Question

Do I need a video processor?

Yes for any wall that takes more than one source: the controller is sized by the pixel count of the finished wall, not by its area.

What the controller does

It takes the source resolution and maps it onto the wall, and it handles switching between sources. A wall without one is locked to a single input format.

Sized by pixel count

The load is the total pixels of the wall. A large wall at a fine pitch can exceed one controller, which is why sizing happens after the layout, not before.

Sources and handover

List the sources at the start: laptop, media player, camera, room system. The input list and the handover briefing are part of the delivery.