JACK Audio on Musescore 3.x not working

• Mar 3, 2019 - 21:08
Reported version
P1 - High
S3 - Major

Steps to reproduce bug:
0. Set up JACK audio server (multiple tutorials on the forums)
1. Open MScore 3.0.x
2. Go to Edit > Preferences > I/O
3. Select the "JACK Audio Server" box
4. Close MuseScore
5. Run JACK Audio Server
6. Open MuseScore

Expected Behavior:
In JACK audio server, MuseScore will be listed under the Readable Audio or MIDI Client tabs. Musescore 2.x shows up as "mscore"

Actual Behavior:
No change is shown, MuseScore 3 is not listed in the server

Don't use JACK
Use Musescore 2

JACK Audio Server worked flawlessly on MS 2, I've never been able to get it working on MuseScore 3.
Both of my Windows 10 machines have this issue.

Operating System, version:
Windows 10 x64
Musescore (stable)


Exactly the same problem here. Works fine in version 2, but not in verson 3.0.5

OS: Debian GNU/Linux 9 (stretch), Arch.: x86_64, MuseScore version (64-bit): 3.0.5., revision: 58dd23d

I'm not an expert on this, but here is my understanding:

Lots of 64-bit systems use 32-bit apps, because many vendors don't want to have to build and support both, and 32-bit versions work on both architectures. Until MuseScore 3, we always shipped our executable as 32-bit. JACK gives you both options, because the 32-bit version can only talk to other 32-bit apps, and same for 64. Sounds like JACK came pre-installed for you, and my, guess is, it came as 32-bit like MuseScore 2 did and many others apps do.

So, if you are finding JACK can talk to MuseScore 2 but not 3, that is pretty strong evidence you are actually using the 32-bit JACK. Try installing the 64-bit version. You'll also need 64-bit versions of all the apps you want to connect to.

Same problem in ubuntu studio 19:04, MS3 not working with JACK audio and MS2.3.2 has not midi channels in the mixer. I hope one day MS works correctly and can use a vst on independently midi channels.

Did you build MuseScore yourself? If not, can you try, using Qt 5.12.4? For me on Windows 10, a current build against Qt 5.12.4 does work - it shows up in the JACK connection window, and I was able to use it to drive the playback in (what else?) MuseScore 2.

I don't know that Qt 5.12.4 is really the differentiator, but it seems a likely guess. 3.2.3 certainly does not work for me out of the box.

See my comment above. As far as I know, it's already working currently on Windows, at least for me. I'm suspecting it might have been a Qt biug that is now fixed already.

In reply to by Marc Sabatella

I downloaded 'MuseScoreSpecial-2018-09-20-0904-master-c07ed54-300-file-format.7z' which was the latest one on the dev page, and still no detection. Clicked the Jack tickboxes in Musescore IO page and closed down; Jack was set up as per the numerous tutorials, clicked Start to start the server; then restarted Musescore and still only have the system/system MIDI connections.

Windows 10 Home 64bit. My usual Musescore is the stable release Jack is 64bit version (the splash page says Jack session support disabled, no idea if that's relevant, it's a build from 2015).

it didn't detect Musescore 2 either, which makes me wonder whether I'm not setting it up correctly or missing out a stage...

First, that's nowhere near the latest, it's actually very old (notice the date, 2018-9-20). The second one on the list is the latest. This is explained above on that page, poorly, and I think it's past time to remove that old "special" build. But anyhow, as I explained above, I think the key is the version of Qt that MuseScore is built with. MuseScore 3.2.3 uses 5.9.6 (?), the nightly builds for Windows currently use 5.12.3, I am using 5.12.4. For me, my own build using 5.12.4 works. MuseScore 3.2.3 does not. Not sure about the nightly build, but feel free to try it (the current one, the old special one isn't good anything any more).

MuseScore 2 was 32-bit, so I think it might be normal the 64-bit version of JACK wouldn't detect it. but MuseScore 3 is 64-bit. There were special 64 bit builds of MsueScore 2 floating around, and 32 bit builds of MuseScore 3, but better to just use the correct version of JACK for your version of MuseScore.

I'm using MuseScore 3.2.3 in Ubuntu 18.04 64 bit with Jack server installed with KxStudio and it is working, what is really important for me as well. Actually I've been always using the newest version from MuseScore, so I tested all releases 3.x as well as the later 2.x ones and it always worked. Always getting the pre-compiled Linux Appimage. I'm even using it together with GrandOrgue using midi Jack connections to control GrandOrgue live from MuseScore. What I still didn't test is using MS midi input.

It's an option when building. But if there is a difference, it more likely to have to do with MinGW vs MSVC. I suspect it will turn out not to be that, though, and maybe something else about our environments - version of JACK, some difference in device driver or DLL's we have loaded, etc.

I can confirm this issue: Windows 8, MS, Jack 1.9.11 (64-bit JackRouter.dll registered). No Jack support means no xjadeo, so no video sync.