Construct tones yourself and play them through /dev/dsp

music_through_dev_dsp.py

#!/usr/bin/python

# Play music without any external files (ie you create the notes yourself)
# through /dev/dsp! Inspired by
# http://www.tldp.org/LDP/abs/html/devref1.html#MUSICSCR

def generate_notes():
    # See http://www.phy.mtu.edu/~suits/NoteFreqCalcs.html for details on
    # calculating the frequencies

    # 440 Hz, a4, is our reference frequency
    a4 = 440
    # There are 12 half steps in the western chromatic scale
    a = 2.0**(1.0/12)

    # /dev/dsp has a default 8000 frames per second, 1 byte per frame.  Let's
    # make each note 2000 frames.
    duration = 2000
    # Maximum volume is \xff
    volume = '\xc0'
    # Mute is halfway between \x00 and \xff
    mute = '\x80'

    base_notes = ["c", "c#", "d", "d#", "e", "f",
                  "f#", "g", "g#", "a", "a#", "b"]
    d = dict()
    for octave in [2, 3, 4, 5]:
        for i in range(len(base_notes)):
            # exponent is the distance in half steps you are from a4
            exponent = 12*(octave - 5) + 3 + i
            # f_n=f_O*(a)^n
            hertz = a4*a**(exponent)
            # Convert Hertz to bytes
            tone = int(8000.0 / hertz)
            buffer = ""
            for t in range(0, duration):
                if t % tone == 0:
                    buffer += volume
                else:
                    buffer += mute
            d[base_notes[i] + str(octave)] = buffer

    # Shorthand for the notes in the octave above middle C
    for note in base_notes:
        d[note] = d[note + "3"]
    # Quarter note rest
    d["rest"] = mute*duration

    return d

def jingle_bells():
    song = ["e", "e", "e", "rest",
            "e", "e", "e", "rest",
            "e", "g", "c", "d",
            "e", "rest", "rest", "rest",
            "f", "f", "f", "f",
            "f", "e", "e", "e",
            "g", "g", "f", "d",
            "c", "rest", "rest", "rest"]
    return "".join([notes[elt] for elt in song])

def oh_christmas_tree():
    song = ["c", "rest", "f", "f",
            "f", "rest", "g", "rest",
            "a", "a", "a", "rest",
            "rest", "a", "g", "a",
            "a#", "rest", "e", "rest",
            "g", "rest", "f", "rest"]
    return "".join([notes[elt] for elt in song])

def deck_the_halls():
    song = ["c4", "rest", "rest", "a#",
            "a", "rest", "g", "rest",
            "f", "rest", "g", "rest",
            "a", "rest", "f", "rest",
            "g", "a", "a#", "g",
            "a", "rest", "rest", "g",
            "f", "rest", "e", "rest",
            "f", "rest", "rest", "rest"]
    return "".join([notes[elt] for elt in song])

def test():
    """
    Step through the octaves.
    """
    base_notes = ["c", "c#", "d", "d#", "e", "f",
                  "f#", "g", "g#", "a", "a#", "b"]
    return "".join([notes[elt + str(i)]
                    for i in [2, 3, 4, 5]
                    for elt in base_notes])

if __name__ == "__main__":
    global notes
    notes = generate_notes()

    f = open("/dev/dsp", 'wb')
    f.write(jingle_bells())
    f.write(oh_christmas_tree())
    f.write(deck_the_halls())
    f.close()