[mythtv-users] HDTV Modeline Help
Cory Papenfuss
papenfuss at juneau.me.vt.edu
Tue Dec 13 06:57:54 EST 2005
On Mon, 12 Dec 2005, Richard Shaw wrote:
> It looks like you're right. I tried a 1080i modeline and it did work. I would
> be happy with that but at 27" the text in Firefox was so I couldn't read it.
> Right now I'm messing with 540p which I have working but it doesn't look very
> good. It could be I'm trying to get it to work in 4:3 ratio instead of 16:9.
> I don't really want to have it in widescreen since it's not a widescreen
> television. I guess I shouldn't complain too much, the picture is otherwise
> good and I only paid $450 for it.
>
Here's the "same" 1080i modeline converted ot progressive-scan
540p.
ModeLine "540p" 37.092 960 980 1004 1100 540 542 547 562 -hsync -vsync
Basically everything is divided by 2 but the interlace isn't there.
That means you still get 33.72kHz horiz, but 60Hz vertical. It's a 16:9
ratio (960x540), but at least it's some semblance of "HDTV standard." You
may be able to coerce the 4:3 ratio you want by setting the DisplaySize in
your xorg.conf... I do that for getting 4:3 with my non-square-pixel
720x480 modeline on my 4:3 set. Something like
DisplaySize 200 150
(since 200/150 = 4/3)
If you really want square pixels and a 4:3 and progressive scan,
you're stuck somewhere between 640x480 and 800x600. That's all the better
the TV will do.
-Cory
>>
>> ModeLine "1080i" 74.175824 1920 1960 2008 2200 1080 1084 1094 1125
>> interlace -hsync -vsync
>>
>> That puts out 33.72kHz HSYNC and 29.970 VSYNC. It will be
>> underwheliming to use as a desktop resolution because it will be huge and
>> very flickery with the interlacing at 30Hz. It should work with the TV
>> though.
>>
>> One of the reasons your modeline generate probably didn't work is
>> because they rarely offer the "interlace" option. That effectively halves
>> the horizontal scanrate required for a given resolution. 30-35kHz pretty
>> much limits you to somewhere between 640x480-800x600 in computer-ese
>> resolutions. Not much more over EDTV.
>>
>> Cheers
>> -Cory
>>
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>>
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>
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--
*************************************************************************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
*************************************************************************
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