a split screen mode that will use 2 cameras, and regular SDL can't do this.
You mean like how multiplayer Halo has two people playing on the same
screen, each getting half of it (not reading input from a video camera,
This shouldn't have anything to do with SDL; in OpenGL, you would call
glViewport to limit rendering to half the screen, render the entire
frame from the first player's viewpoint, then do the same thing on the
other half of the screen (or quarter of the screen, however this is
split between players).
One could also render to a render target (a "framebuffer object" in
OpenGL terms), one for each player, and blit them to the screen with the
framebuffer_blit extension, or just draw the final results as a textured
If you weren't using OpenGL, you could do something similar with SDL's
rendering API for a 2D game.
(EDIT: you edited your post before I replied by email, so this isn't an exact answer to your updated question, sorry.)