HDTV Overscan/Underscan discussion

Mr Latte

Mr Latte

Mr Latte

Soldato
Joined
8 Aug 2003
Posts
9,144
DO YOU KNOW YOUR HDTV IS PROBABLY HIDING VIDEO!

This is aimed more for users that can compare standard sources like DVD playback from a DVD player to the same thing on their PC connected to a HDTV display with custom resolutions.

My Sony V40 internal scaler seems to use a little too much overscan for my liking and its a little on the annoying side.

Questions
1. If possible can some others perhaps go through this process im trying on their models.
2. Is Overscan a problem with a lot of HDTVs and how common may this be?
3. Maybe its just a problem with my model/set?

Ive only really noticed this by accident during HTPC connection.
On my Sony 40" HDTV approx 3.5cm left/right and 1cm+ top/bottom is missing in the overscan process
* to confirm top/bottom size

What this means is when conneting any device to your display directly it probably goes through the same process with the overscan such as this DVD example.

One advantage or difference with PC connectivity though is i can control this loss of video with my HTPC custom resolutions so that i virtually miss nothing. Have any of you guys compared standard sources like DVD players against a PC with DVD set at 720p resolution and also custom PC resolutions like below to see what your display actually hides?

My Latest Settings on my HTPC are:
1200x700 or 1200x692 meaning you get all the video fullscreen but next to none in overscan.
 
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Right well hope this helps illustrate the problem.

Not only can HTPCs offer better quality as mentioned in the other thread but just look at the advantage custom scaling has over my HDTVs internal scaler with regards to overscan.

Stealth NTSC 2:35 Widescreen Via HTPC "Theatretek Software" @ 1200x700 Custom Resolution DVI-HDMI Nvidia 6600
HTPC%20Wide.JPG
 
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Stealth 2:35 Widescreen Via DVD Player 480p Component Using Tvs Scaler
DVD%20Player%20Wide.JPG


The 2:35 image from DVD Player is slightly bigger in height because of the Tvs scaling but can you see whats missing?
 
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I havnt yet closely compared 1:85 / 16:9 ratio movies but its bound to loss information top/bottom as well although not quite as much.

Perhaps the Sony Bravia range is extra safe or its my model with regards this overscan issue but id like to here from anyone else.
 
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How is your dvd player connected to your screen ?

From what ive seen most digital connections will only do 720p and then not 1:1 map, the scaler in the screen then seems to make a mess of it.

Can you not dial out overscan with horz/vert adjustmants on your screen ?
 
The first images contain the information regarding connections
DVD 480p via component Vs PC custom 720p res at 1200x700
(underscan applied to allow full video)

"Dial out" what you mean are you talking about phones now? ;)

Please note the PC isnt the problem its the Tvs internal scaler being over-safe with overscan and its running in normal wide mode not zoomed in any way.

Call me picky but thats a lot of overscan...
 
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As posted on avforums by my fellow compatriot Lyris,

"Go into service mode by turning the TV off. Press I+, 5, Volume Up, then Power On on the remote. Press Menu. Go into the new tab that's appeared at the bottom and change "Wide Mode Selection" to "0 (Normal)". This seems to ease the overscan off a bit for me (on my 2004 model)."

Let me know how you go, waiting on one of these babies being delivered :/
 
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Further Testing:

Tried the display at various resolutions now to emulate different "AV Seperates" sources.

1. 720x480 (HDTV 480p)
2. 1280x720 (HDTV 720p)
3. 1920x1080 (HDTV 1080i)

The reason for doing this is that its let me compare the "Overscan" for each common video source (1,2,3) and compare the "used scene above" for direct overscan comparison.

As i thought the internal scaler scales less with each higher resolution source.
Therefore DVDs will loose more (approx 3.5cm or 8%) than 720p HTDV material (approx 2.5 cm or 6%) and 1080i HDTV will loose the least (approx 1cm 2%) in overscan. These are approximations but highlight that standard defination suffers by far the worst.

It may be how the internal scaler within the current Sony Bravia range works so common gents lets here how your HDTV suffers...
 
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So do you get overscan on sky digital as well then? None of the picture formatting options help this at all in the menu (I assume theres some like in my sony CRT). Not that this will bother me too much, but I like to know these things.
 
ripkord said:
Hmm :/ Its annoying me now. Do you own an xbox360 by any chance?

edit

- no matter, I was going to ask a daft question
Click to expand...

Yes

I cant tell with Sky as i havnt that connected via my PC.
My DVD comparison was with both 480p and 480i with the two DVD players.
 
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whats the overscan like from the 360?
shame you cant play dvds from xbox360 MCE as you have the 4 choices of screen type to choose from, if you know what I mean.
 
ripkord said:
whats the overscan like from the 360?
shame you cant play dvds from xbox360 MCE as you have the 4 choices of screen type to choose from, if you know what I mean.
Click to expand...


See above post i tested both 720p and 1080i resolutions from the HTPC desktop at those resolutions and compared.

Anything with those resolutions will have the same effect X360, SkyHD or DVD-HD / BLU-RAY etc
 
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ripkord said:
yeah but within MCE you can choose from 4:3, 16:9 and 2.35:1.
Click to expand...

Isnt that some form of zoom feature though?
Im guessing as i never tried the X360 for DVDs its not used in the same room as the TV either.
 
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