[mythtv-users] overscan problems with nvidia 8400 GS

Simon Hobson linux at thehobsons.co.uk
Mon Jul 13 06:55:07 UTC 2009

Matthew Harrison wrote:

>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.
>"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.

I think it means exactly that ! How completely f***ing crazy can it 
be to define a standard where the source can supply a high quality 
digital signal that's been scaled to the right size in the decoding 
section (ie where it will create the least artifacts) - and then 
resample it to guarantee some distortion of the picture !
Though to be fair, I suspect the standard doesn't specify how many 
pixels the panel itself has - in which case, it seems crazy that 
manufacturers produce panels with 'non native' resolutions. Why not 
produce a 1776x1000 panel for a 1080 set and avoid the rescaling 
altogether ? I guess I can answer that myself - our less educated 
brothers (and sisters) would probably then refuse to buy it as not 
being "full 1080" :(

The more I find out, the more I think we've been sold a pup here. On 
digital signals, why any need for overscan at all ?

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

More information about the mythtv-users mailing list