From mboxrd@z Thu Jan  1 00:00:00 1970
From: Clemens Ladisch <clemens@ladisch.de>
Subject: Re: Independent usage of two channels
Date: Thu, 22 Jan 2009 12:42:38 +0100
Message-ID: <49785BAE.6090402@ladisch.de>
References: <187c6cc60901220316i65a1558bm4b7c503db062a01e@mail.gmail.com>
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To: Pavel Fedin <sonic.amiga@gmail.com>
Cc: alsa-devel@alsa-project.org
List-Id: alsa-devel@alsa-project.org

Pavel Fedin wrote:
> Is it possible to use two channels of a sound card as two independent
> devices for PCM playback?

The sound card is probably not able to handle two independent mono
streams, but it is possible to use alsa-lib's software plugins to
emulate two devices on top of the real one.

Put this into your ~/.asoundrc or into /etc/asound.conf:

pcm_slave.stereo_slave {
	pcm "hw:0"          # or "hw:1" for the second card ...
	channels 2
}

pcm.left {
	type plug
	slave.pcm {
		type dshare
		slave stereo_slave
	}
	bindings [ 0 ]
}

pcm.right {
	type plug
	slave.pcm { type dshare slave stereo_slave }
	bindings [ 1 ]
}

Then use device names "left" and "right" instead of "default".


HTH
Clemens