[alsa-devel] What are subdevices?

Hi!

I tried this question in the alsa-users mailing list but it doesn't appear to be much active. So I ask here.

I'm facing problems with my system, so decided to learn ALSA to see what's the problem.

My first question -- what's a device and a sub device?

A device seems like the output streams the sound card supports. Like HDMI, DP, analog etc...

So what's a subdevice? Is this related to multichannel? Does it designate physical ports on the card?

Thanks.