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• Buffering without transcoding with FFMPEG CLI Linux

  3 juillet 2017, par Deex

  I’m currently using ffmpeg on my server to transcode a 13Mbit stream down to 6Mbit. For my other broadcasts i’m using the NGINX RTMP module. Sometimes i got some bandwith breakdowns from my internet provider and i saw that the transcoded stream is much more stable, so i would ask you if its possible to use ffmpeg for buffering and to clean out bandwith issues without transcoding the whole video again.

• Can't save matplotlib animation

  19 novembre 2014, par renger

  I am trying to get a simple animation saved using ffmpeg. I followed a tutorial to install ffmpeg, and I can now access it from the command prompt.

  Now I run this piece of code :

  import numpy as np
  
  from matplotlib import pyplot as plt
  
  from matplotlib import animation
  
  
  
  fig = plt.figure()
  
  ax = plt.axes(xlim=(0, 2), ylim=(-2, 2))
  
  line, = ax.plot([], [], lw=2)
  
  
  
  def init():
  
      line.set_data([], [])
  
      return line,
  
  
  
  def animate(i):
  
      x = np.linspace(0, 2, 1000)
  
      y = np.sin(2 * np.pi * (x - 0.01 * i))
  
      line.set_data(x, y)
  
      return line,
  
  
  
  anim = animation.FuncAnimation(fig, animate, init_func=init,
  
                                 frames=200, interval=20, blit=True)
  
  
  
  mywriter = animation.FFMpegWriter()
  
  anim.save('mymovie.mp4',writer=mywriter)
  
  
  
  plt.show()

  I get this error :

  Traceback (most recent call last):
  
    File "<stdin>", line 1, in <module>
  
     File "C:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 523, in runfile
  
      execfile(filename, namespace)
  
    File "C:\Users\Renger\.xy\startups\b.py", line 23, in <module>
  
      anim.save('mymovie.mp4',writer=mywriter)
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 609, in save
  
      with writer.saving(self._fig, filename, dpi):
  
    File "C:\Python27\lib\contextlib.py", line 17, in __enter__
  
      return self.gen.next()
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 166, in saving
  
      self.setup(*args)
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 156, in setup
  
      self._run()
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 183, in _run
  
      stdin=subprocess.PIPE)
  
    File "C:\Python27\lib\subprocess.py", line 711, in __init__
  
      errread, errwrite)
  
    File "C:\Python27\lib\subprocess.py", line 948, in _execute_child
  
      startupinfo)
  
  WindowsError: [Error 2] Het systeem kan het opgegeven bestand niet vinden
  
  </module></module></stdin>

  The last dutch sentence does mean something like : The system can’t find the specified file.

  What do these errors mean, and how can I solve them ?

• FFmpeg segment desktop capture and send over http

  18 décembre 2014, par static

  I’m trying to capture the desktop video and segment it in order to send it over http to my node.js server, where I want to encode it to multiple bit-rates in order to serve it to clients for live streaming.
  The video has to be received in segments in order to create the manifest for live streaming, because i’m trying to use DASH, and to play the video on the client side using dash.js.

  The problem is that i can’t seem to be able to segment the video properly when i’m sending it to the server.

  This is the ffmpeg command that i’ve tried :

  ffmpeg -rtbufsize 1500M -f dshow -r 10 -i video="UScreenCapture"
  
  -vcodec libvpx -crf 10 -quality good -cpu-used 3 -b:v 1000k -qmin 10 -qmax 42  -
  
  threads 2 -vf scale=-1:480 -bufsize 1500 -flags -global_header -map 0 -f stream_
  
  segment -segment_time 2 -segment_format webm -  http://localhost:3000/stream/22

  I’ve managed to send it over http without segmenting the video, but on the server side i need to receive segments that have a duration of 2 seconds so that i can create the manifest.

  Also processing the video on the server side is also going to be done using ffmpeg(fluent ffmpeg module).
  I’m open to any suggestions.