Re: Display bleeding off monitor edges at max resolution

[juan_kerr]

Hello,

I am experimenting and am trying to move from Windows to Linux. I have installed Kubuntu 6.10 Edgy Eft and I also installed the latest NVidia linux drivers (64 Bit) last night.

This was a god send in that I managed to move from the basic 640 x 480 resolution, which was bleeding off the display edges to a mighty 800 x 600!
However everything is now on the screen and I can use it all properlly.

The next step is to ramp it up to my maximum display resolution of 1280 x 720, which the driver will do. However, when I do this I'm back to the display bleeding over the edges of the screen again, so I can't see the full desktop and taskbar. This is on my 32" widescreen LCD TV by the way, if that's relevant.

How do I fix this, while maintaining this resolution?

Previously in Windows I have been able to reduce the display size to fit the dimension of the screen, using the tweak tool on the driver. Is there anything similar for Linux?

Thanks for any help.

[netllama]

Please start X with the following command:
startx -- -logverbose 5

and then generate and attach an nvidia-bug-report.log

Thanks,
Lonni

[Workaphobia]

I'm no expert, so someone correct me if I say anything wrong.

You should be able to customize the display for your monitor by setting an appropriate ModeLine in the Monitor section of your xorg.conf and listing it in your Modes option in your Display subsection. Default VESA modes like "1280x1024" are built in to X, but these defaults don't always align with the screen.

A ModeLine consists of something like this

ModeLine "my_1280x1024_60" 108.00 1280 1312 1424 1688 1024 1025 1028 1066 +hsync +vsync

which happens to work well on my SyncMaster 930B. Starting from a working modeline for your monitor, you can slowly modify the horizontal and vertical timing values to shift the display a little bit. Which parameter is which is defined in the xorg.conf man page. I don't pretend to understand the specifics, I just remember something about experimenting by changing the hsyncstart and hsyncend (values 1312 1424 in the line above) by a couple multiples of 8, and changing vsyncstart/vsyncend (1024 1028 above) by just a few units (multiples of one). You can probably find on google linux instructions on how to alter them by hand.

However, I've heard that specifying a few bad parameters that are out of range can damage your monitor, so use it with caution.

xvidtune is a useful app that creates a modeline for you and allows you to interactively adjust it left, right, up, or down, and see the results. If you're on Suse, I know Sax has a similar tool (although I used to struggle with it). To get a modeline to start out with, I believe you can find what it's using as a vesa default by running with -logverbose 5.

I hope some of that helped.

[mystica555]

Originally Posted by juan_kerr

Hello,

The next step is to ramp it up to my maximum display resolution of 1280 x 720, which the driver will do. However, when I do this I'm back to the display bleeding over the edges of the screen again, so I can't see the full desktop and taskbar. This is on my 32" widescreen LCD TV by the way, if that's relevant.

Out of curiosity, is this an LG 32" tv? I've noticed that some of these (most/all? i only have seen a few of them personally) seem to overscan on HD channels connected even via HDMI.. I'm not entirely sure the reasoning for this. (I work in the consumer electronics industry, albeit at a Radioshack, so the selection of tvs i have seen, isnt so wide..however, side-by-side against an akai, and Panasonic, the LG definitely has overscan, and it bothers me)

Also, if this tv was bought recently, its probable that it has a 1366x768 actual resolution. Try to see if you can get a "x768" rather than "x720" mode, to see if this helps the overscan issues, as the TV may be compensating for what it thinks is a "TV" signal, rather than a "Computer" signal. Seems plausible, however, I have yet to try anything with the tvs at my work.

Mike

[pe1chl]

Originally Posted by Workaphobia

However, I've heard that specifying a few bad parameters that are out of range can damage your monitor, so use it with caution.

You can streak this from your book. It if from the ninetees.

[pe1chl]

Originally Posted by mystica555

i only have seen a few of them personally) seem to overscan on HD channels connected even via HDMI.. I'm not entirely sure the reasoning for this.

It is in the standard. TV standards, including HDTV, specify that a certain area of the frame should not be shown in typical trim, so that there is a bit of tolerance to play with for setup of picture size.

It was designed this way in the CRT days. CRT picture size always varied a little with temperature, age, picture brightness etc.
Furthermore in analoge transmission there could be transient effects at the picture edges that should not be visible on screen. Hence the overscan.

For LCD and plasma, with digital transmission or PC output, it is completely superfluous. But it is in the specs so most TV set manufacturers abide by it.

It causes endless problems for those that want PC output with 1:1 pixel mapping to the screen resolution, but apparently those are not the main clientele for them.

[juan_kerr]

Thanks for your responses. I'm running Kunbuntu 6.10, this is my first venture into Linux, so I'm kind of chucking myself in at the deep end.

The display is a Philips 32" LCD TV and yes, you are right the actual panel resolution is 1365 x 768. I have it connected via a DVI to HDMI lead.

It use it for watching Web, surfing, DVDs, DivX files and my music collection (all MP3).

I have been trawling the net to try and sort this out, with little sucess so far. I think it is an issue with the TV as it did this on XP, it's just that there was the handy overscan adjustment that coudl be done with the NVidia driver in XP.

I'll try the -logverbose 5 command and attach a bug report shortly.