Running "FFMPEG" for several times in winfoms

Question

In a C# Windows application, I try to call "ffmpeg" to multiplex video and audio. It may be called several times. In the first call, everything is fine, but in the next call I have some problems. One problem is that the earlier "ffmpeg" process isn't closed. So, I tried to kill it if it exists. but now I got an error for a disposed object in the following code:

   public static void FFMPEG3(string exe_path, string avi_path, string mp3_path, string output_file)
    {
        const int timeout = 2000;
        Kill(exe_path);
        using (Process process = new Process())
        {
            process.StartInfo.FileName = exe_path;
            process.StartInfo.Arguments = string.Format(@"-i ""{0}"" -i ""{1}"" -acodec copy -vcodec copy ""{2}""",
                                           avi_path, mp3_path, output_file);
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.CreateNoWindow = true;
            process.StartInfo.RedirectStandardOutput = true;
            process.StartInfo.RedirectStandardError = true;

            StringBuilder output = new StringBuilder();
            StringBuilder error = new StringBuilder();

            using (AutoResetEvent outputWaitHandle = new AutoResetEvent(false))
            using (AutoResetEvent errorWaitHandle = new AutoResetEvent(false))
            {
                process.OutputDataReceived += (sender, e) =>
                {
                    if (e.Data == null)
                    {
                        outputWaitHandle.Set();
                    }
                    else
                    {
                        output.AppendLine(e.Data);
                    }
                };
                process.ErrorDataReceived += (sender, e) =>
                {
                    if (e.Data == null)
                    {
                        errorWaitHandle.Set();
                    }
                    else
                    {
                        error.AppendLine(e.Data);
                    }
                };

                process.Start();

                process.BeginOutputReadLine();
                process.BeginErrorReadLine();

                if (process.WaitForExit(timeout) &&
                    outputWaitHandle.WaitOne(timeout) &&
                    errorWaitHandle.WaitOne(timeout))
                {
                    // Process completed. Check process.ExitCode here.
                    process.Close();
                }
                else
                {
                    // Timed out.
                    process.Close();
                }
            }
        }
    }

I get ObjectDisposedException for ErrorDataRecieved event on errorWaitHandle.Set();

First, I want to resolve this error, but if you know any better solution to run the "ffmpeg" for several times please suggest me.

Answer 1

The problem is that for the second time, the "ffmpeg" must overwrite the previous generated video file. Then, it asks a question and waits for the user to allow overwriting. Since I used CreateNoWindow, the user can't reply this message. To resolve this problem I used the option -y to automatically overwrite any previous file.

 process.StartInfo.Arguments 
  = string.Format(@"-i ""{0}"" -i ""{1}"" -y -acodec copy -vcodec copy ""{2}""",
                                               avi_path, mp3_path, output_file);