[pulseaudio-discuss] Alsa output devices, able to use alsa plugin?

[Tanu Kaskinen]

ke, 2009-08-26 kello 12:10 +0800, Ng Oon-Ee kirjoitti:
> Hi all,
> 
> I know back in March there was a conversation about alsa devices to be
> used with load-module module-alsa-sink. Basically, Lennart mentioned
> NEVER to use device=hw:0,0 (I do that, though, as I don't use
> module-hal-detect so that I can choose which modules I want through a
> script). However, I don't see any discussion on how to choose another
> device. So, two questions:-
> 
> 1. Instead of "load-module module-alsa-sink device=hw:0,0", what should
> I be using to load the appropriate device? Assuming I'm not using
> module-hal-detect.

http://www.opensubscriber.com/message/fedora-devel-list@redhat.com/12018387.html

> 2. I'm interested in using an alsa plugin to modify pulse's output
> before it hits my card. Specifically the alsaequal plugin. I have
> specified it in my .asoundrc as below:-
> 
> ctl.equal {
>   type equal;
> }
> pcm.plugequal {
>   type equal;
>   slave { pcm "plughw:0,0" }
> }
> pcm.equal {
>   type plug;
>   slave.pcm plugequal;
> }
> 
> This works properly with aplay -D equal, of course. How do I modify my
> device string in load-module module-alsa-sink to use the 'equal' output,
> so that I can dynamically equalize the output before it hits the
> speakers? Is this even possible?

load-module module-alsa-sink device=equal

You might also want to change the

    slave { pcm "plughw:0,0" }

line to

    slave { pcm "plug:front:0" }

just to reduce ugliness (= unneeded assumptions). I'm not 100% sure that
works, though. If it doesn't, just revert to the old version. Hmm...
since pcm.equal is already of type plug, I think the line can be
simplified to

    slave { pcm "front:0" }

I'm not totally sure about this either (fiddling with alsa config isn't
one of my hobbies).

There are other approaches to equalization, but I don't feel like going
in the details of those if this works for you. If you're interested, I
just point you to this:
https://tango.0pointer.de/pipermail/pulseaudio-discuss/2009-August/004730.html

-- 
Tanu Kaskinen