Converting on the fly would probably be slow anyway.
so how does eltas patched sdl do it? as you can feed that a 32 bit surface and it quite happily turns it into a 16 bit one
Well converting is always slower, but I guess some games are simple enough and don't require that much speed.
But this is the display that's only 16 bit, you can probably still create 32 bit surfaces and blit them and let SDL convert it for you.
I was asking, if blitting a surface with alpha channel onto another surface (with or without alpha) works. So you can have nice anti-aliased sprites.
Sorry if my post was confusing.
I haven't really used SDL for much, but I guess you could still create 32 bit surfaces with alpha, and let SDL convert it... might be slow. Maybe SDL can also handle alpha with 16 bit surfaces too with some kind of mask, I don't know
Feel free to grab it from SVN and play around with it if you want.