[Info-vax] Audio and video technology, was: Re: getting pixel dimensions of monitor

[Simon Clubley]

On 2013-02-05, VAXman-  @SendSpamHere.ORG <VAXman- at SendSpamHere.ORG> wrote:
> In article <38b648d2-c430-4253-a60b-4b189920c08e at ia3g2000vbb.googlegroups.com>, AEF <spamsink2001 at yahoo.com> writes:
>>On Feb 5, 8:47=A0am, Simon Clubley <clubley at remove_me.eisner.decus.org-
>>Earth.UFP> wrote:
>>> On 2013-02-04, AEF <spamsink2... at yahoo.com> wrote:
>>>
>>> > On Feb 3, 8:50=A0am, hel... at astro.multiCLOTHESvax.de (Phillip Helbig---
>>> > undress to reply) wrote:
>>>
>>> >> The numbers come from trial and error. =A0Using them on a different
>>> >> monitor sometimes results in stretched images, so the ratio is probabl=
>>y
>>> >> not the same. =A0Is there some standard way to find out what the ratio
>>> >> really is? =A0(Probably not, otherwise one could set it on the fly.)
>>>
>>> > Uh oh, another case of aspect-ratio disease! Phillip, I wish you luck
>>> > on your endeavor to eradicate this instance of the disease. But it's a
>>> > plague. I've even seen TV's (LG's) with the picture over-stretched!
>>> > That means it would have fit as is but was somehow stretched even
>>> > more.
>>>
>>> The information Phillip needs is encoded in the EDID structure on modern
>>> monitors. On a modern OS (ie: Linux) that information is read automatical=
>>ly
>>> and the graphics controller configures itself as required; there are no
>>> aspect ratio problems at the native resolution.
>>
>>Score one for Linux.
>
> Really?  Then why did I recently spend 2 days dicking about with getting the
> video to work properly when I upgraded???  It's now working at 1920x1080 but
> it didn't happen/configure all by itself!
>

Your old settings were probably retained because a manually configured
setting overrides the automatic detection even across monitor changes.

I've moved from 1280x1024 to 1920x1080 over the last year and in each
case, while my manual 1280x1024 settings (which I had for historical
reasons) were used on the new monitor, all I did was to comment out the
manual settings in xorg.conf and restart X.

In each case, the new monitor was then probed automatically and the
desktop came up just fine at 1920x1080 without any further action
required. This took me just a few minutes and was on unbranded generic
hardware; I am not using anything specifically branded as supporting
Linux.

I could probably have used the desktop widgets to remove the manual
settings but it was easier and quicker to just edit xorg.conf.

While the displays worked just fine after this, in fairness, I should
also point out that while looking through the xorg log file I noticed
that the highest available pixel clock setting had not been used so
I dropped a modeline into xorg.conf and got a very slight improvement
in display quality.

I only did this because I tend to be a perfectionist in this area
and the display was perfectly fine without it and did not have any
noticable problems prior to adding the modeline.

In case this causes you to look at modelines, I must also add a strong
warning: DON'T TRY PLAYING WITH MODELINES YOURSELF UNLESS YOU KNOW WHAT
YOU ARE DOING. If it's a CRT, you can physically damage it. If it's a
modern LCD, it may shutdown before damaging itself but there are still
no guarantees here.

In either case, if you use a faulty modeline that disables your
monitor, you will need another way of getting back into your
system to reverse your changes.

Also, read the various warnings online before playing with modelines
if you don't believe me. :-)

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
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