[pulseaudio-discuss] specifying ALSA mixer control

Lennart Poettering lennart at poettering.net
Thu Mar 26 07:25:28 PDT 2009

On Tue, 24.03.09 09:36, Colin Guthrie (gmane at colin.guthr.ie) wrote:

> 'Twas brillig, and Tomasz Torcz at 24/03/09 08:09 did gyre and gimble:
>> On Tue, Mar 24, 2009 at 01:56:49AM -0500, kyle cronan wrote:
>>> --- pulseaudio-0.9.14/src/modules/module-alsa-sink.c	2009-01-12 17:11:38.000000000 -0600
>>   Have you tried PA 0.9.15, with device profiles? They look like that:
>> http://dżogstaff.fordon.pl.eu.org/2009.03.25-pavc-profiles.png
>> and give separate sinks representing configuration you choose.
> While I could be wrong (as I don't have much hardware to test despite  
> writing the above feature in pavucontrol!), I don't think pulse probes  
> for dual simultaneous outputs at present. As you can see in that  
> screenshot the analog and digial outputs are exclusive...

Yes, right now PA only checks the combinations of 0 or 1 inputs plus 0
or 1 outputs. Combinations of 2 or more outputs are not checked for.

And there's actually a reason for this: Some sound cards allow devices
to be opened multiple times (as in hw mixing). That way multiple
programs may play audio at the same time with their audio being mixed
in hw and output on the same connector. Now, it is not really possible
right now to distuingish the case "Analog and SPDIF audio can be used
completely independantly" and the case "The device may be opened twice
but only either SPDIF or Analog can be used at the same time" --
because in both cases for PA it appears that opening the audio device
twice works. 

> So while it's a step towards not requiring custom setups, it's not  
> completely there yet.

I doubt that it would be so useful to expose this in PA anyway. I
mean, how realistic is it wanting to drive both SPDIF and analog audio
at the same time from the same sound card? Appears to be a very exotic
niche usage to me.


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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