X modeline conversions

[Matthew Gregan <kinetik@ihug.co.nz>]

Hi everyone.

I'm trying to work out a good modeline for X for 1152x864. The reason I'm doing this is because I was installing some new drivers for my video card under Windows and discovered that my monitor can do 1152x864 at an acceptable refresh rate...

I've got the figures from Windows, but I only vaguely understand how they relate to the X modelines, and I can't figure out how to convert them over. Hopefully someone with more experience can point me in the right direction...

Under Windows, this is the info I have about the mode:
Pixel clock: 112320kHz

Horizontal:
Frequency: 70kHz
Front porch: 64 pixels
Sync: 128 pixels
Back porch: 256 pixels
Negative sync polarity

Vertical:
Frequency: 78Hz
Front porch: 1 line
Sync: 3 lines
Back porch: 2 lines
Negative sync polarity

I've tried reading through ESR's XF86 video timings howto, but it wasn't really helpful to my problem. From what I understand, the front/back porch is the time of the rise and fall of the signal, but I don't know how to relate the numbers I have back to anything useful for X.

I've found a modeline already existing in the XF86 config which is very close to what I want (1152x864 at 78Hz, but it's 70.8kHz horizontal frequency is just too much for my monitor to handle).

If anybody can help, or point me in the right direction, I would be very happy. Thanks. :-)

Oh, those Windows figures are from the Matrox monitor customization utility, if that matters...
-- 
Matthew Gregan                                  kinetik@ihug.co.nz