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• What could be causing processes to be left behind ?

  11 novembre 2015, par Alex

  I’m using the Process class to spawn a process (in particular, I’m using ffmpeg.exe to convert some video files). This ffmpeg process spawns more processes (on my computer, the total is 4, I’m guessing one per CPU core ?). If it matters, I’m doing this in a Windows service, although the problem also occurs when just debugging in Visual Studio, so I don’t think it does matter.

  The main ffmpeg process runs as expected and exits, causing the WaitForExit() call to return. Except, unlike when run normally (i.e. in a command prompt), the three processes that were spawned hang around. And they keep hanging around until the process that spawned the original ffmpeg.exe process (i.e. my service) is ended.

  Any ideas what this could be about ?

  My `ProcessStartInfo looks like this :

  _processStartInfo = new ProcessStartInfo(process, string.Join(" ", parameters))
  
  {
  
      UseShellExecute = false,
  
      CreateNoWindow = true,
  
      RedirectStandardOutput = true,
  
      RedirectStandardError = true
  
  };

  I launch the Process like this :

  _process = Process.Start(_processStartInfo);
  
  
  
  _outputReceivedHandler = (sender, e) =>
  
  {
  
      if (OutputData != null) OutputData(e.Data);
  
  };
  
  _process.OutputDataReceived += _outputReceivedHandler;
  
  
  
  _errorReceivedHandler = (sender, e) =>
  
  {
  
      if (ErrorData != null) ErrorData(e.Data);
  
  };
  
  _process.ErrorDataReceived += _errorReceivedHandler;
  
  
  
  _exitHandler = (sender, e) =>
  
  {
  
      if (Exited != null) Exited();
  
  };
  
  _process.EnableRaisingEvents = true;
  
  _process.Exited += _exitHandler;
  
  
  
  _process.Start();
  
  
  
  _process.BeginOutputReadLine();
  
  _process.BeginErrorReadLine();

  If it’s relevant, OutputData, ErrorData and Exited are Action<string></string>, Action<string></string> and Action, respectively.

  The reason I’m keeping the various handlers around is so that I can do this :

  private bool _disposed;
  
  public void Dispose()
  
  {
  
      Dispose(true);
  
      GC.SuppressFinalize(this);
  
  }
  
  
  
  protected virtual void Dispose(bool disposing)
  
  {
  
      if (_disposed || !disposing) return;
  
  
  
      if (_outputReceivedHandler != null) _process.OutputDataReceived -= _outputReceivedHandler;
  
      if (_errorReceivedHandler != null) _process.ErrorDataReceived -= _errorReceivedHandler;
  
      if (_exitHandler != null) _process.Exited -= _exitHandler;
  
      if (_process != null) _process.Dispose();
  
  
  
      _disposed = true;
  
  }

  Though it hasn’t made a difference whether or not I use Dispose(), the problem still occurs.

• What the correct args for ffmpeg conversion

  8 novembre 2013, par Andrew Simpson

  I have a C# app. I am using ffmpge to convert jpgs to an OGG file. I use the process class to write to a stream buffer within my app using piping without having to write the ogg file to a disk. I then upload these bytes to my server where it is written to the hard drive.

  On the server side I want to convert it to say an mp4 format. Again, I want to pipe it out to a stream buffer and allow my User to download the file.

  This is my code :

  Process _serverBuild = null ;

  public byte[] EncodeAndUploadImages(string _args1)
  
  {
  
      byte[] _data = null;
  
      try
  
      {
  
          _args1 = "ffmpeg.exe -i \"c:\\Cloud\\Zipped\\000EC902F17F\\f3e45e44-b61c-472b-8dc1-a8e9b9511497_00007.ogg\" avi -";
  
          _serverBuild = new Process();
  
  
  
          _serverBuild.StartInfo.WorkingDirectory = Environment.CurrentDirectory;
  
          _serverBuild.StartInfo.Arguments = _args1;
  
          _serverBuild.StartInfo.FileName =  @"C:\inetpub\wwwroot\bin\ffmpeg.exe";
  
          _serverBuild.StartInfo.UseShellExecute = false;
  
          _serverBuild.StartInfo.RedirectStandardOutput = true;
  
          _serverBuild.StartInfo.RedirectStandardError = true;
  
          _serverBuild.StartInfo.RedirectStandardInput = true;
  
          _serverBuild.StartInfo.CreateNoWindow = true;
  
          _serverBuild.StartInfo.LoadUserProfile = false;
  
          _serverBuild.ErrorDataReceived += _server_ErrorDataReceived;
  
          _serverBuild.OutputDataReceived += _server_OutputDataReceived;
  
          _serverBuild.Exited += new EventHandler(_server_Exited);
  
          _serverBuild.EnableRaisingEvents = true;
  
          _serverProcessHasFinished = false;
  
          _serverBuild.Start();
  
  
  
          mStandardOutput = _serverBuild.StandardOutput.BaseStream;
  
          mStandardOutput.BeginRead(mReadBuffer, 0, mReadBuffer.Length, StandardOutputReadCallback, null);            
  
          _serverBuild.WaitForExit();
  
  
  
  
  
  
  
  
  
      }
  
      catch (Exception _ex)
  
      {
  
  
  
      }
  
      finally
  
      {
  
          _serverBuild.ErrorDataReceived -= _server_ErrorDataReceived;
  
          _serverBuild.OutputDataReceived -= _server_OutputDataReceived;
  
          _serverBuild.Dispose();
  
      }
  
      return _data;
  
  }
  
  
  
  byte[] mReadBuffer = new byte[4096];
  
  MemoryStream mStandardOutputMs = new MemoryStream();
  
  Stream mStandardOutput;
  
  
  
  private void StandardOutputReadCallback(IAsyncResult ar)
  
  {
  
      try
  
      {
  
          int numberOfBytesRead = mStandardOutput.EndRead(ar);
  
          {
  
              mStandardOutputMs.Write(mReadBuffer, 0, numberOfBytesRead);
  
              mStandardOutput.BeginRead(mReadBuffer, 0, mReadBuffer.Length, StandardOutputReadCallback, null);
  
          }
  
      }
  
      catch (Exception _ex)
  
      {
  
  
  
      }
  
  }

  The error I get (when I test with a bat file and run within a DOS prompt) is :

  

  Obviously my parameters are at fault. I want to keep it simple as I may want to use other formats apart from MP4.

  Thanks

• Windows python can't pass system variables [duplicate]

  14 mai 2016, par Soner B

  This question already has an answer here :

  • python subprocess Popen environment PATH ?
    
    4 answers
    

  I can cut video ffmpeg command prompt like this :

  ffmpeg -ss 00:41:12.200 -i "the_video.mp4" -t 00:00:03.100 -c:v
  libx264 -preset slow -profile:v high -crf 21 "the_video_cut.mp4" -y

  ffmpeg.exe is in C :\Windows\System32

  But I try with python.

  import subprocess as sp
  
  
  
  CRF_VALUE = '21'
  
  PROFILE = 'high'
  
  PRESET = 'slow'
  
  cmd = ['ffmpeg', '-ss', '%s'%start_time, '-i', '"%s"'%inputFile, '-t', '%s'%diffTime, '-c:v', 'libx264', '-preset', PRESET, '-profile:v', PROFILE, '-crf', CRF_VALUE, '"%s_cut.%s"'%('_'.join(file_strip[:-1]),file_strip[-1]), '-y']
  
  
  
  sp.call(' '.join(cmd))

  Error message :

  Traceback (most recent call last):
  
    File "test.py", line 81, in <module>
  
      main(sys.argv[1:])
  
    File "test.py", line 76, in main
  
      isle(inputFile, start_time, diffTime)
  
    File "test.py", line 48, in isle
  
      sp.call(' '.join(cmd))
  
    File "C:\Program Files (x86)\Python35-32\lib\subprocess.py", line 560, in call
  
      with Popen(*popenargs, **kwargs) as p:
  
    File "C:\Program Files (x86)\Python35-32\lib\subprocess.py", line 950, in __init__
  
      restore_signals, start_new_session)
  
    File "C:\Program Files (x86)\Python35-32\lib\subprocess.py", line 1220, in _execute_child
  
      startupinfo)
  
  FileNotFoundError: [WinError 2] Sistem belirtilen dosyayı bulamıyor
  
  </module>

  with try sp.call(' '.join(cmd), shell=True)

  This error message :

  ’ffmpeg’ is not recognized as an internal or external command,
  operable program or batch file.

  If i copy ffmpeg.exe in the same folder test.py, it’s okey, working.