[linux-audio-dev] Jackd and cards with multiple PCM interfaces

[Lee Revell]

On Wed, 2005-12-14 at 12:10 +1030, Jonathan Woithe wrote:
> Hi all
> 
> I am currently working on an ALSA driver enhancement for a card which
> actually contains two seemingly sample-locked ADCs.  I'm making the second
> ADC accessable via a second PCM interface attached to the card.
> 
> In general things work fine - under OSS emulaion I can open both (one as
> /dev/dsp, the other as /dev/adsp).  However, jackd doesn't seem to know
> or care about the second pcm interface on the card and I can't find any
> obvious way to tell jack about it.  It seems suitable entries in .asoundrc
> might help but it's not clear to me that this will work without xruns 
> (see http://www.alsa-project.org/alsa-doc/doc-php/asoundrc.php).
> 
> Can jackd work with multiple PCMs from the same card, and if so, what's the
> best way?

Well, does the hardware have a mechanism to stop and start them in sync?
If so you could modify the driver to expose all the channels as a big
multichannel PCM like I did with the emu10k1 driver.

Lee