If there was a call for suggested ffmpeg effects, then here's one I have been having fun with. How practical or desirable it may be to include among the Cinelerra effects, I don't know. It is fast to run as an ffmpeg script from the command line.
ffmpeg -i $1 -i $1 -i $1 -i $1 -filter_complex "[1:v]hflip[a]; \ [2:v]vflip[b]; \ [3:v]"hflip,vflip"[c]; \ [0:v][a]hstack=inputs=2[top]; \ [b][c]hstack=inputs=2[bottom]; \ [top][bottom]vstack=inputs=2[out]" -s 1280x720 -map "[out]" $2 ffmpeg -i $1 -i $1 -i $1 -i $1 -filter_complex "[1:v]hflip[a]; \ [2:v]vflip[b]; \ [3:v]"hflip,vflip"[c]; \ [a][0:v]hstack=inputs=2[top]; \ [c][b]hstack=inputs=2[bottom]; \ [bottom][top]vstack=inputs=2[out]" -s 1280x720 -map "[out]" $2
The top script flips mirrors and stacks an input video to form a 2 x 2 mirror type kaleidoscope. The second script flips and mirrors 2 x 2 but inside out. If this was to become an F_kaleidoscope effect, then there may be an option switch needed between those two inverse results.
I've brute force scaled at the output, it would clearly be better to divide by 2 at the input/inputs. I've a similar pair of scripts to allow 4 different input videos to be thrown together. Just a suggestion, its very silly, I hope you find it of interest.
