[linux-audio-user] Re: asoundrc and aplay

Arnold Krille arnold.krille at gmail.com
Thu Feb 16 16:14:57 EST 2006

2006/2/16, conrad berhörster <conrad.berhoerster at gmx.de>:
> well, i have 2 soundcards and want to capture from both at the same time
> with
> jack. i don't need sample sync (or such bad things ;=) ) only need the
> signal, each channel individual but into one app, i have written.

Two explain Pauls Jedi-magic:

If you use jack, you want sample-sync. If you don't want sample-sync
and just want to record two independent streams into your software
(assuming you don't want to use it for music[*]) you just have to open
both sounddevices the alsa way and process according to the

[*] If you want to do music with it, you want sample-sync...

Enough things have been said about way two soundcards without syncing
can't be used as one multichannel device, so I won't repeat it here.

I just want to add another trick I learned from my hardware-dealer who
syncs ISDN-cards: Maybe its not enough to just couple their clocks,
they also change the driver to mask the IRQ's from the slave cards and
just react on the master-IRQ and then the driver automaticly
proccesses the data on all cards.
Speaking in the audio-speach of el-cheapo-multichannel: It's not
enough to solder the crystals together, there may be a need to modifiy
the driver. Of course this would make a new soundcard out of it which
exposes its multi-channels to jack directly through the
alsa-interface, no need for .asoundrc-fiddling...
I haven't tested that but I think if it works for ISDN-cards it should
work with soundcards too.


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