Problems getting desired output from Process.Start()

Question

I am working on an application that calls several command line applications to do some post processing on some video files.

Right now I am trying to use Comskip to ide

Answer 1

You must set following:

     process.StartInfo.RedirectStandardOutput = true;
     process.StartInfo.RedirectStandardError = true;
     process.StartInfo.UseShellExecute = false;
     process.OutputDataReceived += new DataReceivedEventHandler(ReadOutput);
     process.ErrorDataReceived += new DataReceivedEventHandler(ErrorOutput);

     process.Start();
     process.BeginOutputReadLine();
     process.BeginErrorReadLine();
     process.WaitForExit();

and catch the output in ReadOutput and ErrorOutput

  private static void ErrorOutput(object sender, DataReceivedEventArgs e)
  {
     if (e.Data != null)
     {
        stdout = "Error: " + e.Data;
     }
  }

  private static void ReadOutput(object sender, DataReceivedEventArgs e)
  {
     if (e.Data != null)
     {
        stdout = e.Data;
     }
  }

Answer 2

See the docs on RedirectStandardOutput. Waiting for the child process to end before reading the output can cause a hang.

It particular, the example says not to do what you have done:

 Process p = new Process();
 // Redirect the output stream of the child process.
 p.StartInfo.UseShellExecute = false;
 p.StartInfo.RedirectStandardOutput = true;
 p.StartInfo.FileName = "Write500Lines.exe";
 p.Start();
 // Do not wait for the child process to exit before
 // reading to the end of its redirected stream.
 // p.WaitForExit();
 // Read the output stream first and then wait.
 string output = p.StandardOutput.ReadToEnd();
 p.WaitForExit();

You should use the events OutputDataReceived and possibly ErrorDataReceived and update the progress bar in the handler.