generic mixer control?

generic mixer control?

[Paul Davis]

i don't enough about ALSA's handling of consumer mixers to know if
this is possible, but ... i was wondering if there is anyway to write
a generic chunk of code for JACK that manipulates a consumer-oriented
card's mixer to provide hardware mixing. the basic process would be to
turn up the "capture gain" volume so that you get to hear whatever
is being recorded. you might have to turn down something else as well,
but thats probably secondary.

its not clear to me whether or not many mixers come with a single
control that can do this, and/or whether there is any standard way to
do this that ALSA "exports" to the world.

any comments? i'd like to provide "hardware monitoring" for users of
consumer oriented cards to supplement the hammerfall and ice1712 stuff
that we already have ...

--p



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Re: generic mixer control?

[Jaroslav Kysela]

On Fri, 13 Sep 2002, Paul Davis wrote:

> i don't enough about ALSA's handling of consumer mixers to know if
> this is possible, but ... i was wondering if there is anyway to write
> a generic chunk of code for JACK that manipulates a consumer-oriented
> card's mixer to provide hardware mixing. the basic process would be to
> turn up the "capture gain" volume so that you get to hear whatever
> is being recorded. you might have to turn down something else as well,
> but thats probably secondary.
> 
> its not clear to me whether or not many mixers come with a single
> control that can do this, and/or whether there is any standard way to
> do this that ALSA "exports" to the world.
> 
> any comments? i'd like to provide "hardware monitoring" for users of
> consumer oriented cards to supplement the hammerfall and ice1712 stuff
> that we already have ...

Although the task is easy, the implementation is not. We definitely need 
to define some abstract controls like this in mixer and describe the 
complicated consumer mixers in configuration files like abstract PCM 
devices.

At the time, you might test if AC'97 is present (most of PCI cards) and 
write specific code for it.

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project  http://www.alsa-project.org
SuSE Linux    http://www.suse.com



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Re: generic mixer control?

[Takashi Iwai]

At Fri, 13 Sep 2002 17:30:55 +0200 (CEST),
Jaroslav wrote:
> 
> On Fri, 13 Sep 2002, Paul Davis wrote:
> 
> > i don't enough about ALSA's handling of consumer mixers to know if
> > this is possible, but ... i was wondering if there is anyway to write
> > a generic chunk of code for JACK that manipulates a consumer-oriented
> > card's mixer to provide hardware mixing. the basic process would be to
> > turn up the "capture gain" volume so that you get to hear whatever
> > is being recorded. you might have to turn down something else as well,
> > but thats probably secondary.
> > 
> > its not clear to me whether or not many mixers come with a single
> > control that can do this, and/or whether there is any standard way to
> > do this that ALSA "exports" to the world.
> > 
> > any comments? i'd like to provide "hardware monitoring" for users of
> > consumer oriented cards to supplement the hammerfall and ice1712 stuff
> > that we already have ...
> 
> Although the task is easy, the implementation is not. We definitely need 
> to define some abstract controls like this in mixer and describe the 
> complicated consumer mixers in configuration files like abstract PCM 
> devices.

yes, this is what i've longed for.
this will make it possible to create a "reasonable" mixer program,
too.

but for this we need an extra database.  and the problem is that the
mixer topology depends not only on the sound chip but on codecs
connected, too.

perhaps exporting pci subdevice id and checking it will give a
workaround for special cards even without changing the driver code
itself.


Takashi


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