Scaling the recording

[realh]

Could you add an option for resizing/scaling the video? For example, my laptop has a hidpi screen of 2560x1440, so it's well-suited to scaling to the standard 1280x720. While we're stuck with software encoding, scaling down should actually reduce CPU load I think, because the extra processing it takes should be more than offset by reducing the amount of encoding.

I can hack a fixed scale in to the GNOME-Wayland path quite easily by prepending videoscale ! video/x-raw,width=1280,height=720 ! to RecorderPipeline, and it should be just about as easy to do for the Xorg-ffmpeg path, but I'll leave it up to you how the GUI option should be provided etc.