gists/python-programming/fm_harmonics_music_generator.py

# fm_harmonics_music_generator.py
#
# Created at 2025-01-01
#
# Most of the code is AI generated, but the script works just fine.
#
# Unfortunately, I don't have enough time to add more typing now.
#
# Author: Intel A80486DX2-66
# License: Creative Commons Zero 1.0 Universal or Unlicense
# SPDX-License-Identifier: CC0-1.0 OR Unlicense

import numpy as np
from scipy.io.wavfile import write
from random import randint, seed, getrandbits, uniform

def extend(l: list, n: int) -> list:
    extended_list = []  # Create a new list to hold the extended values
    for value in l:
        extended_list.extend([value] * n)  # Append the value n times
    return extended_list


def generate_fm_wave(carrier_freq, modulator_freq, duration, sample_rate=44100, modulation_index=1.0):
    """Generate a sine wave using FM synthesis."""

    t = np.linspace(0, duration, int(sample_rate * duration), endpoint=False)
    modulating_signal = np.sin(2 * np.pi * modulator_freq * t)  # Modulator signal
    wave = 0.5 * np.sin(2 * np.pi * carrier_freq * t + modulation_index * modulating_signal)  # FM synthesis
    return wave


def apply_envelope(wave, attack_time, decay_time, sustain_level, release_time, sample_rate=44100):
    """Apply an ADSR envelope to the wave."""

    total_samples = len(wave)
    attack_samples = int(attack_time * sample_rate)
    decay_samples = int(decay_time * sample_rate)
    release_samples = int(release_time * sample_rate)

    # Create the envelope
    envelope = np.zeros(total_samples)

    # Attack
    envelope[:attack_samples] = np.linspace(0, 1, attack_samples)

    # Decay
    if attack_samples + decay_samples < total_samples:
        envelope[attack_samples:attack_samples + decay_samples] = np.linspace(1, sustain_level, decay_samples)

    # Sustain
    if attack_samples + decay_samples < total_samples:
        envelope[attack_samples + decay_samples:total_samples - release_samples] = sustain_level

    # Release
    if total_samples - release_samples > 0:
        envelope[total_samples - release_samples:] = np.linspace(sustain_level, 0, release_samples)

    return wave * envelope


def generate_sine_wave(frequencies, duration, sample_rate=44100):
    """Generate a sine wave for a list of frequencies."""

    t = np.linspace(0, duration, int(sample_rate * duration), endpoint=False)
    wave = np.zeros_like(t)
    for freq in frequencies:
        wave += np.sin(2 * np.pi * freq * t)
    return wave


def create_sound_file(patterns, repetitions, tempo, output_file, carrier, modulator, modulation_index):
    """
    Create a sound file with specified frequency patterns, repetitions, and tempo.

    :param patterns: List of lists containing frequencies (in Hz) for each pattern.
    :param repetitions: Number of times to repeat each pattern.
    :param tempo: Tempo in beats per minute (BPM).
    :param output_file: Name of the output WAV file.
    """
    sample_rate = 44100  # Standard sample rate
    beat_duration = 60 / tempo  # Duration of one beat in seconds
    sound_wave = np.array([])  # Initialize an empty array for the sound wave

    pattern_extension = 10
    extended_patterns = extend(patterns, pattern_extension)

    t = 0
    for i in range(repetitions):  # Repeat the entire pattern
        for pattern in extended_patterns:
            actual_beat_duration = beat_duration / pattern_extension

            # Generate a sine wave for the current pattern
            sine_wave = generate_sine_wave(pattern, actual_beat_duration)

            ## carrier=int(frequency / randint(1, 2))
            ## modulator=randint(int(frequency / 4), int(frequency / 2)) # uniform(frequency / 4, frequency / 2)

            fm_wave = generate_fm_wave(carrier, modulator, actual_beat_duration, modulation_index=modulation_index)

            # Combine the sine wave and FM wave
            combined_wave = sine_wave + fm_wave

            # Apply envelope to the combined wave
            ## combined_wave = apply_envelope(combined_wave, attack_time=0.01, decay_time=8, sustain_level=0.7, release_time=0.2, sample_rate=sample_rate)

            # Append the combined wave to the sound wave
            sound_wave = np.concatenate((sound_wave, combined_wave))

            t += 1

    # Normalize the sound wave to the range of int16
    sound_wave = np.int16(sound_wave / np.max(np.abs(sound_wave)) * 32767)

    # Write the sound wave to a WAV file
    write(output_file, sample_rate, sound_wave)


def harmonics(frequency, count: int, step: int = 1) -> list:
    return [frequency * i for i in range(1, count, step)]


if __name__ == "__main__":
    ## seed(0)

    tempo_multiplier = 4

    randbool = lambda: getrandbits(1) == 1

    min_frequency = 35
    max_frequency = 120
    frequency_limit_diff = max_frequency - min_frequency
    frequency = randint(min_frequency, max_frequency)
    n = 2**randint(1, 5)  # 4/4 beat
    frequency_subtract = frequency // frequency_limit_diff

    negative_frequency_drift = randbool()
    precision = 2
    precision_machine = 10**precision
    frequency_drift_toggle = randbool()
    frequency_drift_max = randint(0, 1) if frequency_drift_toggle else 0
    frequency_drift_value = lambda: randint(-frequency_drift_max * precision_machine if negative_frequency_drift else 0, frequency_drift_max * precision_machine) / precision_machine
    frequency_drift = lambda: frequency_drift_value() if randbool() else 0

    carrier = uniform(frequency / 4, frequency * 2)
    modulator = randint(0, frequency)
    modulation_index = randint(5, 50)

    patterns = [
        harmonics(
            frequency + frequency_drift(),
            randint(
                1,
                16),
            randint(1, 2))

        for i in range(n)
    ]
    repetitions = randint(2, 8)  # 4/4 beat
    tempo = randint(60, 160)
    output_file = "output.wav"

    print(f"Base: {frequency} Hz, frequency drift: {'on' if frequency_drift_toggle else 'off'}")
    print(f"Carrier: {carrier} Hz")
    print(f"Modulator: {modulator} Hz")
    print(f"Modulation index: {modulation_index}")
    print(f"Tempo: {tempo} BPM")
    create_sound_file(patterns, repetitions, tempo * tempo_multiplier, output_file, carrier, modulator, modulation_index)

    print("Done!")