Transparency/chroma keys in mpv or vlc?

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As you may know, when I screencast, I record the entrety of my screen and when I have my face in the bottom right, it is a literal floating mpv window on my desktop. I don't use either video editing or OBS to produce this effect.

There is a little feature I've been thinking to add to this though, and that is using a green screen and chroma keying out the background, leaving only me. I don't know of a way to do this in mpv (or the commonly used alternative vlc), but I was curious if anyone had any experience automatically keying out some color in a video stream as that's sort of what I want to do.

This isn't necessary, and if I really wanted it, I could just use OBS, but I'm curious if there's an established way to do this. Email me at luke@lukesmith.xyz if you have a solution for this.