Sound reasoning

[Евгений Б. Спамаковский]

Hi.

Is there a point to writing a pcm device to have multiple "channel"s in the
same direction?
Say, two SND_FORMAT(AFMT_S16_LE, 1, 0) for record and two for playback, vs.
just one SND_FORMAT(AFMT_S16_LE, 2, 0) in each direction.

pcm_register() has so prominently two arguments 'numrec' and 'numplay' and
even if they are ignored, one can do pcm_addchan() any number of times.
How is this expressed to the user-land programmer?

"Read the code" is a fine answer, but it would be nice if someone can
readily explain the idea behind the options.