why does obs do BitBlt so fast?

[CPPYE]

when obs use dc capture to capture windwo it can reach even beyond 60 fps. when i use the same way to capture window, it can hardly to reach 60 fps. why does obs do BitBlt so fast?

 

[Lain]

You can create a texture with GDI interop in Direct3D, which allows you to get an HDC for it, which you can blit against.

 

[CPPYE]

thank for replying, I have found the reason. The bitblt was slow when you try to cpoy picture form desktop(HWND returned by GetDesktopWindow), But it's same fast to capture other windwos except the desktop.