import wave
import array


### init values

CHANNELS = 2
BIT_RATE = 16
SAMPLE_RATE = 44100
MAX_AMPLITUDE = (2 ** BIT_RATE) / 4

notes = {'c-1': 32.7,
         'c#1': 34.6,
         'd-1': 36.7,
         'd#1': 38.9,
         'e-1': 41.2,
         'f-1': 43.7,
         'f#1': 46.2,
         'g-1': 49.0,
         'g#1': 51.9,
         'a-1': 55.0,
         'a#1': 58.3,
         'b-1': 61.7,
         }

for note in notes.keys():
    for i in range(2, 9):
        notename = note[:2] + str(i)
        notes[notename] = notes[note] * (2 ** (i - 1))


### tone generation code

def generate_tone(tonefreq, length, channels):
    buffersize = int(SAMPLE_RATE * length) * channels * (BIT_RATE / 8)
    step = float(tonefreq) / float(SAMPLE_RATE) * 2

    buf = bytearray(buffersize)
    amplitude = -MAX_AMPLITUDE
    
    bytes_per_sample = BIT_RATE / 8
    
    for i in xrange(0, buffersize, channels * bytes_per_sample):
        amplitude += step * MAX_AMPLITUDE
        
        if amplitude > MAX_AMPLITUDE:
            amplitude = -MAX_AMPLITUDE

        for k in range(channels):
            for o in range(bytes_per_sample):
                buf[i + k * bytes_per_sample + o] = (int(amplitude) >> o * 8) & 0xFF
        
    return buf


### song generation

song = ['c-1',
        'c-2',
        'c-1',
        'c-2',
        'e-1',
        'e-2',
        'e-1',
        'e-2',
        'f-1',
        'f-2',
        'f-1',
        'g#2',
        'g#1',
        'g#2',
        'c-2',
        'c-3',
        ]

song_repeat = 4

wav = wave.open('out.wav', 'wb')

wav.setnchannels(CHANNELS)
wav.setsampwidth(BIT_RATE / 8)
wav.setframerate(SAMPLE_RATE)

for i in range(song_repeat):
    for note in song:
        b = generate_tone(notes[note], 0.27, CHANNELS)
        wav.writeframes(b)

wav.close()