Clever FFmpeg GUI is a small, but smart GUI for FFmpeg.
It processes Audio and Video streams separately.These can be muxed after processing. 
It is for Windows, portable, for x86 and x64. 
Automatic stream detection, Video and Audio stream conversion, Audio volume detection, Audio lenght and pitch modification, Video automatic crop detection, Change aspect ratio, Change Audio and Subtitles stream language. Requires .NET 4.6.

Static builds of ffmpeg, ffprobe, ffplay are needed. (Download link below).
They have to be into the same folder.
 
At the first start you have to specify ther location path. 
That's it.

Enjoy
ProWo

FFmpeg static builds for Windows:
https://ffmpeg.zeranoe.com/builds/ 