[alsa-devel] Capturing from Line and Mic simultaneously

[Christophe Osuna]

Hi,

I would like to capture sound from the Line and Mic inputs
simultaneously. The sound chip seems capable to do so: inside
alsamixer, in the "Capture" tab I can select up to three subdevices,
and from the "Playback" tab I can set the input source one to "Mic"
and the input source two to "Line" (and three to whatever).

When trying to use several output ports at the same time I use four,
six or eight channels. I tried the same thing for input (i.e. use four
channels) but that failed. I guess I have to use subdevices but I have
no idea on how to start working with them.

Could anyone:
 * tell me if ALSA is limited to two capture channels, and in that
case what should be done;
 * point me to some documentation showing what to do, or give me some
general hints

Thanks.