FTA High Defination Community Television

For Community Television to broadcast in High Defination it needs Australian Communications and Media Authority (ACMA) to issue full bandwidth channel digital spectrum, which appears unlikely.

Community Television may only be allocated narrowcast or datacast bandwidth unless they lobby for full bandwidth.

If the public wish to view High Defination Community television they need to convince the Federal Government that there is a need for it.

Many community programs are being made in high defination mainly for screening overseas, it would be a shame if Australian public had to go overseas to view these programs in their magnificent high defination quality.

I would encourage all program providers to Community Television stations to produce their programs in High Defination if you believe the content deserves it or the program is ever likely to be screened in a cinema or large screen outdoor festival setting.

There are media resource centres in Australia and Overseas offering hire and postproduction facilities. Why shoot on 35mm film when you can now shoot on HD Video at a fraction of the cost and still have near 35mm quality.

Unfortunately Australian Commmunity Television Stations (CTV) do not have studio or transmission equiptment for HD Video yet, and are still awaiting allocation of HD Digital spectrum.

HD Television is becoming increasingly popular in Australia in clubs, businesses, festivals and domestic homes where floor to ceiling projection is used. That is the screen size in homes is from floor to ceiling, great for sport such as motor racing, football, even variety shows where you have a front row seat in your own home.

To see what High Defination (HD) equiptment people are using see NRS Group's website or similar websites.

http://www.nrsgroup.com.au/LatestNewsHome.html

They have produced the following programs in High Defination,
World History using Sony HDW-F900,
Earthwalkers using Sony HVR-Z1P (that the excellent 1080i HD format)

The HD Video and Film Production Studios are at rural Cowra's Lachlan Village Estate
http://www.lachlanvillage.com/

Which High Defination Format for Community Television?

Digital Television in Australia

Digital broadcasting commenced in the USA and Great Britain in 1998.

Digital broadcasting started in Australia in the five major metropolitan citys, Brisbane, Sydney, Melbourne, Adelaide and Perth on 1st January 2001.

Most Australians now enjoy digital television.

The change from analogue to digital broadcasting has been compared to two other major historic developments in TV. One was the commencement of television itself and the other, the change from black and white to colour.

Digital signals can transmit up to four times the information as the old analogue system. This
provides broadcasters with the opportunity to entertain and inform us on a number of new levels through free to air (FTA) television

Digital television features include:

High Defination and Standard Defination Formats
Clear, crisp, ghost free pictures
CD quality surround sound
Widescreen format (16:9 aspect ratio, that is width of picture to height of picture)
Extended program Information (including electronic program guide EPG)
Better than DVD quality viewing
Multiview extended program information
Digital radio stations
Datacasting
Interactive Services (due to commence after analogue switchoff, or maybe sooner)

There are about 34 channels in each capital city many of these channels are copies to allow excellent reception now matter where you live, if for any reasion one channel breaks up with poor reception there are many other copies of that channel to tune into.

Broadcasters are transmiting the same programming on digital as is currently received on analogue this is called the simulcast period and will continue until all terrestrial analogue transmitters are turned off on 1st January 2008 this date may change and is currently being reviewed by the Federal Government.

High Defination Digital Television (HDTV) Description

High Definition Television, is Television with definition approximately doubled with reference to the conventional TV both vertically and horizontally and with increased picture aspect ratio. A format with a new screen aspect ratio of 16:9 (the current is 4:3) and capable of reproducing twice the resolution in horizontal and vertical dimensions than existing standard definition(SDTV) broadcast systems.

Australian HDTV Standards

The rest of the world has two HD formats, 1080i (interlaced) and 720p (progressive)

Australian has three HD formats, 576p, 720p and 1080i.

Standard Defination format is 576i (interlaced)

Ideally High Defination Community Television (HDCTV) should tramsmit using the highest format of 1080i, but this may not be possible so 720p may need to be considered.

Channel 10 and Nine use 1080i which is best quality, ABC and SBS use 576p, because they multichannel.

Should Australia stay with DVB-T using MPEG2 or go to MPEG4 ?

Extract from Broadcast Australia’s submission to the House of Representatives Standing Committee on Communications, Information Technology and the Arts Inquiry into the Uptake of Digital Television in Australia 5 May 2005
www.broadcastaustralia.com.au



4.4 Emergence of Advanced Compression Technologies

BA considers the emergence of second-generation DTV compression technology as a highly important technical issue (and opportunity) that requires consideration by government and industry stakeholders. The current standard is known as MPEG-2.This allows the operation of 4-6 SDTV multi-channel services on a standard 19.3-23Mbps (depending on the guard interval used) digital channel. More advanced second generation technology (MPEG-4 or WM9) is rapidly emerging, however, that offers considerable encoding efficiencies over the current MPEG-2 standard and, therefore, the ability to provide a significantly increased number of SDTV and/or HDTV services within the terrestrial Transport Stream.

MPEG-4 is an advanced open compression technology which allows for the provision of SD and HD television services utilising less bandwidth (i.e. more services per digital channel or ‘multiplex’). The additional capacity could also be used for the introduction of interactive services. Its encoding is typically 50% or more efficient than MPEG-2. The development of MPEG-4, Windows Media 9 (a competing proprietary technology) and other applications allows for the running of more simultaneous program streams within a standard 7 MHz channel, as illustrated in the diagram below.:

The number and make-up of channels used in an MPEG-4 environment will depend on choices made by broadcasters relating to standards, quality, programme format and bandwidth allocation – but in any case could clearly represent the opportunity for there to be a quantum leap in the diversity and innovation of programming offered to consumers.

The above diagram demonstrates there is a range of choices available
to broadcasters – for instance to deliver a large number of SDTV sub-channels or to deliver a mixture of SDTV and HDTV channels or to deliver only HDTV channels (once the must-carry obligation in SD format ends).

The MPEG-4 standard is now well-established and tested in the international DTB
forum and is gaining greater industry acceptance in Europe and the US particularly
for distribution and delivery of video services across telecommunications networks.
BA understands that MPEG-4-based terrestrial receivers are expected to become
available in significant numbers from the second half of 2005. Early versions of
MPEG-4 based terrestrial receivers are already available in small numbers.

BA acknowledges that the introduction of MPEG-4 in Australia would result in legacy issues with current reception devices (albeit that the population of these devices is reasonably small). While we realise that such a move will take time, we strongly believe that:

* It is critical that Australian government and industry stakeholders are aware of the rapid emergence of second-generation compression technology and that its
development and ramifications start to be considered now for future implementation, particularly given the context of the government’s reviews relating to the introduction of DTV into Australia;

* There will come a point in the relatively near future (approximately 12-18 months from now) when an important standards-related decision will need to be taken by Australia on this issue (eg. whether or not to adopt an advanced compression technology standard and if so, whether to implement MPEG-4, WM9 H.263 or H.264 or some other standard). This decision point will be driven by the increased adoption of these advanced compression technologies in the world’s leading DTV jurisdictions and the mass availability of (affordable) consumer reception devices;

* Working on this premise, government should be prepared to take a leadership
position on this key standards issue, otherwise there is a real risk of deadlock
amongst existing operators leading to inertia (i.e. as recently occurred in relation
to the API standard for DTV). While acknowledging the understandable
reluctance by government to unilaterally mandate technical standards, this
leadership could take the form of an ABA-chaired working group that seeks to
define a process and milestones for resolution of this issue, with the option of
more direct government involvement in the event of failure by industry to make
substantial progress by predetermined dates;

* The later that Australia leaves the consideration (and selection) of an advanced compression technology standard, the more difficult the size of the receiver legacy issue will be to manage.

BA believes it is critical for Australia to position itself with policy settings today to
ensure the benefits of substantially improving technology and compression are
available for future generations of users of these services.

Obviously, the introduction of an alternative standard will create a legacy situation, however, it is important that Australia adopts a standard (or range of standards) that will serve the needs of the public and provide efficient use of wireless spectrum for many decades to come.

The introduction of interactive television and the development of advanced or
second-generation compression technology will impact substantially on how the
consumer utilises the television programmes and will expand the capacity of the
spectrum to provide additional services. Planning now for future public policy in the digital broadcasting area should take account of these developments.

Hierarchical Modulation Explained

DVB-T Hierarchical Modulation

DVB-T is a flexible system allowing terrestrial broadcasters to choose from a variety of options to suit their various service environments. This allows the choice between fixed roof-top antenna, portable and even mobile reception of DVB-T services. Broadly speaking the trade-off in one of service bit-rate versus signal robustness. But that is not all. The DVB-T specification and indeed all the current chipsets allow “Hierarchical Modulation”.

What is Hierarchical Modulation?
In hierarchical modulation, two separate datastreams are modulated onto a single DVB-T stream. One stream, called the “High Priority” (HP) stream is embedded within a “Low Priority” (LP)stream. Receivers with “good” reception conditions can receive both streams, while those with
poorer reception conditions may only receive the “High Priority” stream. Broadcasters can target two different types of DVB-T receiver with two completely different services. Typically, the LP stream is of higher bitrate, but lower robustness than the HP one. For example, a broadcaster could choose to deliver HDTV in the LP stream.

How does it work?
DVB-T is a multi-carrier system using about 2000 or about 8000 carriers, each of which carries QPSK, 16QAM or 64QAM. QAM (Quadrature Amplitude Modulation) is one of the means at our disposal to increase the amount of information per modulation symbol. Taking the example of 64QAM, the hierarchical system maps the data onto 64QAM
in such a way that there is effectively a QPSK stream buried within the 64QAM stream. Further, the spacing between constellation states can be adjusted to protect the QPSK (HP) stream, at the expense of the 64QAM (LP) stream.

In layman’s terms, good quality reception allows receivers to resolve the entire 64QAM constellation. In areas with poorer quality reception, or in the case of mobile or portable reception, receivers may only be able to resolve the lighter coloured portions of the constellation, which correspond to QPSK.

Considering bits and bytes, in a 64QAM constellation you can code 6 bits per 64QAM symbol. In hierarchical modulation, the 2 most significant bits (MSB) would be used for the robust mobile service, while the remaining 6 bits would contain, for example, a HDTV service. The first two MSBs correspond to a QPSK service embedded in the 64QAM one.
11 0100 (bits “11” are used to code the High Priority (HP) service)

Example of system parameters
A set of parameters, which might be appropriate
for use in a North American 6MHz channel for HD/
SD simulcast, is as follows:

Modulation:
QPSK in regular 64QAM 6MHz DVB-T
Guard interval:1/32

Code rates:
HD (low priority) service: ¾
SD (high priority) service: ½

Video resolution:
HD:720P
SD:480I

Bit rate:
HD layer - 13.6Mbit/s,
SD layer - 4.5Mbit/s

Gaussian noise performance:
HD layer - 19.6dB

Credits: thanks to:
Jeff Gledhill (TandbergTV), Peter MacAvock (DVB), Roger Miles (EBU)