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

jori.hamalainen at teliasonera.com jori.hamalainen at teliasonera.com
Tue Jan 6 11:20:38 CET 2009


> 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.

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. 

Naturally way to determine this is to have test patterns drawn to a screen
and look closely (mag. glass) to see if you have 1:1 mapping. You need to
remember that HDMI/DVI is not a digital bus, it is 'analogue'-type signal 
transferred in digital fashion. Why else you need porches et al at signal 
timing?

With this I mean that HDMI-signal does not say:
-frame coming at resolution 1920x1080p50
-pixel at 0,0 use color 0,0,0
-pixel at 1,0 use color 255,255,255
-pixel at 2,0 use color 0,0,0
...

HDMI says:
- vert. sync
- hor. sync
- front porch time
- (0,0,0),(255,255,255),(0,0,0),.....

And it is up to TV electronics where to place those pixels on LCD panel. And
this is done with overscan settings etc.

- Jori
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