[pulseaudio-discuss] PulseAudio <-> ALSA issues

Nick Thompson rextanka at comcast.net
Tue Jul 8 07:26:31 PDT 2008

Hi Wolfgang,

Does aplay make sound?  if not then you may have a config issue.  I'm  
assuming that aplay is working.

You could try starting the damon from a command line with logging to  
see if there are any logging messages that might explain the issue.

Kill the existing pa with

% pulseaudio -k

Then launch pulseaudio with logging on:

% pulseaudio --log-level=3

You say in your bug that your app is pretty basic in terms of the alsa  
functionality that it uses.  It's quite possible to write alsa  
applications that pulse does not like, but pulse is usually pretty  
good about throwing assertions in this case.  One thing you might want  
to do is to look at the alsa initialization code in the aplay alsa  
application and crib the app setup code from there, or at least  
compare it with yours.

Some alsa tutorial code (IIRC the linux journal examples) on the web  
does not work with pulse in the chain, stuff that pulse expects to be  
set up is not, but in this case pulse asserts.  The code in aplay is a  
good starting point for alsa setup that works well with pulse.



On Jul 8, 2008, at 4:59 AM, Wolfgang Rosenauer wrote:

> Hi,
> I have an application (which is not OSS unfortunately) using ALSA  
> output.
> Sound works fine on systems where no pulseaudio is running but doesn't
> work at all as soon as PA is running (Gnome desktops on latest Ubuntu
> and openSUSE versions were tested).
> I've also opened a bug here:
> https://bugzilla.novell.com/show_bug.cgi?id=405354
> I've rewritten some of the Alsa-using code to fix some issues which  
> were
> in the application but in its current state I can't think of a major
> issue in the app which would cause PA to fail.
> alsa lib doesn't return an error in any of it's calls but sound simply
> doesn't start while it should.
> The device seems to be initialized correctly and PCM stream is written
> to the buffer but stream never starts. The pulse audio config thingy  
> is
> showing the application and offers a volume control for it but  
> that's it.
> Anyone has any hints for me please?
> Thanks,
>  Wolfgang
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