ffmpeg does a very good job of getting rid of a green screen, with a command like this:
ffmpeg -f lavfi -i color=c=black:s=606x1080 -i input.mp4 -filter_complex "[1:v]chromakey=0x70de77:0.1:0.2[ckout]; [0:v][ckout]overlay[out]" -map "[out]" output.mp4
but it replaces the green screen with solid black, whereas I would like it replaced with a transparent background, alpha = 0.
I tried setting the color to
#00000000 (8 zeroes indicating a zero alpha), but that still resulted in a black background.
Strangely, when I set the color to say red, it gives a red tint to many unfiltered areas.
So I would like a transparent background, but I'm also curious what the color option is doing.