Stereo Tool

I don't like qjackctl.
Can you install patchage or catia or patchence?

Your command line looks right to me.
One more thing to check: jackd and alsa_in or _out need to run as the same user. Otherwise they don't see each other.

Thank you. Yes both alsa_out and jackd processes show as same user (me).

I installed Patchance. You don't like QjackCtl but I can not find a way to start the jackd server without it, so I started it with that. Then I ran

/usr/bin/alsa_out -j Card_2 -d hw:CARD=Device,DEV=0 -q 1 2>&1> /dev/null & 

Which threw off

$ Cannot use real-time scheduling (RR/5) (1: Operation not permitted)
JackClient::AcquireSelfRealTime error
$

I suppose I can ignore that?

So I now have a System Capture, a System Playback, and the Card_2 playback devices in both QjackCtl's Graph and in Patchance. I like that Patchance lets me turn off MIDI which I have no need for and clutters the graph. Thank you for the recommendation.

I then launched the first instance of ST JACK and it shows that it is connected to the System I/O devices, as does Patchance (and QJackCtl). But this instance of ST is not showing any audio coming in or going out -- its level meters and waveform display show nothing happening, but it isn't throwing off any I/O errors. Ubuntu's Settings > Sound shows the target USB audio interface as System I and O so that seems okay, but also does not indicate that it's hearing any sound from the input device, and there is no sound coming out of the output device.

Any thought on how I might debug this before I move on to launching a second instance of ST and tell it to use Card_2 for output?

Thank you!

I use zita-mu1 metering for debugging audio. https://kokkinizita.linuxaudio.org/linu ... guide.html

You can ignore the real-time error for now but for better latency and stability I'd recommend to use a pre-configured system like ubuntu studio (which also brings a lot of useful utils).

Maybe you need to enable recording inputs on your primary sound card in alsamixer?

Thank you, Minetti. It's a weekend, you probably have more enjoyable things to do and I appreciate the help with this little project.

alsamixer shows the capture device as turned all the way up, and it also notes that the device does not expose any controls, such as level to play with. This is expected for this simple Class-Compliant device.

I installed zita-mu1 (thank you for that, it's always nice to have metering) and in Patchance I connected the output of the capture device to zita-mu1's inputs 1 but it shows nothing happening.

So . . . something ain't running. I regret that this is such a difficult thing to sort out. Linux!

I'm sorry I don't have anything to add. I just want to interject and thank everybody for contributing to this thread and documenting your work. I'm sure this will be handy for posterity. Linux indeed!

Thank you MrKlorox, this is for me the point of the forums -- to help me debug my setup and provide help for someone other poor soul trying to paste together all the disparate parts of the Linux sound system and make something work (that probably only I am interested in doing!).

Okay. I just rebooted the machine. Something from attempts to get Catia or patedge to work may have gummed up the system.

I now have System soundcard in ==> System soundcard out working. zita-mu1 shows exciting metering fun.

And I have set up my second sound card as an output device with alsa_out.

Good so far!

Now I load the first instance of ST JACK and use it to send audio to the System soundcard. And we have audio!

Next to load up the second instance of ST from a binary with a different name . . . okay, it auto-connects to the same I and O System devices, so re-rout it to send audio to the second output soundcard . . . and YES! It's working! No glitches (yet).

This is good news. I will go back and look at the earlier post that showed how to save things because I want this setup to load and start running on reboot.

There are different approaches to this.

My favourite so far was using systemd to start all the processes including jackd and using aj-snapshot to keep track of the routing.

Another approach is to use a session manager to do the same. The new raysession manager looks promising at first glance.
https://github.com/Houston4444/RaySession

Then all you have to do is start raysession on startup and the alsa_outs and stereotools are managed from the session.

Thank you.

Yes, well, as it says on the linked raysession page, "it benefits from a nice patchbay, a complete manual as well as a splendid web site."

I'm for anything that has a splendid web site!

The page also says, "RaySession doesn't deals with JACK, the recommended user behavior is to use it when JACK is already started."

Which brings up a question I have: Is running QJackCtl my preferred way to start Jack?

And a side question: at the top of the patchance graph screen, there are transport start/stop buttons . . . I'm wondering what they do for a living.

Things are progressing!

I seem to have run into a stability issue. I left everything running overnight and this morning I found that the second Playback sound card, loaded with alsa_out terminated. It's not visible in the patchbays and I see in Terminal:

...
delay = -193
delay = 1175
delay = -11
delay = 1153
delay = 1500
delay = -106
delay = -300
delay = 1756
delay = -1647
err = -11
Write error: Resource temporarily unavailable
$ 

It did re-launch from the command line, and hooked up in the patchbay. But instability in a broadcast environment is a deal killer.

I find this repeated several times in syslog:

2023-07-24T09:09:49.165501-07:00 jack-20428 ST_Jack_1[4228]: Jack buffer starving
2023-07-24T09:09:49.176090-07:00 jack-20428 ST_Jack_1[4228]: message repeated 75 times: [ Jack buffer starving]

Buffer underrun?

[EDIT: I find this: viewtopic.php?t=22053 ]