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• When streaming response in Flask file unplayable

  21 décembre 2015, par nadermx

  I currently have a function that runs ffmpeg enconder on a flv stream from youtube.

  def console(cmd, add_newlines=False):
  
      p = Popen(cmd, shell=True, stdout=PIPE)
  
      while True:
  
          data = p.stdout.readline()
  
          if add_newlines:
  
              data += str('\n')
  
          yield data
  
  
  
          p.poll()
  
          if isinstance(p.returncode, int):
  
              if p.returncode > 0:
  
                  # return code was non zero, an error?
  
                  print 'error:', p.returncode
  
              break

  This works fine when I run the ffmpeg command and have it output to a file. The file is playable.

  mp3 = console('ffmpeg -i "%s" -acodec libmp3lame -ar 44100 -f mp3 test.mp3' % video_url, add_newlines=True)

  But when I have ffmpeg output to stdout via - instead of test.mp3, and stream that response. The file streams fine, is the correct size. But does not play correctly. Sounds chopy, and when I check the properties of the file it doesn’t show the data of it as it does with test.mp3

  @app.route('/test.mp3')
  
  def generate_large_mp3(path):
  
      mp3 = console('ffmpeg -i "%s" -acodec libmp3lame -ar 44100 -f mp3 -' % video_url, add_newlines=True)
  
      return Response(stream_with_context(mp3), mimetype="audio/mpeg3",
  
                     headers={"Content-Disposition":
  
                                  "attachment;filename=test.mp3"})

  Is there something I am missing ?

• How to stop ffmpeg process after it has finished processing in C# ?

  7 janvier 2018, par alan samuel

  I am trying to stop the ffmpeg process once it has finished doing what I want it do, but I am not able to find a way.

  Here is what I have done.

  //Process for running ffmpeg
  
  Process process = new Process();
  
  process.StartInfo.RedirectStandardOutput = true;
  
  process.StartInfo.RedirectStandardError = true;
  
  process.StartInfo.FileName = ffmpegfile;
  
  process.StartInfo.Arguments = commandtorun;
  
  process.StartInfo.UseShellExecute = false;
  
  process.StartInfo.CreateNoWindow = true;
  
  
  
  
  
  process.Start();
  
  process.WaitForExit();
  
  
  
  process.Close();

  The problem is ffmpeg does not tell the process to stop after it has finished executing, so I cant use WaitForExit() call.

  What i tried doing is

  commandtorun = commandtorun+ " && exit";

  to force ffmpeg to close after it finishes executing. Now this works when I try in cmd.

  But when I do the same thing in C#, ffmpeg closes down as soon as the command is executed.

  Is there any way to force ffmpeg or the process to close after the processing is done ?

• How to do HTML 5 video with Flash-free fallback for IE 8

  10 octobre 2013, par forthrin

  I need a simple and clean Flash-free, cross-browser solution for embedding video in a Web page. I came up with the solution below, and wish to hear if someone can improve it even further, including :

  1. Can the method show a still image while buffering the video ?
  2. Can someone verify those conditional comments ? downlevel-hidden and downlevel-revealed got me a bit confused :)

  Video converting as follows (using WMV for IE 8, WEBM for Firefox, and H264 for the rest) :

  ffmpeg -i video.mov -b 3000k -vcodec wmv2   -acodec wmav2     -ab 320k -g 30 out.wmv
  
  ffmpeg -i video.mov -b 3000k -vcodec libvpx -acodec libvorbis -ab 320k -g 30 out.webm

  Markup (using conditional comments to create a fallback to IE 8 users) :

  <video controls="true" autoplay="true" poster="video.jpg">
  
    <source src="video.mov" type="video/quicktime"></source>
  
    <source src="video.webm" type="video/webm"></source>
  
  </video>