def add_piano_riff(roman, duration, piano, show_symbols=False):
'''Given a Roman chord, duration in eighths/quavers and a keyboard
part, generate a riff and add it to the keyboard part'''
# Add a chord symbol at the start
symbol = ChordSymbol(chordSymbolFigureFromChord(roman))
if show_symbols:
print symbol
piano.append(symbol)
# Add the actual notes
filled = 0
while filled < duration:
# NOTE: higher chance to rest if on beat = more syncopated rhythm to piano
if random.randint(0, 1 + filled%2 + filled%4):
# XXX: Must deepcopy, do not change original or it will break bassline
chord = Chord(deepcopy(roman.pitches))
# invert chord randomly, root inversion twice as likely as others
max_inv=len(chord.pitches)
chord.inversion(random.randint(0,max_inv)%max_inv)
# TODO try randomly ommitting some chord notes
# Randomly hold notes for longer if we have longer before
# the next chord change
max_length = min(duration-filled, 4) # Cap at 1/2 bar
length = random.randint(1,max_length)
chord.quarterLength = length/2.0 # length is in eighths
# Add an extra root note 1 octave lower
root = deepcopy(chord.root())
root.octave -= 1
chord.add(root)
# Add the chord at soft volume and update duration
chord.volume = Volume(velocity=16,velocityIsRelative=False)
piano.append(chord)
filled += length
else:
piano.append(Rest(quarterLength=0.5))
filled += 1
def append_chord(part, notes, duration, velocity):
c = Chord(notes, duration=Duration(duration))
c.volume = Volume(velocity=velocity)
part.append(c)
def append_chord(part, notes, duration, velocity):
c = Chord(notes, duration=Duration(duration))
c.volume = Volume(velocity=velocity)
part.append(c)
