[mythtv-users] modelines for an hdtv LCD

[Nick Rout]

I have just acquired a Panasonic TX-32LX500A TV. It has HDMI, component,
svideo and composite and PC inputs. It is widescreen, with native res of
1366x768

I am using as media PC an Epia M9000. 

I am having problems getting X to work well on it.

If I simply run X with a minimal xorg.conf then I get 640x480, I guess
because the TV does not seem to respond to probes about its
capabilities. If I put the refresh rates from the manual into the
monitor section of xorg.conf I get 1400x1050. (somewhat bizarrely given
that its native resolution is 1366x768)

Now I would like to get it going at a 16:9 resolution, which according
to the manual are available at 1366x768 and 852x480. I don't actually have any HD sources, so 852x480 would do nicely. I have tried generating
modelines for the xorg.config file using a number of online and offline
calculators, none of which work for me.

I am not sure why the modeline calculators do not give me the exact
resolutions I want. For example trying to get an 852x480 @ 59.94:

nick at www ~ $ gtf 852 480 59.94

# 848x480 @ 59.94 Hz (GTF) hsync: 29.79 kHz; pclk: 31.46 MHz
Modeline "848x480_59.94"  31.46  848 864 952 1056  480 481 484 497
-HSync +Vsync

Why does it go to 848 when i requested 852? And why doesn't X start at
that resolution, when I specified that resolution in xorg.conf?

Its all a bloody mystery to me! Pointers gratefully received.

Specs
======

The manual states:

"Computer signals which can be input are those with a horizontal
scanning frequency of 31 to 69 kHz and vertical scanning frequency of 59
to 86 Hz. (However, the image will not be displayed properly if the
signals exceed 1,024 lines.) When the aspect mode is set to 4:3, maximum
of 1,024 × 768 dots area of LCD panel is used for display, and when the
aspect mode is set to 16:9, full area (1,366 × 768 dots) of LCD panel is
used for display."

It also has a useful looking table "Input signal that can be displayed" at the back. I have put the three pages into a separate pdf here:

http://homepages.ihug.co.nz/~nickr/panasonic.tvspecs.pdf
-- 
Nick Rout <nick at rout.co.nz>