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• Python : How to convert a mp3 chunk from webstream to .wav samples ?

  13 novembre 2019, par Bendzko

  I’m trying to catch chunks of an mp3 webstream and coverting them into wav samples for signal processing. I tried to catch the audio via requests and io.BytesIO to save the data as .wav file.
  But I think, that I have to convert the mp3 data to wav data, but I don’t know how. (My goal is not to record a .wav file, i am just doing this to test the algorithm.)

  I found the pymedia lib, but it is very old (last commit in 2006), using python 2.7 and for me not installable.

  Maybe it is possible with ffmpeg-python, but I have just seen examples using files as input and output.

  Here’s my code :

  import requests
  
  import io
  
  import soundfile as sf
  
  import struct
  
  import wave
  
  import numpy as np
  
  
  
  
  
  def main():
  
      stream_url = r'http://dg-wdr-http-dus-dtag-cdn.cast.addradio.de/wdr/1live/diggi/mp3/128/stream.mp3'
  
      r = requests.get(stream_url, stream=True)
  
      sample_array = []
  
      try:
  
          for block in r.iter_content(1024):
  
              data, samplerate = sf.read(io.BytesIO(block), format="RAW", channels=2, samplerate=44100, subtype='FLOAT',
  
                                         dtype='float32')
  
              sample_array = np.append(sample_array, data)
  
  
  
      except KeyboardInterrupt:
  
          print("...saving")
  
          obj = wave.open('sounds/stream1.wav', 'w')
  
          obj.setnchannels(1)  # mono
  
          obj.setsampwidth(2)  # bytes
  
          obj.setframerate(44100)
  
  
  
          data_max = np.nanmax(abs(sample_array))
  
  
  
          # fill WAV with samples from sample_array
  
          for sample in sample_array:
  
              if (np.isnan(sample) or np.isnan(32760 * sample / data_max)) is True:
  
                  continue
  
              try:
  
                  value = int(32760 * sample / data_max)  # normalization INT16
  
              except ValueError:
  
                  value = 1
  
              finally:
  
                  data = struct.pack('code>

  Do you have an idea how to handle this problem ?

• Python : How to decode a mp3 chunk from webstream to .wav samples ?

  13 novembre 2019, par Bendzko

  I’m trying to catch chunks of an mp3 webstream and decoding them into wav samples for signal processing. I tried to catch the audio via requests and io.BytesIO to save the data as .wav file.
  I have to convert the mp3 data to wav data, but I don’t know how. (My goal is not to record a .wav file, i am just doing this to test the algorithm.)

  I found the pymedia lib, but it is very old (last commit in 2006), using python 2.7 and for me not installable.

  Maybe it is possible with ffmpeg-python, but I have just seen examples using files as input and output.

  Here’s my code :

  import requests
  
  import io
  
  import soundfile as sf
  
  import struct
  
  import wave
  
  import numpy as np
  
  
  
  
  
  def main():
  
      stream_url = r'http://dg-wdr-http-dus-dtag-cdn.cast.addradio.de/wdr/1live/diggi/mp3/128/stream.mp3'
  
      r = requests.get(stream_url, stream=True)
  
      sample_array = []
  
      try:
  
          for block in r.iter_content(1024):
  
              data, samplerate = sf.read(io.BytesIO(block), format="RAW", channels=2, samplerate=44100, subtype='FLOAT',
  
                                         dtype='float32')
  
              sample_array = np.append(sample_array, data)
  
  
  
      except KeyboardInterrupt:
  
          print("...saving")
  
          obj = wave.open('sounds/stream1.wav', 'w')
  
          obj.setnchannels(1)  # mono
  
          obj.setsampwidth(2)  # bytes
  
          obj.setframerate(44100)
  
  
  
          data_max = np.nanmax(abs(sample_array))
  
  
  
          # fill WAV with samples from sample_array
  
          for sample in sample_array:
  
              if (np.isnan(sample) or np.isnan(32760 * sample / data_max)) is True:
  
                  continue
  
              try:
  
                  value = int(32760 * sample / data_max)  # normalization INT16
  
              except ValueError:
  
                  value = 1
  
              finally:
  
                  data = struct.pack('code>

  Do you have an idea how to handle this problem ?

• Typesetting

  9 juin 2010, par Mikko Koppanen — Imagick, PHP stuff

  Ever had the situation where you have a piece of string which you need to overlay on an image ? Maybe a situation where the area reserved for the string is known in pixels but you need to know the font size to fill most of the area ? Think no more !

  Here is a small example of how to fit a certain piece of a string on to an area of which you know the width and the height or only the width. The magic happens through the ImageMagick CAPTION : format. You can see from the example images how the parameters actually affect the image.

  php

  < view plain text >

  1. < ?php
  2.  
  3. /* How wide is our image */
  4. $image_width = 200 ;
  5.  
  6. /* Give zero for autocalculating the height */
  7. $image_height = 200 ;
  8.  
  9. /* Specify the text */
  10. $text = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
  11.     Mauris lectus mi, mattis non, euismod vel, sagittis nec, ipsum." ;
  12.  
  13. /* Instanciate imagick */
  14. $im = new Imagick() ;
  15.  
  16. /* Create new image using caption : pseudo format */
  17. $im->newPseudoImage( $image_width, $image_height, "caption :" . $text ) ;
  18.  
  19. /* Put 1px border around the image */
  20. $im->borderImage( ’black’, 1, 1 ) ;
  21.  
  22. /* PNG format */
  23. $im->setImageFormat( "png")  ;
  24.  
  25. /* Output */
  26. header( "Content-Type : image/png" ) ;
  27. echo $im ;
  28.  
  29.  ?>

  Here is image with width 100 and height 0 :

  

  Width 100 Height 50 :

  

  Width 200 Height 200 (as you can see the font size is now larger) :