Re: ymfpci : four speakers with OSS-emulation

[Takashi Iwai <tiwai@suse.de>]

At Wed, 13 Mar 2002 08:01:02 -0500 (EST),
Adam K Kirchhoff wrote:
> 
> The solution the Jaroslav gave in that e-mail actually requires changes to
> the ymfpci driver, as I understand it.  Last time I pulled code from CVS,
> this hadn't been done yet.  From the sound of it (based on your
> experience) it looks like it still hasn't been done.  At the moment, I
> don't really understand Alsa (or sound drivers in general) well enough to
> make the change myself, nor do I really have the time to pick up that
> knowledge at the moment.
> 
> However, it's also my impression from Jaroslav's explanation that this
> would simply duplicate the output from the fron channel on the rear
> channel. Can someone let me know if this is correct?

if you only need duplication, this can be done on alsa-lib without
changing the driver itself.
try to add the following in your ~/.asoundrc.

	pcm.ch4dup {
		type plug
		slave.pcm surround40
		ttable.0.0 1
		ttable.1.1 1
		ttable.0.2 1
		ttable.1.3 1
	}

then run like this

	% aplay -D ch4dup foo.wav

To use this technique on OSS emulation, you'll need aoss wrapper
(included in alsa-oss package).
suppose that the application uses /dev/dsp, add the following in
~/.asoundrc.

	pcm.dsp0 pcm.ch4dup

then run your oss application via aoss script

	% aoss foobar


Takashi

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