Can't use Audacity with jamulus


Audacity 2.2.1
LinuxMint 19.2 Cinnamon
Jamulus 3.5.3git
When I record a typical jamulus ( on-line latency corrected) jam session with Audacity, it is spoilt by a regular break in the signal, about every 0.6 seconds, lasting for 0.06 seconds. Almost like a metronome click, but only audible in the recording, and visible in the recorded waveform. The distortion is caused in the recording process, it can’t be heard in the monitoring headphones or speakers.
I cannot isolate the fault by any kind of elimination process. I have to use qjackctl to run jamulus and select Jack Audio as the host, and jamulus as the recording system, and have to connect to a jamulus server, otherwise there is no input to record.

There is something I am doing, I haven’t figured out what, that causes qjackctl to occasionally hang and the whole OS has to be restarted. This happens much more frequently when trying to run Audacity and jamulus together

My hardware is pretty new:
AMD Ryzen 2200 cpu with onboard Radeon graphics
Gigabyte mobo B450 Aorus M

Any help very welcome

Is QjackCtl reporting xruns?

Just checked and it isn’t. The break isn’t exactly regular, just regular-ish. The blank periods are between .01 and .02 seconds, but they are 0.6 seconds apart.

Have you also selected Jack Audio as the host in Audacity? (In the Device Toolbar)

Does the “Project Rate” in Audacity (lower left corner of the main Audacity window) match the Jack sample rate?

Does the “Project Rate” in Audacity (lower left corner of the main Audacity window) match the Jack sample rate?

No, you have solved that problem, many thanks, but there are more probs. Maybe some incompatibility with Audacity, Jack keeps hanging and wont close. I am having to ty a lot of stop and start operations to pinpiint whether Audacity is involved or not, will get back.

Have you also selected Jack Audio as the host in Audacity? (In the Device Toolbar)

I did state that in the affirmative, or that’s what I meant to say…

Thanks for a good start!

Tonight after getting an “unable to connect” message in the jamulus mixer window, I noticed that I was getting XRUNs.
Once this happens I am unable to stop Jack properly. Sometimes it apparently stops after a long wait, but then it won’t start properly, the windows open but there are no graphics inside. So I have to do a reboot.

Usually iI can connect to servers normally, but once I get a “unable to connect” in the jamulus mixer window then I find I cannot close qjackctl.

I can run Audacity, if I start it after I have connected to a server. If I stop recording but leave it open, then shut everything else, then export the Audacity recording and close Audacity, I can restart everything up normally.

But if I stop Audacity recording, leave qjackctl and jamulus open while I export the recording, at the moment I close Audacity, all sound from the jamulus server stops, and although if I disconnect and remake connections in the qjack connections window, I can connect to a server; all sound is distorted, I may even be affecting what other players can hear, and I have to close down, and that means qjack will have hung again and I have to restart. The distortion probably has a name to it, it sounds like very short segments of sound are repeated or echo very quickly, like 10 times per second.

So Audacity is something to do with it but not the only problem

Screenshots attached of one good stop of jack, but I’m afraid I lost count of what was happening when I took the others
Screenshot from 2020-07-10 22-58-01.jpg
Screenshot from 2020-07-10 22-48-27.png
Screenshot from 2020-07-10 22-39-51.jpg
02 Jack stop good.jpg

I’ve never used Jamulus, but I’d imagine that strange bad things could happen if the ping time to the server is not quick enough to keep the system synchronized.