Music Bassline-Generator

Generate musical basslines

DESCRIPTION

This class generates randomized basslines based on named chords.

The "formula" implemented by this module is basically: "Play any notes of the chord, modal chord scale, or chord-root scale (and drop any notes replaced by extended jazz chords)."

The chords recognized by this module, are those known to pychord.

The logic and music theory implemented here, can generate some possibly sour notes. This is an approximate composition tool, and not a drop-in bass player! Import rendered MIDI into a DAW and alter notes until they sound suitable.

Named chords and the keycenter use # and b for accidentals.

To constrain the notes to a chosen set of scale degrees, use the positions attribute illustrated below.

The one and only public method in this class is generate().

generate(chord_name='C', n=4, next_chord=None) # defaults

This method generates n MIDI pitch numbers given a chord_name. If it is called with a next_chord="Am7" type argument, and an intersection of the two scales is performed.

If format is set to ISO, this method returns named notes. If the modal attribute is set, then the chosen notes will be within the Ionian mode of the keycenter setting. If it is not set (the default), notes will be chosen as if the key has changed to the current chord.

SYNOPSIS

from music_bassline_generator import Bassline

bass = Bassline( # defaults:
    keycenter='C', # tonic for modal accompaniment
    modal=False, # only choose notes within the mode
    chord_notes=True, # use chord notes outside the scale
    intervals=[-3, -2, -1, 1, 2, 3], # allowed voicegen intervals
    context=None, # list of note numbers to start the phrase. None=random
    octave=1, # lowest MIDI octave
    format='midinum', # or 'ISO' for named notes
    tonic=False, # play the first scale note to start the generated phrase
    resolve=False, # play the first scale note to end the generated phrase
    positions=None, # allowed notes for major and minor scales
    guitar=False, # transpose notes below E1 (midi #28) up an octave
    wrap=None, # transpose notes above this ISO named note, down an octave
    verbose=False, # show progress
)

scale = bass.scale_fn('C7b5') # 'major'
scale = bass.scale_fn('Dm7b5') # 'minor'
scale = bass.scale_fn('D#/A#') # 'major'

notes = bass.generate('C7b5', 4)
notes = bass.generate('D/A', 4)
notes = bass.generate('D', 4, 'C/G')
notes = bass.generate('D', 1)

bass = Bassline(modal=True)
mode = bass.scale_fn('C7b5') # 'ionian'
mode = bass.scale_fn('Dm7b5') # 'dorian'
notes = bass.generate('Dm7')
notes = bass.generate('Dm7b5')

bass = Bassline(
    octave=3,
    wrap='C3',
    modal=True,
)
notes = bass.generate('C', 4)

bass = Bassline(
    chord_notes=False,
    positions={'major': [x for x in range(6)], 'minor': [x for x in range(6)]} # no 7ths
)
notes = bass.generate('C', 4)

MUSICAL EXAMPLES

from music21 import note, stream
from music_bassline_generator import Bassline

def add_notes(p, notes):
    print(notes)
    for n in notes:
        n = note.Note(n, type='quarter')
        p.append(n)

s = stream.Stream()
bass_part = stream.Part()

bass = Bassline(octave=2)

num = 4

# Autumn Leaves in Amin
for chord in ['Dm7','G7','CM7','FM7','Bm7b5','E7#9','Am7','D7']:
    notes = bass.generate(chord, num)
    add_notes(bass_part, notes)

s.insert(0, bass_part)

s.show()

from music21 import chord, note, stream
from music_bassline_generator import Bassline
from pychord import Chord as pyChord

def add_notes(p, notes):
    for n in notes:
        n = note.Note(n, type='quarter')
        p.append(n)

s = stream.Stream()
bass_part = stream.Part()
chord_part = stream.Part()

bass = Bassline(modal=True, octave=2)

num = 4

# Autumn Leaves in Amin
for my_chord in ['Dm7','G7','CM7','FM7','Bm7b5','E7#9','Am7','D7']:
    c = pyChord(my_chord)
    c = chord.Chord(c.components(), type='whole')
    chord_part.append(c)
    notes = bass.generate(my_chord, num)
    add_notes(bass_part, notes)

s.insert(0, chord_part)
s.insert(0, bass_part)

s.show()

from music21 import chord, note, stream, tempo
from music_bassline_generator import Bassline
from pychord import Chord as pyChord

s = stream.Stream()
bass_part = stream.Part()
chord_part = stream.Part()
melody_part = stream.Part()

def autumn_leaves():
    return [
        ['Dm7','G7','CM7','FM7','Bm7b5','E7','Am7','Am7'] +
        ['Dm7','G7','CM7','FM7','Bm7b5','E7','Am7','Am7'] +
        ['Bm7b5','E7b9','Am7','Am7','Dm7','G7','CM7','FM7'] +
        ['Bm7b5','E7b9','Am7','Gm7','FM7','Bm7b5','Am7','Am7']
    ]

def add_notes(p=melody_part, notes=[], type='quarter'):
    for n in notes:
        if type == 'dotted_half':
            n = note.Note(n)
            n.quarterLength = 3
        else:
            n = note.Note(n, type=type)
        p.append(n)

bass = Bassline(modal=True, octave=2, tonic=True, resolve=False)

num = 4

m = note.Rest(type='whole')
bass_part.append(m)
chord_part.append(m)

for my_chord in autumn_leaves()[0]:
    c = pyChord(my_chord)
    c = chord.Chord(c.components(), type='whole')
    chord_part.append(c)
    notes = bass.generate(my_chord, num)
    add_notes(bass_part, notes)

# melody:
m = note.Rest(type='quarter')
melody_part.append(m)
add_notes(notes=['A4','B4','C5'])
add_notes(notes=['F5'], type='whole')
add_notes(notes=['F5','G4','A4','B4'])
add_notes(notes=['E5','E5'], type='half')
add_notes(notes=['E5','F4','G4','A4'])
add_notes(notes=['D5'], type='whole')
add_notes(notes=['D5','E4','F#4','G#4'])
add_notes(notes=['C5'], type='whole')
add_notes(notes=['C5','A4','B4','C5'])
add_notes(notes=['F5'], type='whole')
add_notes(notes=['F5','G4','A4','B4'])
add_notes(notes=['E5','E5'], type='half')
add_notes(notes=['E5','F4','G4','A4']) # 12
add_notes(notes=['D5'], type='whole')
add_notes(notes=['D5','B4','D5','C5'])
add_notes(notes=['A4'], type='whole')
add_notes(notes=['A4'], type='half')
add_notes(notes=['G#4','A4','B4','E4'])
add_notes(notes=['B4'], type='half')
add_notes(notes=['B4','B4','A4','B4'])
add_notes(notes=['C5'], type='whole')
add_notes(notes=['C5','C5','B4','C5'])
add_notes(notes=['D5'], type='whole')
add_notes(notes=['D5','G4','G5','F5'])
add_notes(notes=['E5'], type='whole')
add_notes(notes=['E5'], type='half')
add_notes(notes=['D#5','E5','F5','F5','D5','D5'])
add_notes(notes=['B4'], type='dotted_half')
add_notes(notes=['F5'])
add_notes(notes=['E5','E5'], type='half')
add_notes(notes=['E5'], type='dotted_half')
add_notes(notes=['A4'])
add_notes(notes=['D5'], type='dotted_half')
add_notes(notes=['C5'])
add_notes(notes=['B4'], type='half')
add_notes(notes=['C5','C5'])
add_notes(notes=['A4','A4'], type='whole')

s.append(tempo.MetronomeMark(number=90)) # set BPM
s.insert(0, melody_part)
s.insert(0, chord_part)
s.insert(0, bass_part)
s.show()

SEE ALSO

https://birka.fhsk.se/wp-content/uploads/2017/02/Autumn-Leaves-in-Am.pdf