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• How convert High bitrate mp3 to lower rate using ffmpeg in android

  23 mars 2018, par Android Team

  We want to convert 320kbps mp3 file to 128kbps mp3 so currently we are using below ffmpeg command but its not working.

  ffmpeg -i input.mp3 -codec:a libmp3lame -qscale:a 5 output.mp3

  Result :-the output bitrate same as input mp3.

  And we are following the FFmpeg Encoding guideline for that here is the link :- https://trac.ffmpeg.org/wiki/Encode/MP3

  so please suggest any solution.

• ValueError : I/O operation on closed file with ffmpeg

  22 mars 2018, par AstroCoda

  I’m trying to get this (minimal working example) code to compile in a virtual environment on Anaconda which I’ve set up in a supercomputing cluster :

  import numpy as np
  
  import matplotlib
  
  matplotlib.use("Agg")
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as manimation
  
  
  
  FFMpegWriter = manimation.writers['ffmpeg']
  
  metadata = dict(title='Movie Test', artist='Matplotlib',
  
              comment='Movie support!')
  
  writer = FFMpegWriter(fps=15, metadata=metadata)
  
  
  
  fig = plt.figure()
  
  l, = plt.plot([], [], 'k-o')
  
  
  
  plt.xlim(-5, 5)
  
  plt.ylim(-5, 5)
  
  
  
  x0, y0 = 0, 0
  
  
  
  with writer.saving(fig, "writer_test.mp4", 100):
  
      for i in range(100):
  
          x0 += 0.1 * np.random.randn()
  
          y0 += 0.1 * np.random.randn()
  
          l.set_data(x0, y0)
  
          writer.grab_frame()

  The thing is, this code works absolutely fine on my local machine (MacOSX) - Anaconda distribution ; Python 2.7 ; same matplotlib and numpy version, and I have ffmpeg on Anaconda ; I have ffmpeg on the cluster as well, albeit at a different version to the one on Python (but no issue with this on my local machine). When I run the code on the cluster, I get :

  Traceback (most recent call last):
  
    File "movie_test.py", line 25, in <module>
  
      writer.grab_frame()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/contextlib.py", line 35, in __exit__
  
      self.gen.throw(type, value, traceback)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/matplotlib/animation.py", line 241, in saving
  
      self.finish()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/matplotlib/animation.py", line 367, in finish
  
      self.cleanup()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/matplotlib/animation.py", line 405, in cleanup
  
      out, err = self._proc.communicate()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 927, in communicate
  
      stdout, stderr = self._communicate(input, endtime, timeout)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 1713, in _communicate
  
      orig_timeout)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 1769, in _communicate_with_poll
  
      register_and_append(self.stdout, select_POLLIN_POLLPRI)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 1748, in register_and_append
  
      poller.register(file_obj.fileno(), eventmask)
  
  ValueError: I/O operation on closed file
  
  </module>

  All the searches I’ve made correspond to relatively simple text write in/out operations, but not for videos. Thanks in advance for the help !

• Sub-pixel rendering with imagettftext()

  8 mars 2016, par user1661677

  I’m creating an image sequence, and encoding it to a video using PHP, GD library and ffmpeg. You’ll see I’m animating the two text layers inversely of each other, on the X axis. And with some simple operators $i/2 and $i/3, I’m trying to make their movement slower in the final animation.

  The problem I’m having is that when the video is rendered out, each layer’s text is only moving ever second, and third frame, respectively. This causes the animation to be a bit ’jerky’ and just not as smooth as Adobe After Effects with it’s ability to support sub-pixel rendering of elements.

  Is there any way to get imagettftext(), or some other method of drawing on images to support sub-pixel rendering ?

  Thank you.

  for ($i = 1; $i <= 125; $i++) {
  
  
  
      // Text on Image
  
      $front = imagecreatefromjpeg('front.jpg');
  
      $white = imagecolorallocate($front, 255, 255, 255);
  
      $text = 'some text';
  
      $text2 = 'some other text';
  
      $font = '/var/www/html/test/OpenSans-Bold.ttf';
  
  
  
      // Add text
  
      imagettftext($front, 60, 0, 1340-($i/2), 720, $white, $font, $text);
  
      imagettftext($front, 35, 0, 1240+($i/3), 800, $white, $font, $text2);
  
  
  
      // Write image to file
  
      imagejpeg($front, "images/".$i.".jpg", 100);
  
  }