Screen Capturing Application Bounty

[Crumb]

Screen capturing is slow because ReadPixelArray() is slow. Applications can't accelerate it.

Very true although if you plan to reduce resolution you can do it before calling ReadPixelArray(), I did some blitter-zoom tests with my PicassoIV 10 years ago. I guess it could be slightly accelerated if resolution is quarter size before calling that function, e.g.:
-you reserve memory for 2 bitmaps: one half the vertical size and the second a quarter of the size of the original screen
-you use the blitter to copy the screen odd lines to the 1st bitmap (the half size one)
-you use blitter to copy the odd columns from the 1st bitmap (the half size one) to the 2nd bitmap (the quarter size one)
-you use the slow ReadPixelArray() to read the small bitmap

Since RTG blitter is quite fast and you only have to move 1/4 of the pixels it should help to gain some speed when resolution is reduced.

[Crumb]

@Crumb

I can't remember if ScreenRecorder scaled it down (using blitter) before ReadPixelArray() (havent touched it lately...) but you hardly see anything if FullHD is scaled down to 320x200...

Quarter of screen size of 1920x1080 pixels would be 960x540 pixels and using 16bits instead of 32bits may help a little. It's still 1MB per frame so not fast to read and later encode.