Converting

Exercise nº 2

On the Prelude nº 4 in E minor, Op. 28, by Frédéric Chopin (1839) — public domain.
Exercise material © 2026 Mario Maurano. All rights reserved.

What you will do: take a MIDI file of a well-known piece, convert it to the Music Motion format and open it in the Score, so you can hear it in Pythagorean tuning, see it written out, and edit or print it.

How long it takes: about twenty minutes. You do not need to read music: it is all clicks. What you need: the files that come with this lesson (Preludio Nº 4 Op28 - E min.mid and .mxl, with the PDF of the score: ⭳ download them here) and a computer with a browser and sound.

Along the way you will understand something that shows up in everything else: why a MIDI file and a MusicXML file are not the same, even if they sound alike.

Three extensions and one word

.mid: MIDI. It stores which key is played and when. What it does not store is which note it is: it writes «key 61», and key 61 can be a C♯ or a D♭. It is the format you find most often on the internet.
.xml · .mxl: MusicXML. The real score: besides the key, it stores how each note is written — whether it carries a sharp or a flat. The .mxl is the same file, compressed.
.mmf: The Music Motion format. It takes that information and gives every note its exact pitch. It is the file the Keyboard, the Score and the Console open.
The copyist: is the PLAYER: the app that reads a MIDI file and turns it into MMF.

THE TWO PATHS

The same piece can come into the Score through two doors. This exercise takes the first one, which is the one you will need almost every time, and at the end compares it with the second.

Path A — from a MIDI file

.mid → PLAYER → .mmf → SCORE

This lesson’s path. It works for any MIDI file you find, and it is the normal case.

The copyist works out the spelling of each note from the key signature in the file, because the MIDI file does not carry it.

Path B — from a MusicXML file

.xml / .mxl → SCORE

Shorter: the Score opens it directly, without going through the Player.

And better, when it exists: the spelling is not worked out, it is written in the file.

We take path A on purpose. Not because it is the best, but because it is the one you will run into: the internet has MIDI files of almost everything and MusicXML of very little. At the end of the exercise we open the same Prelude through path B and compare the two. That is where you see the difference with your own eyes.

PATH A — FROM A MIDI FILE TO YOUR SCORE

1 · Open the PLAYER

From the COSMIC KEYBOARD, the ⊞ player button on the navigation bar. Leave the Cosmic open: it makes the sound for the whole suite, and the Player uses it to play.

The Player just opened, empty, with the drop zone and the navigation bar in view.

2 · Load the MIDI file

Two ways, whichever you prefer:

Drag the file Preludio Nº 4 Op28 - E min.mid and drop it on the Player’s drop zone.
Or click that zone and choose it in the file browser.

TIP: the Player accepts .mid, .midi and .mmf. If you pick an .xml nothing will happen: that one takes path B, straight into the Score.

Check: you should see the file name and, below it, the piece drawn as a grid of bars — each bar is a note, and the higher it sits, the higher the note. If nothing appears, the file was not a valid MIDI file.

The Player with the Prelude loaded: the file name and the piece drawn.

3 · Listen to it

The ▶ button on the transport. The Player sends and the Cosmic sounds: you are hearing the Prelude in Pythagorean tuning, with pure fifths.

Check: if there is no sound, it is almost always one of two things: the COSMIC KEYBOARD was closed, or its volume is down. Open it again and try once more.

4 · The work card (optional)

The 🔍 IDENTIFY work button is Score Intelligence: it recognises which piece it is and what its tempos are, and fills in the work and movement fields.

This step needs a key of your own and an internet connection. If you do not have one, choose not now when it asks: the exercise carries on the same and nothing that follows depends on it. The work and movement fields can be typed in by hand.

5 · Save it as MMF

The SAVE MMF 1.1 button. The file goes to your downloads folder, named after the piece.

Check: look in Downloads for a file ending in .mmf. That is the Prelude, now in the house format. You have just converted it.

The SAVE MMF 1.1 button, with the cursor over it, and the work/movement fields filled in.

6 · Open it in the SCORE

Open the SCORE — from the Player, the ⊞ score button.
Click MENU FILES to open the FILE MENU window.
Choose 📂 IMPORT MMF and select the file you have just saved.

Check: the score has to appear, with its bars and its notes. The Prelude is in E minor, so the key signature — at the start of the staff — has one sharp. If you see an empty page, the file you chose was not the .mmf.

And now the surprise — which is not your mistake. What appears does not look like the printed score: the whole piece has landed in a single channel, CH1, in the bass clef, with the right hand hanging from ledger lines far above the staff. CH2 is empty.

The Player did not get it wrong, and you did not save it wrong: this is how the MIDI file comes. Look inside it and it has a single track, called [Group 2], with all 752 notes mixed into channel 1. The two hands were already merged before you touched anything, and saving it again from the Player would give exactly the same result: nobody can split up what the file never split.

Leave that screen as it is and carry on to PATH B. The comparison is the lesson.

The Score with the .mmf that came from the MIDI file: everything in CH1, in the bass clef, and CH2 empty. It is the «before» picture.

7 · It is yours now: play it and look at it

From here on it is not a recording, it is your score:

Listen to it with the Score’s transport.
Change a note and listen again: what you edit is what sounds.
See it as a page and print it: that is step 8, with the version that comes from the MusicXML file, which is the one worth printing.
Keep it with 💾 EXPORT MMF, so you can open it again whenever you like.

PATH B — AND THE COMPARISON

Now the short path, with the same Prelude, to see the difference:

In the Score, MENU FILES → 📥 IMPORT XML.
Choose Preludio Nº 4 Op28 - E min.mxl.

Check and compare: the first thing jumps out even if you do not read music — now there are two channels, one for each hand, each with its own clef: the right hand in the treble clef and the left hand in the bass clef. It is the same piece you have just seen crammed into a single staff.

And the second, looking closely: find a bar with accidentals — a sharp or a flat on its own, one that is not in the key signature — and look at it in both versions. You have the PDF of the Prelude next to the files: that is the original, and it tells you who is right.

The Score with the .mxl imported: two channels, treble clef above and bass clef below. It is the «after» picture, and it goes right next to 4a.

If a note came out written differently in the version that came from the MIDI file, it is not a mistake in the program: the MIDI file did not carry that information and the copyist had to work it out from the key signature. The version that came from the MusicXML file did not work it out: it read it.

The rule, in one line: if the MusicXML exists, use the MusicXML. If there is only MIDI, that works too — and now you know what to look at after converting it.

And now, with a well-made MIDI file

The zip also contains Preludio Nº 4 Op28 - E min (dos pistas).mid: the same Prelude, exported with one track for each hand. Repeat steps 2 to 6 with it: load it in the Player, save it as MMF and open it in the Score.

Check: this time the piece arrives in two channels — the right hand in the treble clef and the left hand in the bass clef —, almost like the MusicXML version. The Player did not change: the file did. A MIDI file with one track per instrument arrives in order; one with everything mixed arrives mixed. What a MIDI file never carries — slurs, written dynamics, some details of the notation — is corrected afterwards by hand in the Score.

8 · See it as a page and print it

So far you have worked on the strip: the score runs from left to right, without breaks. To see it as it would be on paper:

Press 📄 PAGE, on the second row of the toolbar. The strip turns into sheets: the title, the composer and the systems laid out as in a printed edition.
That same row now shows the sheet settings: how it is displayed (Fit width), how many bars go in each system (Auto bars), the staff size (Staff 4mm), the space between systems (Gap 4mm) and the pages. You can keep editing on the sheet: what you change there changes in the score.
To go back to the strip, press the same button, which now reads ▦ SCROLL, or the Esc key.

The Score in page view, with MENU FILES open and PRINT / PDF in view.

To print it or save it as a PDF:

MENU FILES → 🖨 PRINT / PDF. The print window opens with the sheet exactly as it will come out.
At the top you choose the paper (A4) and what is printed (Full score: the whole score). Below, if you like, the header: title, subtitle, composer, the part name and the ©. These change only the printed sheet, not the score.
If you changed anything, press Refresh to bring the sheet up to date.
Press Print / PDF. Your browser’s print dialog opens: choose your printer, or Save as PDF to keep the file.
Close takes you back to the Score.

The PRINT / PDF window with the Prelude: A4 paper, the header filled in and the first sheet in view.

Check: on the sheet you see the two staves joined by the brace, the title Preludio Nº 4 centred at the top and F. CHOPIN Op. 28 on the right.

Congratulations: you have converted your first piece

Going further

The zip also holds CHOPIN_Prelude-Nº-4-Op28-E el segundo-2CH sin editar.mmf: it is what the Player should give you with the two-track MIDI, saved as MMF. Open it in the Score and compare it with yours.

You now have the Prelude in the Score just as it comes out of the MIDI: the right notes, each exactly in its place. In Exercise no. 2b — Interpreting you start from that same file and give it an interpretation: the pedal, the breathing of the left hand, the inner voice of the chords and the turn in bar 16. At the end you test your ear: how much does a voice have to be brought out to be heard?