I have a video in mp4 which i need to add ASS subtitles to. I have yet another mp4 but i didnt make it myself so its made with a different encoding. Quality is excellent and i dont want to mess up with it, in fact i dont need to touch it in anyway, except by inserting a clip into about the middle. However, i need to put but together in a single video. What do you advice me to do? Whats the best program and settings i can use so i dont lose quality? The easiest thing for me is to do everything with virtualdub but then i can save to avi only.