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Permalink to this day Thursday, December 02, 2004

Our TweakMCE powertoy that I 'program managed' will be out any day now.

Though, unfortunately I dropped the ball on a feature I had really meant to include but completely forgot to. Perhaps I should have scheduled a spec review for the power toy :).

That feature is overscan margin adjustment. In lieu of using the power toy to do it here are the instructions on doing it yourself.

What are overscan margins?

Here is a good little blurb on what overscan margins are and why we have them from Making Computer Graphics NTSC Compliant:

Early TV picture tubes distorted the image near the edges, so it was decided that the picture would be overscanned with the edge of the picture hidden by a plastic bezel. However, when working with video on a computer you see the whole image, so you must always be aware that the edges of your image will not be visible on a TV. The non-visible portion of the image corresponds roughly to the area inset 5% from each edge (about 36 pixels from each side and 24 pixels from the top and bottom). The area inside is often called the "action-safe zone." Make sure that anything that has to be seen is inside this zone.

Additionally, there is another region that is inset 5% from the edges of the action-safe zone known as the "title-safe zone." Older picture tubes still produced some distortion outside this zone, making text harder to read, so titles were always including inside this zone.

Why would I want to adjust my overscan margins?

In MCE 2005 the default display configuration assumes your MCE is connected to a computer monitor or similar display (plasma TV, LCD TV, higher end rear projections) which does not require overscan margin adjustment. This means we are assuming your display is capable of properly displaying the border of the image.

If you are not using a computer monitor/similar display you will likely want to run the 'Display Calibration Wizard'. If you did not run the wizard during 'First Run' (the setup that runs the first time you start MCE 2005) then you can find the Display Calibration Wizard in Settings > General > Media Center Setup > Configure Your TV or Monitor. If during the wizard you choose a display connected via composite, s-video or component and/or your display is a rear projection display then we pull in the UI elements (but not the video stream) by the following amounts:

marginBottom & marginTop: 38 units
marginLeft & marginRight: 51 units

Okay, so why would you want to adjust the value we pull the UI elements in? While testing this feature we found that everyone's TV cropped a different amount around the border. We experimented with a different values but none was ideal. While we believe we picked a safe number you might want to adjust it if you find your display can handle more content then we think it can. You might also want to adjust it if you are using a mouse with your MCE and find that the 2' toolbars are 'floating' a little too much (screenshot of floating toolbars with the TV skin on).

How do I adjust my overscan margins?

There are five registry keys you can adjust to tweak your overscan margins, they are found in HKCU\Software\Microsoft\Windows\CurrentVersion\Media Center\Settings\MCE.PerUserSetting:


If you make changes to any set marginSaved = 1 and restart Media Center.

What do the overscan margins adjust?

They only adjust the Media Center UI. So it does not pull in any video, TV, or DVD content.


Do you have any questions on overscan adjustments? I'd be glad to answer them. Also, I'll follow up this post with a more in general discussion on what we do when we turn the 'TV skin' on as overscan adjustment is only one of about five things.
4:16:23 PM  Permalink to this item []

© Copyright 2005 Matt Goyer.
I work at Microsoft in the eHome division on the Windows XP Media Center Edition team as a Program Manager.

Disclaimer: The posts on this weblog are provided "AS IS" with no warranties, and confer no rights. The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.

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Updated: 4/11/2005; 10:30:14 PM.