OK I’ve had another look at this.
In current versions of Jack there’s a couple of tools called “alsa_in” and “alsa_out”. These allow the input/outputs of additional sound cards to be available in Jack in addition to the current device.
For example, I have an internal sound card (hw:0) and a USB sound card (hw:1)
I started jack running using the USB sound card.
Then ran these two commands:
“on-board” is the name that I chose for the on-board sound card - it can be anything. That sets the name that the new device uses when it appears in the “Connections Kit” of JackCtrl.
This is Audacity recording from the two sound cards:
On limitation for this method is that each device has only 2 recording channels, so Audacity can still only record 2 channels at a time, but when set-up as above it will record a mix of the two sound cards. To be able to record all 4 channels independently you could use Ardour.
Yes you can do that, and you can also have a sink and a source in pulseaudio so you can send/receive streams between jack and pulseaudio, I’ve done that.
You might also be able to create a 4 channel input port in jack to redirect the two sound cards to. I’m not really sure how to do it. I never tried or looked into that, but I have a feeling it could be possible…
See here: http://jackaudio.org/multiple_devices
I’ve not tried JACK2 audio adapter(s) and changing from Jack1 to Jack2 will break too many things on my computer, so I’ll leave that for someone else to try
I was willing to upgrade to jack2 some time ago in the hope of solving another issue I had, but that was breaking too many things too so I gave up on the idea… I worked around the problem by switching to pulseaudio and running jack as dummy and setting up jack sink/source in pulseaudio.
Create in/out ports for the second sound card with alsa_in / alsa_out
Then open an empty instance of JackRack and set the number of channels to the number of recording inputs.
Open Audacity and connect it to JackRack and set the number of recording channels to the number of JackRack channels.
Then connect the recording inputs of each sound card to the JackRack inputs.
For a bit more control you could use a suitable mixer (that needs to have sufficent inputs and outputs) such as “jackmaster” instead of the empty jack rack. or you could add amplifiers into JackRack so that the level of each recording channel can be controlled in software. You can even use real-time effect while recording.
Thanks for all the info guys. Looks like on Linux JACk is pretty easy to use, figures since Linux is it’s native environment. Too bad it isn’t being actively developed on Windows, I guess I’ll be testing it out on one of my Ubuntu pc’s soon.