[alsa-devel] Complex hw buffer with MMAP_COMPLEX?

Adrian Knoth adi at drcomp.erfurt.thur.de
Tue Oct 9 16:09:11 CEST 2012

On Tue, Oct 09, 2012 at 03:49:32PM +0200, Clemens Ladisch wrote:

> > That is, we're dealing with 25 (or 26 for output) interleaved streams
> > with two or eight channels each.
> >
> > How could we represent such a layout in ALSA, that is, how are we
> > talking to userspace? Would one create subdevices and rejoin them via
> > plughw?
> Is it possible to start/stop the streams independently?

No, there's only a single start/stop call for the entire card.

> > Or use MMAP_COMPLEX and then let every application deal with it
> > on its own?
> Alsa-lib can automatically convert this.

The only remaining question is how to tell alsa-lib about the buffer

AFAIKS, there's not even a single driver that uses MMAP_COMPLEX atm.


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