User’s Guide, Chapter 8: Installing MusicXML Readers and File Formats (1)¶
Music21 can import and export a bunch of different musical data formats.
In general, to load a file from disk, call
music21.converter.parse(), which can handle importing all
supported formats. (For complete documentation on file and data formats,
see music21.converter.) If you want to convert a file from the
corpus just use
from music21 import * b = corpus.parse('bach/bwv66.6') b.show() # I've altered this so it's much shorter than it should be...
Okay, so say you’re having some problems seeing things. The first things to ask are:
Do you have Finale, Sibelius, or MuseScore? Even the free version of Finale Notepad will work.
Once you have one of these three installed, we can move on. (It is
possible to use
music21 with Lilypond alone, but that’s much harder
to get configured properly, so please try this first)
Run this command (after the
from music21 import *):
You can say “no” to everything that is “Yes/No”, but make sure that it is finding your copy of MuseScore, Finale, or Sibelius.
Parsing Files in General¶
You can parse a file on your hard drive by calling
music21.converter.parse(). This returns a
Score usually, though sometimes
Part (for a format that only handles single
Opus (for multiple scores bound
together) comes back instead. You won’t do much with that unless you
assign it to a variable, such as
c = converter.parse('/Users/cuthbert/Desktop/myXML.xml')
If you’re on a PC, one of the things to notice is that you can use forward slashes, as in:
c = converter.parse('C:/Users/cuthbert/Desktop/myXML.xml')
Or you can use backslashes, as long as you put an
r before the quote
before the file name:
c = converter.parse(r'C:\Users\cuthbert\Desktop\myXML.xml')
If you’re in the directory of the file, you can just use the local
filename (for instance if you start in
/Users/cuthbert/ you could
If the file you want is on the web, we can give a URL to the
music21.converter.parse() function that points to the desired
file. Assuming proper system configuration (which we will get to further
in Chapter 24), the file will be
downloaded and parsed.
url = 'http://kern.ccarh.org/cgi-bin/ksdata?l=cc/bach/cello&file=bwv1007-01.krn&f=xml' sAlt = converter.parse(url) sAlt.measures(1, 5).show() # show first 5 measures
Usually, the file format can be guessed from the filename, but if the
filename does not have a suffix (Damn you, OS X!) or the URL has the
wrong suffix, you can give a
format="FORMAT" parameter to the file:
c = converter.parse('/Users/cuthbert/Desktop/myXML', format='musicxml')
One of the things you’ll notice over time is that once you parse a file
music21 once, the next time you parse it it’ll be between 2 and
5 times faster. That’s because we save an optimized version of the file
the first time you create a file, and subsequent times you open it it
will check to see if the original file has changed, and if it hasn’t, it
will read the optimized version instead.
For most people, this will work 100% of the time. But if you’ve done
something sneaky (like changed the file without changing its
modification time) or you’ve changed the format of the
parser, or if something’s not right, or if you just want to do things
slower, you can put a
forceSource=True keyword into the
c = converter.parse('/Users/cuthbert/Desktop/myXML.xml', forceSource=True)
By the way…if you’ve read any really old
music21 publications, you
parseWork mentioned instead of
parse. It’s the same
thing, so anywhere you see
File types available to
Music21 can read and write a lot of different file formats. Some of
them are pretty obscure. Some of them are world standards. The
converter module’s capital-c-
Converter object can give a list
of some of them. Each tool to work with one format is called a
subConverter. Here are the formats that
music21 can read:
[music21.converter.subConverters.ConverterABC, music21.converter.subConverters.ConverterCapella, music21.converter.subConverters.ConverterClercqTemperley, music21.converter.subConverters.ConverterHumdrum, music21.converter.subConverters.ConverterMEI, music21.converter.subConverters.ConverterMidi, music21.converter.subConverters.ConverterMuseData, music21.converter.subConverters.ConverterMusicXML, music21.converter.subConverters.ConverterNoteworthy, music21.converter.subConverters.ConverterNoteworthyBinary, music21.converter.subConverters.ConverterRomanText, music21.converter.subConverters.ConverterScala, music21.converter.subConverters.ConverterTinyNotation, music21.converter.subConverters.ConverterVolpiano]
And the formats that it can write:
[music21.converter.subConverters.ConverterBraille, music21.converter.subConverters.ConverterLilypond, music21.converter.subConverters.ConverterMidi, music21.converter.subConverters.ConverterMusicXML, music21.converter.subConverters.ConverterRomanText, music21.converter.subConverters.ConverterScala, music21.converter.subConverters.ConverterText, music21.converter.subConverters.ConverterTextLine, music21.converter.subConverters.ConverterVexflow, music21.converter.subConverters.ConverterVolpiano]
To output a file, either call
.show("format") on the stream (where
format can be
midi, etc.) or to keep the
file on disk, use
Some of the available formats will be listed below; the most important
ones for now are the output formats (since music21 will figure out
inputs automatically). They are
Some formats have sub-formats, for instance both
lilypond have a
.png subformat which converts directly to a
.png file. To use that, call
Some formats have abbreviations also, so
musicxml is also
lily, and (for ease of typing),
Getting and working with MusicXML Files¶
A whole bunch of MusicXML files can be found at the following URLs.
MusicXML files sometimes have the extension
.xml and sometimes
.mxl. Usually the latter are compressed music XML files; they load
just the same.
The format for musicxml, is, of course,
Getting and working with Humdrum Files¶
Humdrum is a file format developed by David Huron at Ohio State
University which is great at encoding works for computational analysis.
The Humdrum format includes many subformats (“spine classes”) of which
music21 supports the general class, the
kern format, and the
dynam dynamics format.
Parsing Humdrum files is exactly as parsing other data formats. Simply call the music21.converter.parse() function on the desired file path or URL.
sBach = converter.parse('http://kern.ccarh.org/cgi-bin/ksdata?' + 'l=users/craig/classical/bach/cello&file=bwv1007-01.krn&f=kern')
Over one hundred thousand Kern files can be found at the following URL.
Getting and working with ABC Files¶
ABC is a text-based format that can encode lots of musical types, but is especially great for monophonic songs, such as folk songs. If you’re in the folk song world, you’ll love working with ABC.
Parsing ABC files is exactly as parsing other data formats. Simply call
music21.converter.parse() function on the desired file path
o = converter.parse('/Users/cuthbert/Documents/Music21/praludium.abc')
Large collections of ABC are available from numerous on-line repositories. The following links are just a few of the many resources available.
ABC Opus files¶
Note that many ABC files define more than one complete musical work. If
an ABC file defines more than one work, an
Opus object is returned. Opus objects, a
Stream subclass, provide convenience methods for accessing multiple
You can get a whole bunch of pieces together just by parsing the file. For instance, here’s an Opus:
o = corpus.parse('josquin/ovenusbant') o
Reference work numbers (e.g., the “X:” metadata tag in ABC) are stored
Metadata objects in each contained
Score. Access to these numbers from the Opus is available with the
music21.stream.Opus.getNumbers() method. Additionally, the
Score object can be directly obtained with
o = corpus.parse('josquin/ovenusbant') o.getNumbers()
['1', '2', '3']
s = o.getScoreByNumber(2) s.metadata.title
'O Venus bant'
Direct access to Score objects contained in an Opus by title is
available with the
o = corpus.parse('essenFolksong/erk5') s = o.getScoreByTitle('Vrienden, kommt alle gaere') s
'Vrienden, kommt alle gaere'
Some ABC files, such as those in
corpus/essenFolksong have hundreds
or thousands of files. The way we’ve been doing things before is to
parse all of them and then select the one we want. If you know the
number of the file you want, however, you can pass to
number=X attribute to get
just that one. It will return a
s = corpus.parse('essenFolksong/erk5', number=2) s
ABC single-part Opus files¶
In some cases an ABC file may define individual parts each as a separate
score, sort of like a Renaissance partbook. When parsed, these parts can
be combined from the Opus into a single Score with the
For instance, here is Josquin’s “Mille Regretz” (spelled with an s) stored as four individual parts each as its own score:
o = corpus.parse('josquin/milleRegrets') len(o.scores)
So, that’s not too helpful. We can run
mergeScores to bring them
into a single score with four parts.
s = o.mergeScores() s.metadata.title
Parsing Musedata Files¶
Musedata is a format devised by Walter Hewlett (yes, of HP lineage) in the 1980s that is highly memory efficient. Probably not the best format for modern computers, but there’s a huge collection of Musedata files out on the net of many standard repertory pieces.
Both stage 1 (limited encoding) and stage 2 (rich encoding) Musedata
file formats are supported by Music21. Multi-part Musedata (stage 2)
files, zipped archives, and directories containing individual files for
each part (stage 1 or stage 2) can be imported with the
music21.converter.parse() function on the desired file path or
Note that access restrictions prevent demonstrating Musedata conversion. Downloading or using Musedata files requires sending a written access agreement to the owners.
Parsing MIDI Files¶
MIDI input and output is handled in the same was other formats. Simply
music21.converter.parse() function on the desired file
path or URL.
Remember (or learn if you haven’t yet), that MIDI has no information
about enharmonic spelling (C# and Db are the same), and that detecting
the lengths of notes can be difficult.
Music21 does very well with
MIDI files that were created in notation software or sequencing
software, but has a harder time handling MIDI files created by recording
live input. For those files, we suggest converting the MIDI files in
software such as Finale that has a more sophisticated MIDI to MusicXML
music21’s core strengths is the number of different file
formats it handles. Some people who don’t use
music21 for anything
else use it as a format converter. We’re happy about that, but think,
hey, there’s a lot more that you can do with it than that. Let’s move on
in the next chapter to one of the tools that
music21 has for
analysis that almost nothing else out there has:
Chapter 9: Chordify which reduces
scores to chordal collections.