From alsa-devel-owner@alsa.jcu.cz  Tue Mar 10 17:17:42 1998
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Date: Tue, 10 Mar 1998 17:17:29 +0100
From: Thomas Sailer <sailer@ife.ee.ethz.ch>
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Subject: Re: Mixer
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Jaroslav Kysela wrote:

> I get only PDF about CS4236B chip, I didn't found any file named
> HWMNL.PDF on CreativeLabs WWW/FTP.

It's somewhere hidden in a developer package, don't remember
exactly... I've put it temporarily onto
http://www.ife.ee.ethz.ch/~sailer/hwmnl.pdf

> What about add direction (parent channel pointer) to mixer channel info.
> Program can detect which channels should be modified to get final
> output.

Yes, this is the netlist approach, you essentially "draw"
a schematic of the mixer, quite like an electrical
engineering schematics program. This is certainly the most flexible
and the only way to represent every feature of the mixer,
but makes it somewhat difficult for the application.
But if the library provides enough functions to manipulate
that it's certainly doable...

> At this point can be a little bit difficult to detect Master (output)
> channel, but this should be done by testing of channel name. Master should
> be first channel, too.

If we use a netlist approach, we would have the following elements
(possibly more)

Ports
Volume elements (with boundary/step size)
Switches
Summing elements
Special functions like low/high pass filters
(Wires implicitly)

Ports would then have attributes, such as
input/output, what kind of input/output (such as
Mic, Line, ADC, DAC, headphone out, line out etc.)

> There should be done some changes in API for multitrack PCM (Gravis
> UltraSound), too.

What do you mean by multitrack? Cards with more than 2 channels?

Tom

