Avanti GUI + FFMPEG make a perfect open source alternate to Adobe Media Encoder. The Avanti GUI also needs “Avisynth” optionally for some extra features. but basically if you intend to own a desktop tool for your video/audio needs, such as conversions, audio extraction, video extraction etc etc: then this is the thing for you. Avanti with FFMPEG renders Adobe Media Encoder completely unnecessary.
Avanti can be downloaded from: http://avanti.arrozcru.com/
Avanti comes with some rather intriguing tools for bit-rate calculations, fixed file size conversions, size estimations, frame crop editor and much more. As instructed on their site you need to download ffmpeg executable separately from specified links according to your operating system platform. Just drop it into the ffmpeg folder and you are good to go.