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• H264/MP4 live stream from ffmpeg gets delayed

  1er octobre 2018, par paunescuionica

  I’m transcoding a MJPEG stream to H264/MP4 using ffmpeg. As client I’m using VLC.

  I use this command line :

  ffmpeg \
  
    -use_wallclock_as_timestamps 1 \
  
    -f mjpeg \
  
    -i "http://127.0.0.1:4100/getMjpegStream=L" \
  
    -f mp4 \
  
    -vcodec libx264 \
  
    -movflags frag_keyframe+empty_moov+faststart \
  
    -tune zerolatency \
  
    -crf 30 \
  
    -preset ultrafast \
  
    -g 1 \
  
    -reset_timestamps 1 \
  
    -vsync 1 \
  
    -flags global_header \
  
    -r 15 \
  
    -listen 1 \
  
    -fflags flush_packets \
  
    -avioflags direct \
  
    -flush_packets 1 \
  
    *output_URL*

  If I set the output_URL to this :

  udp://127.0.0.1:5000?pkt_size=1316

  it works just fine. I start ffmpeg, then after some time I start VLC with this URL udp://@127.0.0.1:5000, and it plays (almost) real time. The delay is 1-2 seconds, which is acceptable. And this delay is constant, it does not depend on when I start VLC. I can stop and reopen VLC and it keeps going realtime.

  But I need this stream to also be viewed in browser (in a HTML5 video), so I normally use this for output_URL :

  http://127.0.0.1:5000

  In VLC I use this URL http://127.0.0.1:5000 and it also works fine, but only if I start VLC immediately after I start ffmpeg. If there is a significant delay between the start of ffmpeg and the start of VLC, then that delay will be noticeable in the playback. Let’s say that I start ffmpeg at time T then after 10 seconds (at T+10) I start VLC. I have this behavior in VLC :

  • It starts, and it displays the frame at time T and then the stream freezes
  • After 10 seconds, the streaming resumes in VLC and it starts playing, but the image is 10 second behind ‘realtime’
  • This delays is constant, it does not recover from it

  Is there a way to solve this ?

  • Instruct ffmpeg to start transcoding only when the client connects ?
  • Instruct ffmpeg to not buffer transcoded stream until the client connects ? (with current command line, it clearly buffers because when VLC starts at T+10, the first frame displayed is from time T) ?

  Thank you !

• Python : movie stream into pygame

  4 mars 2019, par user1533267

  Quick challenge :

  I’m streaming part of my desktop screen trough the network using the following :

  Server

  $ ffmpeg -f x11grab -s 800x600 -r 30 -i :100 -an -q 10 -f mjpeg - | nc -lp 5000 

  Client

  $ nc <computer address="address"> 5000 | ffplay -
  
  </computer>

  I would like to display the following stream inside my pygame opengl window on the client, I read some documents on pygame.movie and found :

  "Load a new MPEG movie stream from a file or a python file object."

  Would it be possible to load the stream into pygame ?
  I need it to be as responsive as possible, and right now im seeing about 500ms lag.

  Any ideas ?

  Thanks.

• Gstreamer Multiple Source with Single Sink Implementation in PythonGST

  11 octobre 2018, par biswajitGhosh

  I’m new to Gstreamer as well as Python-GST also. I have to collect multiple source raw video stream data into a single sink, I don’t know, if it is possible or not.

  Lets explain more my scenario :

  I have 2 video source server for now, one is my webcam and another is just an mp4 file, I did open those source using following command

  Source1 :

  gst-launch-1.0 v4l2src device=/dev/video0 !
  ’video/x-raw,width=640,height=480’ ! x264enc pass=qual quantizer=20
  tune=zerolatency ! rtph264pay ! udpsink host=127.0.0.1 port=5000

  Source2 :

  gst-launch-1.0 filesrc location = file_name.mp4 !
  ’video/x-raw,width=640,height=480’ ! x264enc pass=qual quantizer=20
  tune=zerolatency ! rtph264pay ! udpsink host=127.0.0.1 port=5000

  I’m trying to send both stream data to localhost 5000 port after encoding with H264.

  For receiving I have a Python Sink Server like this :

  import gi
  
  gi.require_version('Gst', '1.0')
  
  gi.require_version('GstApp', '1.0')
  
  from gi.repository import GObject, Gst, GstApp
  
  
  
  GObject.threads_init()
  
  Gst.init(None)
  
  GST_DEBUG="6"
  
  
  
  class Example:
  
      def __init__(self):
  
          self.mainloop   = GObject.MainLoop()
  
          self.pipeline   = Gst.Pipeline.new("Pipeline") 
  
          self.bus        = self.pipeline.get_bus()
  
          self.bus.add_signal_watch()
  
          self.bus.connect("message", self.on_message)
  
          # self.bus.connect('message::eos', self.on_eos)
  
          # self.bus.connect('message::error', self.on_error)
  
          # self.bus.connect("sync-message::element", self.on_sync_message)
  
  
  
          #Create QUEUE elements
  
          self.queue1     = Gst.ElementFactory.make("queue",          None)
  
          self.queue2     = Gst.ElementFactory.make("queue",          None)
  
  
  
          # Create the elements
  
          self.source     = Gst.ElementFactory.make("udpsrc",         None)
  
          self.depay      = Gst.ElementFactory.make("rtph264depay",   None)
  
          self.parser     = Gst.ElementFactory.make("h264parse",      None)
  
          self.decoder    = Gst.ElementFactory.make("avdec_h264",     None)
  
          self.sink       = Gst.ElementFactory.make("appsink",        None)
  
  
  
          # Add elements to pipeline
  
          self.pipeline.add(self.source)
  
          self.pipeline.add(self.queue1)
  
          self.pipeline.add(self.depay)
  
          self.pipeline.add(self.parser)
  
          self.pipeline.add(self.decoder)
  
          self.pipeline.add(self.queue2)
  
          self.pipeline.add(self.sink)
  
  
  
          # Set properties
  
          self.source.set_property('port', 5000)
  
          self.source.set_property('caps', Gst.caps_from_string("application/x-rtp, encoding-name=H264,payload=96"))
  
          self.sink.set_property('emit-signals', True)
  
          # turns off sync to make decoding as fast as possible
  
          self.sink.set_property('sync', False)
  
          self.sink.connect('new-sample', self.on_new_buffer, self.sink)
  
  
  
  
  
  
  
  
  
      def on_new_buffer(self, appsink, data):
  
          print "exec two..."
  
          appsink_sample = GstApp.AppSink.pull_sample(self.sink)
  
          # with open('example.h264', 'a+') as streamer:
  
          buff = appsink_sample.get_buffer()
  
          size, offset, maxsize = buff.get_sizes()
  
          frame_data = buff.extract_dup(offset, size)
  
          print(size)
  
          # flag, info = buff.map(Gst.MapFlags.READ)
  
          # streamer.write(info.data)
  
          # print(info.size)
  
          return False
  
  
  
      def run(self):
  
          ret = self.pipeline.set_state(Gst.State.PLAYING)        
  
          if ret == Gst.StateChangeReturn.FAILURE:
  
              print("Unable to set the pipeline to the playing state.")
  
              exit(-1)
  
  
  
          self.mainloop.run()
  
  
  
      def kill(self):
  
          self.pipeline.set_state(Gst.State.NULL)
  
          self.mainloop.quit()
  
  
  
      def on_eos(self, bus, msg):
  
          print('on_eos()')
  
          self.kill()
  
  
  
      def on_error(self, bus, msg):
  
          print('on_error():', msg.parse_error())
  
          self.kill()
  
  
  
      def on_message(self, bus, message):
  
          t = message.type
  
          if t == Gst.MessageType.EOS:
  
              print "End of Stream :("
  
              self.kill()
  
          elif t == Gst.MessageType.ERROR:
  
              err, debug = message.parse_error()
  
              print "Error: %s" % err, debug
  
              self.kill()
  
  
  
  
  
      def on_sync_message(self, bus, message):
  
          print message.src
  
  
  
  
  
  example = Example()
  
  example.run()

  Firstly AppSink callback does not working, I don’t know why ? I think I have to make that configuration correct into Python Code. Can any one please help to figure it out ?

  Secondly when I tried with FFMpeg and FFPlay I got so many H264 encoding issues like this :

  

  Main confusion is Can GStreamer handle Multiple Source data into a single sink(I need to distinguished each video frame).

  Thanks a lot.