[vdr] 1:1 pixel mapping - a waste of time?

Ville Aakko ville.aakko at gmail.com
Tue Jan 6 15:59:01 CET 2009


2009/1/6  <jori.hamalainen at teliasonera.com>:
>
>> I don't know how to do the latter, and even if it is possible in all
>> cases. In my setup, I have set up my video card to 1:1 to the panel I
>> have (fullHD), since I have material in several different resolutions,
>
> This is the theory. But you need to remember that you are using TV set as
> a monitor, and typical TV sets, even FullHD ones implement overscan on HDMI
> input. Some TVs disable overscan via special switch.

Yes, you are right. On my Sony it is called "Täyskuiva" (in finnish),
when I had not enabled it, thie TV did overscan IIRC.

> But having overscan it means that having the 1:1 mapping is a bit harder.
> You need to find out how much is the real visible resolution and define X-
> screen to that resolution.

I'm not sure what you mean by the above, surely you need to setup X to
use the native resolution of the panel? Perhas you meant something
different, as I did notice when I did my setup; that fgrlx (yuch, I'm
an user of the dreadful fglrx) does a terrible underscan by default,
becase it reports a larger screen area trough the HDMI that is
actually used (?). I'd assume that nvidia, intel & perhaps some others
do this better by default.

It is beyond me why an ouput that is used for a digital display uses
any kind of over/underscan, but that really was the case. Then I
stumbled on this:

<http://www.phoronix.com/forums/showthread.php?p=36734#post36734>

And got 1:1 mapping at all refresh rates ever since. Thoguh, I still
get terrible tearing - I've heard that the radeon driver should be
better in video use, but I couldn't get it to work on my card, and I
also need DRI... I should've bought nvidia, damn.

I used a small program called lcdtest to test the 1:1 mapping. Believe
when I say you do notice the difference =). Also I use a desktop and
it is drawn exactly to the edges as it should be.


-- 
-- 
Ville Aakko - ville.aakko at gmail.com


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