TuneTransformer is a MuseScore 3.x plugin that shifts the notes of a melody to fit given chords. Watch the overview video here.

Click on the green <> Code button and select Download ZIP. Place tune-transformer.qml and TuneTransformer.js in the folder that MuseScore has been configured to look for plugins in. General instructions for installing and using plugins can be found here.

1. Add chord symbols on top of a melody.
2. Then, run the plugin. The plugin will shift the notes of the melody to fit the chords.
   • If a note in the melody falls on a strong beat, then the note will be shifted to the nearest note in the most recent chord.
   • If a note in the melody falls on a weak beat, then the plugin calculates a scale that fits the most recent chord, and the note in the melody will be shifted to the nearest note in that scale.

To protect a section of the melody from being shifted, add a chord symbol with the text N.C. (no chord) above the first note of the section. This plugin has no effect on notes that do not have a most recent chord symbol. For this reason, the plugin resumes shifting notes at the next chord symbol after the N.C. chord symbol.

This plugin relies heavily on the ExpandChordSymbols plugin's calculation of which notes belong in a given chord.

1. The plugin does a poor job of spelling notes. Currently, it always spells the note between F and G as F#, even in the context of an Eb minor chord.
2. The plugin does not support chords with multiple alterations to a single note. For example, C7b9#9 is not supported, and will be interpreted as C7#9.

This plugin uses segments to navigate throughout the score. Cursors are not used because, for some reason, in the code below which uses cursors, Line A causes all but the first segment to be skipped.

// For each segment in the score, ...
do {
    console.log("Current segment: " + cursor.tick);

    for (var staff = 0; staff < numStaves; staff++) {
        console.log("Current staff: " + staff);
        cursor.staff = staff;

        for (var voice = 0; voice < numVoices; voice++) {
            console.log("Current voice: " + voice);
            cursor.setVoice(voice); // Line A

            // For each chord, for each note, alter its pitch.

        }
            
    }

} while (cursor.next()); // (returns false at the last segment)

I had to put all the code in one .js file because it seems that MuseScore allows imports in .qml files but not in .js files.

Otherwise, I would have separated my code from the code I took from the ExpandChordSymbols plugin.

Time signatures are read from the measure (parent of the segment) and not from the segment itself. This is because of the following behaviour:

var measure = segment.parent;
console.log(measure.timesigActual.numerator);    // Prints the actual numerator.
console.log(measure.timesigActual.denominator);  // Prints the actual deminominator.
console.log(segment.timesigActual.numerator);    // Always prints one.
console.log(segment.timesigActual.denominator);  // Always prints zero.