Make a chord progressions

chord_pregression_player.py

from pydub import AudioSegment
from pydub.generators import Sine, Square, WhiteNoise
from pydub.playback import play

# From https://gist.github.com/jiaaro/339df443b005e12d6c2a
def note_to_freq(note, concert_A=440.0):
  '''
  from wikipedia: http://en.wikipedia.org/wiki/MIDI_Tuning_Standard#Frequency_values
  '''
  return (2.0 ** ((note - 69) / 12.0)) * concert_A



def beat_duration_from_bpm(bpm=120.0):
    minute = 60 * 1000.0
    return minute / bpm



class ChordParsingError(Exception): pass

SCALE_SHAPES = {
    ""
}
CHORD_SHAPES = {
    # major
    "": (0, +4, +7),
    
    # minor
    "m": (0, +3, +7),
    
    # diminished
    "dim": (0, +3, +6),
    
    # diminished
    "dim7": (0, +3, +6, +9),
    
    # 7
    "7": (0, +4, +7, +10),
    
    # minor 7
    "m7": (0, +3, +7, +10),
    
    # maj7
    "maj7": (0, +4, +7, +11),
}
# MIDI Note numbers
NOTE_NUMBERS = {
    "A": 57,
    "A#": 58, "Bb": 58,
    "B": 59, "Cb": 59,
    "C": 60,
    "C#": 61, "Db": 61,
    "D": 62,
    "D#": 63, "Eb": 63,
    "E": 64, "Fb": 64,
    "F": 65, "E#": 65,
    "F#": 66, "Gb": 66,
    "G": 67,
    "G#": 68, "Ab": 68,
}
def parse_chord(chord):
    """
    returns the frequency of each note in a chord with the
    root nearest to near_freq
    """
    try:
        if len(chord) > 1 and chord[1] in ("#", "b"):
            root = chord[:2]
            shape = CHORD_SHAPES[chord[2:]]
        else:
            root = chord[0]
            shape = CHORD_SHAPES[chord[1:]]
    except IndexError:
        raise ChordParsingError
    
    root_note = NOTE_NUMBERS[root]
    chord_notes = [root_note + dlta for dlta in shape]
    
    return [note_to_freq(note) for note in chord_notes]

def anchored_chord(chord, anchor_freq=250.0):
    freqs = parse_chord(chord)
    root = freqs[0] / 8
    while freqs[-1] < anchor_freq:
        freqs.append(freqs.pop(0) * 2)
    while freqs[0] > anchor_freq:
        freqs.insert(0, freqs.pop() / 2)
    freqs.insert(0, root)
    return freqs
    
def make_chord(chord, duration=1000, generator=Sine):
    freqs = anchored_chord(chord)
    output = generator(freqs[0]).to_audio_segment(duration=duration, volume=-10)
    for freq in anchored_chord(chord):
        output *= generator(freq).to_audio_segment(duration=duration, volume=-20)
    return output.fade_in(10).fade_out(250)
    
beats = beat_duration_from_bpm(120)
progression = (
    make_chord("Cm", 4*beats)
  + make_chord("G7", 4*beats)
  + make_chord("Fm", 6*beats)
  + make_chord("G7", 2*beats)
)
tick = WhiteNoise().to_audio_segment(5, volume=-15)
for i in range(16*2):
    progression = progression.overlay(tick, position=i*(beats/2))

play(progression)