thydzik’s technology blog

The last few days I have been pulling my hair out over my new HD TV not working with my Home Theatre PC, specifically when switching from HDMI input to TV and back again. The HDMI signal is lost and can only be reset by either rebooting the PC or unplugging and replugging the HDMI cable.

This problem seems to affect ATI video cards only, with NVIDEA updating their drivers to fix this. ATI states that Catalyst drivers at version 7.3 or higher have fixed this problem, but that wasn’t the case for me. A Google search for ati hdmi edid shows a number of users with the same problem.

Hence, I present to you my solution; hdmiOn.
hdmiOn is a tiny program that turns the monitor off and on, which resends the EDID data bringing back the TV to life. Suggested usage is to assign the program to a function or hotkey.

Program was tested on my Sony BRAVIA KDL46X3100 with a ATI HD 2400 PRO.

Download hdmiOn.exe

As requested, source code is as follows.

#include <windows.h>

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
	// Turn off monitor
	SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) 2);
	// Turn on monitor
	SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) -1);

	return 0;
}