Oz Nahum Tiram – March 29, 2016
Morse fun with Python
Python is a fun programming language, and making real stuff can be done with really quickly. This last weekend, I wanted to play a little bit with making Python speak. Well not really speak, but make sounds.
Hopefully, you know what Morse Code is. Truth is, that you will find a lot of Morse Code translations examples with Python, because it's a loved programming example.
But none of the examples I saw had whistles and bells, and I wanted to learn how to use wave files in Python. With a little help from Andrew Ippoliti Blog post about [wave files in Python], and with the help of pyalsaaudio I made the following program:
import argparse
import wave
import math
import re
import struct
import sys
import tempfile
morsetab = {
'A': '.-', 'a': '.-',
'B': '-...', 'b': '-...',
'C': '-.-.', 'c': '-.-.',
'D': '-..', 'd': '-..',
'E': '.', 'e': '.',
'F': '..-.', 'f': '..-.',
'G': '--.', 'g': '--.',
'H': '....', 'h': '....',
'I': '..', 'i': '..',
'J': '.---', 'j': '.---',
'K': '-.-', 'k': '-.-',
'L': '.-..', 'l': '.-..',
'M': '--', 'm': '--',
'N': '-.', 'n': '-.',
'O': '---', 'o': '---',
'P': '.--.', 'p': '.--.',
'Q': '--.-', 'q': '--.-',
'R': '.-.', 'r': '.-.',
'S': '...', 's': '...',
'T': '-', 't': '-',
'U': '..-', 'u': '..-',
'V': '...-', 'v': '...-',
'W': '.--', 'w': '.--',
'X': '-..-', 'x': '-..-',
'Y': '-.--', 'y': '-.--',
'Z': '--..', 'z': '--..',
'0': '-----', ',': '--..--',
'1': '.----', '.': '.-.-.-',
'2': '..---', '?': '..--..',
'3': '...--', ';': '-.-.-.',
'4': '....-', ':': '---...',
'5': '.....', "'": '.----.',
'6': '-....', '-': '-....-',
'7': '--...', '/': '-..-.',
'8': '---..', '(': '-.--.-',
'9': '----.', ')': '-.--.-',
' ': ' ', '_': '..--.-',
}
reverse_morsetab = {v:k for k,v in morsetab.items()}
def write_signal(wavef, duration, volume=0, rate=44100.0,
frequency=1240.0):
"""
rate = 44100.0 # Sample rate in Hertz
duration = 0.1 # seconds
frequency = 1240.0 # hertz
"""
for i in range(int(duration * rate * duration)):
# max volume 32767.0
value = int(volume*math.sin(frequency*math.pi*float(i)/float(rate)))
data = struct.pack('<h', value)
wavef.writeframesraw(data)
def text_to_morse(text, seperator=" / "):
"""translate a string to morse code in dot dash form"""
morse = []
for word in text.split():
morse_word = []
for w in word:
morse_word.append(morsetab[w])
morse.append(' '.join(morse_word))
return seperator.join(morse)
def morse_to_wav(text, file_=None):
char2signal = {'.': 0.2, '-': 0.4, '/': 0.5, ' ': 0.2}
if not file_:
_, file_ = tempfile.mkstemp(".wav")
wav = wave.open(file_, 'w')
wav.setnchannels(1) # mono
wav.setsampwidth(2)
rate = 44100.0
wav.setframerate(rate)
for char in text:
write_signal(wav, char2signal[char], volume=32767.0)
write_signal(wav, 0.2, volume=0)
wav.writeframes('')
wav.close()
return file_
def play(f, card='default'):
try:
import alsaaudio
except ImportError:
print("You need to install pyalsaaudio")
device = alsaaudio.PCM(card=card)
# Set attributes
f = wave.open(f, 'rb')
device.setchannels(f.getnchannels())
device.setrate(f.getframerate())
# 8bit is unsigned in wav files
if f.getsampwidth() == 1:
device.setformat(alsaaudio.PCM_FORMAT_U8)
# Otherwise we assume signed data, little endian
elif f.getsampwidth() == 2:
device.setformat(alsaaudio.PCM_FORMAT_S16_LE)
elif f.getsampwidth() == 3:
device.setformat(alsaaudio.PCM_FORMAT_S24_LE)
elif f.getsampwidth() == 4:
device.setformat(alsaaudio.PCM_FORMAT_S32_LE)
else:
raise ValueError('Unsupported format')
device.setperiodsize(320)
data = f.readframes(320)
while data:
# Read data from stdin
device.write(data)
data = f.readframes(320)
def morse_to_text(text, seperator=" / "):
"""translate dash dot morse code to ascii text"""
translated = []
words = text.split(seperator)
for word in words:
clear = []
chars = word.split()
for c in chars:
clear.append(reverse_morsetab[c])
translated.append(''.join(clear))
return ' '.join(translated)
if __name__ == '__main__':
parser = argparse.ArgumentParser(
prog=sys.argv[0],
description='a simple morse generator and translator',
formatter_class=argparse.HelpFormatter)
parser.add_argument("-o", help="Specify the output format: text or sound",
choices=['text', 'sound'])
parser.add_argument('-f', help="Specify the file to write", action='store',
type=str)
parser.add_argument('-d', action='store', default='default')
parser.add_argument('args', nargs=argparse.REMAINDER)
args = parser.parse_args()
if len(sys.argv) < 2:
parser.print_help()
sys.exit()
if args.o == 'sound':
morse = text_to_morse(' '.join(args.args))
f = morse_to_wav(morse, file_=args.f)
if not args.f:
play(f)
else:
text = ' '.join(args.args)
if re.search("[a-z]+", text.lower()):
conv = text_to_morse(text)
else:
conv = morse_to_text(text)
if not args.f:
sys.stdout.write(''.join(conv))
sys.stdout.write('\n')
sys.stdout.flush()
else:
f = open(args.f, 'w')
f.write(morse+'\n')
Using the program is a fun:
$ python morse_translator.py "hello world"
.... . .-.. .-.. --- / .-- --- .-. .-.. -..
Or the other way around:
$ python morse_translator.py .... . .-.. .-.. --- / .-- --- .-. .-.. -..
hello world
And the real fun is:
$ python morse_translator.py -o sound hello world
This will beep the morse code to your speakers! And if you want to save the file:
$ python morse_translator.py -o sound -f hello.wav hello world
That was it, weekend fun with Python and Morse code. You can download the complete code here.
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