[mythtv-users] S-video & widescreen - both in and out

[David]

Nigel Metheringham wrote:

>On Fri, 2005-04-01 at 08:49 +0100, David wrote:
>  
>
>>PS I think Nigel's problem is fundamentally that he's sending an X 
>>display to a device with non-square pixels.
>>    
>>
>Well ideally I would like to get square pixels (even if I actually make
>it so I have squashed horizontally pixels, and an overall stretch on
>display by the TV to make em square again)  - but I can't find a 16:9
>type mode that TV out.
>  
>
I don't think you can.
from : 
http://www.creativevideo.co.uk/pages/cvp_info_widescreen_explained.htm
"It’s a common misconception that there are more pixels in a recorded 
16:9 SD image than a 4:3 one because in reality all PAL D:1 images are 
actually 720x576 pixels, it’s just that a true 16:9 image is 
anamorphically squeezed into 720x576 pixels…"

So a TV signal (again, AFAIK) only contains 720x576 pixels.
A widescreen TV signal has the same number of pixels but each pixel is a 
different shape (in fact, for anamorphic, they're not even the same 
shape as each other - I *think* anamorphic is not relevant here)

So (again AFAIK) there's no point in messing about with resolutions - 
the card will essentially scale to 720x576 anyway.

This all changes for 16:9 projector (and probably 16:9 plasma/lcd 
screens and HDTV) where there are a different number of pixels.

My projector actually has 856x480 (square) pixels (the US is a big 
market so I get stuck with NTSC height <sigh>) so in my case the 
applications can just scale the video and it all looks fine!
(This is just by way of giving you a decent argument to give to the wife 
to buy a projector <grin>)

>>X (AFAIK) can't handle non-square pixels whereas video has anamorphic 
>>compression (and maybe other things...)
>>    
>>
>Sounds about right, shame I can't get things consistent right through
>the system....
>
A thought just occured.
X *can* do this - but not all X apps will take it into account - but I 
think Qt is better at it than most... I'd expect Myth to aspire to 
improve too.

Can you edit your XF86Config-4 file and go to the Monitor section, then 
add in a line like this:

Section "Monitor"
...
DisplaySize 728 270
EndSection
Where the numbers are the width and height of your widescreen display in 
mm (give or take 5mm is fine)

This will tell X that your pixels are not square. I don't think it will 
be a panacea (I expect your fonts won't be 'square') but it may help some.

David