custom modeline help needed

[brake16]

Good Morning

I've been trying for the past couple of weeks to fix the overscan on my KDE destktop (Orbiter displays fine).  I'm out of ideas, and I could use some help.

My 1080p Samsung DLP TV is connected by HDMI to the hybrid.  Orbiter displays nicely.  KDE desktop is overscanned by a couple percent on all sides, top & bottom: on the bottom, I can't see about half of the panel.  I've customized the modeline ad nauseum to no avail.  Here are some of the websites I've looked at
http://forum.linuxmce.org/index.php?topic=7732.0
http://ubuntuforums.org/showthread.php?t=1003099&page=2
http://wiki.linuxmce.com/index.php/Display_Drivers
http://en.wikipedia.org/wiki/Modeline
http://www.mythtv.org/wiki/Working_with_Modelines
http://www.mythtv.org/wiki/Modeline_Database
http://www.mythtv.org/wiki/Configuring_TV_output

I've tried various EDID settings, with no effect.

I've tried countless different "customized" modeline settings using calculators, the MythTV Modeline Database, and Google + Samsung + Modeline.  When I tried making my own tweaked modeline using the instructions found here (http://ubuntuforums.org/showthread.php?t=1003099&page=2), I was able to change the size of the screen, but not the position.  Some background numbers:

148.5 1920 2008 2052 2200 1080 1084 1089 1125 (This is my default 1080p setting, slightly overscanned on all screen edges).
148.5 1800 2008 2052 2200 980 1084 1089 1125 (This makes the display region smaller, so that I can see the right & bottom edges of the generated display...ie: the mouse pointer stops moving at the black edge on the right & bottom)
148.5 1800 1887 1931 2200 980 1084 1089 1125 (This should have moved the "screen edges" to the right, but nothing changed(?!?).  Very confusing).
148.5 1800 1886 1930 2200 980 1084 1089 1125 (This gives an unusable display)

Also, using or excluding +/-hsync or +/-vsync made no difference to the result (yes, I tried all the iterations on several of the modelines.  I even tried using HSync & VSync, since there's a disparity on some of the MythTV pages about capitalization).

My PS3 displays 1080p content on the TV without problem, so the issue should be in the hybrid somewhere.

I'm running 7.10 on the hybrid.

Any help?  My head's starting to hurt from this wall it keeps banging on.

Bryce

[merkur2k]

I cant really give any specifics here, but i just went through the same thing with my 720p set.
It all boiled down to some outright wrong information in the industry, very basic stuff too.
ALL 720p sets advertise themselves as having native res ov 1366x768. This is WRONG for as far as i can tell every set out there! Its actually 1360x768. As soon as I configured a modeline for that, all my problems went away. pixel perfect display in both lmce and kde desktop.
Even the EDID response contains the incorrect 1366x768 resolution.
I would suspect that 1080p sets have the same problem, but it may take some digging to find the exact resolution needed.

[geekyhawkes]

Interesting on the 720p issue, i was wondering why my modeline hadnt solved the overscan within the KDE desktop.   Merk, could you post your 720p custom modeline please?  It would give me a starting point to try and get my overscan sorted (again!)

[brake16]

I cant really give any specifics here, but i just went through the same thing with my 720p set.
It all boiled down to some outright wrong information in the industry, very basic stuff too.
ALL 720p sets advertise themselves as having native res ov 1366x768. This is WRONG for as far as i can tell every set out there! Its actually 1360x768. As soon as I configured a modeline for that, all my problems went away. pixel perfect display in both lmce and kde desktop.
Even the EDID response contains the incorrect 1366x768 resolution.
I would suspect that 1080p sets have the same problem, but it may take some digging to find the exact resolution needed.

Thanks for that.  It lead me to investigating incremental modeline changes, which convinced me to try it first on my Vista setup with powerstrip.  Reading the powerstrip FAQ's (http://forums.entechtaiwan.com/index.php?topic=24.0), I found this:

• You must know the resolution your monitor wants, and you must understand that not all resolutions are possible. In particular, note that graphics cards generally do horizontal timings in character clocks of 8 pixels, not individual pixels. Unless you have a ATI X1k, NVidia digital connection, Matrox Parhelia or early Kyro, your desired horizontal resolution should be evenly divisible by 8, and your vertical resolution should be an even number.

So your 1360 will probably also work at 1368, but then you'd be overscanned by 2 pixels .

For me, it seems that I will get no resolution (haha) to my small problem, since my TV will not cooperate with the customization guide (http://ubuntuforums.org/showthread.php?t=1003099&page=2).  For now, I used a portion of that guide and limited my screen resolution to 1845x1040.  This gives me a well-lined-up bottom & right edge.  The left and top edge are still overscanned mildly.  To compensate for this, I moved my desktop icons over, and configured the panel so that it's right-justified, and only 97% long.  This makes it look like it fits perfectly.  Of course, anytime I open a window, it is off the top & left edges of the screen, but then again, may this be the worst thing that happens to me.

After all this was done, I readjusted the Orbiter spacing and offset (Advanced, Advanced, Adjust spacing and offset) to make it fit the new screen.

For those curious, apparently the PS3 & X-Box developers took a note from the TV/film folks and made use of "title safe" and "action safe" areas (http://en.wikipedia.org/wiki/Overscan) to compensate for overscan. 

Also, for those curious, it is sometimes possible to go into your HDTV's service menu and turn off overscan so that your TV acts more like a computer monitor.  This would not be advisable if you still plan to hook up other appliances to your TV.  (Of course, all the "secret" tips for getting into my TV's service menu don't work).

Lastly (this one's for your geekyhawkes), according to the MythTV modeline database (see link in first post), this is a standard EDID modeline from an HDTV:
ModeLine "1360x768" 85.50 1360 1424 1536 1792 768 771 778 795 -HSync -VSync

Hope this helps somebody
Bryce

[merkur2k]

Yep, I had eventually found that on this page: http://www.nvnews.net/vbulletin/showthread.php?t=88638

[colinjones]

Yes, switching to "PC Mode" is often a good idea. Also, many Samsung screens have a "Just Scan" mode in their Aspect Ratio menu, which forces it to use the supplied timing instead of guessing its own! This was necessary for me to get rid of overscan on mine for 1080p50 (1080p60 of course worked perfectly! Even though there are very few countries that use 60Hz for TV!!) Problem is, Samsung in their wisdom made this option non-persistent, so you have to reset it every time resolution changes, source changes, etc!

[geekyhawkes]

Thanks guys, between the details above and the following wiki post i have solved my overscan and now have mce running at 1080 (and not 720)! 

http://wiki.linuxmce.org/index.php/Custom_Display_Resolutions

Sweet! 

Thanks again