Converting IR code of Nikon remote trigger to a wave file.

ir_nikon.py

#!/usr/bin/env python

import sys
from itertools import *

from wavebender import *

def half_wave(frequency=19000, framerate=44100, amplitude=0.5,
        skip_frame=0):
    for s in sine_wave(frequency, framerate, amplitude,
            skip_frame=skip_frame):
        if s > 0:
            yield s
        elif s < 0:
            yield -s
        else:
            yield 0.0

def ir_wave1(us, frequency=19000, framerate=44100):
    nsamples = framerate * float(us) / 1000000
    return islice(sine_wave(frequency, framerate, 1.0), nsamples)

def ir_wave2(us, frequency=19000, framerate=44100):
    nsamples = framerate * float(us) / 1000000
    skip = 0.5 * framerate / frequency # 180 degree
    data = sine_wave(frequency, framerate, 1.0, skip_frame=skip)
    return islice(data, nsamples)

def ir_off(us, framerate=44100):
    if us < 0:
        us = -us
    nsamples = framerate * float(us) / 1000000
    return islice(repeat(0), nsamples)

def ir_left(us):
    if us > 0:
        return ir_wave1(us)
    else:
        return ir_off(us)

def ir_right(us):
    if us > 0:
        return ir_wave2(us)
    else:
        return ir_off(us)

def ir_channels(seq):
    '''
    seq = [100, -100, 200] # 100us on, 100us off, 200us on
    '''
    ch1 = [ir_left(us) for us in seq]
    ch2 = [ir_right(us) for us in seq]
    return [[chain.from_iterable(ch1)], [chain.from_iterable(ch2)]]


def nikon():
    # http://ilpleut.be/code-nikonremote
    return ir_channels([2000, -27830, 390, -1580, 410, -3580, 400,
                        -63200,
                        2000, -27830, 390, -1580, 410, -3580, 400])


if __name__ == '__main__':
    channels = nikon()
    samples = compute_samples(channels)
    write_wavefile(open('nikon-trigger.wave', samples)