MusicXML to MIDI converter

MusicXML to MIDI converter, including accompaniment generator using Musical MIDI Accompaniment (MMA).

Installation

• Install xmllint (included in libxml2 on most platforms)
• Install xmlstarlet at https://xmlstar.sourceforge.net/ (included in most Linux distributions)
• Install jd at https://github.com/josephburnett/jd
• git submodule update --init --recursive
• npm install && npm run build

Convert a MusicXML score to MIDI

• npm run --silent convert:unroll song.musicxml > song-unrolled.musicxml to unroll a MusicXML score by expanding all jumps and repeats
• npm run --silent convert:mma song.musicxml > song.mma to both unroll a score and convert it to an MMA script
• npm run --silent convert:groove groove-name [chords="A,B,C"] [tempo=X] [count=Y] [keysig=Z] > groove.mma to generate a groove MMA script
• npm run convert:midi /path/to/song.mma to convert an MMA script to MIDI file at /path/to/song.mid
• npm run --silent convert:timemap song.musicxml > song.timemap.json to convert a score to a timemap JSON file

Serve a conversion API endpoint

• PORT=3000 npm run start:develop for development (including hot-reload)
• PORT=3000 npm run start:server for production
• curl -sSf -F"musicXml=@test/data/salma-ya-salama.musicxml" -F"globalGroove=Maqsum" http://localhost:3000/convert -o "salma-ya-salama.mid"
• curl -sSf -F"groove=Maqsum" -F"chords=I, vi, ii, V7" -F"count=8" http://localhost:3000/groove -o "maqsum.mid"
• curl -sSf -F"jq=.[] |= {groove,description,timeSignature}" http://localhost:3000/grooves.json

Other operations

• Validate a MusicXML score: npm run --silent validate:musicxml song.musicxml
• Find MusicXML scores with an XPath query: npm run --silent query:filter /path/to/musicxml/folder/or/file //xpath/query
• Query MusicXML scores with an XPath query: npm run --silent query:select /path/to/musicxml/folder/or/file //xpath/query
• Extract an Ableton ASCL tuning from a MusicXML score: npm run --silent convert:tuning song.musicxml > song.tuning.ascl
• Extract a pitchset JSON listing from a MusicXML score: npm run --silent convert:pitchset song.musicxml > song.pitchset.json
• Scrape MusicXML examples from the official site: ./src/js/musicxml-examples.js --output=./test/data/examples
• Convert MMA grooves to MusicXML: ./src/js/musicxml-grooves.js --output=./test/data/grooves
• Convert MIDI to JSON and back: ./src/js/midi-json.js < source.mid | jq [..] | ./src/js/midi-json.js > target.mid

Theory of operation

This converter creates a valid MMA accompaniment script out of a MusicXML score. The MMA script is then converted to MIDI using the bundled mma tool. To accomplish this, the converter expects to find the following information in the sheet:

• Chord information, expressed as harmony elements. MMA recognizes a large number of chords, but MusicXML's harmony representation is more general and can lead to invalid chord names. Refer to chords.musicxml for a reference on how to express all MMA-supported chords.

• Melody information, expressed as note elements. This is converted to an MMA SOLO sequence for each measure.

• Optional playback style information, expressed as sound/play/other-play elements with attribute @type = 'groove'. The content of this element represents the "groove" that is passed to MMA to generate an accompaniment. In case no such playback style information is found, or the specified style is not mapped to an existing MMA groove, the chords are played back as per the lead sheet without further accompaniment. Note that several styles can be specified in a single sheet, since the sound element is associated with measure or measure/direction elements. The groove can be overridden with the argument globalGroove.

The tools contained here can also convert the score to a so-called "timemap" JSON file, which lists timing information for each measure. This is needed for consumers that wish to synchronize the MusicXML with the MIDI, such as musicxml-player:

[
  {
    // 0-based measure index (integer)
    // This index can be repeated in the timemap in case the measure itself is repeated, e.g. with |: repeated sections :| and D.S. sections.
    measure: number,

    // 0-based offset in milliseconds (real)
    timestamp: number,

    // duration in milliseconds (real)
    duration: number
  },
  // ...
]