MSCZ File Documentation

Summary

An MSCZ (MuseScore Compressed Score) file is a sheet-music document created by MuseScore, the free, open-source scorewriter. It stores the notated score — staves, notes, lyrics, layout — as XML inside a ZIP container, not recorded audio. Its MIME type is application/x-musescore. Open and edit a .mscz file with MuseScore; to share it, export to PDF, MusicXML, or MP3.

Technical details

FeatureValue
Full nameMuseScore Compressed Score
File extension.mscz
MIME typeapplication/x-musescore
Format typeMusic-notation document (sheet music)
Container / base formatZIP archive
Score encodingXML (the contained .mscx file)
DeveloperMuseScore (Werner Schweer; now Muse Group)
IntroducedMuseScore project since 2002
Current version lineMuseScore 4 (released December 2022)
Open standardPartial — open-source app, app-specific XML schema
Byte orderN/A (ZIP structures are little-endian)
Magic number50 4B 03 04 ("PK", ZIP local file header) at offset 0
Uncompressed twin.mscx (same score as plain XML)
Holds audio?No — playback is synthesized from the notation
Typical contentsscore.mscx, META-INF/container.xml, thumbnail, embedded images/audio
Backward compatibleMuseScore 4 opens MuseScore 3 files
Export targetsPDF, MusicXML/MXL, MIDI, MP3/WAV, PNG/SVG
Related extensions.mscx, .musicxml, .mxl, .mid, .gp
CategoryDocument / music notation
Specification URLmusescore.org/en/handbook/4/file-formats
File signature (magic bytes)
50 4B 03 04

Offset 0, 4 bytes. An MSCZ is a ZIP archive, so it begins with the ZIP local file header PK\x03\x04 — the same signature you see in DOCX, XLSX and APK. The bytes 50 4B are the initials of ZIP's co-author Phil Katz. Rename a .mscz to .zip and any archiver will unpack it, revealing the .mscx XML score, a META-INF/container.xml manifest and a thumbnail.

What is an MSCZ file?

MSCZ stands for MuseScore Compressed Score. It is the native save format of MuseScore, a free and open-source music-notation program developed since 2002, originally by Werner Schweer and now under Muse Group. An .mscz file is sheet music: it describes a notated score — instruments, clefs, time and key signatures, notes, rests, lyrics, chord symbols, dynamics, page layout and styling — so the score can be edited, transposed, played back and printed. It is not a recording. Any sound you hear when a .mscz plays is generated on the fly by MuseScore's playback engine from the notation, so a category label of "audio" is a misclassification.

Technically an MSCZ is a ZIP archive. That single design choice explains most of the file's behaviour: it starts with the ZIP signature, it can be opened by any archiver, and it bundles several parts (the score, a manifest, a thumbnail and any embedded media) into one compressed container. The companion .mscx is the same score saved as a single uncompressed XML file. The sections below take the container apart, look at the XML score model inside it, and explain how MuseScore 4 changed the layout. The format is documented in the MuseScore Handbook.

The ZIP container and its members

Open an .mscz as a ZIP (rename it to .zip, or point an archiver at it) and you find a small set of named entries. MuseScore writes them in a fixed arrangement so the application can locate the main score without scanning every member.

my-song.mscz  (ZIP)
 ├─ META-INF/container.xml     manifest: path of the root score file
 ├─ my-song.mscx               the score itself, as XML
 ├─ Thumbnails/thumbnail.png   rendered preview of page 1
 └─ (optional)
     ├─ images/*               embedded pictures placed on the score
     └─ audio/*                captured audio or custom samples

The META-INF/container.xml file is the entry point. It is a tiny XML manifest whose <rootfiles> element gives the path of the primary .mscx inside the archive, so MuseScore reads the manifest first and then loads whatever score it names. This mirrors the container convention used by MusicXML's compressed .mxl and by EPUB and ODF documents: a fixed manifest location pointing at the real payload. The thumbnail lets file browsers and MuseScore's own start screen show a preview page without opening the full score. Embedded images and audio are only present when the score references them.

Because the container is an ordinary ZIP, the .mscx inside is usually stored with DEFLATE compression, which is why a compressed .mscz is noticeably smaller than the equivalent bare .mscx. It also means an .mscz is self-contained: distributing one file carries the score, its preview and any linked media together.

The MSCX score model

The real content is the .mscx file, an XML document that encodes the score as a tree. At the top is a <museScore> element carrying a version attribute, which is how the program knows which schema generation it is reading. Below that, a <Score> element contains the parts, the staves and the measures.

<museScore version="4.20">
  <Score>
    <Part> ... instrument, MIDI program, staff setup ... </Part>
    <Staff id="1">
      <Measure>
        <voice>
          <TimeSig><sigN>4</sigN><sigD>4</sigD></TimeSig>
          <Chord>
            <durationType>quarter</durationType>
            <Note><pitch>60</pitch><tpc>14</tpc></Note>
          </Chord>
          <Rest><durationType>quarter</durationType></Rest>
        </voice>
      </Measure>
    </Staff>
  </Score>
</museScore>

Each <Staff> holds a run of <Measure> elements, and each measure holds up to four <voice> layers. Inside a voice, the musical events appear in time order: a <Chord> (one or more simultaneous <Note> elements) or a <Rest>, each with a <durationType> such as quarter or eighth. A note's <pitch> is a MIDI note number, while <tpc> ("tonal pitch class") records the note's spelling on the circle of fifths so the engraver knows whether to draw, say, F♯ or G♭ even though both sound the same pitch. That distinction between sound (pitch) and spelling (tpc) is central to notation and is exactly what a plain MIDI export throws away.

MSCZ versus MSCX

MuseScore can save the same score two ways. .mscz is the compressed, bundled default: smaller, and able to carry embedded images and a thumbnail. .mscx is the single uncompressed XML file, with no bundling. The XML content is identical between them, so the choice is about packaging, not about what the score can express. The .mscx form is handy for version control (a text diff shows exactly which notes changed) and for hand-editing the XML. To get from one to the other you can Save As in MuseScore, or simply unzip the .mscz and pull out the .mscx.

What MuseScore 4 changed

MuseScore 4, released in December 2022, kept the ZIP-plus-XML design but revised the internal schema and the playback pipeline (the current line uses a new engraving and audio engine). The format stayed backward-compatible in the reading direction: MuseScore 4 opens MuseScore 3 .mscz files, upgrading the older schema on load. The version attribute on the root element is what drives this: it tells the program which generation of the score model it is parsing so it can apply the right conversions. Files re-saved in MuseScore 4 are written in the newer schema and may reflow layout when opened, which is why very old MuseScore 1 or 2 scores can shift when re-engraved. Saving from a newer version does not generally open cleanly in an older one.

Getting a score out: PDF, MusicXML, MIDI, MP3

Because the .mscz schema is MuseScore-specific, sharing a score with someone who does not run MuseScore means exporting to a neutral format, and each target keeps a different slice of the data. Exporting to PDF (File › Export › PDF) produces a fixed, printable page image: it preserves the exact engraving but is no longer editable as notation. Exporting to MusicXML (or its compressed .mxl) is the way to move the score into another notation program such as Sibelius, Finale or Dorico, because MusicXML is the interchange standard for notation; most notes, lyrics and structure transfer, though MuseScore-specific styling may shift. Exporting to MIDI keeps the notes and timing for use in a DAW but drops layout, articulations and lyrics, and collapses the pitch spelling described above. Exporting to MP3 or WAV renders the playback to actual audio — this is how you obtain a "recording" from a file that never stored one. The reverse, importing, is how MuseScore reads MusicXML, MIDI and formats such as Guitar Pro into a new score.

Frequently asked questions

Is an MSCZ file audio or sheet music?

Sheet music. The file stores music notation as XML, not a waveform. The sound you hear is synthesized by MuseScore from the notes at playback time, so nothing is lost by there being no audio inside; you can render audio at any time by exporting to MP3 or WAV.

How do I open an MSCZ file without MuseScore?

There is no faithful editor besides MuseScore, but you can view and play the score by uploading it to musescore.com in a browser, or ask the sender for a PDF (to read and print) or MusicXML (to open in another notation app). To just inspect the raw score, rename the file to .zip and extract the .mscx XML.

What is the difference between MSCZ and MSCX?

Both are MuseScore scores with identical XML content. MSCZ is a compressed ZIP that also bundles images and a thumbnail; MSCX is the same score as one uncompressed XML file. MSCZ is the smaller default; MSCX is convenient for version control and manual editing.

References