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.
Keep reading to learn more about bringing your small-screen life to the big leagues.
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 [source: Kindig]. 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
If you read our article “How do I know which cables to use?” then 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. In the next section, we’ll share some troubleshooting tips.
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 [source: Komando].
Source: electronics.howstuffworks
