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UK Terrestrial High Definition TV (HDTV) trials for London in 2006
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Thursday 25th May 2006
Early in May 2006, two extra multiplexes appeared at channels 27 and 31 (522MHz & 554MHz) from the Crystal Palace Transmitter in the UK.
These two frequencies are to be used by the major channel providers for demonstration of the first UK Terrestrial based High Definition Television (HDTV) transmissions.
Starting in early June 2006, a range of programmes will be shown in the new HDTV formats that will only be receivable by people in the London area, and only those
taking part in the official consortium trials with the correct reception equipment.
These trials will last a year, and lead the way to a fuller coverage of HDTV within the UK in the near future. Because of the pioneering nature of these broadcasts, Nebula
of course has an interest in the outcome of these trials to enable us to stay at the leading edge of Digital TV reception. The trials are also similar to other trials taking place elsewhere
in the world (eg Singapore) where we are also actively staying ahead of developments.
The broadcasts are being made in the H.264 (Advanced Video Codec) format at a variety of resolutions and bit-rates. There are several different 'flavours' of H.264 video, and
in keeping with the high-quality broadcast nature of the channel providers, they are using the High Profile Level 4 version. This allows for a very high bitrate to be used so that
picture artefacts can be kept to a minimum.
Audio is transmitted in 5.1 AC3 (Dolby) for true surround-sound.
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The disadvantage of all of this quality is the amount of processing that is required by the decoder in order to achieve it. In the case of a hardware decoder, the processing time can
be more or less forgotten, but in the case of a PC it becomes a very serious issue.
Higher resolutions (up to 1920 x 1080) and high bitrates taken together with new compression technology such as Context Adaptive Binary Arithmetic Coding (CABAC), and image cleanup techniques mean that a
standard PC is no longer capable of decoding the video in real-time without recourse to some very advanced acceleration techniques.
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Nebula Electronics already has an H.264 Main-Profile decoder currently distributed with the software and activated via our H.264 licensing for viewing 'mov' files.
We also have an H.264 High-Profile decoder (it decoded the images shown on this page), but it is still at an early stage of development.
Nebula will use the trials data to hone our High-Profile decoder to the current level of efficiency enjoyed by our current MPEG2 decoder, but this will involve a considerable amount of work. Aside from implementing hardware
acceleration using MMX, SSE and SSE2 technology, additional hardware acceleration will be necessary by utilising the GPU present in the current range of graphics cards if the decoding is to be performed in real-time
on a generally available PC.
We'll post a guide as to the kind of PC you'll need once the trials have begun, but it's safe to say that you'll need considerably more than that dusty old 1GHz with onboard graphics.
As our decoder becomes faster and more error resilient, we'll post updates to our DigiTV application away from the main release path to allow users in the London area to provide us with feedback on the operation of our
HDTV reception.
Unfortunately, because we implement an H.264 decoder in our application, a licence fee is payable to the patent holder for each unlocked copy of the code that we distribute. We have therefore linked the
operation of our High-profile decoder with the licensing scheme adopted for our current H.264 Main Profile decoder. Anyone that already has an H.264 generic licence
will automatically get access to our High-Profile decoder when it's released as well.
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Non-licence holders will only be able to view H.264 content for one minute, but the required licence is very cheaply available and can be purchased from within the 'Licensing' settings page of DigiTV.
At least to start with, only Pentium 4/Mobile and AMD 64 processors will be supported, although support for AMD XP processors may be added in the future.
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Please note that any software releases that are capable of H.264 High Profile decoding are entirely experimental and the software should not be used for day-to-day viewing. This software is made available for the purposes of
gathering data about our H.264 implementation across a variety of real-world installations only.
All images decoded with the DigiTV H.264 High-Profile Decoder and are Copyright © BBC and ITV. The full size images are best viewed at 1920x1200 screen resolution. All images have been JPEG compressed so may not represent the full quality of the video data.
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