Using Flat Panel TV as External Monitor

[dave2001]

I'm attempting to get my 12.04 kubuntu thinkpad t-500 laptop to work properly with my Samsung plasma flat-panel TV. I have an ati Radeon 3650 HD Mobility discrete GPU. I have the proprietary drivers installed. I am connecting them via a display-port-to-HDMI cable. Everything seems to work fine, except the size of the picture. The TV reports that it is receiving the full resolution signal at 1920x1080. However, there is a black border surrounding the entire desktop on the TV screen. I can't use it like this because of screen burn-in. I've tried messing with various TV settings, to no avail. I've also tried to use Catalyst Control Center, but I'm more familiar with Nvidia stuff, so maybe I missed something there. The fact that the TV reports it is getting a full 1920x1080 signal leads me to believe the computer is actually putting out the picture the way it appears on the TV.

Any help greatly appreciated, I'd love to watch videos on my 52" plasma instead of a laptop!

This lappy dual boots Win7, and everything seems peachy with the TV there, so I know the hardware can do it.

[Simon]

I am running a 22" Emerson LCD TV. Screen "burn" is not an issue with modern TV. The old CRT (cathode ray tube) was made from heavy glass and coated inside with phosphorus. Hours of bright white would burn the phosphorus off the inside of the tube. Today LCD uses a Liquid Crystals to filter the light from a white lighted back panel. This is why when your screen turns black you still get a white halo unless the light panel is off. Enough history...

Have you gone into your TV menu and looked for screen resize and adjustment?

If that is not available you could look into other options using; xrandr in a terminal window. I believe scaling would help;

xrandr --output <your output name here> --mode 1920x1080 --scale 1.2x1.2

or maybe try messing with the --rate (refresh) to access help use -h.

[HalationEffect]

@Simon - you must have missed where dave2001 said his screen is a *plasma*, not an LCD. Plasma screens are indeed susceptible to burn-in (in fact, they used to be even more susceptible to it than CRTs but the latest plasma tech is now on a par with CRTs with respect to burn-in). Even LCDs aren't totally immune either.

http://en.wikipedia.org/wiki/Screen_..._OLED_displays

[Simon]

LCD can get a "memory image" (extremely rare) normally caused by extreme dark images, but they go away after you power down. As the wiki article you linked says " In more typical usage profiles this image persistence in LCD is only transient. Both plasma-type and LCD-type displays exhibit a similar phenomenon called transient image persistence, which is sometimes confused with screen burn but is not permanent.".

But resizing the screen won't prevent an image burn (even if his TV is susceptible to it). He describes a black border around his screen. If he is in danger of an image burn I would recommend his screen saver be set to black out 10 to 15 minutes of no usage. However I have left my LCD TV run all day and night without issue.

Back to the sizing issue; I have messed with some settings using xrandr you may have to look through the man pages for an answer there.

[dave2001]

Thanks for the input guys! Halation is indeed correct, I have a plasma TV. It is also a couple years old, before the protection effects were as advanced, so burn-in is a concern.

I have exhausted all the possibilities in the TV options, so no wiggle room there.

I have not messed with xrandr before, I will have to check that out. Thanks for the suggestion Simon!

[HalationEffect]

LCD can get a "memory image" (extremely rare) normally caused by extreme dark images, but they go away after you power down. As the wiki article you linked says " In more typical usage profiles this image persistence in LCD is only transient. Both plasma-type and LCD-type displays exhibit a similar phenomenon called transient image persistence, which is sometimes confused with screen burn but is not permanent."

"Typical usage profiles" I would hazard to guess means use as a domestic TV set. Using a TV as a computer monitor long-term isn't a typical usage profile. LCD computer monitors should have more robust built in mitigation strategies than LCD TV sets, because a computer monitor's typical usage profile will require it.

Immediately preceding the sentence you quoted was a sentence that explicitly states that LCDs can suffer from burn-in: "For LCDs, burn-in develops in some cases because pixels permanently lose their ability to return to their relaxed state after a continued static usage profile". They even show a photo of an LCD screen with "extreme burn-in".

Sure, it's not common, and for most use cases it won't ever be an issue, but to say that it can't ever happen with LCD screens is incorrect. I stand by my phrase "not totally immune"; they are nearly immune, but not quite 100% so.

[dave2001]

I certainly didn't mean to start a burn-in debate on the kubuntu forums!
Even if I wasn't concerned about burn-in, I'd want to get rid of the black border around my desktop simply for aesthetics, and to utilize the full extent of my TV screen. Three inches all the way around takes away a lot of screen area.

[sithlord48]

since you are using the properitay driver you will have to adjust the properties of your video using the ATI tool

kdesudo amdcccle

look for the overscan settings. iirc by default its set to underscan 15%. (haven't used them in a while been using the open driver w/ my Radeon 6670HD / 4830HD )

[dave2001]

since you are using the properitay driver you will have to adjust the properties of your video using the ATI tool

kdesudo amdcccle

look for the overscan settings. iirc by default its set to underscan 15%. (haven't used them in a while been using the open driver w/ my Radeon 6670HD / 4830HD )

Thanks Sithlord! That did the trick easy and quick. I figured I was missing a setting somewhere. Appreciate the help!

[woodsmoke]

overscan is the problem

woodsmoke