[gentoo-user] SurroundSound, Pulseaudio & CPU Usage

[Gustavo Campos]

Hello my fellows. Before my trouble I'll tell you a little story.

I'm a (not so happy) owner of a Audigy SE 7.1 soundcard, unable to do
hardware mixing. I own a 7.1 home theater system, so to hear sound
from all satellites I use an Alsa fake device to upmix 2.0 to a 7.1
stream, using the route alsa-plugin. As this uses a slave PCM that in
fact is a multi PCM (surround71), the sound device gets locked
everytime I listen to any sounds. That means I can't watch a video
while hearing music, flash sounds won't work either... and worse:
crossfading in media players refuse to work as well.

After months trying to figure out a way to hear sound with the
deserved freedom in my PC the only solution I found was pulseaudio.
Basically I route ALL sounds to pulseaudio by default, and pulseaudio
routes to my fake upmix device. When I want to hear a 5.1 or 7.1
sound, like a DVD, I have to specify the surround71 or surround51
devices for that, and in the end I got my soundcard locked anyway.
That was not a perfect solution, but I was happy enough not to break
my crappy creative card apart.

But I was not happy for long, so I began to be very very upset with a
fact: as you can see, Amarok is now using 19% of my CPU, while
pulseaudio is using 16:

13967 gucampos  20   0  179m  57m  28m S   19  5.7   0:14.51 amarokapp
14174 gucampos  20   0 18424 3488 2756 R   16  0.3   0:03.67 pulseaudio

That's a top. The commom average is 10 for amarok and 8 for
pulseaudio, which I still believe to be too much for my system (3.0Ghz
Pentium 4 Prescott, 2x512 DDR400). I thought that the realtime
priority of pulseaudio could be the problem, so I disabled it, and the
problem remains. Google returns me lots of people complaining, but no
actually solutions. Besides that, my sound now is a bit choppy
sometimes, which I believe is pulseaudio's high cpu usage fault.

My point is:

Is there any way to tell pulseaudio not to eat my cpu that much?
Or better: Is there a solution that would allow me to be a happy child
without having to use pulseaudio and it's extra layer between me and
my beloved hardware?

You guys can't imagine how much I played with google and alsa without
solution before I surrended to pulseaudio. If you show me a better
solution I'll feel myself stupid, but happy.

-- 
Gustavo Campos

Ciência da Computação / Computer Science - UFMG
-- 
gentoo-user@l.g.o mailing list