On Tue, Feb 28, 2012 at 03:30:24AM +0100, Frank Steinmetzger wrote:
>
> > dmix *may* be able to handle multiple audio streams (in practice, in
> > my personal experience, it always requires more work than PA); but it
> > will never be able to do the other stuff PA handles.
>
> This seems like a dumb question (for I was a strict PA denier until recently
> and have been using alsa-only since always), but does PA handle OSS
> applications better than alsa/dmix? Whenever I want to use sidplay, which only
> speaks OSS, I need to stop all other audio programs (e.g. press Stop in the
> Clementine player if it's only paused), or else /dev/dsp was busy.
PA doesn't care about oss (/dev/dsp). It opens the soundcard through
normal alsa interface (which means /dev/dsp becomes busy). You can
either kill pulseaudio, or tell pulseaudio to suspend the correspondig
sink (not sure what exactly happens if an audio stream through PA is active
etc..).
Regarading oss (/dev/dsp) and plain alsa, it is the same, if something
opens the soundcard through alsa, /dev/dsp becomes busy... (even when
using dmix in alsa, because /dev/dsp is handled by a kernel modules,
dmix is userspace).
There is however a way to amke oss work with dmix through aoss (a small
program that preloads a binary, that 'hijacks' calls to open /dev/dsp
and 'reroutes' that to alsa, works most of the time, but can have
problems if the program does some weird things...)
In that case aoss opens the alsa device "pcm.dsp" (or dsp0, i'm not sure
right now), which you can easily point to dmix...
from my /etc/asond.conf:
========================================
pcm.dsp {
type plug
slave.pcm "duplex"
}
pcm.dsp0 {
type plug
slave.pcm "duplex"
}
pcm.!default {
type plug
slave.pcm "duplex"
}
pcm.duplex {
type asym
playback.pcm "dmix:0"
capture.pcm "dsnoop:0"
}
========================================
Then you can run (even multiple) 'aoss mpg123 file.mp3 ...'
You can also make this to work alongside pulseaudio, if you configure
pulseaudio to use the dmix device instead of directyly using the hw
device.
Nnote that this might cause problems, you have to disable pulseaudio's
autodetect and configure all soundcards manually, and using dmix
introduces some additional overhead and probles, also such setup is most
probably not supported by pulseaudio etc... However it also enables you
tu run plain alsa apps alongside PA (officialy you should just configure the
!default device to use the PA alsa plugin is simpler and it should work
better, though I had some problems with some apps) and more importantly
to run multi PAs simultaneusly (ie for multiple users...)
yoyo
