[mythtv-users] overscan problems with nvidia 8400 GS

Tortise tortise at paradise.net.nz
Tue Jul 7 01:14:34 UTC 2009

Interesting replies with good points thank you Johnny and Brian.

I wonder if it might be fairer to say NVIDIA has an opportunity rather than a responsibility?  The problem is not made by them, they 
certainly could look to (and have done in the past) address it in Linux drivers.  This seems a kludge to me with risks of image 
blurring, for best images I'd prefer 1:1 pixel matching.

Since writing about this here, I have considered some more the issue of when should a manufacturer be responsible for fixing 

My answer is that when they promoted a set to a certain display resolution, without further clarification, the set should fully 
display that resolution, which means the viewer should see that full resolution and not 5% off the edges.

I calculate 5% overscan equates to showing 81% of the pixels sent to the monitor, which means the consumer is effectively cheated 
19% of the display area.

SD sets to my knowledge were silent on this aspect, so that seems fair enough to me, there is nothing to fix.

HD ready sets that are said to display e.g. "1080i as native resolution" should display the full 1080i.

The historical perspective is interesting in understanding how the problem has been perpetuated.  It does not take away a 
manufacturers obligations that they create for themselves and that was fairly and unwittingly accepted by reasonable consumers.

Another issue perhaps worth touching on here is the question of forseeability and "future proofing" "HD Ready" TV's.  I think given 
the industries readiness and willingness to "invest" in HDCP for consumer benefit (I look forward to understanding what the 
feature's benefit is) well into the future provides a useful precedential benchmark for TV overscanning and how "HD ready" a set 
should be and particularly over what future time frame future proofing should apply..  I can amplify on this for New Zealand if 
anyone is interested - there may be useful parallels in other countries also.

I think its actually really quite simple, if the TV manufacturer promoted a TV display resolution then the set should provide it. 
(With option of no overscanning)  Manufacturers might be resistant to providing the first few but once the precedent is confirmed 
they will likely become more obliging.

----- Original Message ----- 
From: "Johnny" <jarpublic at gmail.com>
To: "Discussion about mythtv" <mythtv-users at mythtv.org>
Sent: Tuesday, July 07, 2009 1:52 AM
Subject: Re: [mythtv-users] overscan problems with nvidia 8400 GS

> I've been studying this for some time now as I also enjoy the overscan problem. While mythtv can fix it for mythtv it does not fix
> it for the desktop.
> If consumer / users lobby their retailers and higher up the chain some more appropriate and permanent fixes might come our way.
> The question has been asked which NVIDIA cards have the problem e.g. the 8400 has been "named" in the subject. As best I can tell
> it is not a card model problem, they all share the same "problem" but not of their making. Lets get the root of the problem fixed.
> I look forward to hearing comments in response to the tortise's view of things.

It is true that overscan is caused by the TV and not the video card,
however, the problem of displaying stuff from a computer on a TV is
shared by the TV and the video card. In the case of SD TVs, they were
never intended to be hooked up to a computer and so it is unreasonable
to hope for them to fix this issue. So in my opinion, if Nvidia
provides a TV out option they do have some responsiblity to help me
display stuff correctly on that TV (especially since overscan is
standard in many many TVs).

Also for most older TVs it will be more than a firmware fix. The
overscan is probably set in hardware rather than software. Also the
reason people are focusing on Nvidia is that the ability to fix
overscan was available in all of their cards for many years. It is
only recently since 8xxxx and above that the overscan setting was
removed. I imagine the hardware that supported the feature changed and
they just haven't got around the rewriting the code for the newer
hardware, because as you mentioned there are other higher priority
things to be done first. However, a friend confirmed for me that he
can adjust overscan with his 8800 on Windows. So it seems that it is
only the Linux driver that hasn't been updated with this feature. It
seems much more likely that a single video card maker will re-enable a
feature in their new cards than getting a whole myriad of TV
manufacturers to redesign their hardware and provide firmware updates
for older sets. So for those of us with this issue on our existing
sets, Nvidia providing a fix is really the only reasonable option.
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