[mythtv-users] Minor Screen Refresh Visible

C.T. Paterson i.adore.my.64 at gmail.com
Wed Jul 30 18:12:50 UTC 2008


2008/7/30 Petteri Matilainen <pmatil at gmail.com>:
> Dan Ritter wrote:
>> On Wed, Jul 30, 2008 at 09:28:44AM -0400, C.T. Paterson wrote:
>>
>>> 2008/7/30 Dan Ritter <dsr-myth at tao.merseine.nu>:
>>>
>>>> On Wed, Jul 30, 2008 at 08:39:54AM -0400, C.T. Paterson wrote:
>>>>
>>>>> 2008/7/30 Petteri Matilainen <pmatil at gmail.com>:
>>>>>
>>>>>> VGA->SCART adapter cable. Do I need to modify the xorg.conf modeline?
>>>>>> Any help is greatly appreciated.
>>>>>>
>>>>> My experience does not suggest I had a modeline problem - but it's
>>>>> possible.  Where did you get yours from?  I've got an LCD HDTV, and
>>>>> some of them are known to supply incorrect modelines to Xorg (google
>>>>> for a "UseEDID" xorg option).  Mine appeared to be one of them, so I
>>>>> obtained mine by running "gtf" on the command line, and used the
>>>>> generated modeline in my xorg.conf.
>>>>>
>>>> You could certainly be running with a modeline that your LCD
>>>> does not quite like. I just acquired an LCD, and discovered that
>>>> the NVidia built-in 1920x1080_60 mode was horrendously
>>>> overscanning horizontally. The manual contained all the required
>>>> timings, though, and I built a perfect modeline out of that.
>>>>
>>> If you're inclined, Dan, I'd be interested to know how.  My knowledge
>>> of modelines is pretty slim - and while my manual has a bunch of
>>> information in it - I wouldn't know how to construct a modeline out of
>>> it (although gtf seems to have served me well).  I'm merely curious.
>>>
>>
>> What LCD do you have? Is the manual online? I'd be happy to
>> help.
>>
>> An X modeline is not black magic; it's a list of timings, mostly
>> in terms of pixels:
>>
>> Rate HDisplay HSyncStart HSyncEnd HTotal VDisplay VSyncStart VSyncEnd VTotal
>>
>> You know the HDisplay and VDisplay fields immediately: those are
>> the visible pixels. The Rate is the pixel clock, in millions per
>> second. That should be in the manual.
>>
>> Manuals like to specify FrontPorch, BackPorch and Sync;
>> considers there to be offsets to add to the previous entry, so
>> we get:
>>
>> HDisplay
>> HSyncStart = HDisplay + FrontPorch
>> HSyncEnd = HSyncStart + BackPorch
>> HTotal = HSyncEnd + Sync
>>
>> Then, for vertical timing, it works out the same way.
>>
>> Adding +/- HSync and +/- Vsync flags indicates the polarity of
>> the signals; again, that should be in the manual.
>>
>> -dsr-
>>
>>
> Sorry to jump in, but I have a 16:9 CRT TV, for which I don't know the
> correct timings. "Standard PAL" from mythwiki is not it, because there's
> too much overscan IMO and the picture is not centered (seen when in 4:3
> mode). I'll have to play with modeline when I have the time. Don't know
> how modeline affects the vertical "artifacts".

In addition to modeline, I've also used screen positioning as
controlled through the TV (don't imagine a tube is clever enough to
let you do that), and there are offsets that I've used in Setup ->
Appearance.

Many ways to skin a cat...

-- 
"My country is the world, and my religion is to do good."
 -- Thomas Paine


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