[mythtv-users] Sync rates for Sharp 32 inch LCD

Wed Jan 25 18:18:52 UTC 2006

kteague at speakeasy.net wrote:
>> -----Original Message-----
>> From: Richard Bronosky [mailto:mythtv at bronosky.com]
>> Sent: Tuesday, January 24, 2006 07:59 PM
>> To: 'Discussion about mythtv'
>> Subject: Re: [mythtv-users] Sync rates for Sharp 32 inch LCD
>>
>> I want to make sure that people don't buy/refuse to by on mixed info.  I
>> DO have my KnoppMyth box <http://www.bronosky.com/index.php?p=21>
>> displaying on my Sharp Aquos LC-32D4U with a simple DVI->HDMI cable.  My
>> concern is fixing the overscan.  I want to know the technical
>> capabilities of the TV so that I don't hose it with the wrong sync rates.
>>     
>
> Well, seeing that you've already lurked in another thread:
>    http://72.14.203.104/search?q=cache:_fHc8RVDkzUJ:mysettopbox.tv/phpBB2/viewtopic.php%3Ft%3D7446%26+LC-32D4U+modeline&hl=en&gl=us&ct=clnk&cd=1&client=firefox-a
>
> ... and that you're new to Linux, the best I can do at this point is offer more pointers.  Please forgive me if I get too basic.
>
> The gentleman in that thread was having a similar problem as you.  He found that, if he starts X using startx --logverbose 6, X would provide him with verbose logging, which is normally output to /var/log/XFree86.log.0.  This is where he found X had outputted some display ranges.  Armed with this information, he went to http://xtiming.sf.net/cgi-bin/xtiming.pl, making some small tweaks based on the information he received, in attempts to produce a proper modeline without overscan.
>
> While you can easily find modelines for various resolutions on the Internet (Google is your friend), 
Actually Yahoo! is my friend, since they sign my paychecks
<http://www.bronosky.com/index.php?p=13>.
> the timings that produce these resolutions may not coincide with your display adapter, as well as your TV.  If we were back in 1996, I would say, "Be careful when experimenting with timing modes, and fully understand what you're doing before you implement it".  However, in this day and age, VESA standards have come a long way, and it's been ages since I've seen a display that is not compliant with the latest VESA standards.  Things this standard should provide you are:
>
>    - Drop sync with frequency is OOB (Out of Band).  If you throw a timing at it that is too high for the display to support, it should drop sync to the display and, normally, the power LED on the display will illuminate in orange.
>
>    - DDC (Direct Data Channel).  This is a standard method for communication between the display adapter and the display.  This is the channel that is used by the display adapter to query the display for EDID information.
>
>    - EDID (Extended Display Information Data).  Displays contain this information to tell the display adapter which resolutions and timings it supports.
> Back in the days, when monitors complied to earlier (or no) VESA standards, when one would fiddle with X timings, the documentation 
>
>   
Great info.  That should be posted everywhere that modelines are mentioned.
> I'm not sure if your display is fully VESA compliant, so I'll be on the safe side here and say, "Be careful when experimenting with timing modes, and fully understand what you're doing before you implement it". :-)  That said, check out:
>    http://www.avsforum.com/avs-vb/archive/index.php/t-546124.html
>
>   
Awesome thanks for this link.
> Also be sure to read and fully understand:
>    http://www.tldp.org/HOWTO/text/XFree86-Video-Timings-HOWTO
> ... be warned; it's not for the faint of heart.
>
> I recently installed Debian (Etch) on a newly purchased clone box I built.  It has a EVGA GeForce 7800 GT and is attached to a Westinghouse LVM-37w1.  The LVM-37w1 has a native resolution of 1920x1080 and can support the following:
>    1600x900
>    1280x1024
>    1280x720
>    1152x864
>    1024x768
>    800x600
>    640x480
> In <cough>WinXP</cough>, I can get all of these resolutions besides 1280x720, although I know the monitor can display it.  The same for Linux, however, I could probably get 1280x720 if I threw it in my Modes line.  In Linux, all I had to do was:
>    1. Use nVidia's "nvidia" driver, rather than the "nv" driver supplied by ?the kernel?  The nv driver would hard-lock my box after logging in to GDM (Gnome Display Manager).
>    2. Modify my /etc/X11/xorg.conf to include the HorizSync and VertRefresh my display supports.
>    3. Modify my Modes line in my /etc/X11/xorg.conf to:
>       Modes     "1920x1080" "1600x900" "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
>
> >From here, I restarted X, it read the Modes line from my /etc/X11/xorg.conf, ran some EDID queries via DDC, found the timings my monitor supports, and displayed a GUI.  It was that easy.  However, keep in mind that I mentioned your display may not be fully VESA compliant, may comply to some older VESA standard, or may only support VESA on a certain input.  Your luck may vary with this solution.
>
> Perhaps one of the first things I'd do is to contact Sharp.  I know you've done this and they were not much help, but ask them if the monitor will drop sync if it's supplied with a frequency that is OOB.  If it does, then you should feel safe when experimenting with video timings, as it shouldn't open up the small chip with the white smoke.  Dig a little deeper and see if they can answer if it supports VESA standards, which VESA standard revision it supports, and if it only supports VESA standards on certain inputs.
>
>   
If I find out it does have the protections you mention above, I guess I
could try to push the limits until it drops sync.  Then I'd know it's
DC, H, and V sync rates. :-D

> Secondly, I'd read the X-video-timings HOWTO until my eyes bleed, brain is swollen, and I feel confident that I can tweak X timings to match what my display could handle.
>
> Once you fully understand video timings, you can work with your currently working, yet overscanning, config and tweak it to fit your displays needs.  This is the only way to go if you're not getting cooperation from Sharp.  The road will not be easy, but it's definitely achievable.
>
> Good luck!
>   
It seems that There are 2 modelines in play here.  One when I chvt[1-6]
and one that XFree86 is using on chvt7.
How do I get my terminal [1-6] to use the new modeline? (What file is it
using for conf?)
All the changes I make are to /etc/X11/XF86Config-4.  Is there a way to
modify the display mode of the boot process?
How early can this be done?  (The BIOS screens are a pain)
> - Ken 
>
>
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>   

-- 
Thank you for your time,
--==<< R i c h a r d   B r o n o s k y >>==--

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	http://www.gossamer-threads.com/lists/ivtv/users/
	http://knoppmythwiki.org/
I may have missed the answer there, in which case, please point out the article to me, but don't say "check forum X."

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