[mythtv-users] overscan problems with nvidia 8400 GS

Brian Wood beww at beww.org
Sun Jul 12 23:11:49 UTC 2009


On Sunday 12 July 2009 16:31:38 Matthew Harrison wrote:
> Brian Wood wrote:
> > On Saturday 11 July 2009 05:40:03 Matthew Harrison wrote:
> >> Brian Wood wrote:
> >>> The best solution was to use regulated power supplies, but that was
> >>> very expensive with voltages in the hundreds and currents in the
> >>> hundreds of milliamps, so this was not done except in the most
> >>> expensive commercial units. It was simpler and cheaper to just overscan
> >>> the sets, and nobody seemed to mind. It's why a TV picture is divided
> >>> by a SMPTE standard into "safe action", "safe title" and the "rest", so
> >>> nothing important would happen in the area missed by many TV sets.
> >>> Typical manufacturer's solution: screw the customer in the interest of
> >>> making more money.
> >>
> >> That's quite a cynical view. Do you really think the customer would have
> >> paid lots more in order to get a fractionally higher visible resolution?
> >
> > I'm a cynical fellow, Most customers were not aware they had any
> > alternatives.
>
> I wonder how consistent modern sets are. I've not dug out the relevant
> standards to check, but Wikipedia has this interesting nugget on the
> following page.
>
> http://en.wikipedia.org/wiki/Overscan
>
> "With the accuracy attainable with digital type displays (e.g. plasma
> <http://en.wikipedia.org/wiki/Plasma>, LCD
> <http://en.wikipedia.org/wiki/LCD> etc.), the area presented to the
> viewer is precisely defined. For 1080i or 1080p material only the
> central 1776x1000 pixels are presented to the viewer. For 720p material
> it is only the central 1152x648 pixels."
>
> I hope that doesn't mean that I have to scale HD video up in order to
> correctly display it on my 1920x1080 LCD.

Or watch it in a window?

I wonder if standards (if there are any) are different for "TV Sets" 
and "Computer Monitors", though the line between them is getting fuzzy.

Most people don't understand the difference between seeing something at its 
native resolution and seeing it scaled. As long as the screen is full they 
are happy. Present company excepted, of course.

Look at the horrible distortions people are willing to put up with to fill 
their 16:9 screens with 4:3 material. I know they say television adds ten 
pounds, but that's ridiculous.

The CNN crawl looks interesting with some of those non-linear stretching 
schemes.

-- 
Brian Wood
beww at beww.org


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