1 # Generate imperfect sine waves
3 # Design notes. Produces ~= (user requested) s of raw audio
4 # We're aiming for an 8-bit'ish effect, so we're going with
5 # 8125 Hz, 8 bit sampling, but faking it out to
6 # CDDA output (44100 Hz, 16 bit signed) for easier conversion to ogg
7 # by multiply the value by 256 (after roundin) and repeating it 4 times.
16 def gen_sine(freq, secs):
17 filename = 'beep%s.pcm' % freq
18 # We generate freq cycles and sample that OUTPUT_RATE times
19 per_cycle = OUTPUT_RATE / freq
21 for x in range(per_cycle):
22 rad = float(x) / per_cycle * 2 * math.pi
23 y = 256 * int(MAX * math.sin(rad))
24 data.extend([struct.pack('<i', y)] * 4)
25 output = open(filename, 'w')
26 # This is correct because OUTPUT_RATE = CDDA rate / 4 and we repeat
27 # the samples 4 times, so this works out to CDDA rate
28 for x in range(int(freq * secs)):
29 output.write(''.join(data))
31 print 'Wrote output to %s' % filename
35 print 'Unexpected input'
36 print 'Usage gen_sound <freq> [<length>]'
37 print ' where <freq> is the frequency in Hz (int)'
38 print ' and [<length>] is the time in seconds (float) - default 0.25'
41 if __name__ == "__main__":
43 freq = int(sys.argv[1])
45 secs = float(sys.argv[2])
48 except Exception, exc:
50 print 'Error was', exc