You can easily implement a progress bar if running ffmpeg. The output of ffmpeg while running is something like:

frame= 3366 fps=465 q=31.0 Lsize=    6474kB time=140.35 bitrate= 377.9kbits/s

And it is refreshed ~twice per second. You can parse that line and get the data you need to display the progress. When you run in the command line, you only see one line being updated all the time, but what ffmpeg does is to write the line followed by . That s why you don t see multiple lines. However, when using StreamReader.ReadLine() on the error output of the program, you get one line for every update.

Sample code to read the output follows. You would have to ignore any line that does not begins with frame , perhaps use BeginErrorReadLine()+ErrorDataReceived if you want reading lines to be asynchronous, etc., but you get the idea (I ve actually tested it):

using System;
using System.Diagnostics;
using System.IO;

class Test {
        static void Main (string [] args)
        {
                Process proc = new Process ();
                proc.StartInfo.FileName = "ffmpeg";
                proc.StartInfo.Arguments = "-i " + args [0] + " " + args [1];
                proc.StartInfo.RedirectStandardError = true;
                proc.StartInfo.UseShellExecute = false;
                if (!proc.Start ()) {
                        Console.WriteLine ("Error starting");
                        return;
                }
                StreamReader reader = proc.StandardError;
                string line;
                while ((line = reader.ReadLine ()) != null) {
                        Console.WriteLine (line);
                }
                proc.Close ();
        }
}

There s a wrapper library over FFmpeg for .NET.

I have found this post few weeks ago when I was looking for answer for my problem. I tried to start ffmpeg process and pass arguments to it but it take sooo long to do everything. At this point I use Xabe.FFmpeg as it doing this out of the box and don t have to worry about ffmpeg executables because have feature to download latest version.

bool conversionResult = await new Conversion().SetInput(Resources.MkvWithAudio)
  .AddParameter(String.Format("-f image2pipe -i pipe:.bmp -maxrate {0}k -r {1} -an -y {2}",bitrate, fps, outputfilename))
  .Start();

There is documentation available here that shows how to get current percent of conversion.

I just found fflib at sourceforge. Looks pretty promising, haven t used it though.

How about writing a C++/CLI wrapper around ffmpeg s native interface and then calling your wrapper interface from your application?