Been trying this for some time now with little to no results.
I have an MP4 of characters recorded against a Green Screen and have managed, through FFMpeg to strip out the green screen with an Alpha Key chroma filter in to a WebM.
However, the background is always black and is either not output as transparent or does not render transparent.
Here is the command I'm currently using, which "in theory" should be working, but just outputs a black background:
ffmpeg -f lavfi -i color=c=black:s=1280x720 -i input.mp4 -vcodec libvpx-vp9 -acodec libvorbis -pix_fmt yuva420p -filter_complex "[1:v]chromakey=0x339E3E:0.1:0.1[ckout];[0:v][ckout]overlay[o]" -map [o] -map 1:a -auto-alt-ref 0 output.webm
I have even tried using a transparent background texture of the same video dimensions as well
ffmpeg -i bg.png -i 3.mp4 -vcodec libvpx-vp9 -acodec libvorbis -pix_fmt yuva420p -filter_complex "[1:v]chromakey=0x339E3E:0.1:0.1[ckout];[0:v][ckout]overlay[o]" -map [o] -map 1:a -auto-alt-ref 0 output.webm
No Joy
Getting a bit frustrated as most information out there seems out of date or does not even work any more, please help!.