New feature to test: MIDI out

MuseScore 2.1 and previous versions can send MIDI messages to external devices or synthesizers using JACK. Jack offers many great professional features, but unfortunately it’s hard to install on Windows and macOS, as it’s primarily a Linux software.

For many years, we didn’t want MuseScore to have an easier way to send MIDI events to the outside world, for two main reasons.

  1. MuseScore is first and foremost a music notation software. Its purpose is to easily create beautiful sheet music. Playback is nice, but the core team wants to focus on the notation.
  2. We were (and still are) worried that if we offer minimal support for MIDI out, we would get many feature requests to improve it, sometimes in ways that are not possible, or that we prefer to not spend our time on, or that would make MuseScore complex to use for users who don’t care about MIDI.

Eric Fontaine was not happy with this state of affairs and really wanted to make MuseScore usable on a low end device where the internal synth takes a lot of CPU cycles and MIDI out would be more performant. So he checked the various available libraries (RtMidi, PortMidi etc…) and decided to use PortMidi, which MuseScore already uses for MIDI in. After > 100 comments and some code, we now have MIDI out in master! You can test with a nightly build.

How to enable MIDI out

MIDI out is not enabled by default. You need to go to Preferences / I/O and choose an option for MIDI output. If you use an external device, it’s probably the name of your device. If you use a software synth, you might need virtual MIDI cables. Note that MuseScore will send MIDI events out to the selected device but it will also send the events to its own built-in synthesizer. If you don’t want to hear the built-in synth, you will need to either lower the volume, or remove the SoundFont in View / Synthesizer.

2017-05-29 10_25_25-MuseScore Preferences.png

Note about output buffer latency: if this is set to 0, then messages are sent as soon as possible after MuseScore sends them to PortMidi, and might sound before the playback cursor. You can set this greater than 0 to try to find a value that will cause the notes to sound at the same time of the playback cursor.

What you can do currently with this feature?

  • Play a simple score through an external MIDI device (keyboard, synthesizer, etc…)
  • Play a simple score through a virtual instrument in standalone mode

What you can’t do with this feature?

  • Play an overly complex score out of the box. MuseScore is not a sequencer and its basic MIDI support is limited to the default 16 channels (also, no automation, no custom sysex etc…)
  • Send a MIDI song position event
  • Send a MIDI clock signal
  • Synchronize different MIDI devices or software together

This feature might evolve depending on your feedback. However, we will make sure that we do not overload the software with dozens of options dedicated to MIDI out specifically.



that's a great news. But... I don't see these parameters in the latest nightly builds (MuseScoreNightly-2017-05-29-1951-2.2-3bfcab8.7z on Windows 10 64 bits).
A friend of mine have it working fine on Mac....
Is there a problème on windows ?

You need a build from master, not 2.2 (a PR adding this new feature to 2.2 is pending, see, but not yet merged)

I have a question: does this mean that MuseScore will be able to drive some VST plugin, maybe via some sort of vst host like this one? My idea is NOT to make MuseScore a dedicated sequencer (there are so many and so good around already), rather, provide some higher quality audio feedback while writing sheet music.

Yes ! I tried it with Addictive Keys and The Galaxy II pianos on a Kontakt Player. Works fine. Just had to install LoopBe1 as a virtual midi cable (on windows).
I also used it to send midi datas from MuseScore to a vsti loaded in REAPER and Cubase 8 Le.
Works fine too !!!!!

Many thanks, I was not even aware of LoopBe1 existence.

Tested some scores out on Windows 10, using loopMIDI virtual cable with the Pianoteq and ARIA plugins loaded in REAPER - it works really well! Just have to make sure that when MuseScore is started, no MIDI-input tracks are armed for recording, or else it will fail to connect to them.

About the output latency - when set to zero, the MIDI is indeed heard before the MuseScore synth, but still in sync with the cursor. Because of this, I think it is the synth that is late, not the MIDI that is early.

I had no problem to record midi datas from MuseScore in REAPER. Just use a WASAPI driver in REAPER, arm your midi track, launch the recording the go back to musescore and launch the playing. It worked for me

Untitled.jpg Darn. I set everything up to send midi out to an editor but I keep getting this error "qt core" cannot be found. Attached screen shot. Tried reloading. There are some longer duration notes (half notes) that sustain and then drop suddenly. I want to attempt to smooth out the release, decay times by adjusting in steps the envelope generator.

Strange enough that dll is listed in your screenshot, so is definitely not missing.

It looks as if you're attempting to run the program from within the 7zip archive. Unzip it first.

Here is the bin unzipped with nightly.exe double clicked

The error message can't find platform "windows in" is attached. But it is in the platform folder

thanks for all the help. Its time for a new computer. The operating system is not supported and its not even a genuine copy. (whatever that means)

I tried out some software synths with an exported MIDI file. They sounded pretty awful. But the possibility of 16 individual channel assignments is appealing

Untitled 2.jpg 127.28 KB

Yes, exactly the sequence of messages I get. (occasionally i got a "qt5 core" is missing)


Any reason you're using a nightly from May 29th rather than the latest from June 8th? Please give that a try, it does start cleanly here for me (Windows 7).
Are you by chance still on Vista, like Shoichi?
Also your latest screenshot S
shows that there are Windows updates panding and that Microsoft Defender has some alerts.

Ok. i will try again with the latest. Yes, vista like Shoichi.

OK, please realize that Vista is no longer supported. Consider upgrading to 7 or even 10.

Ciao Jojo, on Vista Windows Update goes in loop (since it came out 10);
AVG lock defender (Disabled by Group Policy)


Well possible that MuseScore master doesn't work any longer on Vista, it uses Qt 5.8 (while 2.x uses Qt-5.4), well possible that not only Microsoft, but also Qt stopped supporting XP and Vista.

Just wanted you to know that I tried out the first June 12 master nightly build with a yamaha P-115 connected to a Windows 10 laptop through USB and it all worked beautifully. I'm keeping my fingers crossed that at least this basic MIDI output support stays in as I have been unable to find anything else for Windows that can decently do score editing and supports MIDI output and is freeware. Plus, I just bought the MuseScore book.

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