BIOS: Technology Means Business

HDTV (high-definition television) is the new standard in television technology. It provides widescreen picture quality similar to 35mm film along with compact disc (CD) sound quality. HDTV is part of several standards incorporated into digital television (DTV).

HDTV is the technology of the future. It offers much higher resolution and clarity than analogue TV and over twice the resolution of DVDs. Basically, DTV is composed of three separate standards: HDTV 1080 (1080 lines of resolution, 16:9 aspect ratio), HDTV 720 (720 lines of resolution, 16:9 aspect ratio), and SDTV (480 lines of resolution, 16:9 or 4:3 aspect ratio).

The biggest breakthrough in broadcasting since colour TV, HDTV offers wider pictures with greater detail and the clarity of motion pictures. Compared to standard television (NTSC and PAL), a 'true' HDTV image has twice the luminance definition - vertically and horizontally - and is 25 per cent wider. In addition, a standard television aspect ratio is 4:3 (four units wide, three units high), while the HDTV aspect ratio is 16:9 - much closer to the average widescreen image shown in movie theatres.

However, the biggest difference and the greatest appeal of HDTV, is its clarity. True HDTV pictures are composed of 1080 active lines (1125 total) whereas current standard television pictures are composed of only 486 active lines (525 total). While it is possible to see the lines that make up standard television pictures, HDTV lines are not at all noticeable. The fine-grained picture contains five times more information compared to a standard television picture - the difference in video and sound quality is dramatic!

Interlaced versus non-interlaced
Regular colour television is scanned at 480i, which means there are 480 vertical lines that are scanned in an interlaced format. This means that at any given time, only half of the picture is on the screen at a time. While one frame will only display the odd lines (1, 3, 5), the next frame will only display the even lines (2, 4, 6). This happens so fast that the human eye is tricked into thinking that it is only seeing one picture.

This is contradictory to progressive (or non-interlaced) scanning, which means each frame is displayed all at one time. Instead of interlacing the lines, each frame is displayed as you would guess, being line 1, line 2, line 3, and so on. The end result is a much sharper image that looks much better. Although the difference in an interlaced signal and a progressive signal is the way the picture is scanned, it does have a big difference on the resulting image.

True HDTV signals are signals that are broadcast in a format of 720p or 1080i. 720p means that there are 720 horizontal lines that are scanned progressively and 1080i means there are 1080 horizontal lines that are scanned in an interlaced format. Although there is a big difference in the number of horizontal lines, the fact that 720p is progressive and 1080i interlaced means that the resulting pictures are very similar.

Digital TV versus HDTV
Digital TV, such as that provided by BskyB in the UK, is not the same as HDTV. Digital TV is almost always regular television signals (ATSC) that are being broadcast in a digital format instead of the regular analogue format. It has nothing to do with DTV or HDTV, though it is possible for cable companies to send HDTV signals through their digital cable service. Every year the number of cable providers supporting HDTV is increasing tenfold. Look for your local cable provider to provide you with HDTV sometime soon - if it doesn't already. BskyB will be the first to offer HDTV in the UK, expected early next year.

Getting HDTV
There are three ways of receiving HDTV broadcasts, although the options are restricted to where you live or work. If your local cable provider currently supports HDTV then you can receive those signals from them. Pricing and the number of channels it carries depends on where you live. You will also need to get a HD decoder box from the cable company to watch these signals.

Over-the-air is a means of setting up an antenna and receiving channels from local broadcast towers. If you are in a large metropolitan area then chances are good that you can already receive free HDTV over the air. You will need to get a separate decoder box to watch these signals and in many cases will have to mess around with the setup a bit before everything is running smoothly.

Finally, almost anyone can receive HDTV via a satellite company. Indeed, almost all satellite companies currently - or plan to - carry high definition channels. You will need to get a special HD decoder from the satellite company to watch these signals and you usually will have to pay a price increase for this service as well.

A regular VHF/UHF antenna will work for receiving HDTV signals. However, even though a regular old VHF/UHF antenna will pick up HDTV signals, you might need a newer antenna with a pre-amp to actually receive the channels. This will depend on how far you live from the local broadcast towers, how powerful the signals are that they are actually broadcasting, and what your local terrain is like. For instance, do you have large buildings, big trees, foothills near you?

HD sources
It's not only HDTV broadcasts that take advantage of HD. For instance, Microsoft's Xbox videogames console can output true HD signals at resolutions of 720p and 1080i. However, there are quite a few games for most of the newer video games consoles that support 480p.

For instance, almost every title for the Xbox supports 480p, while only a few of Sony's Playstation 2 games support 480p. Nintendo's GameCube and Sega's Dreamcast also have some titles that run in 480p mode. The next-generation consoles, namely Microsoft's Xbox 360 and Sony's Playstation 3, will also support HD.

If you don't have a progressive DVD player, get one now. DVD is encoded in the 480p format. The 'P' stands for progressive and 'I' stands for interlaced. Regular television is displayed in the 480i format, which is the format for standard, non-high definition televisions. To get the best possible picture with DVD-Movies you need a progressive scan DVD player. A non-progressive DVD player will only output the standard 480i signal.