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Hitachi HDTV + Nvidia DVI, interlaced timings, need help please

572 Views 9 Replies 5 Participants Last post by  zothen
I recently upgraded from using my Radeon 9500 over component dongle to a Geforce 5950 Ultra over DVI and I'm having a helluva time trying to get a 1776x999 or 1776x1000 interlaced resolution to work. My HDTV is a Hitachi 57XWX20b.

When I try to add this resolution right off the bat in the Nvidia drivers, the image is unviewable so I can never get to the advance timings tab to try to fix it.

In Powerstrip, the interlaced check box is faded out and after posting a thread on the entech forum, I was told Powerstrip does not support interlaced resolutions over DVI for Nvida cards, or at least not on my Nvidia card.

So now I'm stuck and would appreciate any helpful advice.

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I've been able to "trick" powerstrip into making interlaced resolutions now but I'm still not having any luck. I've tried every 1776x1000i or 1776x999i resolution that I've found on avsforum on the entech support site.

I've also tried to modify this resolution in the nVidia custom resolution app but it has a bug that changes my 1000 pixel count to 2000 or 4000 as soon as I start changing some parameters.

I think part of the problem may be that Hitachi uses a different scanrate for 1080i than the 33.75kHz that the other manufacturers uses. The other problem may be trying to use a DVI connection with 1776x1000 or 1776x999.

Can people who have a working 1776x1000i or 1776x999i resolution please post their timings if you have not already posted them somewhere on this forum.

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If you are creating interlaced resolutions with NVidia, try making your pixel count 1/2 of the total resolution, because the pixel count is per field, not frame.

Just curious - but why those resolutions? Why not native 1920x1080i or 1280x720p?
Ah, thanks for the advice Vern, I will try that tonight.

I want to get rid of overscan. Besides being afraid of missing some small piece of movie information, eventually I'd like to play games on it as well as watch movies although I'm not sure how possible that is over a DVI connection. Most games display useful information on the very outsides of the screen.

With my Radeon 9500 over component dongle I could switch to 4:3 resolutions to play games. I'm not sure if DVI is 16:9 only or what because when I've tried to switch the desktop to a resolution like 1024x768, it still outputs an overscanned 16:9 deskop.

So is a DVI connection not an option for games?
As I mentioned in my PMs, the DVI on this thing is twitchty. It wants some pretty precise timings.
I tried inputting a 1776x500 pixel count in Nvida custom rez app and Powerstrip and couldn't get either one to work.

After doing more searching I now believe it's almost impossible to make a custom interlaced resolution over DVI. I haven't found any posts where someone has claimed to get 1776x1000i or 1776x999i over DVI.

For whatever reason, the tolerances for front porch, back porch, and syncwidth must be much tighter for digital than they are for analog. So to get this working, one would actually need to know the proper way to adjust these values for different resolutions. I've never seen anyone talk about a formula for calculating these values so I can only assume that in the past, people have just resorted to blind guessing and tweaking which doesn't work very well for interlaced DVI resolutions.

I've decided my solution is to purchase Geforce 6600 AGP card with component outputs to get the best video quality and have game resolutions available as well.

Have u tried the newest beta drivers? See below

I purchased the hdmi to dvi cable and currently have it hooked up to my 51f510 and I have tried 1280x720 and 1920x1080. 1280x720 works but I get overscan... when I try 1920x720 the nvidia driver 6672 automatically puts it at 1766x993 with virtually no overscan. I have a nvidia fx5200 with new beta drivers. The new beta drivers have HDTV selections in the outputs and detect the 51f510 as "Hitachi PTV" although for the connection it states it is Component rather then HDMI/DVI. I do not think that is a big deal.
The latest driver version I've tried is 65.90 so I'll give the 66.72 drivers a try tonight. Also, if they don't automatically work, I will try making a 1766x993 resolution just in case there is something special about that resolution as opposed to 1776x1000 or 1776x999.

Thanks for you help.
Those 66.72 drivers worked like a champ for interlaced 1080i custom 4x3 resolutions. They function similiar to the new ATI catalyst drivers where you can set a check box that states "Treat your Digital Display as an HDTV" and set your your output to 480p, 720p, or 1080i. Then after that, there are three modes you can pick which are

- Underscan to fit the screen

- Overscan shift to fit the screen

- normal adapter output

Picking the first option for 1080i, the relution switches to 1776x993. At this resolution my Hitachi 57XWX20b had about 1 or 2 percent underscan at the top and only a couple of pixels worth on the bottom. If I tried to switch to to 1024x768, the output would stay at 1080i and I would get a reduced size 1024x768 image on the screen. Using the Nvidia custom resolution function I added a 4x3 resolution of 1328x996 for 1080i and play a little Battefield Vietnam just fine.

There were some problems with this though. The underscan portion of the the bottom of the screen would display of flickering mirror of the used portion of the screen. Also, in 720p when I tried to switch to a 4x3 resolution like 800x600, the screen would switch to an overscanned 16x9 resolution.

They still have a long way to go before the whole custom resolution is where it needs to be for htpc users but at least they seem to be working on it. What would be nice is to have a GUI for screen size adjustment like the ATI drivers when using the component dongle.
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