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• How to get output from ffmpeg process in c#

  13 juillet 2018, par Anirudha Gupta

  In the code I written in WPF, I run some filter in FFmpeg, If I run the command in terminal (PowerShell or cmd prompt) It will give me information line by line what’s going on.

  I am calling the process from C# code and it’s work fine. The problem I have with my code is actually I am not able to get any output from the process I run.

  I have tried some answers from StackOverflow for FFmpeg process. I see 2 opportunities in my code. I can either fix it by Timer approach or secondly hook an event to OutputDataReceived.

  I tried OutputDataReceived event, My code never got it worked. I tried Timer Approach but still, it’s not hitting my code. Please check the code below

          _process = new Process
  
          {
  
              StartInfo = new ProcessStartInfo
  
              {
  
                  FileName = ffmpeg,
  
                  Arguments = arguments,
  
                  UseShellExecute = false,
  
                  RedirectStandardOutput = true,
  
                  RedirectStandardError = true,
  
                  CreateNoWindow = true,
  
              },
  
              EnableRaisingEvents = true
  
          };
  
  
  
          _process.OutputDataReceived += Proc_OutputDataReceived;
  
  
  
          _process.Exited += (a, b) =>
  
          {
  
              System.Threading.Tasks.Task.Run(() =>
  
              {
  
                  System.Threading.Tasks.Task.Delay(5000);
  
                  System.IO.File.Delete(newName);
  
              });
  
  
  
              //System.IO.File.Delete()
  
          };
  
  
  
          _process.Start();
  
          _timer = new Timer();
  
          _timer.Interval = 500;
  
          _timer.Start();
  
          _timer.Tick += Timer_Tick;
  
      }
  
  
  
  
  
      private void Timer_Tick(object sender, EventArgs e)
  
      {
  
          while (_process.StandardOutput.EndOfStream)
  
          {
  
             string line = _process.StandardOutput.ReadLine();
  
          }
  
          // Check the process.
  
  
  
      }

• 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

• 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);