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• Add buffering to real time input stream with c++ ffmpeg

  7 octobre 2018, par Joel

  I am writing a c++ program in which I am handling a real time udp video stream with the ffmpeg library.

  The video input fps is 25 frames per second in avarage. The gap between two frames can be 10 , 20, 40 milliseconds, but sometimes it can be around 80 milliseconds.
  In those times, when the gap is around 80 milliseconds, the video seems choppy or stuck,

  When I open the same stream with the ffplay player(using the ffplay.exe), using a simple
  "ffplay.exe udp ://ip:port" command, the video has a little delay (around 50 millisends) with respect to the origin stream, but it runs much more smoothly.

  Can I set a buffering time or any minimal delay so that the delay between the frames will be much more steady, in my c++ program ?
  If so, how can I do this ?

  Thanks,
  Joel

• How to server video from FFMPEG in Python/Flask ?

  13 mai 2020, par Jelling

  How does one stream the bytes returned by FFMPEG out via HTTP using Flask ? I have googled extensively and just cannot seem to find a working example.

  



  Here's how I'm loading my video file using ffmpeg-python ; this works.

  



  foo, _ = (
    ffmpeg
    .input('./example.mp4')
    .output('pipe:', format='rawvideo', pix_fmt='rgb24')
    # .output('pipe:', vframes=1, format='image2', vcodec='mjpeg')
    .run(capture_stdout=True) 
)


  



  And my best guess at outputting the video via HTTP :

  



  @app.route('/stream')
def stream():
    def gen():
      # do stuff but what?
    return Response(gen(), status=200,
                    mimetype='video/webm',
                    headers={'Access-Control-Allow-Origin': '*',
                                "Content-Type": "video/webm",
                                })


  


• Stopping rq worker doesn't stop underlying ffmpeg process

  23 mars 2020, par sqr

  I am fairly new to python and rq, and have come to a point I can’t solve by myself.

  I am using ffmpeg-python to encode livestreams, this is distributed in rq workers and displayed on a web app using flask, but since the livestreams can go on forever, I need some way to stop this process while it is still in execution. Opening the terminal where the rq worker is executing the task and pressing ’q’ (ffmpeg shortcut to quit) works, and marks the job as OK, but I need to be able to do this from my web app.

  I have tried getting the worker ID and sending it a SIGKILL, this stops the worker but the task continues running, which is something I don’t understand at all. It’s as if the actual ffmpeg process was being executed somewhere else and stopping the worker didn’t stop ffmpeg. Note that I am not using ffmpeg.run_async, I am using ffmpeg.run which as far as my limited knowledge goes, should not be executed asynchronously. While the streaming is being encoded the worker is marked as busy and has the Job ID properly assigned, so I really don’t understand why, when the worker is killed, the underlying process is still in execution.

  If instead of sending a SIGKILL I send a SIGTERM, the worker says it’s waiting for a warm exit and is never closed, as the ffmpeg process is still doing it’s thing.

  One of my ideas was trying to send a ’q’ keystroke to the worker (which I have no idea how to do even though i’ve been doing some research) or trying to switch from rq to celery, that supposedly supports the cancellation of tasks that are being executed.

  This is my routes file

  @app.route('/streamings', methods=['GET', 'POST'])
  
  @login_required
  
  def streamings():
  
  ...
  
      if form2.submit_stop.data and form2.validate():
  
          conn1 = Redis.from_url('redis://')
  
          queue = rq.Queue('tasks-q', connection=Redis.from_url('redis://'))
  
          workers = rq.Worker.all(queue=queue)
  
  
  
          for worker in workers:
  
              peine = worker.get_current_job_id()
  
              if peine == form2.fld1.data:
  
                  os.kill(worker.pid, signal.SIGKILL)

  and this is my tasks file

  def restream(origin, server, stream_key):
  
      stream_server = generate_url(server, stream_key)
  
      try:
  
          stream_map = None
  
          stream1 = ffmpeg.input(get_manifest(origin), re=None)
  
          stream2 = ffmpeg.input('mosca_66.png')
  
          stream_ol = ffmpeg.overlay(stream1, stream2, x='main_w-overlay_w-50', y='50')
  
          a1 = stream1.audio
  
          stream = ffmpeg.output(stream_ol, a1, stream_server, format='flv', vcodec='libx264', acodec='aac', preset='medium', g='120', crf='23', maxrate='4M', bufsize='5M', channel_layout='stereo')
  
          print(stream.get_args())
  
          ffmpeg.run(stream)
  
      except:
  
          set_complete() 

  Any insight on possible solutions would be greatly appreciated.

  Thanks