Python : 모스코드를 소리로 나타내기

번역된 모스부호(모스코드)를 소리로 나타내는 코드이다.

행사를 준비하며 만들었던 코드이지만, 그 행사가 코로나19로 인해 무기한 연기되었다...

역시 이 코드 또한 인터넷에 올라온 자료들이 많지 않기에, 글을 올린다.

본인이 맡은 프로젝트를 빠르고 효율성있게 마무리할 수 있기를 바란다.

(아무리 간단한 프로젝트여도 예상시간의 적어도 3배는 해야..)

여담으로, 코드에 나와있는 예제 모스코드는, 2020 수능특강 영어 지문의 일부이다.

https://stackoverflow.com/questions/33879523/python-how-can-i-generate-a-wav-file-with-beeps 해당 코드를 참고하였다.

중요주석, docstring은 수정하지 않았다.

import math
import wave
import struct
import time

# Audio will contain a long list of samples (i.e. floating point numbers describing the
# waveform).  If you were working with a very long sound you'd want to stream this to
# disk instead of buffering it all in memory list this.  But most sounds will fit in 
# memory.

audio = []
sample_rate = 44100.0


def append_silence(duration_milliseconds=500):
    """
    Adding silence is easy - we add zeros to the end of our array
    """
    num_samples = duration_milliseconds * (sample_rate / 1000.0)

    for x in range(int(num_samples)): 
        audio.append(0.0)

    return


def append_sinewave(
        freq=440.0, 
        duration_milliseconds=500, 
        volume=1.0):
    """
    The sine wave generated here is the standard beep.  If you want something
    more aggresive you could try a square or saw tooth waveform.   Though there
    are some rather complicated issues with making high quality square and
    sawtooth waves... which we won't address here :) 
    """ 

    global audio

    num_samples = duration_milliseconds * (sample_rate / 1000.0)

    for x in range(int(num_samples)):
        audio.append(volume * math.sin(2 * math.pi * freq * ( x / sample_rate )))

    return


def save_wav(file_name):
    print('in')
    # Open up a wav file
    wav_file=wave.open(file_name,"w")

    nchannels = 1
    sampwidth = 2

    # 44100 is the industry standard sample rate - CD quality.  If you need to
    # save on file size you can adjust it downwards. The stanard for low quality
    # is 8000 or 8kHz.
    nframes = len(audio)
    comptype = "NONE"
    compname = "not compressed"
    wav_file.setparams((nchannels, sampwidth, sample_rate, nframes, comptype, compname))

    # WAV files here are using short, 16 bit, signed integers for the 
    # sample size.  So we multiply the floating point data we have by 32767, the
    # maximum value for a short integer.  NOTE: It is theortically possible to
    # use the floating point -1.0 to 1.0 data directly in a WAV file but not
    # obvious how to do that using the wave module in python.
    k = len(audio)
    i = 0
    st = time.time()
    for sample in audio:
        i +=1
        if i % 100000 ==0:
            print( time.time()-st,"초" )
            st = time.time()
            print((i/k) *100 ,'%')
        wav_file.writeframes(struct.pack('h', int( sample * 32767.0 )))

    wav_file.close()

    return

txt = "-... . -....- -.-. .- .-. . ..-. ..- .-.. .-.-.-"
dic = {'-' : 0.2, '.' : 0.1}
for morse in txt:
    if morse != ' ' :
        append_sinewave(duration_milliseconds = dic[morse] * 1000)
    else :
        append_silence(duration_milliseconds = 0.1)
    append_silence(duration_milliseconds = 100)

save_wav("output1.wav")

단, 시간이 매우 오래걸린다는 점은 참고하자. 

이부분은 이후에 수정할 예정이다.