SDL_VideoModeOK (3)

#include "SDL.h"

int SDL_VideoModeOK(int width, int height, int bpp, Uint32 flags);

SDL_VideoModeOK returns 0 if the requested mode is not supported under any bit depth, or returns the bits-per-pixel of the closest available mode with the given width, height and requested surface flags (see SDL_SetVideoMode).

The bits-per-pixel value returned is only a suggested mode. You can usually request and bpp you want when setting the video mode and SDL will emulate that color depth with a shadow video surface.

The arguments to SDL_VideoModeOK are the same ones you would pass to SDL_SetVideoMode

SDL_Surface *screen;
Uint32 bpp;
.
.
.
printf("Checking mode 640x480@16bpp.
");
bpp=SDL_VideoModeOK(640, 480, 16, SDL_HWSURFACE);

if(!bpp){
  printf("Mode not available.
");
  exit(-1);
}

printf("SDL Recommends 640x480@%dbpp.
", bpp);
screen=SDL_SetVideoMode(640, 480, bpp, SDL_HWSURFACE);
.
.

SDL_SetVideoMode, SDL_GetVideoInfo