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bool DDrawOverlay::render(const QImage & img) {
	if (!canRender) return false;

	ZeroMemory(&ddsd, sizeof(ddsd));
	ddsd.dwSize = sizeof(ddsd);

	HRESULT r = lpOverlay->Lock(0, &ddsd, 
		DDLOCK_WAIT | DDLOCK_WRITEONLY, 0);
	if (r != DD_OK)
	{
		return false;
	}	
	BYTE* surfbits = (BYTE*)ddsd.lpSurface;
	WORD* pixptr;

        unsigned int* imgBits = (unsigned int*)(img.bits());

	int R0,R1, G0,G1, B0,B1;
	WORD Y, U, V;

	for(int i = 0; i < m_h; i++)
	{
		pixptr = (WORD*)surfbits;		
		for (int p = 0; p < m_w; p+=2)
		{
			R0 = (*imgBits & 0x00FF0000) >> 16;
			G0 = (*imgBits & 0x0000FF00) >> 8;
			B0 = *imgBits++ & 0x000000FF;

			R1 = (*imgBits & 0x00FF0000) >> 16;
			G1 = (*imgBits & 0x0000FF00) >> 8;
			B1 = *imgBits++ & 0x000000FF;

			// U0 Y0 V0 Y1  U2 Y2 V2 Y3  U4 Y4 V4 Y5

			U = WORD(((-148*R0 - 291*G0 + 439*B0) >> 10) + 128);
			Y = WORD(((257*R0 + 504*G0 + 98*B0) >> 10) + 36) << 8;
			V = WORD( ((439*R0 - 368*G0 - 71*B0) >> 10) + 128);
			*pixptr++ = U|Y;

			Y = WORD(((257*R1 + 504*G1 + 98*B1) >> 10) + 36) << 8;
			*pixptr++ = V|Y;

		}
		surfbits += ddsd.lPitch;		
	}
	lpOverlay->Unlock(0);

	return UpdateOverlay();
}