You mean like this? https://iangetz.com/projects/ffmpeg-builder/
I'm a CLI guy, but `openssl` is insanely complex and I think it would benefit the ecosystem immensely if someone built a wrapper CLI that made it easier to complete the small handful of popular use cases that 90% of us have to go to Google to remember.
https://gist.github.com/tayvano/6e2d456a9897f55025e25035478a...
If you make a GUI out of this, it will be a pain in the ass... and ugly!
Luckily, there are many ffmpeg frontends, that select just a tiny subset of commands that are most often needed (like yours and many others), and the same things exist for openssl, eg:
I guarantee you, 10000%, that it will still be more usable than CLI is without having to google everything. FFMPEG is so complex that doing anything with it feels like talking in some ancient archaic code known only to the video tech wizards, and a GUI would absolutely make that better.