Digital TV

Pages: 1 2 3 »» Next

What is digital television?

Digital television is a replacement technology for existing free-to-air analog services. It provides better picture quality and reception, plus a variety of new features that enhance the viewing experience.
The digital television industry in Australia is using the DVB standard, first developed in Europe, rather than the American-developed ATSC standard. DVB is proving to be a very high quality system and is being used in many countries around the world. In Australia it will replace the existing analogue PAL system in approximately 2010, which since 2000 it has been running concurrently with.

What benefits does free to view digital television provide?

Free to view digital television is a far more efficient and flexible transmission system than the current analogue system. It allows broadcasters to offer viewers a range of new and different services.

Australian digital television features include:

'Ghost free' reception
Widescreen 16:9 pictures
Standard Definition pictures (SD)
High Definition pictures (HD)
High quality audio and surround sound
Multi-channel programming
Closed Captioning of programs for the hearing impaired
Electronic Program Guides (EPGs) with 'now & next' program information for some channels
In selected markets, on-screen program guide channel with today's program information for Nine Network, Seven Network, Network Ten & SBS
In selected markets, HD channels
Additional program enhancements during selected programs

Explanations of Digital Television Terms

What is widescreen?

Digital television is broadcast in a native widescreen mode. Widescreen television has a different aspect ratio (ratio of width to height) than traditional analogue television. The aspect ratio of a widescreen is 16:9, while Australian viewers have been accustomed to viewing a 4:3 aspect ratio since television began in this country.

For some time now television production has been converting to widescreen, with the majority of local television programming now being made in widescreen while increasing amounts of overseas programming shown in Australia is also being made available in a widescreen format.

Widescreen is simply a television picture format that allows television networks to broadcast television programs that offer a more natural, wider picture. Sometimes known as "16:9", this refers to the aspect ratio (the ratio of width to height) of a widescreen picture.

For the technically minded, the aspect ratio for standard televisions is 4:3 (1.33:1) which gives the screen 1.33 inches of width for every inch of height. An aspect ratio of 16:9 (approx. 1.76:1) gives 1.76 inches of width for every inch of height. This gives the picture 30% more width than a 4:3 television picture.


TV with 4:3 aspect ratio	Widescreen TV with 16:9 aspect ratio

Widescreen and Digital Television

Widescreen is the native picture format for digital television broadcasts in Australia. Most new Australian programs and an increasing number of overseas sourced programs are now produced for widescreen. Widescreen pictures will, in many cases, literally mean you will get to see more of the picture.

Most movies are currently made in 16:9 and are converted to 4:3 on analogue to allow you to watch them on television or video, so there is a lot of information that you don't currently see on your television that you would see in the cinema version of the film. Digital television allows the vision of a film director to be more accurately maintained by preserving as close to the original aspect ratio of the movie.

Live sporting events will benefit in particular from the extra detail and wider picture allowing more of the action to be shown. The 2008 Olympics from Beijing will be shot with cameras with 16:9 widescreen lenses. This will be the first Summer Olympics in 16:9 widescreen.

This does not mean that all programs that are broadcast on digital television are shown in a widescreen picture format. Older television programming and television archive footage in particular, is still often shown in its original 4:3 format.

Is a Widescreen Television the same as a High Definition Television?

The answer is no. Not all widescreen televisions are designed to display High Definition pictures

High Definition broadcasts are only available in Australia on free to view digital television and provide the highest picture quality available via broadcast today.

For the viewer, this means crystal clear pictures with up to three times the horizontal and up to twice the vertical resolution of a standard digital television broadcast (known as Standard Definition). This allows broadcasters to provide amazingly detailed, lifelike images that can approach film quality, with clear, sharp edges, realistic colours and greater depth of vision.

To receive and watch free to view High Definition television you either need a television or display panel with an in-built High Definition digital television reception capability (a High Definition digital tuner) or an High Definition set top box connected to a High Definition capable television or display panel.

The following table provides a summary of the differences between Standard Definition and High Definition digital television broadcasts in Australia.

Standard Definition Digital	High Definition Digital
Transmitted at all times - 24 hours a day, 7 days a week. The majority of programming broadcast in High Definition (with the exception of High Definition demonstration loops and certain regional markets where commercial broadcasters provide a single national broadcast) is currently simulcast in Standard Definition.	Each broadcaster is required to transmit at least 1040 hours per year of High Definition programs in Sydney, Melbourne, Adelaide and Perth. This is the equivalent of 20 hours per week for each broadcaster. From 1 April 2005, each broadcaster in the Queensland, New South Wales & Victorian 'aggregated' regional markets, Darwin and Tasmania is also required to transmit at least 1040 hours of High Definition programming per year. This requirement will commence in Mildura from 1 January 2006. In other Australian markets that have commenced digital television broadcasts, High Definition quotas generally apply within two years of the commencement.
Mainly widescreen (16:9) programming with some older programs, archival and overseas shows shown in 4:3 format.	All High Definition programming is produced in a widescreen (16:9) format picture.
Improved picture resolution - similar in quality to that provided by standard DVD Players.	Highest available picture quality - up to three times the horizontal and twice the vertical resolution of Standard Definition broadcast programming (when viewed on an High Definition capable display). The benefits of High Definition television broadcasts at their highest resolution are particularly noticeable when using projection equipment and on larger televisions and display panels with resolutions of at least 1024 pixels horizontally and at least 720 lines vertically.
MPEG digital stereo sound - similar to CD quality.	Mpeg or DD 2/0 or DD 5.1.
Some programs are enhanced with Dolby Pro Logic surround sound or with Dolby Digital.	Some broadcasters provide programming enhanced with Dolby 5.1 surround sound where this type of soundtrack is available.
Standard Definition picture format: 576i (576 horizontal lines interlaced) supported by all broadcasters Data Rate: 5-7 Mbps 576 horizontal lines interlaced x 720 active pixels Vertical frequency: 50Hz interlaced	High Definition picture formats in use: 576p (576 horizontal lines progressive) transmitted by SBS data rate: 10-13 Mbps 576 horizontal lines progressive x 720 active pixels vertical frequency 50Hz progressive 720p (720 horizontal lines progressive) transmitted by ABC data rate: 10-13 Mbps 720 horizontal lines progressive x 1280 active pixels vertical frequency 50Hz progressive 1080i (1080 horizontal lines interlaced) transmitted by Seven, Nine, Ten, WIN, Prime, Seven QLD, NBN & Southern Cross Ten, Tas Digital data rate 13-15 Mbps 1080 horizontal lines interlaced x 1440 active pixels broadcast by all broadcasters excluding Ten and Nine Perth 1080 horizontal lines interlaced x 1920 active pixels broadcast by Ten and Nine Perth vertical frequency 50Hz interlaced
Most late model analog televisions and display panels are capable of displaying 576i pictures when attached to either a Standard Definition or High Definition set top box. An integrated Standard Definition digital television cannot display High Definition programs.	High Definition monitors and display panels, when connected correctly to a High Definition set top box, are capable of displaying High Definition programming at the highest quality. An integrated High Definition digital television is capable of displaying High Definition programs at the highest quality.