Stereo Tool

I had similar experiences in the past and switched to Zita ajbridge instead. But that too gave dropouts, far less severe than crashing.

Problem is most likely clocks drifting apart too quickly.

I can't remember why you need dedicated sound cards rather than a big one with lots of outputs?

KPOV is a non-profit Community radio station that gets funded by donations and underwriting by local folk. No advertisers, no government money. So I like to work up inexpensive solutions.

For example: using stereotool + some modest hardware is a lot less expensive than an Orban Optimod 5700i at US$4700 !

For testing here on my dinky little Linux laptop before I configure the target mini-PC, I am using two cheap-o sound card. A Behringer UCA222 for the shared input device and one of the output devices, and a little $12 no-name USB interface for the other output device. Most certainly not the devices I'd be using in the air chain.

So if it's a clock-drift thing then that suggests to me that devices like these class-compliant USB audio interfaces have their own internal clocks; and if so, then drift would certainly be an issue and an all-in-one device with a shared clock would be the way to go. I sorta-kinda of assumed that they get their clocks over the USB interface.

Thank you for looking at this.

I'm supporting a regional non-profit community network, which luckily receives constant (but little) public funding. So I fully understand your desire to get this done with as little as possible.

Yes, my suggestion would indeed be to go for a Behringer UMC1820 and a small-ish PC. The UMC1820 is also class compliant but because it all runs from a single device, the whole setup is quite straightforward. It's like your current one but without the alsa bridges. I have one running 24/7, no complaints, never (for years now).

But maybe try zita ajbridge first.

While typing I looked up the Behringer UMC204HD - that has 2 ins and 4 outs, anyone who can confirm it's detected by ALSA?

Thank you for the assistance.

If it is true that class-compliant devices don't get their clocks from the system, then drift could be a problem. Sure.

In the meantime, a clean reboot, a loading of JACK* and then zitabridge-j2a, and now I have a Playback device in Patchance and QJackCtl. I don't love that zitabridge wants the device as "hw:x,y" because those pointers are moving targets whenever Linux boots, but maybe I can use a card name there. More testing required...okay, that works.

Anyway, I get no audio output from the zitabridged Playback soundcard. Zita-MU1 confirms that both instances of ST are outputting audio, and the System output device used by ST_0 has audio, but nothing audible from that second sound card used by ST_0. It did work with alsa_out.

Working with little money and Linux either toughens a fellow up or sends him home crying.

* QJackCtl -- I'm still using that to start JACK, have to find how to in Terminal.

I'm using systemd to start jack. I configure it once using qjackctl to start & stop, then everything hopefully is saved and then use this service file:

[Unit]
Description=JACK 2
After=sound.target
BindsTo=sound.target
Requires=dbus.socket

[Service]
Type=dbus
BusName=org.jackaudio.Controller
ExecStartPre=/bin/sleep 10
ExecStart=/usr/bin/jack_control start
ExecStop=/usr/bin/jack_control stop
ExecStopPost=/usr/bin/pkill -9 jackdbus
SuccessExitStatus=0
RemainAfterExit=true

[Install]
WantedBy=default.target

Put it in: ~/.config/systemd/user/jack.service
reload systemd with systemctl --user daemon-reload and enable with systemctl --user enable jack.service
Then reboot and see if you have a running jack after logging back in.

Then stereotool can also run in systemd using:

[Unit]
Description=Stereotool
After=jack.service
BindsTo=jack.service
After=graphical-session.target
BindsTo=graphical-session.target

[Service]
LimitRTPRIO=infinity
LimitMEMLOCK=infinity
Environment="DISPLAY=:0"
Environment="XAUTHORITY=/home/<your_username>/.Xauthority"
ExecStart=/full/path/to/stereo_tool_gui_jack_64
Restart=always
RestartSec=2

[Install]
WantedBy=default.target

Put in another file in ~/.config/systemd/user and do like with jack.

Thank you for documenting that here. Definitely on my to-do list.

In the meanwhile I need to find why zitabridge-j2a does not give any output on my second sound card. It worked with alsa_out. The bridge device loads without error and it shows up in Patchance, it can be connected to, I confirm there is audio on that connection with Zita-mu1 and that same audio cheerfully comes out of the primary sound card. Pulseaudio (System Settings > Sound in Ubuntu) is not camping on that output device.

I suppose it's possible that this cheap-o device I'm using for testing simply doesn't play nice with zitabridge, though it does with alsa_out

It's Card 1:

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: HDMI [HDA Intel HDMI], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Device [USB Audio Device], device 0: USB Audio [USB Audio]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 2: PCH [HDA Intel PCH], device 0: CX20756 Analog [CX20756 Analog]
  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
jack@jack-20428:~$ aplay -L

and I do this:

zita-j2a -d hw:Device -r 48000 -p 256 -n 2

And no joy.

[EDIT: I installed Audacity and loaded a mp3 and pointed Audacity at the Jack Audio Connection Kit and pressed play and connect in Patchance the output to zita-j2a and still no sound. So . . . I guess it don't work.]

Setting aside the non-working bridge issue and moving on, I have put in the systemd startup routine for JACK, and it works. Thank you for that!

I'll get to the Stereotool one, shortly.

(A note to others who might stumble across this Topic: If you want to confirm that JACK is running using a tool like ps, be aware that if you do this:

ps aux | grep jack

and if your username happens to be jack -- as mine is -- you're gonna see a whole lot of irrelevant output.)

ANYWAY - JACK is not getting input from the System Recording device. I'm pretty sure that this is because the OS grabbed that sound card when it rebooted and claimed it for Pulseaudio/Pipewire. This according to Ubuntu's Settings > Sound. I told Sound to use the laptop's internal mic, but I'm still not getting any audio into JACK.

Question: What is my command to stop/start or restart the JACK daemon?

Thank you!

Followup Question: How do I tell Ubuntu to keep its mitts off this USB audio interface and mind its own business?

I see that I forgot to answer this, so for the sake of completeness:

I'm hoping to run two instances of Stereotool -- one to provide aggressive processing for the FM broadcast, the second to provide gentle processing for the station's live stream and for show archiving purposes

So one box with one analog-to-digital converter to be shared by the two stereotools, and with two digital-to-analog converters for output, everybody sharing the same clock to avoid drift and buffer over/under glitches.

I'm back -- miss me?

So -- I've switched to Ubuntu Studio. It comes with QjackCtl to start JACK. I put in the systemd method that Minetti suggested earlier in this thread, rebooted, and it does launch JACK but it also added two Pulseaudio entries the graphs -- System Capture and System Playback. Don't know why.

So I disabled the daemon and rebooted, and used QJackCtl to start JACK. I'm okay with that as long as I can arrange it to start on reboot.

Now there are only the desired JACK items in the graphs.

zita-j2a somehow managed to auto-launch (?) and I now have two instances of ST running, sharing the same capture sound card and each outputting to their own separate playback sound cards.

I'm going to leave this running for a couple days to see if I get any glitchy buffer under/over runs caused by using separate sound cards. Then I'll look at getting things to load on reboot and come up running.

Thank you for the help here!

UPDATE: Both instances of ST are messed up, it sounds like alien music coming out of both. QJackCtl's message window shows many many XRUN errors. Before I go about blaming the software, I should probably unpack and configure the target computer, a Beelink SER mini-computer that has a lot more horsepower than this little Core i3 machine I am doing my testing on. It is laboring mightily, so I better remove that limitation from the equation.

Onward!

[EDIT: At this point I realize that this thread has very little to do with ST per se and is more about how to hammer Linux into behaving how I want it to do. Apologies for spamming the forum, and my gratitude to those who are providing guidance!]