Connect Your Computer to Your TV

There's something painfully ironic about sitting on your
living room couch, just a few feet away from a beautiful
widescreen HDTV, watching a movie on your tiny laptop. Yet
this is what most of us do when we download movies or TV
shows onto our computers.

The same goes for showing off our latest digital photos to
friends. We all huddle around the 15-inch computer display
while the TV screen goes unused. And what about that
PowerPoint presentation you just gave at work? Wouldn't it
have looked 1,000 times better on the wall-mounted plasma
display in the conference room?

There are many compelling reasons why we want to connect our
computers to our televisions, especially now that HDTVs are
so popular. Everything from movies to photos to work
presentations were made for the big-screen experience.

The first personal computers used TVs for monitors, but
computer graphics technology quickly outpaced the image
quality on standard-definition TVs (SDTVs). The typical
modern computer monitor has the ability to display images at
a much higher resolution than a regular TV. A computer
monitor can display more individual pixels than an SDTV.

Even today, hooking a computer to an SDTV only makes sense if
you want to use your computer as a DVD player. If you try to
use an SDTV as a monitor, you'll have a hard time getting
your full desktop to fit on the screen.

But with the advent of high-resolution, high-definition TVs
like flat-panel LCDs, plasma, LCoS, and DLP displays,
televisions now make excellent computer monitors. In fact,
that's what the manufacturers of PC-based media centers are
trying to achieve. The tricky part is figuring out exactly
which TVs work with which computers and how to connect them
all together.

Screen Resolution and Aspect Ratio

Many people are familiar with the concept of screen
resolution. Resolution is a measurement of how many
individual pixels your TV or computer monitor can display at
once. The old cathode ray TV (CRT) in your basement can
display the equivalent of about 300,000 pixels. The latest
HDTVs can display more than 2 million pixels. With more
pixels, the image can be rendered in greater detail. It's the
difference between painting a portrait with a thick sponge
block or a small, delicate brush.

The standard way to classify TV resolution is with numbers
like 480i, 720p, 1080i and 1080p. The bigger the number, the
greater the screen resolution. The little "i" and "p" stand
for interlaced and progressive scan. This has to do with the
way in which the image is rendered on the screen. Refresh
rates on TVs and computer monitors are measured in hertz.
A refresh rate of 60 times per second translates to 60 hertz.
An interlaced-scan TV refreshes half of the screen image 60
times per second. It refreshes the odd-numbered horizontal
lines first and then the even-numbered lines. The result is
that the full screen refreshes 30 times a second.

On a progressive scan television, the entire screen refreshes
60 times a second. The result is that progressive scan TVs
have a noticeably smoother image when watching sports or
other video with fast-moving action. All computer monitors
are progressive scan [source: PCMag.com]. Some even have
refresh rates faster than 60 times a second. This is why
interlaced SDTVs make for lousy computer monitors. When you
scroll, the image can't refresh fast enough to keep things
smooth. As a result, you see that telltale flicker.

Resolution is important, but you must also take a screen's
aspect ratio into account. Your goal when hooking your TV up
as a monitor is to make the entire image fit within the
boundaries of the TV screen. SDTVs use a 4:3 aspect ratio --
the ratio of the screen's width to its height is 4 to 3.
HDTVs have a native 16:9 aspect ratio. While many computer
monitors share those aspect ratios, not all of them do, and
your computer may support many different screen resolutions
with different aspect ratios.

In fact, your computer's preferences are unlikely to tell you
the aspect ratio, and instead will tell you the resolution.
The horizontal x vertical measurement is also the most common
way to label computer monitor resolution. Some typical
monitor resolutions are 640 x 480, 800 x 600 and 1024 x 768.
If you don't know your monitor resolution, you can find out
by going to whatismyscreenresolution.com. If you aren't
connected to the Internet and you're using a Windows PC,
right-click on the desktop and choose Preferences. Then
choose the Settings tab. On a Mac, go to System Preferences
and click Displays.

The trick is to find the resolution that best fits the TV's
aspect ratio. This may not be as big a deal as it sounds,
though. Modern operating systems can usually match the
attached monitor's aspect ratio automatically. If your
computer doesn't, you can manually adjust the settings in
your computer's preferences to make it fit.

But there's more to hooking these two machines together than
resolution and aspect ratio. You still have to get the
information from the computer to the TV. In order to do that,
we've got to solve the cable conundrum.

Computer TV Cables

You know there is a baffling number of audio/video cables on
the market. You'll have to make some sense of the different
types of wiring necessary to connect your computer to your
TV. First you need to figure out what kinds of audio/video
outputs your computer has and what kinds of audio/video
inputs your TV has. If you're lucky, you'll find a match
right away. But depending on the type of equipment you own,
you may need to get creative.

First, let's talk about which cables you'd use to connect
a computer to a standard-definition TV. The most common video
inputs on an SDTV are composite, S-video and component video.
On computers, the most common video output is S-video. On
a desktop PC, you'll find the 9-pin S-video jack on your
graphics card next to where you connect your monitor.

Some Windows laptops also have S-video-out jacks, but most
have 15-pin VGA jacks for connecting to external monitors.
Luckily, it's easy to find adapters and special cables that
have VGA connectors on one end and S-video connectors on the
other. Apple also sells a wide variety of adapters to connect
Mac desktops and laptops to the S-video or composite jack on
SDTVs.

Even if you have an old TV that only accepts coaxial video
cable (the one-pin variety that's mostly used for cable TV
and satellite connections), you can use something called
an RF converter box that can convert S-video or VGA input
into coaxial output.

For connecting a computer to an HDTV, it's the same story.
The most common HDTV inputs are component video, DVI and
HDMI. If your graphics card doesn't have one of these
outputs, then you'll need to buy a special converter box or
adapter. For example, if your computer only has a VGA jack
and your HDTV only accepts HDMI, then you'll need to buy
a small box that will convert the signal for you.

If you're serious about playing high-definition content from
your computer on your HDTV, then you should upgrade to
a graphics card with a DVI or HDMI output. Most newer Apple
laptops come with a Mini DisplayPort video output that easily
connects with the DVI or HDMI inputs on an HDTV.

All of the cables that we've mentioned so far are video-only
cables, which means that you'll need separate cables to
handle your audio. The easiest solution is to connect some
computer speakers to your audio card's headphone or audio-out
jack. If you want to use your TV's built-in speakers, then
you'll need to buy a 1/8-inch stereo mini-plug-to-RCA cable.

For the best possible audio, you'll need to invest in
an audio card for your computer with either an optical or
digital coaxial audio output. These connections carry
high-bandwidth digital audio signals using cables that can be
plugged directly into your home theater receiver.

Even if you have the right cables and have done your homework
about resolutions, you still might have some problems
connecting your computer to your TV.

Computer to TV Troubleshooting

The biggest problem with connecting your computer to your TV
is that, generally speaking, computers and TVs don't display
at the same resolutions. For example, the closest thing to
the HDTV resolution 720p (1280 x 720) is a monitor display
mode called XGA (1280 x 960). Not quite the same. And the
closest thing to 1080p (1920 x 1080) is a monitor display
mode called WUXGA (1920 x 1200). Again, not quite the same.

The result, in most cases, is something called overscan,
where the full computer screen image doesn't fit on the TV
screen. Overscan is a bigger problem on SDTVs where the
native screen resolution is much smaller than your computer's
display. If you're going to use an SDTV as a monitor, plan on
lowering your screen resolution to 800 x 600.

HDTVs also have overscan problems, but usually only the very
edge of the computer image gets cropped. A bigger problem
with HDTVs is when the TV refuses to display a signal that
doesn't fit its native resolution.

Luckily, most HDTVs have the ability to scale incoming
signals to match their native screen resolution. This
involves either upconverting lower-resolution signals in the
attempt to bring the resolution up to high definition or
downconverting higher-resolution signals for lower-resolution
screens. It's not perfect, but for most casual viewers,
there's little to no noticeable loss in image quality.

In rare cases, the HDTV won't recognize the resolution of the
signal sent by your computer. When you connect an external
display to your computer, most graphics cards will
automatically try to find a good match for the display's
native resolution. If this doesn't work, you will probably
need to edit your resolution with third-party software.

Two programs are considered the best solutions for solving
connectivity problems between a computer and a TV: PowerStrip
for Windows and DisplayConfigX for Mac. Both of these
programs allow you to match your graphics card's resolution
precisely with the native resolution of your TV. If your HDTV
is 1080p, you can go into one of these programs and switch
your computer's resolution to 1920 x 1080, even if this
wasn't previously an option.

Avoid increasing the refresh rate on your graphics card,
unless you have a 120-hertz HDTV. If you send a signal with
a refresh rate over 60 hertz to a normal HDTV, you could
damage the TV.