[alsa-devel] Issue with Alsa and PulseAudio

[Takashi Iwai]

At Tue, 26 Aug 2008 16:21:13 +0100,
Colin Guthrie wrote:
> 
> Hi Ash,
> 
> Ash wrote:
> > Hello, I have a media application that uses alsa as its sound
> > renderer. It has worked on numerous systems without any problems
> > until I came across a mandriva distro that bundles with PulseAudio.
> > The alsa pulseaudio plugin is installed correctly, however I am
> > having weird problems.
> > 
> > When I am setting up my hw params, and I call
> > snd_pcm_hw_params_any(), I get an "Operation not permitted" error. I
> > am not sure why this is happening, anyone else see this before? I am
> > using pulseaudio version 0.9.9 and alsa 1.0.16.
> > 
> > Thanks in advance!
> 
> I'm the Mandriva PulseAudio maintainer. Most distros are now shipping PA 
> by default now so I doubt your problem will be specific to Mandriva :)
> 
> However, I'm not expert enough in the ALSA API to know specifically what 
> snd_pcm_hw_params_any() actually does, but I'd imagine (this is just a 
> guess) that this is something that is either not implemented in the 
> IOPLUG system (on which the pulseaudio alsa plugin builds) or something 
> not implemented in the pulseaudio alsa plugin itself.
> 
> Hopefully someone more versed in this can explain the reason why it 
> fails. :)

There is no alsa-lib code that returns -EPERM by itself.
Usually this error comes from the ioctl, but in this case, it must be
from pulse plugin.  And, pcm_pulse.c contains no EPERM, it must come
from the pulseaudio itself.

So, my rough guess is that PA is running by a different user
(e.g. root) that doesn't allow you to connect it.

Of course, first I'd do is to upgrade alsa-lib and alsa-plugins.
1.0.16 is fairly old.


Takashi