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• What is the most performant way to render unmanaged video frames in WPF ?

  18 avril 2017, par superware

  I’m using FFmpeg library to receive and decode H.264/MPEG-TS over UDP with minimal latency (something MediaElement can’t handle).

  On a dedicated FFmpeg thread, I’m pulling PixelFormats.Bgr32 video frames for display. I’ve already tried InteropBitmap :

  _section = CreateFileMapping(INVALID_HANDLE_VALUE, IntPtr.Zero, PAGE_READWRITE, 0, size, null);
  
  _buffer = MapViewOfFile(_section, FILE_MAP_ALL_ACCESS, 0, 0, size);
  
  Dispatcher.Invoke((Action)delegate()
  
  {
  
      _interopBitmap = (InteropBitmap)Imaging.CreateBitmapSourceFromMemorySection(_section, width, height, PixelFormats.Bgr32, (int)size / height, 0);
  
      this.Source = _interopBitmap;
  
  });

  And then per frame update :

  Dispatcher.Invoke((Action)delegate()
  
  {
  
      _interopBitmap.Invalidate();
  
  });

  But performance is quite bad (skipping frames, high CPU usage etc).

  I’ve also tried WriteableBitmap : FFmpeg is placing frames in _writeableBitmap.BackBuffer and per frame update :

  Dispatcher.Invoke((Action)delegate()
  
  {
  
      _writeableBitmap.Lock();
  
  });
  
  try
  
  {
  
      ret = FFmpegInvoke.sws_scale(...);
  
  }
  
  finally
  
  {
  
      Dispatcher.Invoke((Action)delegate()
  
      {
  
          _writeableBitmap.AddDirtyRect(_rect);
  
          _writeableBitmap.Unlock();
  
      });
  
  }

  Experiencing almost the same performance issues (tested with various DispatcherPriority).

  Any help will be greatly appreciated.

• Stream frame from video to pipeline and publish it to HTTP mjpeg via ffmpeg

  18 juillet 2018, par Rafał Sardaw

  Let’s say I have very simple program which has been written in C++ with usage of OpenCV 3.4 under Windows 10.

  VideoCapture cap("test.avi");
  
  Mat frame; 
  
  while(true){
  
      if (!cap.read(frame))  
  
      { 
  
          break;
  
      }
  
      // SEND FRAME TO PIPE
  
  }

  It’s just simple example of reading frame by frame avi video, but in the end it’s going to be server-side application which produces modified stream from few ip cameras. I want to use html5 video tag to display output directly on website, but it’s quite hard to find useful information related with that topic ( for Windows ). If I understand it correctly I need to define pipeline and send there MJPEG stream, with help of FFMPEG, where FFMPEG will create local HTTP server on specific port. Anyone ever challenged similar task under Windows ? I guess that 80% of task is related with proper usage of ffmpeg command line tool, one of my priorities is minimal modification of application.

  So to make long story short, I have application which I can call directly from command line :

  stream_producer.exe CAMERA_1 

  and I want to be able to see MJPEG stream under :

  http://localhost:1234

  which can be displayed on local website in intranet.

  Regards.

• avfilter/vf_geq : use per-thread AVExpr for expression evaluation

  28 décembre 2019, par Marton Balint

  avfilter/vf_geq : use per-thread AVExpr for expression evaluation
  There was no consensus about separating AVExprState from AVExpr so here is a
  
  minimal patch using the existing AVExpr to fix ticket #7528.
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] doc/filters.texi
  • [DH] libavfilter/vf_geq.c