I was playing with a 4-fold split screen. Loaded 4 x JellyFish HD in 4 tracks, each lower track 5 seconds displaced. Per track, I set the projector to Z: 0.500, and justified top/bottom right/left so that each video occupied one quarter of the screen.
I then attached effect f_drawbox to each track, set x/y/width/height to 0/0/1920/1080, color green, thickness 10. Each of the four windows now had a border.
However, if you look closely, you see there is a 1 pixel gap horizontally and vertically between the windows, see attached picture. It also shows up if you render. I don't understand this. It should be pixel-perfect filled, 1920 = 2 x 960.
I probably can get rid of the gap by making Z very slightly larger, but why is there a gap?
Watching your screenshot I see more than 1px gap between two video frames.
I think that f_drawbox draws a line from the boundary of the video frame to the inside.
So, between two video frame, face to face, the thikness is doubled.
If the thikness is 10px, face to face between two video frames there are 10+10 px, or at least that is what I see.
I suspect the gap is because of rounding errors in the floating point calculations of the positions. The X and X positions should be + and minus 480 and 270 (0,0 is the middle of the screen), and the Info of each projector shows a slight deviation from those values.
So I ended up setting Z to 0.502, and X and Y to + and / 479 and 269. Now all align nicely, and the borders in the middle overlap so that it does not look twice as wide as the corner borders.
Good to know. Is there a good tip that we should add to the manual or is this being in the forum sufficient?
I was actually trying to make a spli screen tutorial with subtitles, that would be better. There are 3 ways (that I know now) to make a 4-fold split screen, although this one is the most flexible.
Another way, for a Project format 1920x1080.
If the 4 video in the Compositor have not to be zoomed In/Out, it could be useful to use Sketcher plugin to draw three "lines": frame, vertical line and horizontal line.
The thikness of the frame's lines have to be doubled.
This Sketcher may be put in a new, empty, Video track (called "VFX_Line") so you can enable/disable when you want. The Projector of the videos may be setted to Z=0.500.
