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• Frames grabbed from UDP H264 stream with ffmpeg are gray/distorded

  12 septembre 2019, par Clément Bourdarie

  I am grabbing frames from a udp h264 stream with Javacv’s FFMPEG on windows, and putting them into a JavaFX imageview. The problem is that most of the image isn’t received well (it is gray, distored...) :

  

  I used to have the same problem before and I made it work by using flush on the frame grabber after each frame, but I forgot to save my work and lost it, and this time the correction doesn’t work.

  Here’s the part where i configure/launch FFMPEG :

          final Java2DFrameConverter converter = new Java2DFrameConverter();
  
  
  
          // Show drone camera
  
          FFmpegFrameGrabber grabber = new FFmpegFrameGrabber("udp://227.0.0.1:2200");
  
  
  
          grabber.setFrameRate(_frameRate);
  
          grabber.setFormat(_format);
  
          grabber.setVideoBitrate(25000000);
  
          grabber.setVideoOption("preset", "ultrafast");
  
          grabber.setNumBuffers(0);
  
  
  
          grabber.start();
  
  
  
          // Grab frames as long as the thread is running
  
          while(_running){
  
                 final Frame frame = grabber.grab();
  
                 if (frame != null) {
  
                     final BufferedImage bufferedImage = converter.convert(frame);
  
                     if (bufferedImage != null) {
  
                           _cameraView.setImage(SwingFXUtils.toFXImage(bufferedImage, null));
  
                     }
  
                  }
  
                  Thread.sleep( 1000 / _frameRate );// don't grab frames faster than they are provided
  
                  grabber.flush();
  
          }
  
          _grabber.close();

  _format is "h264" and _frameRate is 30.

  Also, the system is flooded with prints like these (I’m not sure they are related to the problem though) :

  [h264 @ 00000000869c0a80] Invalid NAL unit 4, skipping.
  
  [h264 @ 00000000869c0a80] Invalid NAL unit 4, skipping.
  
  [h264 @ 00000000869c0a80] Invalid NAL unit 4, skipping.
  
  [h264 @ 00000000869c0a80] Reference 6 >= 4
  
  [h264 @ 00000000869c0a80] error while decoding MB 115 14, bytestream 1979
  
  [h264 @ 00000000869c0a80] concealing 6414 DC, 6414 AC, 6414 MV errors in P frame
  
  [h264 @ 0000000078f81180] Invalid NAL unit 0, skipping.
  
  [h264 @ 0000000078f81180] Invalid NAL unit 0, skipping.
  
  [h264 @ 0000000078f81180] concealing 4811 DC, 4811 AC, 4811 MV errors in B frame

  I don’t understand why it doesn’t work anymore

• C# on linux : FFmpeg (FFMediaToolkit) on linux System.IO.DirectoryNotFoundException : Cannot found the default FFmpeg directory

  6 mai 2021, par Jan Černý

  I have C# project in rider and FFMediaToolkit installed via NuGet. I made instance of MediaBuilder. When I hit run I get this error message :

  


  /home/john/Projects/Slimulator/bin/Debug/net5.0/Slimulator /home/john/Projects/Slimulator/test_mazes/small-maze-food2.png
Loading file /home/john/Projects/Slimulator/test_mazes/small-maze-food2.png
Unhandled exception. System.IO.DirectoryNotFoundException: Cannot found the default FFmpeg directory.
On Windows you have to set "FFmpegLoader.FFmpegPath" with full path to the directory containing FFmpeg shared build ".dll" files
For more informations please see https://github.com/radek-k/FFMediaToolkit#setup
   at FFMediaToolkit.FFmpegLoader.LoadFFmpeg()
   at FFMediaToolkit.Encoding.Internal.OutputContainer.Create(String extension)
   at FFMediaToolkit.Encoding.MediaBuilder..ctor(String path, Nullable`1 format)
   at FFMediaToolkit.Encoding.MediaBuilder.CreateContainer(String path)
   at Slimulator.AnimationBuffer..ctor(String videoPath, Int32 height, Int32 width, Int32 frameRate) in /home/john/Projects/Slimulator/AnimationBuffer.cs:line 11
   at Slimulator.Simulation..ctor(Space space, String seed, String outputVideoPath) in /home/john/Projects/Slimulator/Simulation.cs:line 12
   at Slimulator.Launcher.Main(String[] args) in /home/john/Projects/Slimulator/Launcher.cs:line 8

Process finished with exit code 134.


  


  When I go to https://github.com/radek-k/FFMediaToolkit#setup I find just this :

  


  


  Linux - Download FFmpeg using your package manager.

  


  You need to set FFmpegLoader.FFmpegPath with a full path to FFmpeg libraries.

  


  If you want to use 64-bit FFmpeg, you have to disable the Build -> Prefer 32-bit option in
Visual Studio project properties.

  


  


  I have already installed FFmpeg package via pacman and I am still getting these error.

  


  How can I fix this so I can use FFMediaToolkit without problem on linux ?
  
Thank you for help

  


  EDIT1 : I use Arch linux.
EDIT2 : There is related issue on github : https://github.com/radek-k/FFMediaToolkit/issues/80

  


• FFMPEG (WINDOWS) - Jerky Videos with vidstabdetect & vidstabtransform

  26 avril 2016, par Onish Mistry

  I require to stabilize multiple video clips and finally stitch all the clips, along with images into one final video. These "Scenes" consisting video clips as well as images also can have overlays like Texts and/or other Images.

  Basically the code I have in place as of now does everything for me just fine, where all the video clips are first converted into frame images. It then reads all the frames, puts on the overlays, adds a fade transition in-between "Scenes".

  Coming to the issue I am facing with stabilization, when I extract image frames out of the stabilized video clip and simply try to recreate video from those extracted image frames, it comes out with a weird jerk, almost like as if it is missing those stabilization calculations or something, not sure. It still looks a bit stabilized but with missing frames. I have checked duration and number of frames extracted, everything matches with the source, non-stabilized video.

  Below is the command used to stabilize the video, result of which is a perfectly stabilized video.

  ffmpeg -i 1.MOV -r 30 -vf vidstabdetect=result="transforms.trf" -f null NUL && ffmpeg -i 1.MOV -r 30 -vf vidstabtransform=smoothing=30:input="transforms.trf" -vcodec libx264 -b:v 2000k -f mp4 results.mp4

  Below is the command I use for video to image :

  ffmpeg -i results.mp4 -r 30 -qscale 1 -f image2 %d.jpg

  Below is the command I use for image to video :

  ffmpeg -i %d.jpg -r 30 -vcodec libx264 -b:v 2000k -f mp4 final.mp4

  Any help or suggestions are welcomed and appreciated.

  Thanks,