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• C# process FFMPEG output from standard out (pipe) [duplicate]

  30 janvier 2018, par Alexander Streckov

  This question already has an answer here :

  • Getting Binary Data from StandardOutput
    
    1 answer
    
  • Capturing binary output from Process.StandardOutput
    
    3 answers
    

  I want to extract the current image from the FFMPEG standard output and show it on a C# form. The stream source itself is a h264 raw data which converted into image and piped to the standard output. Here is my code, but I have no idea how to process the output (maybe MemoryStream) :

  public Process ffproc = new Process();
  
  private void xxxFFplay()
  
  {
  
      ffproc.StartInfo.FileName = "ffmpeg.exe";
  
      ffproc.StartInfo.Arguments = "-y -i udp://127.0.0.1:8888/ -q:v 1 -huffman optimal -update 1 -f mjpeg -";
  
  
  
      ffproc.StartInfo.CreateNoWindow = true;
  
      ffproc.StartInfo.RedirectStandardOutput = true;
  
      ffproc.StartInfo.UseShellExecute = false;
  
  
  
      ffproc.EnableRaisingEvents = true;
  
      ffproc.OutputDataReceived += (o, e) => Debug.WriteLine(e.Data ?? "NULL", "ffplay");
  
      fproc.ErrorDataReceived += (o, e) => Debug.WriteLine(e.Data ?? "NULL", "ffplay");
  
      ffproc.Exited += (o, e) => Debug.WriteLine("Exited", "ffplay");
  
      ffproc.Start();
  
  
  
      worker = new BackgroundWorker();
  
      worker.DoWork += worker_DoWork;
  
      worker.WorkerReportsProgress = true;
  
      worker.ProgressChanged += worker_ProgressChanged;
  
      worker.RunWorkerAsync();
  
  }
  
  
  
  public void worker_DoWork(object sender, DoWorkEventArgs e)
  
  {
  
      try
  
      {
  
          var internalWorker = sender as BackgroundWorker;
  
          Process p = e.Argument as Process;
  
          buffer = new MemoryStream();
  
          bufferWriter = new BinaryWriter(buffer);
  
          using (var reader = new BinaryReader(p.StandardOutput.BaseStream))
  
          {
  
              while (true)
  
              {
  
                  bufferWriter.Write(1);
  
                  var img = (Bitmap)Image.FromStream(buffer);
  
                  pictureBox1.Image = img;
  
                  //get the jpg image
  
              }
  
           }
  
       }
  
       catch (Exception ex)
  
       {
  
             // Log the error, continue processing the live stream
  
       }
  
   }

  Any help would be appreciated !

• lavu : use address-of operator checking clock_gettime

  8 décembre 2020, par Marvin Scholz

  lavu : use address-of operator checking clock_gettime
  When targeting a recent enough macOS/iOS version that has clock_gettime
  
  it won't be a weak symbol, in which case clang warns for this check
  
  as it's always true :
    warning : address of function 'clock_gettime' will always
  
    evaluate to 'true'
  This warning is silenced by using the address-of operator to make
  
  the intent explicit.
  

  • [DH] libavutil/time.c

• CreateProcess fails when dshow is used in commandline

  3 juillet 2019, par ark1974

  Trying to launch ffmpeg using CreateProcess.

  Issues :

  1) Can’t use dshow in the commandline.

  2) RTMP streaming with the STDIN piped don’t show the stream.

  Questions :

  1) What are the ceveats in the commandline pertaining to CreateProcess api ?

  2) What’s is the way round ? How can the issue be fixed ?

  This code works :

  BOOL bSuccess = CreateProcess(NULL,
  
      L"ffmpeg.exe -y -loop 1 -i kites.jpg  out.mp4",         
  
      NULL,   
  
      NULL,
  
      TRUE, 
  
      CREATE_NEW_CONSOLE, 
  
      NULL, 
  
      NULL,
  
      &siStartInfo,
  
      &piProcInfo);

  CreateProcess fails when dshow is used. However it works as command line in console.

  BOOL bSuccess = CreateProcess(NULL,
  
      L"ffmpeg.exe -y -loop 1 -i kites.jpg  -f dshow  -i audio=\"Stereo Mix(Realtek High Definition Audio)\"  out.mp4",
  
      NULL,
  
      NULL,
  
      TRUE,
  
      CREATE_NEW_CONSOLE,
  
      NULL,
  
      NULL,
  
      &siStartInfo,
  
      &piProcInfo);

  Edited : ( with absolute path, still no luck)

  std::wstring cmdArgslistSetChannel = L"ffmpeg.exe -y -loop 1 -i c:\test\kites.jpg  -f dshow  -i audio=\"Stereo Mix(Realtek High Definition Audio)\"  out.mp4";
  
  bSuccess = CreateProcess(NULL, 
  
          &cmdArgslistSetChannel[0],
  
          NULL,          
  
          NULL,          
  
          TRUE,          
  
          CREATE_NEW_CONSOLE,            
  
          NULL,          
  
          NULL,          
  
          &siStartInfo, 
  
          &piProcInfo);