[LAU] Mulitple sound caards with Jackd

Robin Gareus robin at gareus.org
Mon Sep 20 23:30:21 UTC 2010

Hi Jonathan,

On 09/21/2010 12:36 AM, Jonathan E. Brickman wrote:
>> netjack over localhost does not make sense. you can just use jackd on
>> your primary soundcard and alsa_[in|out] on your secondary. but the
>> realtime resampling will either chew up insane amounts of cpu, or
>> degrade the sound, or both. ok for telephony or for listening to
>> unimportant stuff over small speakers, but not for serious work.

> The point is, with netjack over localhost there is no realtime
> resampling. 

but you gain nothing. The netjack-slave does not have a soundcard
attached to it. It connects to the master-jack which 'speaks' with the
soundcard. You still need alsa_in/out to connect additional devices.

You can also run two jackd's which connect to hardware directly and use
jacktrip to connect the two jackd's .. and there may even be more

Either way: Unless the sound-cards share the same clock, there is no way
to _not_ resample.

The above statement is true for any audio-interface on any OS.
Sorry to disappoint you.

As Joern outlined, audio clock synchronization can be accomplished by
various means. You can pick up a soldering iron and follow
or buy dedicated hardware that offers it. The technical term is

Check the recent thread on LAU 'ambidec:..'
for a cheap solution.


> I have a very high quality PCI sound card with RCA outs,
> and when I gig with this rig I don't want to be lugging around the USB
> device I'm going to need for additional inputs.
> J.E.B.

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