The big difference between the data signal produced by a computer graphics card and the video signal that most TVs are configured to accept has to do with overscan.

Integrating MCE with Video Displays

Scott Varner | Niveus Media

Integrating MCE with Video Displays

The big difference between the data signal produced by a computer graphics card and the video signal that most TVs are configured to accept has to do with overscan.

by Scott Varner


Few people will argue the arrival of AV and PC Convergence. This is a great time for those who like to experience new ways to enjoy entertainment and use the technology that is all around us in our everyday walk of life. Unfortunately, the TV manufacturers didn't get the word that some of us would be connecting data sources to their displays…

When I first began to evaluate televisions for their ability to display a High Definition signal from a Media Center PC, I quickly realized that televisions were unlikely to be designed to display content from a PC. Funny how that works, TVs are primarily designed for video and computer monitors for data. These are two very different situations. Some of us remember the distinctions in data grade projectors versus video projectors; what a difference in capabilities and price! Today is not so much different with HDTV. While most HDTV sets have the ability to connect to a PC signal via the standard VGA connector, many TVs limit the input on this connection to "standard" PC resolutions, which don't include HDTV signals and are generally 4:3 aspect ratios.

Media Center PCs have truly addressed the source element of this equation with outputs ranging from composite video on some basic systems to DVI & HDMI on most of the current crop of AV oriented Media Server type PCs. I'm not sure why anyone would want to use a composite video output but hooking up a High Definition signal from a high quality Media Center via HDMI/DVI can yield outstanding results and state of the art performance- if you plan ahead properly.

The big difference between the data signal produced by a computer graphics card and the video signal that most TVs are configured to accept has to do with overscan. Even in the world of 720p and 1080p inputs, most TVs take these incoming signals, process them through their chassis and output an image which is overscanned to fill the display, and then some. With video signals this is critical because of unwanted artifacts on the very edge of the picture. Originally overscan was used not only to mask these artifacts but also to deal with deteriorating power supplies, which over time would cause the image on the CRT to slowly shrink. The more overscan used, the longer it would take for the image to shrink to be smaller than the visible area of the tube. Fast forward to today…

With fixed pixel displays, the image size can't shrink but we still deal with overscan. It is unusual that a TV with a native resolution of 1280 x 720 will pass a 720p signal pixel for pixel with no modification. This seems illogical, yet it is the norm with today's HDTV sets. There are sets that avoid this situation and these displays can be an excellent choice when it comes to displaying data-based signals

When choosing a display to go along with a High Definition Media Server, it is often the best call to choose a display which allows for signals connected via HDMI or DVI to be displayed pixel for pixel as output by the source. In other words, the 720p image isn't stretched by 5% to overfill the screen. This capability is usually an adjustment in the set up of the display when it is available. It may be labeled as Pixel Match or Native or may be an adjustment for the input type with a switch between Video and PC signal types. However it is handled by the display, if this functionality is available, you will have the best experience with content displayed from one of the highest performance sources we have available today- the High Definition Media Server.

While data oriented inputs are often found on the better brand displays, this is not limited to only expensive TVs. There are some very modestly priced TVs that have this capability. Do your research and you can choose a display that fits both the budget for the system as well as the application. If you avoid displays that require adjustments to the output signal to compensate for how they overscan the image you will see the entire image from edge to edge. Paying attention to this characteristic will yield the best results when connecting a high performance AV server into your system. If you don't use one now, chances are pretty good you will someday.

With the convergence of AV and PC technology, planning ahead for proper video display integration can avoid some of the pitfalls experienced when hooking a PC to a TV. Pick the proper display ahead of time and enjoy the results.


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