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• org.bytedeco.javacv.CanvasFrame showImage is hanging

  24 août 2018, par user3911119

  An IOS device is uploading h264 files (3 sec videos) to a server. Each file is successfully readable by VLC.

  Using FFMpegFrameGrabber, I grab each frame and try to display them using CanvasFrame.showImage as below. However, the method call hangs.

  CanvasFrame canvas = new CanvasFrame("ios");
  
  canvas.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  
  canvas.setAlwaysOnTop(true);
  
  canvas.setResizable(true);
  
  try(FileInputStream fis = new FileInputStream(file))
  
  {
  
      try(FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(fis))
  
      {
  
          grabber.setFormat("h264");
  
          grabber.start();
  
          while(true)
  
          {
  
              Frame frame = grabber.grabImage();
  
              if(frame != null)
  
              {
  
                  canvas.showImage(frame);
  
              }
  
          }
  
      }
  
  }

  Am I doing anything wrong in the above code ?

  EDIT#1 : When I try to save the buffered image for the frame, a valid image is saved.

  BufferedImage image = converter.getBufferedImage(frame);
  
  File outputfile = new File("png_file");
  
  ImageIO.write(image, "png", outputfile);

• Backgroundworker quits itself and calls Runworkercompleted function

  5 mai 2017, par yjs990427

  I am using youtube-dl in a cmd process running in a backgroundworker process in wpf application to update its status to a text box asynchronously. There are times in my application that ffmpeg has to work in through the process. However, at the time that ffmpeg process is called (right after youtube-dl’s work is finished) and starts running, backgroundworker calls Runworkercompleted method and kills itself. ffmpeg is called from youtube-dl.

  Is there any fix that make the backgroundworker still work until the ffmpeg’s work is done ? Thanks.

  My DoWork method :

  private void downloadWorker_DoWork(object sender, DoWorkEventArgs e)
  
          {
  
              BackgroundWorker worker = sender as BackgroundWorker;
  
              Process process = new Process();
  
              string[] scripts = (string[])e.Argument;
  
  
  
              string dir = scripts[0];
  
              string scriptText = scripts[1];
  
  
  
              process.StartInfo.FileName = "cmd.exe";
  
              process.StartInfo.WorkingDirectory = dir;
  
              process.StartInfo.Arguments = "/C set path=%path%;" + System.AppDomain.CurrentDomain.BaseDirectory + "&" + scriptText;
  
              process.StartInfo.CreateNoWindow = true;
  
              process.StartInfo.UseShellExecute = false;
  
              process.StartInfo.RedirectStandardOutput = true;
  
              process.StartInfo.RedirectStandardInput = true;
  
              process.StartInfo.RedirectStandardError = true;
  
  
  
              process.Start();
  
  
  
              while (!process.StandardOutput.EndOfStream)
  
              {
  
                  if (downloadWorker.CancellationPending)   // if and only if user calls Abort
  
                  // would this if statement be the problem?
  
                  {
  
                      foreach (var youtube in Process.GetProcessesByName("youtube-dl"))
  
                      {
  
                          youtube.Kill();
  
                      }
  
                      process.Kill();
  
                      e.Cancel = true;
  
                      return;
  
                  }
  
                  else
  
                  {
  
                      string line = process.StandardOutput.ReadLine(); 
  
                      worker.ReportProgress(1, line);                  // reports its status to UI
  
                  }
  
              }
  
          }

  My RunWorkerCompleted method :

   private void downloadWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
  
          {
  
              if (e.Error != null)
  
              {
  
                  MessageBox.Show(e.Error.Message);
  
              }
  
              else if (e.Cancelled == true)
  
              {
  
                  MessageBox.Show("Download Aborted!\r\nYou will need to delete the .part file in the download folder.", "Abort");
  
              }
  
              else if (musicCheckBox.IsChecked == true)
  
              {
  
                  MessageBox.Show("Music Download finished.", "Successful");
  
              }
  
              else if (videoCheckBox.IsChecked == true)
  
              {
  
                  MessageBox.Show("Video Download finished.", "Successful");
  
              }
  
              // CMDoutputTextBox.Text = "";
  
              downloadBtn.Content = "Download!";
  
              downloadBtn.IsEnabled = true;
  
          }

  edit : The backgroundworker produces this output and calls RunWorkerFinished method. ffmpeg does nothing after the output.

  [ffmpeg] Converting video from mp4 to mkv, Destination: TAEYEON 태연_Why_Music Video-WkdtmT8A2iY.mkv

• stream usb webcam via http using vlc without transcoding using mjpeg signal from webcam

  10 novembre 2020, par Peter Nußreiner

  I wanna stream my (Microsoft live) USB webcam using vlc from a raspberry.
While it works perfectely fine with transcoding my raspberry does not have enough power.

  


  So I checked the output formats of my webcam using :

  


  ffmpeg -f v4l2 -list_formats all -i /dev/video0


  


  wich gives me the following output :

  


  [video4linux2,v4l2 @ 0x559d5aee36c0] Raw       :     yuyv422 :           YUYV 4:2:2 : 640x480 1280x720 960x544 800x448 640x360 424x240 352x288 320x240 800x600 176x144 160x120 1280x800
[video4linux2,v4l2 @ 0x559d5aee36c0] Compressed:       mjpeg :          Motion-JPEG : 640x480 1280x720 960x544 800x448 640x360 800x600 416x240 352x288 176x144 320x240 160x120
/dev/video0: Immediate exit requested


  


  when running my streaming command :

  


  cvlc v4l2:///dev/video0:chroma=h264:width=1280:height=720 --sout '#standard{access=http,mux=ts,dst=192.168.178.27:8080,name=stream,mime=video/ts}' -vvv


  


  I get the following error :

  


  mux_ts mux warning: rejecting stream with unsupported codec YUY2
main mux error: cannot add this stream
main decoder error: cannot create packetizer output (YUY2)


  


  along with many other lines of information.
As far as I can interpret the error, vlc wants to use the YUY2 RAW signal of my webcam.
Is there any way I can force vlc to use the mjpg output of my camera ?

  


  I've already tried to use 'chroma=mjpg' without success.
Transcoding is not an alternative as my raspi has by far not enough power.

  


  I've also read about using ffmpeg for streaming, maybe someone has an alternative solution since I'm very new to the whole topic of websites and stuff

  


  It will (or should) be used as a live webcam for a windsurfing spot.
Therefore I need a fluent video with at least 10fps to judge the situation. A delay of a minute or so is no problem.
The basic idea was to stream the video to a webserver and embed the image in a website. I've got good internet connection at the spot.

  


  But for now I want to try it locally on my pc.