HD and Freesat questions and answers
Al posted some very good questions about HD and Freesat.
"I know upscalers are not HD, they merely interpolate a SD signal to make it fit a HD screen"
It is very confusing that HD is used to mean several different technologies. High Definition refers to:
- the resolution the number of picture cells of the screen;
- the resolution of the encoded pictures;
- the resolution of the source material;
- as "HDMI" the digital connector between a set-top box and a display;
There are also a number of associated technologies, which come under the name MPEG4. These are used to encode the pictures, audio and data that you recognise as a TV signal.
Standard Definition (SD) is shorthand to refer to the resolution of PAL-type televisions. Technically this is called MP@ML, Main Profile at Main Level.
"My point was where a programme has been recorded in SD only, then it is still possible to have a HD only transmission service by the use of upscaling those programs to HD format - something I understand Sky do now with some of their content."
This is not necessary. MPEG 4 can work with sources at any of the defined resolutions. As a rule you should always transmit the material in the original format wherever possible. Interpolation before the data compression just results in unnecessary data, or a poor encoding.
"Point is it allows a HD only format channel in the interim between some programs and all programs being recorded in HD. "
This is exactly what you would expect from the history of television. BBC One started as BBC Television in monochrome, 405-line and moved first to 625-line colour and then to MPEG2 digital widescreen. This is true for all UK services.
You would expect the next transformation to be to HD.
"As for the hundreds of channels on Freesat currently, I understood that Sky Freesat and BBC Freesat were different entities."
The Eurobird 1 & Astra 2A/2B/2C/2D at satellites over the equator at 28.2E provide transmission services for the UK.
Broadcasters are quite free to upload any content to these satellites. Each transponder carries a digital stream in MPEG2 format that each has ten or more television channels.
Some of these services are free-to-air, some are encrypted. Anyone is free to point a dish at it and use a suitable decoder to watch the services.
The BBC and ITV channels are unencrypted and numerous. Each BBC and ITV region has to be carried on the satellites, as this is the only way to replicate the local services provided terrestrially.
To add to the confusion there are some services that are what is termed "soft encrypted", which means a card is required to decode them, but no subscription is required.
So, "Freesat From Sky" comprises all the free-to-air services PLUS a number of soft encrypted channels: Channel 4, five, five Life, five US and Sky Three. The Sky service also includes the Sky Electronic Programme Guide.
"The Sky Freesat being Sky's current free to air system and BBC Freesat being a BBC / ITV collaboration producing a new satellite service."
Sky's Digibox set-up is a special version of a satellite receiver. It contains a special Sky subscription card system, the Sky EPG and also a software system called "OpenTV".
The BBC/ITV Freesat service, called just "Freesat", will use all the existing free-to-air satellite broadcasts and provide a non-Sky EPG. There will be no subscription system and it will have the MHEG-5 software, as all Freeview boxes have.
In addition the boxes will be able to decode MPEG4 transmissions, which will allow high-definition services to be carried.
The Freesat boxes will be of various types, from a basic box to a high-end personal video recorder (PVR), like Sky+. Without the monthly fee, however.
"However, if they are the same, then the answer is still yes. If it is the same service then either way its done, those 9 million boxes will have to be changed one way or another."
This is always a dilemma of digital technology. If you make cheap, mass market decoders you have to fix the standard. All the Sky boxes out there are MPEG2, DVB-S.
So, all new HD services and any other SD services encoded with MPEG4 are totally invisible to anyone with an "old" box.So yes, over time, the whole system will move to MPEG4 in HD.
This provides an interesting question. If you have a SD channel, do you use MPEG4 or MEPG2?
"It's far better to set a defined changeover date and switch off the existing Freesat service on that date in favour of a new HD only service than to confuse consumers by having two parallel systems with intermixed programming of ever changing proportions that leaves people unsure about what, when and where to get HD content."
It might be, but it is not just Freesat from Sky people using the current free-to-air transmission, but all those Sky subscribers too. Until they have all got MPEG-4 boxes, you can't move to HD.
"I know you next reply will be what about the consumers who've only just bought a Sky Freesat SD box? Well the answer is: - exactly the same scenario will apply whether the switchover is made by gradual means, someone somewhere will have only just bought an SD Freesat box. "
I understand that the idea is that ALL Freesat boxes will be able to decode MPEG4, even if they output a downscaled version of HD channels on the SCART.
There is going to be many years of people moving from SD to HD satellite reception.
"If Sky wanted to soften the blow, then a simple trade in discount scheme for those who've bought boxes in the last 6 months would suffice I'm sure."
There's not much in this for Sky. Remember that Sky only provide a very few of their channels. They provide the subscription services, but they do not play-out, encode, multiplex, uplink most of the channels.
The only way that Sky will start swapping out boxes will be if they can make more money. At some point, as with the analogue satellite closedown, it becomes cheaper to force customers to have a new box than waste money on inefficient transmissions.
"All of this gradual rollout rubbish not only confuses consumers by blurring the issues of what programming is available where and when and what equipment is needed (2 parallel types) - this is quite contrary to the claims that it is avoiding confusing consumers."
You are right. Confusion isn't the half of it.
In the US, there has been a very simple transition from analogue, 4:3, SD to digital 16:9 HD. Each SD channel has simply transformed into a HD channel.
Whilst in the UK, we have transformed so slowly that the early start has meant that by the time we achieve terrestrial switchover, the technology will be out of date.
"The current analogue switch over is the slowest and most confusing thing out!! If that's the government's idea of helping consumers they should stick to politics."
To be honest, the government's policy is to not intervene. The satellites are provided by two companies, SES Astra and Eurobird. The uplinking by several UK companies, including BT. The channels by hundreds of broadcasters.
It is policy that the providers can do as they please.
"This current policy is also putting the UK behind the rest of the world."
Not really. Everyone in the EU is in the same kind of boat.
"I believe JVC has already announced that it's to start manufacturing test sets for the next generation of TV's dubbed 4k2K (4096x2160 pixel resolution) and that broadcasting trials of this format will commence in 2011 in Japan."
You can't measure other countries expectations against our current position. Also, other countries are more bothered about consumer choice than government income.
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