What would be helpful is more information on the original file (the one you are trying to encode as 720p). A program I use to find details about a clip I am not quite sure about is GSpot (http

/www.headbands.com/gspot/). Download and open the file in the program. It will give you information about the clip (frame rate, aspect ratio, codec, etc.). Post that information here and I may be able to help determine what you can do.