USB and FireWire Simultaneously?

Installation & Configuration Linux
#1

I’d like to simultaneously record a USB input and a FireWire input, but it’s not clear to me that this is possible. Specifically, I have a Boss IR-2 pedal which can output via USB, and an M-Audio FireWire Solo. If I set up QJackCtl for FireWire (selecting the firewire driver and the (default) interface), then I can see my FireWire Solo in the Audio panel. If I plug in my IR-2 to a USB port, then I can only see the IR-2 in the ALSA panel - in the Readable Clients / Output Ports, it shows up as “28:IR-2” and if I expand that, it shows “0:IR-2 MIDI 1”; in the Writeable Clients / Input Ports I see “14:Midi Through” (which expands to “0:Midi Through Port-0”) and “28:IR-2” (which expands to “0:IR-2 MIDI 1”). The MIDI panel is blank in any case.

I can use the IR-2 if I set up a QJackCtl with Driver = alsa and Interface = hw:IR2,0, but then I can’t connect my FireWire Solo.

Is there a way to record both simultaneously?

The reason for this is to capture the DI signal, which routes from the IR-2’s send to a DI box and from there into the FireWire solo via XLR, simultaneous to the processed signal coming out of the IR-2 via USB.

Are 2 simultaneous instances of QJackCtl possible, with different interfaces?

I suppose another option would be to route the guitar cable output into the FireWire Solo input, but then I’m introducing another a digital-to-audio conversion, and then an audio-to-digital, conversion, rather than keeping everything digital.

Any suggestions?

Thank you.

#2

jackd can only use one audio device at a time.

If you want to keep using JACK, start jackd with one device (say the firewire device) and then add the USB soundcard, using alsa_in/out commandline tools (they come with jackd). e.g.

alsa_in -d hw:IR2

This which resamples to synchronize the clocks of the USB soundcard to match the firewire one. and makes the USB inputs available as jack audio sources.

#3

Fantastic, and exactly what I was looking for - thank so much, Robin!

Out of curiosity, I note you say, “If you want to keep using JACK…” - is there a non-JACK way to do this?

Thanks again!

#4

Ardour’s ALSA backend has support for multiple devices. There is no GUI for it though, you have to manually set an environment variable. here (assuming you use Ardour 8 form ardour.org:

ARDOUR_ALSA_EXT=hw:IR2 Ardour8

(see PipeWire Multiple Devices HowTo - #2 by x42 for a quick reference on ARDOUR_ALSA_EXT)

–

Another option is to use pipewire.org, which is a drop-in replacement for JACK and directly offers all available soundcards. Note however that you need a very recent version of pipewire v1.2.2 for pro-audio. It is still under heavy development and older versions had various issues.

#5

Thanks very much - will explore Pipewire after this project.

#6

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