[mythtv-users] overscan problems with nvidia 8400 GS

Brian Wood beww at beww.org
Sat Jul 11 14:11:46 UTC 2009


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 would much rather spend my money on a better tube or decoding
> electronics than reducing a small amount of overscan to a very small
> amount of overscan and think it's quite an elegant solution.

The real answer with consumer sets was to manually set the picture parameters 
(height, width) to show the entire picture, and adjust as the set aged.  
Stations even used to transmit test patterns which would assist this process.

Back when I worked for a TV station we had to re-set all the consumer sets we 
bought for people's offices, because the users *did* notice the overscan.

The problem was that "small" amount of O/S became larger and larger with some 
sets, since there was no standard for how much O/S was tolerable.

Of course things like the CNN crawl didn't exist back then, if they had the 
overscan would have been obvious to many folks.

>
> Matt,
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-- 
Brian Wood
beww at beww.org


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