SDL, Windows, and Vsync or double buffering in emulators

vanfanel · Post by **vanfanel** » Thu Apr 23, 2009 9:41 am

hello there

Even if DirectX is the way to go for Windows app, some emulator programmers choose sdl nowadays as an abstraction layer on a higher level for their emus, improving portability.
The problem is that SDL relies on DirectX, or GDI, or whatever you configure it for... It can be done in compile-time, and there are enviroment variables to set default render API... All in all, very confusing.

I have compiled my own version in Linux, with DirecfFB support, wich supports double buffer. It works fine if I set the video enviroment variable to directfb, but most good emulators are for Windows.

So let's fix the OS: let's say I am on WindowsXP. Do you guys know how to configure it in order to force a double buffer in every application using SDL?

AamirM · Post by **AamirM** » Thu Apr 23, 2009 12:35 pm

No, there is no global setting to force double buffering in all applications using SDL (if thats what you meant).

If your favourite emu doesn't have double buffering support, you'll have to add it yourself or ask the developer to add it.

creaothceann · Post by **creaothceann** » Thu Apr 23, 2009 3:18 pm

My Nvidia control panel lets me configure vertical synchronization to be on, off or selectable by applications.

That should at least work with SDL apps using DirectX and maybe OpenGL (not tested).

vanfanel · Post by **vanfanel** » Thu Apr 23, 2009 3:30 pm

NVidia is always a step ahead when it comes to graphics controllers: it's Linux controllers are INCREDIBLE (insecure, yeah, I don'y run a server so I don't give a f**k about my desktop security).

Have you tried it with SDL?? doe sit work for every SDL app using DirectX??

Mednafen · Post by **Mednafen** » Thu Apr 23, 2009 3:59 pm

Be warned, some emulators may malfunction if you force their video refreshes to be synchronized to vertical blank/retrace at 60Hz and they were not designed for it.

Out of curiosity, what emulator(s) are you referring to?

vanfanel · Post by **vanfanel** » Fri Apr 24, 2009 9:29 am

I was thinking about 68k macintosh emulators, not Mednafen.
The best emulators around (SnesGT, KEGA Fusion, WinUAE, Nestopia, MAME...) don't depend on SDL and it's tearing windows implementation. That's lucky...

AamirM · Post by **AamirM** » Fri Apr 24, 2009 10:32 am

Your best option is to ask the developer(s) of the emu to add support for vsync.