Comment by idoubtit
Even when I don't use directly ffmpeg, I often use tools that embed ffmpeg. For instance, I've recently upscaled an old anime, ripped from a low quality DVD. I used k4yt3x/video2x, which was good enough for what I wanted, and was easy to install. It embedded libffmpeg, so I could use the same arguments for encoding:
Video2X-x86_64.AppImage -i "$f" \
-c libvpx-vp9 -e crf=34 -o "${f/480p/480p_upscale2x}" \
-p realcugan -s 2 --noise-level 1
To find the best arguments for upscaling (last line from above), I first used ffmpeg to extract a short scene that I encoded with various parameter sets. Then I used ffmpeg to capture still images so that I could find the best set.
About 10-ish years ago, my then employer was talking to some other company about helping them get their software to release. They had what they believed to be a proprietary compression system that would compress and playback 4k video with no loss in quality.
They wouldn't let us look into the actual codecs or compression, they just wanted us to build a front-end for it.
I got to digging and realized they were just re-encoding the video through FFMpeg with a certain set of flags and options. I was able to replicate their results by just running FFMpeg.
They stopped talking to us.