I am trying to make an area all green outside of the main subject (that has a small green screen aro

Hi, I have got a video on my timeline but the green screen I used is not wide enough for me to use chroma keying i wonder if there is a way to mask areas and make them a solid green to effectively widen the green screen area, without this my video will be a small portrait type which is not going to be good. Any help will be greatly appreciated, thanks. Richard

Welcome, Richard, to fcp.co

no need to 'extend' the green: just crop your clip with the green, using the Crop tool.
Or, apply a Mask from the Effects tab.

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