It would be disappointing if the Direct3D 9 API was ignorant of a few continents worth of video standards, but fortunately this doesn't seem to be true at least on Windows 7. There are no supported refresh rates below 57 hertz. For example, if the application specifies 63 hertz, 60 hertz will be used. Checking the docs for the IDirect3D9::CreateDevice() method revealed this ominous comment:Īn unsupported refresh rate will default to the closest supported refresh rate below it. Strangely, the old ChangeDisplaySettings() call had no problem selecting the 50Hz mode and the control panel showed 50Hz available, but a check with the DirectX Caps Viewer revealed that the mode wasn't showing up in the Direct3D APIs. Then I tried the Direct3D 9 code, and it refused to do the mode switch. The test ran fine and the monitor happily switched into a PAL-compatible refresh rate. Problem is, a 50Hz mode wasn't showing up in the mode list for my monitor, so I opened the NVIDIA control panel and added a custom 50Hz mode. Displaying PAL video on a 60Hz display doesn't look very good because of the difference in frame rates - you get a beat at the difference between the rates, 10Hz in this case - and so it's better to change the display mode to match.

I spent some time today trying to get some Direct3D 9 code to switch the display into 50Hz refresh so it could display PAL video.

Gpu caps viewer directx test