This is a small, but smart GUI for FFmpeg.

It processes Audio and Video tracks separately.
These can be muxed after processing.
 
It is for Windows, portable, for x86 and x64. 
It needs static builds of ffmpeg.exe, ffplay.exe and ffprobe.exe, located somewhere on your computer.
At the first use you have to specify the location of ffmpeg, ffprobe and ffplay. 
That's it.

Enjoy
ProWo

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