Re: [Alsa-user] "Unknown field slaves" with virtual multi-channel device

[Takashi I. <ti...@su...>]

At Thu, 14 Feb 2013 23:09:45 +0100,
Clemens Ladisch wrote:
> 
> Sheldon Hearn wrote:
> > I gutted /usr/share/alsa/alsa.conf so that it just loads
> > /etc/asound.conf
> 
> Aaargh!
> 
> That file contains all the default definitions.
> Please restore the original from the alsa-lib package.
> 
> > Is there a way I can get debugging output from ALSA while it processes
> > its configuration, so that I can try to make sense of this?
> 
> Unfortunately not.

True...  Maybe printing the configuration item in question would be
helpful.  (Oh wait, do we have a function to print a config item at
all?)

> > pcm.multi {
> >   type multi;
> >   slaves.a.pcm "hw:0,0";
> >   [...]
> > }
> >
> > pcm.multi {
> >   type hw;
> >   card 0;
> > }
> >
> > The second pcm.multi stanza redefines the device called multi using
> > the hw plugin. invalidating the configuration statements in the first
> > stanza.
> 
> Actually, this _merges_ both definition; the result is the same as:
> 
>   pcm.multi {
>       type hw
>       slaves.a.pcm "hw:0,0"
>       ...
>       card 0
>   }

Yes.  If you want to redefine (override), you'll need to put "!"
prefix:

pcm.!multi {
	....
}


Takashi