music21 helpers

music21_helpers.py

import music21 as m
import copy

# replace x.show('midi') with play(x)
# to solve problem of first note(s) not playing
# in many web browsers

def play(x):
    """Returns nothing. Outputs a midi realization of x, a note or stream.
    Primarily for use in notebooks and web environments.
    """
    if isinstance(x, m.stream.Stream):
        x = copy.deepcopy(x)
        for subStream in x.recurse(streamsOnly=True, includeSelf=True):
            mss = subStream.getElementsByClass(m.stream.Measure)
            for ms in mss:
                ms.offset += 1.0
    if isinstance(x, m.note.Note):
        s = m.stream.Stream()
        s.append(m.note.Rest(1))
        s.append(x)
        x = s
    x.show('midi')
    
    
######   

def tiny(x):
    """ Returns a stream based on x, a string of tinynotation
    which may include chords:
    "c e g chord{c e g}"
    
    Do not include 'tinynotation: ' in the string.
    """
    
    tnc = m.tinyNotation.Converter(x)
    tnc.bracketStateMapping['chord'] = ChordState
    s = tnc.parse().stream
    return s   


# this class is from the music21 documentation
class ChordState(m.tinyNotation.State):
    def affectTokenAfterParse(self, n):
        super().affectTokenAfterParse(n)
        return None # do not append Note object
    def end(self):
        ch = m.chord.Chord(self.affectedTokens)
        ch.duration = self.affectedTokens[0].duration
        return ch