I am the developer of XT-Audio (a project similar to PortAudio) which provides a unified interface to a couple of audio I/O backends on windows and linux, among them JACK. XT-Audio is implemented as a C interface to these backends, and on top of that, bindings for C++, .NET and Java. Along with the core library, I also provide a couple of sample programs (for each language) and a GUI demo application which is implemented in .NET only. The problem I currently run into is: when testing JACK using the GUI sample (a WinForms application, run using Mono), I run into the SuspendRefNum and JackClient::Execute errors immediately after starting an audio stream (jack_activate) and after this point the application becomes unstable. QJackCtl message window shows my app's ports being immediately disconnected and I receive "server not running" errors. However this ONLY happens when testing using my winforms demo app. I also provide a c++ console sample app (runs JACK fullduplex by just copying input to output) and a .NET sample console app which does the same thing. Both run without problems 100% of the time. So at first I tried to find the error in my winforms app, but i've been going through it for a couple of weeks now and can't seem to find anything obviously wrong with it. Errors mentioned at
https://github.com/jackaudio/jack2/issues/307 look very similar to what i'm encountering but i'm not sure they are actually related. Are there any known problems that might cause the SuspendRefNum/JackClient::Execute error sequence? I'm kind of at a loss here and any help would be greatly appreciated. I'm running ubuntu 20.04 with jack 1.9.12. I also tried various things like running the demo app before starting the JACK server, the other way around, killing pulseaudio, using pasuspender etc, all to no avail. My XT-Audio project is at
https://github.com/sjoerdvankreel/xt-audio. Binaries for the current version are at
https://sjoerdvankreel.github.io/xt-audio. Don't know if it's of any help, but all of this used to run just fine under ubuntu 16.x (can't remember jack version).
