[snblg]

My problem is solved and I do not use Kodi anymore.
Kodi is great, but Vlc does exactly what I need.
I do not need any media center as I only work with desktop computers.
Music is my main concern : I do not watch Tv.

Configuring Vlc so that it plays midi files is really easy under Linux : 10 lines to follow here.
Vlc manages libraries (Médiathèque into french) : I've added all my media inside Vlc Gui from my folders by simple drag and drop actions: fast, ! - No drag and drop with Kodi.
Adding my files (total 170 Gb ) is faster under Vlc vs Kodi.
Probably because Kodi fills a database, Vlc, no.
Not sure a database is necessary for my needs : it's so fast to search and find under Vlc !

Vlc plays midi with good quality under Linux : it also uses soundfonts from my Native Maschine Studio Software/hardware that runs under Windows. Moving from one soundfont to another one is really easy.

Using mouse and keyboard with Vlc is easier than with Kodi :
try to copy and paste some text to Kodi search window ...
mouse disappears under Kodi, you have to move it...

Of course, Vlc plays files from samba shares, as Kodi does, but Vlc does not fill my local harddisk with thumbnails.
My .kodi folder was over 1.5 Gb after 3 weeks use.
My .vlc folder : 92k !

I also use another software : QSynth; it's not related to Vlc, but it's also useful.

Bye and have fun with Kodi.

Below, files from Samba share from my desktop server.