So you’re in the market for an HDTV? Well, look no further. This FAQ is designed to aid and assist all of you in this brand new world of increased clarity and resolution. Although this is not the definitive source for HDTV information, it has been designed as an easy-to-read reference to the main points of the HDTV world.
What is HDTV?
It stands for High Definition TeleVision. It’s the latest television standard and it allows for high resolution and a more film-like viewing experience with complete support for widescreen formats. On top of that HDTV broadcasts can carry a digital audio signal, such as Dolby Digital 5.1.
What resolutions does HDTV support?
640x480 interlaced (480i) *16:9 not taken into account here
640x480 progressive (480p) *16:9 not taken into account here
1280x720 progressive (720p)
1920x1080 interlaced (1080i)
1920x1080 progressive (1080p) *Note that 1080p is not common on most HDTV sets, nor does it have a lot of support at this point.
A television’s horizontal lines of resolution are called “scan lines.” With interlacing each image refresh only contains the odd scan lines or the even scan lines, never both at the same time. It takes two passes, each at 1/60 fps to draw a complete picture. Even then, the complete picture is never truly displayed. However, this is all acting so fast that our eyes just see one complete picture every 1/30fps. Interlacing was originally designed because of the limited bandwidth of original TVs. In this modern day and age, interlacing is horribly antique and not the best way of displaying a picture or drawing 60fps sources. Some common problems caused by interlacing are flickering, shimmering, and stair-stepping.
Progressive scan is the TV drawing a complete picture every frame. Not only do broadcasts move more realistically, but due to the increased bandwidth of the video signal images are more clear and defined.
What is EDTV?
EDTV is simply like your regular analog TV, except that it can also display a 480p signal. EDTVs are not HDTVs, and are definitely worth staying away from if you really want to buy an HDTV.
What’s the difference between “HD” and “HD-Ready?”
The difference here is that an HD-Ready television will accept any HD signal but not through over-the-air broadcasts. An HD-Ready TV is devoid of the necessary HD Tuner. An HD television has a built-in HD Tuner. Just plug n’ play!
What about for you European folks? Well, an HD-Ready set in EU must display a minimum of 720p, must be able to have component in along with either a DVI or HDMI input, and be able to display the following resolutions:
1280x720 @ 50 and 60Hz progressive (“720p”) and
1920x1080 @ 50 and 60Hz interlaced (“1080i”)
What are all of these video connections for?
To accommodate HDTV’s higher bandwidth requirements there have been some exciting and new video connections that you can use. To make sure no one is confused here is a complete listing of all video connections in order from worst to best and the video quality they provide.
RF (sometimes referred to as coax cable). RF cable uses radio frequency to send both audio and video information to your television set. This is the worst type of video connection you can have.
SCART. This cable is most commonly used in European countries. It’s a 21-pin cable that is bi-directional and carries video and audio.
Composite (sometimes referred to as RCA). Composite cable uses one dedicated cable for video (commonly colored yellow) and two for audio (left channel [commonly colored white] and right channel [commonly colored red]). This offers a clearer picture than RF, but is marred by the limited bandwidth of the cable. Reds have a tendency to bleed into other colors and pixel-crawl (where it looks like tiny dots are moving along the edge of items, sometimes referred to as dot-crawl) are common problems with this type of connection.
S-video. S-video is a video only cable, which offers a very clear and detailed picture. S-video cables separate the video signal into color and black & white information. This separation allows for increased detail and does not suffer from pixel-crawl or any of the other problems associated with RF or composite cables. If you have S-video, use it! The end of the cable almost looks like a PS/2 adapter.
Component (sometimes referred to as RGB cable). Component cables are the minimum requirement to view high-definition signals. It is the best of the analog cables (RF, composite, and s-video). Component separates the video signal into black&white, and the colors red, green, and blue. Component cables don’t offer all that much more clarity than s-video on traditional sets. Component cables are usually colored green, red, and blue and are bundled with left and right audio cables.
DVI-D (Digital Visual Interface). DVI-D cables carry the video information in a completely digital state. DVI cables will transmit HDTV signals. Think of it as a component cable in terms of visual quality, but with the ability to copy-protect the video signal (see What is HDCP?)
HDMI cable (High-Definition Multimedia Interface). In terms of quality HDMI is about the same as DVI in that it also transmits the signal digitally. HDMI also carries an audio signal with the video signal, so it’s an all-in-one cable.
What is HDCP?
We can all thank Metallica for this one. Since the inception of Napster, corporations around the globe have been paranoid about protecting their intellectual properties. HDCP, which stands for High-bandwidth Digital-Content Protection, encrypts HD signals as they are passed along the video cable. All in all, HDCP was designed as a way to maintain the integrity of HD sources and prevent unauthorized reproduction. DVI and HDMI cables utilize HDCP.
What types of HDTV can I get for (insert dollar amount here)?
All HDTVs are not created equal. Some feature different technology to produce the beautiful moving pictures we see. Here are the different types coupled with their pros and cons. Naturally higher-end HDTVs will yield higher end results.
Direct-view TVs are what we are most familiar with, with a glass front tube encased in plastic. DV TVs have a tendency to not be bigger than 36”. They are mainly limited to CRT technology-based tubes (see CRT).
Rear-Projection TVs use CRT tubes, LCD, or DLP technology to reflect the image off of mirrors from inside the unit, thus projecting the image out through the front of the TV. This technology allows for bigger display sizes.
This is essentially the same principle as the movie theater. A "projector" is seated behind the person with the image projected onto a wall or screen in front.
CRT (Cathode Ray Tube)
This is the television technology we’ve been using for almost ¾ of a century. Similar to the PC monitor you’re using right now, this is essentially TV’s technology refined throughout the years. CRT based HDTVs are easily the least expensive of the group. CRT-based TVs (especially direct-view) offer the best picture quality out of all the technology.
Least expensive, excellent picture quality, great black levels (black is truly black), technology is mature, excellent viewing angle
RPTVs are Prone to burn-in (see What is burn-in?), larger sets have a big profile, sets are fairly heavy, RPTVs may require fine-tuning of picture (i.e. convergence) initally and periodically afterwards
LCD (Liquid Crystal Display)
LCD elements glow red, green, or blue to display the picture. Gameboy Advances use LCD screens, and are a good example of the technology.
Good picture quality, very thin profile, very affordable, excellent viewing angle, no need for convergence
“Stuck Pixels” can occur (where single LCD elements are permanently stuck glowing red, green, or blue), blacks levels aren't as good as CRTs
Countless pockets of gas are jolted with electricity to glow red, green, or blue. A neon sign acts in a similar fashion.
Excellent picture quality, very thin profile, available in large sizes (up to 80")
Especially prone to burn-in (see What is Burn-in?), very high price tag, black levels still bested by CRT
DLP (Direct-Light Projection)
DLP TVs use millions of tiny mirrors to refract the television image out of the unit. Think of it as a super RPTV, but with a better technology base
Awesome picture quality, very thin profile, very affordable
Some notice a “rainbow effect,” where streaks of colors can be seen by moving one’s eyes rapidly across the screen
What is Burn-In?
This is where a static image gets permanently imprinted into the HDTV display technology. Stock-tickers, letter-boxing, and pillar-boxing are such an example. If a static image is displayed on the screen for a lengthy period of time, it gets “stuck,” and the shadow of the image is forever displayed on your set. This is irreversible and very expensive to correct (often requiring a complete replacement of the main technology of the TV). The best way to combat this is to give your set a break every few hours, especially if you’re playing video games (which have lots of static images, such as HUDs). Either turn off the TV set or watch a TV channel for about fifteen minutes or more. With a little common sense and care, you’ll never encounter this problem.
What's this jazz I hear about native resolutions?
Your HDTV's native resolution can be a very confusing aspect of your purchase. The vast majority of all HDTVs have a native resolution, one where they offer a pure signal without any downscaling or upscaling. Most DLP, LCD, and Plasma sets have a native resolution of 720p, while CRT-based sets have a native resoltuion of 1080i. Let's take a DLP set for example. It has a native resolution of 720p. A 720p source displayed on our DLP set will be displayed pixel-for-pixel. Now what about when we try to display 1080i? Well, the DLP set is incapable of displaying the 1080i signal at that very resolution, due to it's native res being 720p. The set must now downscale your 1080i signal to be displayed at 720p. A 480p signal, then, would be upscaled to 720p. Naturally the image quality will be best at its native resolution, but most consumers cannot notice a decrease in image quality if your HDTV source is upscaled (or downscaled). This aspect of HDTVs is very subjective to each individual's preferences. I have a CRT HDTV and I like to run all of my progressive-scan sources downscaled (or in the case of 480p, upscaled) at 540p, while keeping my 1080i signals at 1080i. I could very well run everything upscaled to 1080i, but again, this is all personal preference.
I have an HDTV, can I get HDTV programming now?
For the viewing of HDTV television programming, you need an HDTV decoder. HDTVs either come with an HDTV broadcast decoder or they don’t. If your particular set came with a built-in decoder, then all you need to do is hook up some rabbit-ears to your set and tune in to any channel displaying an HDTV signal. Otherwise you need an HDTV decoder to receive and display HDTV broadcasts. HDTV decoders are sold by themselves or they can come packaged with a Cable or Satellite TV receiver. Once you have a decoder you can enjoy all of the benefits of an HDTV signal.
Video games or movies as an HDTV source don’t follow this decoder rule. If you have a video game system that outputs HDTV or a DVD player that is progressive scan, then technically the HDTV decoder is already built into the particular electronic component. All you need to do is just hook up the component to your HDTV and your HDTV will do the rest.