How to use MIDI Keyboard with Musescore

It's not needed to install any program.

Musescore by default was not using ALSA audio on my installation. It was only needed to select ALSA at preferences menu and it just worked!

to see if the MIDI was recognized just type aconnect -i

pauloh@mccartney:~$ aconnect -i
client 0: 'System' [type=kernel]
    0 'Timer           '
    1 'Announce        '
client 14: 'Midi Through' [type=kernel]
    0 'Midi Through Port-0'
client 20: 'CH345' [type=kernel]
    0 'CH345 MIDI 1    '

This last 'CH345' is my MIDI controller and it is shown only when connected.

To more details about MIDI I read this article from Rafał Cieślak

You need to select PortAudio into MuseScore Preferences I/O panel.

Please, check about the very important parameters:

1) API: To me, at least, it should be ALSA

2) Audio Device: System Default

3) MIDI Input, and MIDI Output: You have to select your recognized external MIDI device here.

Then... Close MuseScore and Open it again.

You will be able to use the external MIDI device BUT... There is some "bugs" because the internal MuseScore way to play the score (it is not full General MIDI Standard compatible).

In the new MuseScore 3, I couldn't find an ALSA option, until I checked the PortAudio box (I'm on Ubuntu 18.04 LTS):

Seems like they integrated it.

Don't forget to first turn on the piano (and connect it) and then start MuseScore. Works great with the Yamaha P-45 which I connected through USB (which I used here).

me@mycomputer:~$ aconnect -i
client 0: 'System' [type=kernel]
    0 'Timer           '
    1 'Announce        '
client 14: 'Midi Through' [type=kernel]
    0 'Midi Through Port-0'
client 20: 'Digital Piano' [type=kernel,card=1]
    0 'Digital Piano MIDI 1'