Crash when Switching MIDI I/O if Jack Control is not running

• Sep 24, 2014 - 04:05
S2 - Critical

When working on a project, I switched over to the JACK Audio Server. After this, MuseScore 2 would not allow me to play my music. When I went to switch back to Port Audio, I clicked apply and soon after MuseScore crashed.

This is running on Windows 7, anyone else have a similar problem?


MuseScore will play through JACK if you have JACK installed and configured.
I don't have this problem on Windows XP.
Could you write if you have crashes permanently or just in some cases?
Also, please, could you provide a list of steps to reproduce (maybe you did some additional actions?).
Version of your OS (32/64 bit) and a MuseScore version (+revision number) could help.

This was in fact permanent to when I had switched it.

Version: 2.0, Beta 1
OS: WIndows 7 64-Bit


Edit->Preferences->I/O->Use JACK Audio Server
Clicked "OK"
Music does not play
Edit->Prefernces->I/O->Use PortAudio
At this point, MuseScore would either crash or it would play the music, but not on the defined instrument (i.e. Guitar played Aux. Percussion, Drumset was now a Piano, random occurrences as such).

I just ran into this too. Same steps. I had changed to the Jack option the other day to test Jack. When I tried to switch back to PortAudio,, it crashed upon hitting either OK or Apply. BTW, when I switch to PortAudio, the dropdowns in that group were all empty - nothing to select in any of them. I suspect that's related to why the crash happens. I had also quit then restarted MuseScore between the time I switched to Jack and when I tried to switch back. And at the time I restart MuseScore, Jack was not running.

BTW, Vern_Dog, if you don't have Jack installed and running and configured to route MuseScore's output to something else, I think it is normal that MuseScore would not play. If you *do* have Jack installed, running, and configured to route MuseScore's output to something else, and that other thing won't play, you should file that as an issue separately, but be sure to include all relevant info about how you have configured Jack, what you are routing MuseScore's output to, and how you know the problem is with MuseScore and not with whatever you are routing its output to.

Anyhow, the full set of steps is this:

0) make sure Jack is not running
1) start MuseScore
2) Edit / Preferences / I/O
3) change to Jack
4) OK
5) quit MuseScore
6) start MuseScore
7) Edit / Preferences / I/O
8) change to PortAudio
9) OK

Result: crash

The crash occurs here; "seq" is 0:…

Yes, I have had this happen too, whilst testing Jack.
It is an intermittent problem.

In my case I had to resort to a factory reset in order to clear the problem.

It hasn't happened again since, so I can't really shed any more light :(

I'm running Windows 8.1pro

Thanks for the testing.
Status: I am testing on linux and searching for the similar cases (switching between JACK and ALSA/PulseAudio etc...).

Crash confirmed on Ubuntu 13.04.

May be relevant or not, I don't know: Linux Mint 17 here, current git master self-compiled.

I recently (approx, a week ago) switched (back) to ALSA audio from Jack (because of some JACK instabilities not relevant here): no crash, neither when pressing [OK] after setting the new I/O parameters, nor at next MuseScore start-up.

I did not have sound (through ALSA) immediately at next MuseScore start-up, but it was due to JACK and dbus deamons still running in background: at next system restart, everything worked correctly.

Previously, Jack was also working correctly while playing back (the instabilities I mentioned above were not connected with playback).

So, for what is worth, I cannot confirm this under my Linux.



Title Crash when Switching MIDI I/O Crash when Switching MIDI I/O if Jack Control is not running

A little more info.

I discovered tonight that if you start Jack from Jack control and then switch to PortAudio there is no crash.


MuseScore 2.0 beta 1
Windows 8.1 pro

@Miwarre You can reproduce crash if JACK is not installed or jackdbus is not running. I didn't want to uninstall JACK, so I simply did "sudo chmod -x /usr/bin/jackdbus" to prevent launching the daemon.

We have crash in these situations:
1. MuseScore started with JACK driver, switching to PortAudio.
2. MuseScore started with ALSA driver working via JACK, switching to PortAudio. new

In general : MuseScore should start with non-working driver, you should switch to working driver.