Java process is failing when I attempt to capture stderr

Posted on 2011-02-23
Last Modified: 2013-11-13
I am attempting to capture the stderr output of ffmpeg (see the sample code below). I have no problem capturing sdtout but the application hangs when I attempt to read stderr.

 try {
//banner is written to stderr
                 ProcessBuilder pb = new ProcessBuilder("c:\\bin\\ffmpeg.exe","-h");
                  String line;
                  Process p = pb.start();
                  BufferedReader input =
                    new BufferedReader
                      (new InputStreamReader(p.getInputStream()));
                  while ((line = input.readLine()) != null) {
                  BufferedReader input1 =
                          new BufferedReader
                            (new InputStreamReader(p.getErrorStream()));
                        while ((line = input1.readLine()) != null) {
                catch (Exception err) {

I tried c# and it worked as expected

 see below

            string error;
            string output;
            ProcessStartInfo psi = new ProcessStartInfo(@"c:\signal\publisher\bin\ffmpeg.exe", "-h");
            psi.RedirectStandardOutput = true;
            psi.RedirectStandardError = true;
            System.Diagnostics.Process reg;
            psi.UseShellExecute = false;    
            reg = System.Diagnostics.Process.Start(psi);
            using (System.IO.StreamReader myOutput = reg.StandardOutput)
            { output = myOutput.ReadToEnd(); }
            using (System.IO.StreamReader myError = reg.StandardError)
            { error = myError.ReadToEnd(); }
          //  Console.WriteLine(output);

Any idea's why this doesn't work in java?
Question by:JonMny
  • 2
LVL 92

Accepted Solution

objects earned 500 total points
ID: 34966378
you'll need to read it in a separate thread

Author Comment

ID: 34966743
LVL 92

Expert Comment

ID: 34966844
should really find some time to update that code, its getting a little outdated.

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