13 Dec
2005
13 Dec
'05
9:38 p.m.
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?
Regards
jonathan
14 Dec
14 Dec
5:34 a.m.
Can jackd work with multiple PCMs from the same card,
and if so, what's the
best way?
jack opens hw:0,0,0 thru hw:0,0,7 on my card. no idea how this would
be different from a hw:0,0 thru hw:0,7 or hw:0,0 thru hw:7,0 from a
driver standpoint - guess id try making them show up contiguously as a
subdevice of a single PCM but you can always use jack_diplomat even if
theyre seperate cards entirely..
2:05 p.m.
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
11:45 p.m.
Lee
I'll have to check this. The ADCs are independent in that they *can* be
operated concurrently with different parameters. However, AFAIK they both
operate off the same master clock signal and thus will sample simultaneously
if both are sampling at the same nominal rate. As to whether they can both
be *started* simultaneously in hardware I can't say at present. That may be
a stumbling block.
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.
Thanks for the pointer - I'll check it out; I looked in a few other drivers
for clues but obviously picked the wrong ones.
Regards
jonathan
6851
days inactive
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3 comments
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Jonathan Woithe -
Lee Revell