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View Full Version : HDTV (over\under)scan...... explain this one to me


nVidiaGuru
03-29-06, 09:56 PM
I have a samsung 23" LCDTV 1366x768 native resolution
(here is the model http://www.pricegrabber.com/p__Samsung_LN_R238W_23_LCD_TV,__7676891 )

I know 1366x768 is not the 720p standard, but i cant even get the 1280x720 to work corectly.

I have now tried this with two different cards..... a 7800gt in my main rig, and a 6600gt AGP in the secondary. Ive tried the last set of 7x.xx drivers and one of the earlier 82.xx drivers with the 7800gt both of which did not produce a good image or run the correct over\under-scan. Im using the 84.20 drivers on the 6600gt which gave a better image (still not great) but the over/under-scan is still messed up

When i set the display res to 1280x720 i lose about a taskbars-worth of image all the way around the screen with the overscan options set to "native"

"Overscan shift" doesnt fix it, but its not supposed to AFAIK its just supposed to shift the screen

The "underscan" DOES allow me to fit the image fully on the screen with the help of "overscan compensation" HOWEVER it does this by lowering the resolution to 1200x664

I tried a dvi>hdmi converter and the component cables with the 7800gt and only the component cables with the 6600gt

there are no drivers for the TV AFAIK so its setup as plug and play default display, which i suppose could have something to do with it

im confused and i need help all i want is 1280x720 without losing part of the image (nana2)

nicnac
03-30-06, 01:33 AM
yo i have the same problem
just a diferent tv weird
all my 16:9 res are messed up
all 16:10 work fine

nVidiaGuru
03-30-06, 04:08 AM
i found our problem

"What the TV does is ZOOM by about 5% on the incoming image by allowing part of the image to go beyond the viaiable sceen boundaries.
So when you apply Overscan Compensation with the card drivers you do not change the resolution you are outputting such as 1920x1080 but what the driver does is zoom out about 5% so that the actual frames being transmitted have a black border on the both sides and the top and the bottom. When the TV receives this and does it overscan you end up the image properly filling the visable screen.
No a TV does not work like a computer monitor when it comes to verticle and horizontal size. Some HDTVs work like PCs when using the VGA interface and like CRT TVs when using the component, or HDMI/DVI interfaces."

post#2
http://www.avsforum.com/avs-vb/showthread.php?t=645201&highlight=Overscan+Compensation

Digital_Trans
03-31-06, 07:52 AM
That's why I got a Dell Ultrasharp 24.3" LCD Monitor Widescreen Model: 2005FPW. I love this thing. Would love to upgrade to the 30" if the price drops.