generate-sine-tone-wav.py

# https://stackoverflow.com/questions/33879523/python-how-can-i-generate-a-wav-file-with-beeps

import math
import wave
import struct

audio = []
sample_rate = 44100.0


def append_silence(duration_milliseconds=500):
    num_samples = duration_milliseconds * (sample_rate / 1000.0)
    for x in range(int(num_samples)): 
        audio.append(0.0)
    return


def append_sinewave(
        freq=440.0, 
        duration_milliseconds=2000, 
        volume=1.0):
    global audio # using global variables isn't cool.
    num_samples = duration_milliseconds * (sample_rate / 1000.0)
    for x in range(int(num_samples)):
        audio.append(volume * math.sin(2 * math.pi * freq * ( x / sample_rate )))
    return


def save_wav(file_name):
    wav_file=wave.open(file_name,"w")
    nchannels = 1
    sampwidth = 2
    nframes = len(audio)
    comptype = "NONE"
    compname = "not compressed"
    wav_file.setparams((nchannels, sampwidth, sample_rate, nframes, comptype, compname))
    # WAV files here are using short, 16 bit, signed integers for the 
    # sample size.  So we multiply the floating point data we have by 32767, the
    # maximum value for a short integer.  NOTE: It is theortically possible to
    # use the floating point -1.0 to 1.0 data directly in a WAV file but not
    # obvious how to do that using the wave module in python.
    for sample in audio:
        wav_file.writeframes(struct.pack('h', int( sample * 32767.0 )))
    wav_file.close()
    return


append_sinewave(freq=20, volume=0.1)
# append_silence()
# append_sinewave(volume=0.5)
save_wav("sine-wave-20hz.wav")