Ports to Know: What's In/What's Out On Today's TVs

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There once were two ways to get a signal into a TV: an RF connector (left) for antenna or cable and an A/V for composite video and stereo audio. Then, the VCR age succumbed to HDTV, inputs multiplied, and buying a set became more like shopping for a computer. To help you figure out which inputs are hot and which are not, we're introducing a new series focusing on features. This one rates TV connections.

Your new DTV set should embrace at least one set of A/V inputs (right) in order to accommodate legacy equipment such as an old games console or video cassette player. Digital cameras with a TV output have typically attached to the TV's composite video (yellow) input. Most consumer camcorders, too, share the show on a TV using the set's conventional A/V inputs. Unfortunately, composite video is not high-def capable. Neither is a multi-pin S-Video connection (below left).

An S-Video connection does produce better-looking video than a composite cable. but the perceived improvement was left behind in the Analog Age. That's because no matter how many megapixels you've set your camera resolution for or if you're shooting video in high defintion, what you'll see on your HDTV screen connected through composite or S-Video will be a lower-res version image. Neither connection has the bandwidth to exceed VGA (640 x 480) resolution. While TV manufacturers still include composite video, they're now less likely to retain any S-Video input at all since if you really want a sharper picture, you're more likely to plug into a digital connection.

As for that RF connector, the main reason to use it is to take advantage of the TV's internal tuner. If you plan to receive free over-the-air TV, the RF input is where you still screw in the cable from an antenna. You may also be able to get some cable TV channels this way. However, the vast majority of viewers receive their TV channels exclusively through a cable or satellite subscription, and the tuner is built into a separate component like a DVR. (The outboard tuner used to be called a set-top box or STB, but since TVs have become so thin, the term no is no longer applicable.)

The entry point for connecting the picture from a high-definition DVR or a Blu-ray Disc player or even a DVD player is through the TV's set of red, blue, and green component video inputs. The trio has the bandwidth to carry a high-def signal, though the audio signal must arrive through a different connection.

Component video, which transmits analog signals, is being eclipsed by all-digital HDMI connections, which also carries the audio. The more HDMI ports your TV has, the merrier, since HDMI is showing up on all types of souce components. However, if you've set up a home theater sound system, the receiver is likely to have multiple HDMI inputs, and by switching your source in the receiver, one HDMI input on your TV should serve your day-to-day needs. An extra HDMI port is good for a temporary connection, like the one you use when you come in the door with some just-shot high-def home video.

If you want to connect the picture on a computer directly to the TV, the most likely way to do so is by attaching a cable to the TV's VGA port, also called a PC input or 15-pin D-Sub. This is an analog signal without sound, but you can get high-def image quality. The  VGA input (right) on the TV offers an array of 15 holes divided along  three lines. To get sound from the computer to the TV, you'll likely use an audio cable with one-pin for the computer and stereo plugs for the TV. However, computer manufacturers are increasingly including an HDMI output, making a single cable connection possible.

You've probably been hearing a lot about the "Connected TV." This refers to the type of TV that can stream content from a computer on your home network or a limited number of sites on the Internet. This type of TV almost always has an Ethernet (RJ-45) jack (left) for attaching the same type of cable you use for linking computers to your router or cable modem. Some advanced TVs may embed Wi-Fi reception, but even these will include an Ethernet jack for use when a Wi-Fi signal isn't available.

Finally, newer TVs are including one or more USB ports that look just like the ports on your computer. However, unlike your computer, you can't easily install software to take advantage of new devices you plug in. Depending on the TV model, you may be able to attach a USB storage device or camera and play music, photos, and videos directly--all controlled using the TV's remote. Even if the TV doesn't recognize a particular format, you should at least be able to recharge the battery in the camera or music player.

There are a few other TV inputs with their glory days largely behind them besides S-Video. They include FireWire (also known as i.Link) and a CableCARD slot (which allows access to premium channels when the cable is attached to the RF input without requiring an external cable box to authorize reception.)

In terms of outputs from the TV, the most compelling reason to use one is for sending 5.1 digital audio to your receiver from the built-in tuner while watching over-the-air TV. An optical digital audio output (left) is more frequently used than a coaxial digital audio output (which looks like an orange-colored version of a composite video port), but you should be sure that your receiver has a compatible input. Your TV may also have a set of stereo audio outputs for analog outboard sound. Typically, a headphone jack is only found on TVs with smaller-size screens. The TV may also have a memory card slot so you can transfer, for example, an SD card from your camera to the TV, and depending on the firmware in the TV, play photo slideshows, music, and standard or high-def video. However, some TV manufacturers have been moving away from card slots and toward USB inputs so you can connect a camera directly or use an optional card reader.

There are lots of ports-a-calling on today's TVs. Hopefully, this overview will help you decide what you'll need on your new set for plugging into a world of entertainment components..

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I found this discussion on "Ports To Know" both well written and helpful.. Thank you, Kenc 

Many legacy DVD are composite with no component outputs.

In this digital age composite and component are dinosaurs and ready to be extinct. most dvd/vcr combos don't even have a tuner anymore. even DVI,the prdecessor of HDMI, ist about to die gradually.Digital is the way of the future. unfortunately it gives the consumer no control and the providers decide what you can see and what not.

why are there even analog broadcasts in the cable and why is not everything broadcast in HD?

USB has conquered many TV's already and many customers have shot their TV by plugging in a UBS stick with pictures on it into the USB--SERVICEport. A highly costly mistake.

But this is not the end. Who knows what ports we get in the future?  Maybe an allround multimedia port with terabit/sec speed ??

Nice discussion.  Easy to understand. 

However, because HDMI ports look so much like computer "DisplayPort" ports, some discussion of the differences would also be useful.    See:  http://en.wikipedia.org/wiki/DisplayPort

Yes?  No?

I always wondered which connection will give better image quality - S Video or VGA - when my laptop is connected to TV. Now I am clear. Thank your for the well informative write up

In response to two questions:

1. Why does cable still carry analog channels?

Because of the legacy of cable-ready television sets in which viewers plugged the cable directly into the tuner of their TV sets, bypassing the need for a set-top box (STB). There are still a lot of those conventional TVs in peoples' homes that are often used as secondary sets in a bedroom or den. In some cases people don't want to accommodate a STB or pay to lease one. In other cases the cable company doesn't want the expense of providing millions of STBs to accommodate TVs whose days are numbered. Eventually, though, analog broadcasts on cable will disappear because they're incredible bandwidth hogs. In the 6 MHz space of one analog channel, four to six standard-def digital channels or a combination of one high-def channel and perhaps one or two standard-def channels can be squeezed in.

2. Which provides better video quality: S-Video or VGA?

VGA delivers more bandwidth, potentially producing a higher-resolution picture.