msdparser 2.0.0b1

Simple MSD parser (rhythm game format)

msdparser

Simple MSD parser for Python. MSD is the underlying file format for many rhythm games, most notably both StepMania simfile formats (.sm and .ssc).

Installing

msdparser is available on PyPI. During the current 2.0 beta phase, make sure to pass --pre to pip:

pip install --pre msdparser

Parsing

parse_msd takes a named file or string argument and yields parameters as named (key, value) tuples:

>>> from msdparser import parse_msd
>>> with open('testdata/Springtime.ssc', 'r', encoding='utf-8') as simfile:
...     for (key, value) in parse_msd(file=simfile):
...         if key == 'NOTEDATA': break     # stop at the first chart
...         if not value: continue          # hide empty values
...         print(key, '=', repr(value))
...
VERSION = '0.83'
TITLE = 'Springtime'
ARTIST = 'Kommisar'
BANNER = 'springbn.png'
BACKGROUND = 'spring.png'
MUSIC = 'Kommisar - Springtime.mp3'
OFFSET = '-0.090'
SAMPLESTART = '105.760'
SAMPLELENGTH = '15'
SELECTABLE = 'YES'
DISPLAYBPM = '182'
BPMS = '0=181.685'
TIMESIGNATURES = '0=4=4'
TICKCOUNTS = '0=2'
COMBOS = '0=1'
SPEEDS = '0=1=0=0'
SCROLLS = '0=1'
LABELS = '0=Song Start'

Serializing (v2.0+)

To serialize key/value pairs back into MSD, construct an MSDParameter for each pair and stringify it:

>>> from msdparser import MSDParameter
>>> pairs = [('TITLE', 'Springtime'), ('ARTIST', 'Kommisar')]
>>> for key, value in pairs:
...     print(str(MSDParameter(key=key, value=value)))
...
#TITLE:Springtime;
#ARTIST:Kommisar;

parse_msd yields MSDParameter instances, so you could read & write MSD in a single loop:

>>> from msdparser import parse_msd, MSDParameter
>>> with open('testdata/Springtime.ssc', 'r') as simfile, open('output.ssc', 'w') as output:
...     for param in parse_msd(file=simfile):
...         if param.key == 'SUBTITLE':
...             param = param._replace(value=param.value + ' (edited)')
...         output.write(str(param))
...         output.write('\n')

Prefer to use MSDParameter over interpolating the key/value pairs between #:; characters yourself. The str() implementation inserts escape sequences where required, preventing generation of invalid MSD.

Documentation

https://msdparser.readthedocs.io/en/latest/

The MSD format

In general, MSD key-value pairs look like #KEY:VALUE; - the # starts a parameter, the first : separates the key from the value, and the ; terminates the value. Keys are not expected to be unique.

Comments start with // and persist until the end of the line. They can appear anywhere, including inside values (or even keys).

Keys and values can be blank. The : separator can even be omitted, which has the same result as a blank value.

StepMania recovers from a missing ; if it finds a # marker at the start of a line, so this parser does too.

Escape sequences

Modern applications of MSD (such as the SM and SSC formats) have escape sequences: any special character (:, ;, \) or comment initializer (//) can be treated as literal text by prefixing it with a \. This behavior is enabled by default.

Older applications like DWI treat backslashes as regular text, and thus do not permit a literal ; in keys or values, nor : in keys. This behavior can be replicated by passing escapes=False to parse_msd or MSDParameter.serialize.

Multi-value parameters

Some keys (such as the SM format's STEPS) are expected to have multiple :-separated values. For simplicity, this parser always treats : in a value literally, leaving any multi-value semantics up to client code to implement. (In other words, #KEY:A:B; deserializes to ('KEY', 'A:B'), rather than ('KEY', ['A', 'B']) or similar.)