Re: [Jack-Devel] ALSA PCM substreams

Le Tue, 03 Dec 2013 11:27:31 -0800,
"Gabriel M. Beddingfield" <[hidden]> a 飲it :

> On 12/03/2013 10:31 AM, Fred Gleason wrote:
> >> Any idea where the whole `substream' concept is documented?  I'm
> >> still fuzzy on what it's intended to solve.
> >
> > For cases where an application needs to play multiple PCM streams
> > simultaneously out of the same physical output (and doesn’t want to
> > muck around with mixing them in software).  That said, I’ve only
> > seen one card (outside of the high-end pro-audio domain) that
> > actually has this capability.
> 
> Thanks!
> 
> >> Even if it's hardware mixing, I think it still makes sense for
> >> JACK to open them.
> >
> > I disagree.  It sounds like the caiaq driver is just getting this
> > wrong.  If the two subs are producing output at two different
> > physical ports, they should be implemented as separate PCMs.  I’d
> > file a bug report.
> 
> I disagree about two PCM's.  What I want is _one_ PCM. :-)

If I compare it with the emu10k1 driver, hw:0,1 will provide you
the "normal" PCM device, and hw:0,2 provide 16 separated in and out
into one PCM device.

> 
> Unfortunately... these drivers have been out for a while and making
> big changes like this likely break userspace.

So, the driver must provide hw:0,3 with 4 separated in and out for use
with JACK.

Dominique

> 
> -gabe
> 
> 
> Jack-Devel mailing list
> [hidden]
> http://lists.jackaudio.org/listinfo.cgi/jack-devel-jackaudio.org

1386101889.13549_0.ltw:2, <20131203213754.25c55c91 at tux dot fritz dot box>