Test framework

sound.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from wavebender import *
from itertools import *


formanta = [0, 10, 19, 28, 36, 44, 50, 55, 60, 62, 64, 64, 62, 60, 55, 50, 44,
            36, 28, 19, 10, 0, -10, -19, -28, -36, -44, -50, -55, -60, -62,
            -64, -64, -62, -60, -55, -50, -44, -36, -28, -19, -10]
oberton = [0, 12, 23, 32, 38, 41, 42, 42, 42, 40, 38, 36, 34, 32, 30, 28, 26,
           24, 22, 20, 18, 16, 15, 13, 12, 10, 9, 7, 6, 4, 3, 1, 0, -1, -3, -4,
           -6, -7, -9, -10, -12, -13]

formanta_init_amp = 180
oberton_init_amp = 200
formanta_fade_step = 200
oberton_fade_step = 150


def fastmul(a, b):
    return (a * b) >> 8


def bell_wave():
    pos = f_step = o_step = f_amp = o_amp = 0
    period = len(formanta)

    while True:
        if 0 == f_step:
            f_step = formanta_fade_step
            if 0 == f_amp:
                f_amp = formanta_init_amp
                o_amp = oberton_init_amp
                o_step = oberton_fade_step
                pos = 0
            else:
                f_amp -= 1
        else:
            f_step -= 1

        if 0 == o_step:
            o_step = oberton_fade_step
            if 0 < o_amp:
                o_amp -= 1
        else:
            o_step -= 1

        sample = 128 + \
                 fastmul(formanta[pos], f_amp) + \
                 fastmul(oberton[pos], o_amp)
        yield sample
        pos = (pos + 1) % period


channels = ((bell_wave(),),)
samples = compute_samples(channels, None)
write_wavefile(sys.stdout, samples, None,
               nchannels=1, sampwidth=1, framerate=9600000/256/4)