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This code creates a sound file in Sun's simple AU audio format of a sine wave of given frequency, duration and volume.

# create a soundfile in AU format playing a sine wave
# of a given frequency, duration and volume
# tested with Python25   by vegaseat     29jan2008

from struct import pack
from math import sin, pi

def au_file(name='test.au', freq=440, dur=1000, vol=0.5):
    """
    creates an AU format audio file of a sine wave
    of frequency freq (Hz)
    for duration dur (milliseconds)
    at volume vol (max is 1.0)
    """
    fout = open(name, 'wb')
    # header needs size, encoding=2, sampling_rate=8000, channel=1
    fout.write('.snd' + pack('>5L', 24, 8*dur, 2, 8000, 1))
    factor = 2 * pi * freq/8000
    # write data
    for seg in range(8 * dur):
        # sine wave calculations
        sin_seg = sin(seg * factor)
        fout.write(pack('b', vol * 127 * sin_seg))
    fout.close()

# test the module ...
if __name__ == '__main__':
    au_file(name='sound800.au', freq=800, dur=2000, vol=0.8)
    
    # if you have Windows, you can test the audio file
    # otherwise comment this code out
    import os
    os.startfile('sound800.au')

I'm having a problem running this code with Python 3.1. It complains that the argument of fout.write() must be bytes or buffer, not str. Anyone know how to fix this?

Here is the modification of vegaseat's code that will work with both Python27 and Python32:

# create a sound file in AU format playing a sine wave
# of a given frequency, duration and volume
# vegaseat code modified to work with Python27 and Python32

from struct import pack
from math import sin, pi

def au_file(name='test.au', freq=440, dur=1000, vol=0.5):
    """
    creates an AU format sine wave audio file
    of frequency freq (Hz)
    of duration dur (milliseconds)
    and volume vol (max is 1.0)
    """
    fout = open(name, 'wb')
    # header needs size, encoding=2, sampling_rate=8000, channel=1
    fout.write(pack('>4s5L', '.snd'.encode("utf8"), 24, 8*dur, 2, 8000, 1))
    factor = 2 * pi * freq/8000
    # write data
    for seg in range(8 * dur):
        # sine wave calculations
        sin_seg = sin(seg * factor)
        val = pack('b', int(vol * 127 * sin_seg))
        fout.write(val)
    fout.close()
    print("File %s written" % name)


# test the module ...
if __name__ == '__main__':
    au_file(name='sound440.au', freq=440, dur=2000, vol=0.8)

    # if you have Windows, you can test the audio file
    # otherwise comment this code out
    import os
    os.startfile('sound440.au')
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