Stereo Tool

Hi, I'm trying to get ST-Jack to play nice with two sound cards.

The idea being to have two instances of ST running, both sharing one sound card for capture input, and each ST having its own separate soundcard for output.

I have on hand both flavors of ST (standalone and standalone-Jack), Qjackctl, and qpwgraph. Pipewire is installed and seems to be running.

I cannot manage to sort this out. qpwgraph doesn't show the sound cards, but they are there because I can use them with one instance of ST-jack directly, input to output. But routing seems to be my main obstacle.

Any sort of a helping hand would be appreciated.

Thank you!

EDIT: Ubuntu 22.04

As far as I know you need at least Ubuntu 23.04 for pipewire. It is available for 22.04 as well but does need additional configuration.

Thank you. I did put in the additional configurations to get pipewire up and running on 22.04, and with one instance of Stereotool standalone I was able to use the external usb audio interface as the Input card, and a second one as the Output card. But as soon as a second instance of Sterotool was launched, and not even connected to input or output cards, the first instance immediately started glitching and clocking errors all over the place with the output audio slowly speeding up and slowing down.

I'm going to configure another PC with 23.04 and try again.

UPDATE: Nope. I have tried Ubuntu 22.04 and 23.04. I have tried Pipewire and I have tried JACK. Makes no difference. In all scenarios is it possible to connect two instances of ST to one sound card for input. In all scenaries it is possible to connect one instance of ST to a first sound card for output, the second instance to a second sound card. In all instances it doesn't take but a few seconds for the sound from both to start glitching, speeding up and increasing in pitch, then sloooowing down with decrease of pitch. In fact, all it takes is a second instance of ST to be launched without connecting it to a sound card for the glitching to start. Somehow two instances start tussling about clock rates or something and the whole thing falls over. It was a valiant effort. I don't know how the first instance of ST knows a second instance has been started without the the second being connected to a sound card -- some mysterious thing found in the underpinnings of ST or Linux -- but here I am.

Try to create a virtual alsa sound card using 'sudo modprobe snd-aloop', to which you can plum in one input or output. Here i would also advice you to try to run the other istance of ST in alsa mode. Pipewire can recognize that and i think jackd2 too.
I would also like to remind that when ubuntu does it's weird audio tricks, get rid of pulseaudio entirely (or when you have pipewire make sure it is replaced with pipewire-pulse and also jack with pipewire-jack). This does not apply when you are using standalone jackd2, of course.

So far I tried to reproduce what you have.

I have a Ubuntu Studio 23.04 running jack on top of pipewire with a RME HDSP card built-in and a cheap USB interface. I can see the fun of pipewire when I plug in the USB device, the capture ports appear instantly without me pressing any buttons.

The signal chain is as follows:
Audio in via VLC stream, to 2 stereo tool instances (standalone jack versions), then to zita-mu1 to be able to switch each independently to the cheap USB output. Sounds fine.

I can see the inputs of the HDSP in Patchence (the patchbay I used) but have not yet found the correct input to capture analogue audio. HDSPmixer shows input, though. Will try later.

Thank guys, for providing some ideas.

Hitman, do I understand you to be suggesting that I run one instance of ST as Standalone_JACK, and the other instance as Standalone_ALSA.

While I find that two instances of ST_JACK can't run without causing all kinds of exciting glitching, running one JACK and one ALSA does not upset the JACK instance . . . so far, so good.

What I can't figure out is how to get the output of the capture sound card into the input of the ALSA ST. It is wired via JACK into the JACK ST, and that works fine. I ran the suggested 'sudo modprobe snd-aloop'. Here is the output of arecord -l:

jack@jack-20428:~$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: PCH [HDA Intel PCH], device 0: CX20756 Analog [CX20756 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: Device [USB Audio Device], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 3: CODEC [USB Audio CODEC], device 0: USB Audio [USB Audio]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 4: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
  Subdevices: 7/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 4: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7

The target input device is "card 2: Device [USB Audio Device]"

The running ALSA ST does not show that as an input option. Here are my choices:

https://imgur.com/a/EENrxuJ

None of the options pick up the audio from the card. Meanwhile, over in JACK land, that instance of ST is getting audio from the card. So the card is working.

You will need a more graphical representation as the input of the loopback alsa device would be linked to a jack output/vice versa. At least one of the connections will be made in the patchbay, outside of ST.
Take a screenshot also of Carla->patchbay(if on jackd2) or qpwgraph(if on pipewire) with both of those ST instances running. From here the connection should be easy, it only needs to have no more conflicts.
For me personally two jack instances of ST work if i set the patchbay to exclusive, but i'm on a more barebones distro. One runing as alsa basically prevents any crossfeeding connection from being made.

Thank you. I am running Qjackctl -- the graph window shows only the JACK instance of ST and the the operating system's "SYSTEM" I/O cards as set in the OS's Settings > Sound. The ALSA ST does not show.

Running the loopback command did not add any additional devices to the graph.

This being the Ubuntu 23.04 distro, the OS is running Pipewire.

So, what's going to be my patchbay of choice? Carla or qpwgraph?

Qpwgraph, although almost identical front end wise to the graph of qjackctl, it has: 1. the addition of an Exclusive mode under Patchbay you need to turn on, and 2: if the two programs don't show the same thing, it means pipewire-jack/pipewire-alsa don't work, or there's some other conflict.
I will try different combinations of what you need and report back, just out of curiousity.

LE1: I don't think you need the one of the ST instances in alsa mode, if the patchbay is Exclusive and they are working properly (check above) should work anyway with both in jack. The loopback is just so that it's set as one's input or output to go around whatever Ubuntu is doing to it's audio config.

LE2: Didn't ask, are you using stable 9.9x or beta 10.01, cause in the beta you can rename the binaries to have a different audio device name, to also help with conflicts.
And also i need to test this in ubuntu actually, so tomorrow most likely, it's getting kinda late here in Europe