Playing in 18-note scale

README.md

Prerequisites: Python 3.7, pip.

Install dependencies:

pip install -r requirements.txt

Turn on sound and run:

python ./scale18.py

requirements.txt

pyaudio==0.2.11
numpy

scale18.py

import sys
import random
import pyaudio
import numpy as np

SAMPLE_RATE = 44100
SCALE_SIZE = 18
BASE_FREQUENCY = 440.0
BASE_OCTAVE = 4

# (note, octave, length, volume)
MELODY = [
  (0,  2, 8, 0.5),
  (1,  2, 8, 0.5),
  (2,  2, 8, 0.5),
  (3,  2, 8, 0.5),
  (4,  2, 8, 0.5),
  (5,  2, 8, 0.5),
  (6,  2, 8, 0.5),
  (7,  2, 8, 0.5),
  (8,  2, 8, 0.5),
  (9,  2, 8, 0.5),
  (10, 2, 8, 0.5),
  (11, 2, 8, 0.5),
  (12, 2, 8, 0.5),
  (13, 2, 8, 0.5),
  (14, 2, 8, 0.5),
  (15, 2, 8, 0.5),
  (16, 2, 8, 0.5),
  (17, 2, 8, 0.5),
]

class Synth:
  def __init__(self):
    self.pyaudio = pyaudio.PyAudio()

    self.stream = self.pyaudio.open(
      format=pyaudio.paFloat32,
      channels=2,
      rate=SAMPLE_RATE,
      output=True
    )

  def play_sine(self, frequency, duration=1.0, volume=0.5):
    samples = (np.sin(2 * np.pi * np.arange(SAMPLE_RATE * duration) * frequency / SAMPLE_RATE))
    self.stream.write(volume * samples.astype(np.float32))

  def __del__(self):
    self.stream.stop_stream()
    self.stream.close()
    self.pyaudio.terminate()

scale = [BASE_FREQUENCY * pow(2, i / SCALE_SIZE) for i in range(SCALE_SIZE)]
synth = Synth()

for (note, octave, length, volume) in MELODY:
  assert(note >= 0 and note < SCALE_SIZE)

  print(f"{note}:{octave}/{length}", end=' ')
  sys.stdout.flush()

  frequency = scale[note] * pow(2, octave - BASE_OCTAVE + 1)
  duration = 16.0 / length
  synth.play_sine(frequency, duration=duration, volume=volume)

print('')
del synth