I have hundreds of music videos I have either downloaded or made myself using ATI TV Wonder. I have been storing these on a Seagate FreeAgent 1.5tb ext. USB drive. Space is now becoming an issue. These files are in mostly vob, mpg, mp4, mkv and avi formats. I want to compress the ones that are not already in avi format. Can someone suggest a program to convert these in batch. My only requirements are that I want to convert to avi and maintain the original size (ex. 720x480). The input files will be all different sizes. I have tried AVS Video Convertor and ImTOO AVI/MPEG convertor but these change the original size.