hello again,
after going through the forum if found a suggestion by Dan:
‘The td.rota shader should work fine for positioning your images in the texture and you can composite them together with another slab. If you don’t have much experience with shaders and slabs, have a look in jitter-examples/render/.

With rota i can position live video for one input.
How can i do the same for three video inputs or more?
i tried the raw and columns but its not as fluid and controllable as using the number boxes for setting the position of the frames .
thanx for your help on how to keep positionning control over three slabs outputing to one same window…
lochoi