On Tue, Feb 25, 2014 at 08:39:14AM -0500, Paul Davis wrote:
> On Tue, Feb 25, 2014 at 8:25 AM, Jörn Nettingsmeier <
> nettings@stackingdwarves.net> wrote:
>
> >
> > If the maximum channel count is always fixed by the hardware, what is the
> > point of the corresponding jackd option? As I said, I don't remember if
> > ever doing something other than throwing the "cannot set channel count"
> > error...
>
>
> imagine you have an N (where N > 16) channel device but only channels 1-4
> are connected. the channel count option stops you from having to look at
> N-4 useless channels on the device all the time.

AFAIK, when using the MMAP access mode, you always get the full channel
count. Which makes sense, since what gets mapped into user space may
very well be an actual HW buffer having a fixed layout (which may be
interleaved, complex-interleaved, etc.)