sources to pulse.  So trying to move them 
> around will not work.  Here's something I wrote up on the subject:

I think you didn't understand the distinction PA makes between sinks
and source-outputs, resp. sources and sink-inputs. I.e. clocked
vs. non-clocked.

Please shut up with your complains. Learn how Free Software works. 

I don't take complains. I only take patches, suggestions and bug reports.


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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