I need to create a simple projector loop for an art gallery that projects a quotation on a wall for 20 seconds, then transitions into a different quotation for 20 seconds, and finally transitions back to the first quote. This would then loop continuously.
-- if I want to show the text as a "light" colour on a dark grey wall, how would I set up the colour in my AE composition? Would I use a black background and white text?
-- also, for looping to work, is that set up by the media player or can I set up looping in the AE file?
I know this may be a noob question but I've never worked with projections before.
Yes, use a black background.
Render and export a movie to play as a loop in a media player; don't use After Effects as a playout system.
Oh, and test your workflow with a projection onto the wall before you get very far into the project. Verify that the system will work before spending/wasting a lot of time on the design part of the process.
You can't project the absense of light (black). For a wall to reflect the projection it must be 'reflective' and a lighter value than the image projected on it. That's just simple physics. The higher the ambient light the more contrast required in the projected image.