[Alsa-user] Split stereo input?

[deadrabbit <dea...@gm...>]

After more digging around, I found an answer on the wiki: dsnoop.
There's even an example of exactly what I'm trying to do here:
http://alsa.opensrc.org/Dsnoop#Recording_from_left_or_right_channel

However, I've hit one more stumbling block. I can split the devices with
dsnoop, but I can only record with one at a time. When I try to record
both with arecord (arecord -D record_left foo.wav and arecord -D
record_right bar.wav), I get this error:

ALSA lib pcm_dsnoop.c:574:(snd_pcm_dsnoop_open) unable to open slave
arecord: main:564: audio open error: Device or resource busy

Does anyone know a way around this?

Thanks