05.The lowdown on digital TV
Here are some answers to frequently asked questions on digital and high definition TV. Also read our comprehensive guide to digital TV.
For information on digital TV and the closing down of the analogue TV service across the county see the Government's Digital Switchover Taskforce website.
What is high definition?
- Higher definition or resolution essentially means you get more detail, but not necessarily a better overall image.
- Some TVs are ‘HD ready’. This means they can display a high-definition signal, but they may display it at different resolutions. If not, to receive HD you'll have to buy an HD set-top box (currently the most common digital set-top boxes are standard-definition, and a high-definition box will set you back a little more).
- Theoretically, HD provides superior-quality pictures with better definition via several TV channels.
- But from what we’ve seen, at smaller screen sizes (under 94cm) the difference between standard and high definition doesn’t seem to warrant the extra expense, particularly given the range of extra channels in the HD format remains limited.
- In fact, the chief advantage of HD currently seems to be that it can broadcast Dolby Digital sound (as favoured by the movie industry). So if you have a Dolby Digital 5.1 surround-sound system or home theatre hooked up to your HDTV set-top box, you’ll be able to take advantage of programs broadcast in that sound format.
With broadcasts going digital between now and 2013, Chris Ruggles tells you what you need to know about the DTV switchover.
The essentials
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Built-in digital tuner means you don’t need to buy a set-top box to receive digital TV. For most people, standard-definition (SD) or high-definition (HD) doesn’t matter, as not much HD-only TV is being broadcast, although more will be in future.
- Look for easy-to-use sockets that allow you easy access to the connections for DVD players, cable TV and so on. If you're wall-mounting the TV, access is very important to avoid having to take it off the wall to change a plug.
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HDMI (high-definition multimedia interface) is an all-digital connection for both sound and video in one cable. You may not have many gadgets with HDMI output at the moment, but we expect most will have them in the future, so it's worth looking for at least one HDMI socket.
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DVI/VGA input If you want to use your TV as a computer display, you’ll need one with a DVI input for newer computers or a VGA input for older ones. An HDMI socket will do if your computer has an HDMI output, but not many do at the moment. DVI-to-HDMI adapters are quite inexpensive to purchase.
The benefits of digital
- Better reception: No more ghosting or 'snow', so you'll get clearer pictures. If your analogue reception is very good, the difference will be marginal, but if it's very poor you may not be able to receive digital TV at all. This is one reason why analogue TV may well be around for a while yet.
- Better audio - CD quality on standard-definition broadcasts and Dolby on some HD broadcasts. To make the most of this you'll probably need to feed the audio through a sound system.
- TV programs in widescreen (16:9) aspect ratio.
- Multi-channel programming enables broadcasters to introduce extra programs you can watch on a different channel from regular free-to-air programming.
- Closed captions are great if you're hearing-impaired or when other people don't want to hear the TV. They're available with all prime-time programs. Much like regular subtitles in most ways, closed captions have the advantage of also captioning sound effects and colour coding different 'voices'.
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Onscreen program and channel guides to save you having to buy a TV guide (limited channel information in some areas).
- Multiviews and enhancements, with some programs. For example, some sporting events may allow you to choose the camera angles and the commentary you prefer and allow you to view extra statistical and other information.
- Interactive TV (iTV) provides opportunities for viewers to interact directly with the broadcast. One-way iTV delivers extra program information that you can opt to view or not. Two-way iTV will enable viewers to send information back, potentially letting you participate in polls and surveys, play along with quiz shows, interact with sports shows, hire movies (video on demand); it may even provide gambling and betting services. You can expect to be charged for some interactive services.
Which resolution?
It’s easy to get confused in the HD world. High definition for TV sets refers to the number of pixels on the screen; anything above 1366 x 768p is generally called HD. On the other hand, high-definition sources, such as Blu-ray and HD TV broadcasts, can be anything from 720 x 576p at the low end of HD broadcasting up to 1920 x 1080p. The "p” stands for progressive, which gives a more stable picture than an interlaced picture (which usually has an “i” after the number).
There isn’t really a simple definition for high-definition TV sets either. The size of the screen must be taken into account, because this influences the size of individual pixels. At smaller screen sizes (under 94cm) the difference between standard and high definition doesn’t seem to warrant the extra expense.
The quality of the image is not necessarily tied to the number of pixels. Colour accuracy, smooth transitions between colours and blacks that don’t look muddy or lose detail are more important. The TV’s picture processor handles these functions, and more pixels may actually make it harder for the processor to deliver a good image.
In previous tests, we compared the performance of lower-resolution TVs against high-resolution models and found resolution has little influence on overall picture quality.
Do I need widescreen to watch digital TV?
Widescreen is the standard for digital television, which we’re all meant to have converted to by 2013. But because overseas programs are still shot in a variety of formats, you’ll be putting up with black sidebars on a wide screen when a program is in the traditional 4:3 format for some time yet.