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Author Topic: TV Overscan Problems  (Read 14536 times)

benn600

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TV Overscan Problems
« on: November 26, 2007, 10:22:46 pm »

I have a 27" JVC LCD TV that I'm having overscan issues with.  I'm hoping someone can help me solve the problem.  I can get the model number if needed.

The native resolution as I have read online is 1280x768...so it is slightly greater vertically than 720P.  I have tried various settings near the native resolution but they all provide strange results.

The 720P computer resolution setting is greatly overscanned and I need about 5% overscan help in Media Center--but the video and OSD are still not perfect.  Ideally, I want direct 1:1 pixels, obviously!  I even have it on the Full setting, which you'd think would display perfectly 1:1 with no overscan.

Other settings come close.  At the display's native resolution, it fills it perfectly but it looks like some serious processing is being done because everything is fuzzy and then becomes sharp as things move around--some sort of digital processing.  It looks horrible with jagged edges and strange artifacts with moving objects.

I've tried a few other settings as well.  Maybe that is the best I can get with this TV.  If anyone has any general ideas for me to try, great...otherwise I'll lookup the model next time I'm near the set.

Thank you!
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jmone

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Re: TV Overscan Problems
« Reply #1 on: November 29, 2007, 03:57:05 pm »

Benn, you don't mention what connection type you are using but given you comments I'd say it will be HDMI/DVI, Compoent etc not VGA.  As you are probably aware, TV's all use overscan to cut of the ragged edges of traditional Analog broadcasts giving a nicely displayed edge to edge picture.  Directors produce their TV/Movie content with this in mind so when playing DVD's etc you should not lose anything "important" (note: some TV's have a bigger overscan than others).  The problem with HTPC's of course using a "TV" connection is that it gets hard to see important parts of the desktop (start buttons, menues, etc) as they tend to be in the overscaned areas.

OK - You have a "few" options depending on your connection type:
1) Use VGA - If your TV has a VGA Input you can use this and assign a 1280 x 768 res and it will act just like a big monitor and should be sharp and clear.  You will get no overscan but your PC will have to do the scaling to this resolution.  Other downside is that you typlically can not feed VGA via your AV Receiver.

2) Use HDMI/DVI/Component etc - Your best setting will be 720p, and the TV will see your HTPC just like it was any other AV Device so Overscan is the default but you could try:
a) Overscan Compensation in Video Drivers - Pending your the made / model and OS you may have the ability to apply Overscan Compensation in your drivers - this effectivly drops the resolution on your PC and still embeds it into your 720p signal.  I've found this very problematic on many makes / models (eg nVidia on Vista is tough).
b) Overscan Compensatin in MC12 - You've seen this and it helps with T'View menus only.
c) 1:1 Pixel or "PC" Mode on your TV - Your TV may allow you to set an option on how to treat the incoming signal and effectivly change the mapping it uses (eg mine does).  This is the best option but you will have it or you won't.  FULL is not the correct setting (it will have Overscan), try looking for PC or 1:1.  The downside is that you may need to change back to FULL for other inputs unless your TV has an intelligent mode

Good luck (you will need it)
Nathan
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benn600

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Re: TV Overscan Problems
« Reply #2 on: December 01, 2007, 02:36:08 am »

Thanks for the information.

I am using Digital DVI.  Reviews for the TV from Cnet say that it won't even accept a computer DVI signal so that throws a red flag.  However, it does work fine for me.  Full seemed the correct choice.  I would have tried any other options but I do not recall any other options other than Full.  I would think DVI or VGA would both provide a 1:1 pixel relationship but this TV is supposed to have some fancy digital processing--which I don't want!  It has no VGA input.  I am in fact using the MC overscan compensation and it absolutely helps in the menus, just not in video or the OSD.  I'm coping and understand how important the TV is in this mix--it needs to be able to handle the signal correctly.

Generally, I don't use any other inputs.  I have a DVD player but 100% of our DVDs are on the server so that's essentially pointless.  MC on my HTPC is the key.  And VCR?  TV isn't really a concern, either.

I exhausted all the TV settings that I could see so I wasn't really expecting a quick fix.  I will in fact need extra luck.  Perhaps finding a driver for the TV would allow the PC to send a specific resolution that would be interpreted correctly and not overscanned.
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jmone

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Re: TV Overscan Problems
« Reply #3 on: December 01, 2007, 05:22:39 am »

Benn - what is your:
- TV
- Graphics Card
- OS

There will be an "overscan correction" option on either the TV or card.....
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benn600

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Re: TV Overscan Problems
« Reply #4 on: December 01, 2007, 01:25:05 pm »

TV: JVC LT-26WX84
http://support.jvc.com/consumer/product.jsp?archive=true&pathId=80&modelId=MODL027112

Video Card:
I have using my low-end ATI 9250 and my high end ATI 2900XT.

OS
XP Professional

Media Management
iTunes



HAHA, JUST KIDDING
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jmone

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Re: TV Overscan Problems
« Reply #5 on: December 01, 2007, 02:06:10 pm »

I think your stuffed on the JVC doing anything to help but your ATI Catalyst control panel should have Overscan Compensation that you can use.  No idea how well it will work with you but you have a better chance than Vista/nVidia/HDMI combo that only had limited overscan support and the Intel/HDMI combo where overscan is not supported at all. 
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benn600

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Re: TV Overscan Problems
« Reply #6 on: December 01, 2007, 02:10:06 pm »

OK, I'll look into it.  I'm sure it won't be optimal because isn't it reducing the usable pixel count anyway?  Of course I'm not going for optimal at this point...otherwise I'd go buy a new, fancy TV, which I am absolutely not doing.  I'm content.  Thank you!
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