sound_encoder.py

import sys
import argparse
import numpy as np
import pyaudio
from scipy.io import wavfile

from constants import *

class Encoder:
  def __init__(self):
    self.num_channels = 1
    self.bits_per_sample = 16
    self.amplitude = 0.5

    self.p = pyaudio.PyAudio()
    self.stream = self.p.open(format = pyaudio.paInt16,
                  channels = 1,
                  rate = RATE,
                  output = True,
                  frames_per_buffer = AUDIOBUF_SIZE)

  def string2sound(self, somestring):
    samples = None
    count = 0
    binform = ''.join('2' + format(ord(i), 'b').zfill(8) for i in somestring)
    soundlist = []
    for b in binform:
      freq = ZERO
      if (b is '1'):
        freq = ONE
      elif (b is '2'):
        freq = CHARSTART
      soundlist = np.hstack((soundlist, self.getbit(freq)))
    return soundlist

  def encode2wav(self, somestring, filename):
    soundlist = self.string2sound(somestring)
    wavfile.write(filename,RATE,soundlist.astype(np.dtype('int16')))

  def encodeplay(self, somestring):
    soundlist = self.string2sound(somestring)
    self.stream.write(soundlist.astype(np.dtype('int16')))

  def getbit(self, freq):

    music=[]
    t=np.arange(0,BIT_DURATION,1./RATE) #time

    x = np.sin(2*np.pi*freq*t) #generated signals
    x = [int(val * 32000) for val in x]

    sigmoid = [1 / (1 + np.power(np.e, -t)) for t in np.arange(-6, 6, 0.01)]
    sigmoid_inv = sigmoid[::-1]

    xstart = len(x) - len(sigmoid)
    for i in range(len(sigmoid)):
      x[xstart + i] = x[xstart + i] * sigmoid_inv[i]
      x[i] = x[i] * sigmoid[i]

    music=np.hstack((music,x))
    return music

  def quit(self):
    self.stream.stop_stream()
    self.stream.close()
    self.p.terminate()

if __name__ == "__main__":
  parser = argparse.ArgumentParser(prog="sound_encoder")
  parser.add_argument('text', help="The text to encode")
  parser.add_argument('filename', help="The file to generate.")
  args = parser.parse_args()

  enc = Encoder()
  enc.encode2wav(args.text, args.filename)