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• Playing RTSP in WPF application with low latency using FFMPEG / FFMediaElement (FFME)

  22 mars 2019, par Paboka

  I’m trying to use FFMediaElement (FFME, WPF MediaElement replacement based on FFmpeg) component to play RSTP live video in my WPF application.

  I have a good connection to my camera and I want to play it with minimum available latency.

  I’ve reduced the latency by changing ProbeSize to its minimal value :

  private void Media_OnMediaInitializing(object Sender, MediaInitializingRoutedEventArgs e)
  
  {
  
    e.Configuration.GlobalOptions.ProbeSize = 32;
  
  }

  But I still have about 1 second of latency since the very beginning of the stream. I mean, when I start playing, I have to wait for 1 second till the video appears and then I have 1s of latency.

  I’ve also tried to change following parameters :

  e.Configuration.GlobalOptions.EnableReducedBuffering = true;
  
  e.Configuration.GlobalOptions.FlagNoBuffer = true;
  
  e.Configuration.GlobalOptions.MaxAnalyzeDuration = TimeSpan.Zero;

  but it gave no result.

  I measured time-interval between FFmpeg output lines (the number in the first column is the time, elapsed from the previous line, ms)

   ----     OpenCommand: Entered
  
     39     FFInterop.Initialize: FFmpeg v4.0
  
      0     EVENT START: MediaInitializing
  
      0     EVENT DONE : MediaInitializing
  
    379     EVENT START: MediaOpening
  
      0     EVENT DONE : MediaOpening
  
      0     COMP VIDEO: Start Offset:      0,000; Duration:        N/A
  
     41     SYNC-BUFFER: Started.
  
    609     SYNC-BUFFER: Finished. Clock set to 1534932751,634
  
      0     EVENT START: MediaOpened
  
      0     EVENT DONE : MediaOpened
  
      0     EVENT START: BufferingStarted
  
      0     EVENT DONE : BufferingStarted
  
      0     OpenCommand: Completed
  
      0     V BLK: 1534932751,634 | CLK: 1534932751,634 | DFT:    0 | IX:   0 | PQ:     0,0k | TQ:     0,0k
  
      0     Command Queue (1 commands): Before ProcessNext
  
      0        Play - ID: 404 Canceled: False; Completed: False; Status: WaitingForActivation; State: 
  
     94     V BLK: 1534932751,675 | CLK: 1534932751,699 | DFT:   24 | IX:   1 | PQ:     0,0k | TQ:     0,0k

  So, the most the process of "sync-buffering" takes the most of the time.

  Is there any parameter of FFmpeg which allows reducing a size of the buffer ?

• gstreamer h264 multicast missing SPS/PPS information

  6 mars 2015, par RBI

  I have two video streaming units capable of streaming live video inputs :

  • AXIS Q7424-R Video Encoder
  • EPIPHAN VGADVI Broadcaster 99460 -

  I am using gstreamer to view these streams on client terminals running linux. I am interested in the h264, rtp multicast streams (which both units support).

  I can stream the Epiphan video using the following gstreamer pipeline :

  gst-launch-0.10 udpsrc multicast-group=ADDRESS port=PORT caps='application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264' ! rtph264depay ! ffdec_h254 ! autovideosink

  However, this pipeline does not work for the Axis unit as I get the following error repeatedly :

  ffmpeg:0:: non-existing PPS referenced
  
  ffmpeg:0:: non-existing PPS 0 referenced
  
  ffmpeg:0:: decode_slice_header error
  
  ffmpeg:0:: no frame!
  
  ffdec_h264: decoding error (len:-1, have_data: 0)

  I have read that this error means that the ffmpeg decoder is missing the SPS/PPS information provided by a keyframe. The axis unit has a GOV parameter which is the interval at which i-frames are sent ; it is set to 32.

  Note that I can view both units’ rtp streams in unicast with the following :

  gst-launch-0.10 rtspsrc location=rtsp://ADDRESS:PORT/... latency=100 ! rtph264depay ! ffdec_h264 ! autovideosink

  Since unicast works and the unicast and multicast pipelines are the same (except for the source), my guess is either :

  • My udpsrc caps are simply incorrect for the axis stream (and I don’t really know where/how to verify it)

  • or, the axis multicast format/encoding is different and requires a modification to the pipeline (I find this unlikely since unicast is working and I don’t understand why the encoding would change between unicast/multicast).

  Any suggestions are appreciated as I am limited by my knowledge of gstreamer and media formats in terms of what to try next.

• x86 : Avoid some bypass delays and false dependencies

  11 octobre 2015, par Henrik Gramner

  x86 : Avoid some bypass delays and false dependencies
  A bypass delay of 1-3 clock cycles may occur on some CPUs when transitioning
  
  between int and float domains, so try to avoid that if possible.
  

  • [DH] common/x86/deblock-a.asm
  • [DH] common/x86/mc-a.asm
  • [DH] common/x86/pixel-a.asm
  • [DH] common/x86/predict-a.asm
  • [DH] common/x86/sad-a.asm
  • [DH] common/x86/x86util.asm