At the moment my favourite way to do (simple) elaborations and conversions of multimedia file is FFMPEG. But i understand that is not exactly the most user-friendly tool around, so if you don't want to open the terminal and read the man page of FFMPEG perhaps you could take a look at Yakito. Yakito is a free and open media files converter, using the benefits of the project FFMPEG to achieve maximum compatibility with most multimedia formats and codecs.Unlike other solutions, Yakito is not intended to be a simple frontend interface to manage an installation of FFMPEG, but uses this engine to convert/encode video in an independent way (FFMPEG it's integrated in the executable itself, so it's transparent).For this it relies on Jave , another free software project.