Convert video from mp4 h263 to h264 - - repost

A WPF application that converts all files in a filder from mp4 (h263) (or any other supported file by windows media player) to mp4 (h263) And we need the possibility to (easy) set the target bitrate, framerate and resolution of video (and audio) in the main application. (A simple textbox that outputs the file that is being converted in the other thread) We would like it to be written in C# We need the program before the 31 of july.