HDTV in the UK

[rolfw]

Yes very undesirable in any application involving sampling just a bit more visual with video signals. In order to minimise aliasing it is necessary to sample the signal a minimum number of times. The Nyquist sampling theorem provides us with the answer. The theroem states that if a continuous bandwidth limited signal contains no frequency componants higher than Fm, then the original signal can be recovered without distortion if it is sampled at at a sampling rate (Fs) of at least 2Fm samples per second. i.e. the minimum rate is Fs = 2Fm (where Fs is the sampling frequency). This is sometimes referred to the Nyquist Rate. In practice however one uses Fs > 2FM this then provides us with a guardband.

Dedicated to Eugene who probably knew this but doesn't know what to do at a party !

So what's anti-aliasing then?

 

[Llew]

You use a low-pass filter before the ADC converter to cut off frequencies higher than the sampling frequency. Those higher frequencies cause 'foldover' into the wanted frequency band, i.e. 'aliasing'. The low-pass filter in theory eliminates anything higher than the sampling rate.

Llew

 

[Llew]

When we did all this stuff re Nyquist sampling for our telecomms exams in the 70's, it was as it applied to voice frequencies over the telephone network. Didn't envisage using it for video systems then. Older and wiser (I don't think)...

Llew

 

[Topper]

When we did all this stuff re Nyquist sampling for our telecomms exams in the 70's, it was as it applied to voice frequencies over the telephone network. Didn't envisage using it for video systems then. Older and wiser (I don't think)...
Llew

Older true but for sure not wiser. I used all this exactly the same although this was in the 90's when I retrained having decided textile engineering was no longer the flavour of the decade. I nearly fell asleep during this lecture Llew but I did fall asleep at the next. Converting signals from the analogue domain to the digital domain using integration techniques Ah yes Laplace Transforms Ahgghhghgh.

 

[BarMoo]

Sorry, just caught up on the thread. Is the thread now about Analogue PAL 625 Line UHF TV RF, or, MPEG4 HDTV ?

I can understand posts about 'aliasing' in an analogue world. However, artifacts in a digital world are somewhat different.

While a 100Hz TV might need a gazillion correction toys to make a picture look bearable - that's only because the 'digital' tuner and subsequent processing is nasty and cheap. [off track] I took time out from slagging off 100Hz TV's last week to look at the latest. Wish I hadn't now.

No! the picture quality still sucks. Mind. These days the award for worst picture imaging lies firmly with LCD. I'm turning into a vynl man.

Back to the thread. The HD signal path is all digital and remains digital till it gets to your digital HD ready TV (although this is not exactly true of SKY's soon-to-be-launched HD ST. In short, there shouldn't be any problems.

The most likely artifacts to occur on screen are the usual basic ones. Blocking (signal errors), Quantisation Errors (native to all compression*), Posterisation (a weird effect that flattens similar shades/tones or colour in a wierd way and looks very analogue) and then there's concatenation. I'm bored already. Technically, these are all artifacts and there's a whole load more. Later, perhaps.

Back in the real world, we are more likely to REALLY notice aliasing on really old shows. Two cases in point: Fawlty Towers and Yes Minister. Studio based (with 16mm inserts) recorded onto a long gone video tape format called QUAD (tape width 2") with cameras that needed the light of a thousand suns.

[Trivia] 'engineers' were known to make edits by physically slicing the tape (head rotation was near vertical and so allowed beared men to splice between the tracks).

[Not Trivia] What is clear is that shows from this era don't convert to the digital domain with dignity: psycotic attempts to compress grain from wobbly 16mm transfers and tube cameras. Moreover, the original recording system doesn't help. Perfectly OK for valve TV's of the 70's/80's, er, but not now. If your still reading this, technically, we are talking about a look on par with ITV News Channel.

My point is thus. In a digital world, these problems will establish themselves at the point of conversion: but won't, necessarily, manifest themselves within the workings of my TV.

I imagine that HD will only highlight these errors more vivaciously. Yes, anti-aliasing toys at the broadcaster end will come in very handy. Fawlty Towers on Blu-Ray HD-DVD - should be fun

Till then, the best TV for these old shows is a 50Hz one - and connected by RF. Not joking, its true, ask AnalogueSat.


Ramble over - Have Fun,

Mark.


*Don't know about MPEG4 or DVB-S2

 

[gameboy]

Back in the real world, we are more likely to REALLY notice aliasing on really old shows. Two cases in point: Fawlty Towers and Yes Minister. Studio based (with 16mm inserts) recorded onto a long gone video tape format called QUAD (tape width 2") with cameras that needed the light of a thousand suns.

[Trivia] 'engineers' were known to make edits by physically slicing the tape (head rotation was near vertical and so allowed beared men to splice between the tracks).

Now on Fawlty Towers that must have been some job.

Fawlty broke one of the golden rules of broadcasting ' don't cut in sections of 4 seconds or less' as this distracts and annoys the viewer.

Fawlty did this often, but manage to get away with it.

Next time you watch, if you remember this, you'll see what I mean.

 

[BarMoo]

@Gameboy,

I hope I didn't imply that every cut was made by splicing this 2" tape, LOL.

It was a brutal affair afterall and didn't always work: like the joints might come undone. Spilced archived tapes often fell apart. The usual stuff.

4 seconds is a long time these days, isn't it.

Something totally different but still on cutting: when the Eurovision came to Birmingham (at the height of overcutting of music in the UK) the speed at which the show was initially cut had to be slowed down because most european broadcasters hadn't yet seen/adopted this frantic style of cutting. Besides, racey cutting of a folk song from Romania does't quite do it for me somehow

Since then, most music is now cut at a reasonable rate; so, as you said, its nice to see some golden telly rules are still appropriate even these days, LOL

I'll look out for the Fawlty cuts (sic) the next time I pull them out. I watched Yes Minister only a couple of weeks ago - hence why the artifacts are still fresh in my head.

I must find something more stimulating to occupy my time,

Mark.

 

[gameboy]

BETZDORF, Luxembourg, Aug. 8, 2005 SES ASTRA, an SES GLOBAL company, has secured a long-term contract to provide British Sky Broadcasting (Sky) with three additional 28.2 degrees East transponders.

Sky will take advantage of the increased availability of transponder capacity to transmit its forthcoming package of high-definition (HD) television services, which is due to be launched in the UK and Ireland in the first half of 2006. The Sky HD service will deliver substantially superior picture quality than standard-definition television broadcasts and will include a range of channels including sports, movies, general entertainment and documentaries.

The launch of HD is part of Sky's continuing commitment to lead innovation in television entertainment following its previous introduction of the UK's first digital television service, first interactive television service and first integrated Digital Video Recorder. Sky believes that the introduction of HD will strengthen further the distinctiveness of the digital satellite platform and appeal to the increasing number of consumers who seek to enhance their viewing experience with HD Ready display equipment. In addition to the package of channels to be offered by Sky, other broadcasters on the digital satellite platform will also be able to take advantage of its HD capabilities to enhance the experience offered to their viewers.

Richard Freudenstein, BSkyB's Chief Operating Officer, said: "The launch of HD is a significant development in broadcasting, offering a step change in quality that will strengthen Sky's appeal to existing and future customers. Innovation and technology leadership will remain at the core of the Sky brand as we progress towards our target of 10 million customers.

"Sky has enjoyed a long-running and co-operative relationship with ASTRA. We look forward to extending this relationship into the HD arena as a result of this agreement."

SES ASTRA's President and CEO, Ferdinand Kayser, said: "We have been a partner of Sky since the launch of its UK DTH services in 1989. This important deal is an excellent endorsement of the quality and strength of our service and highlights BSkyB's long-term confidence in ASTRA."

 

[BarMoo]

In addition to the package of channels to be offered by Sky, other broadcasters on the digital satellite platform will also be able to take advantage of its HD capabilities to enhance the experience offered to their viewers.

MPEG4 (rather DVB-S2) can accomodate upto 9 HD channels per transponder. Nine x Three = 27. Its not difficult to read between the lines - is it?

Can't wait to see how this unfolds.

Have Fun,

Mark.

 

[gameboy]

HD Football from S*y?

....EVS has concluded multi-million deals in the U.K. market for its new platform, XT(2), which has been successfully released last June during the Confederations Cup in Germany. More than 30 XT(2) hybrid SD/HD systems have been ordered by BSkyB and independent production companies for the outside production in High-Definition of the U.K. Premier League and new near-live studio applications.

Ahead of the BSkyB HD service launch in the U.K. and Ireland in the first half of 2006, Sky has already committed the XT(2) as a key element of its new HD production workflow. From the beginning of the new season, the Premier League is being partly captured in the High-Definition format.

These deals pave the way for a wider market acceptance of the newly launched XT(2) but mainly provides more visibility for the current year and confirms the 2005 guidance: a transition year compared to 2004 with a weak first half and a much stronger second half-year.

 

[BarMoo]

For those that are interested - the XT[2] is a server that can play back up to 12 HD channels simultaneously and is shipped with (amongst other features) six configurable digital video ins/outs.

Its a hard drive - with some ...

Have Fun,

Mark.

 

[dabba]

having recently tried the HDTV stuff on astra on my humble 19" lcd dvi lcd with my skystar2 im amazed at the picture quality, Its all the excuse I need to upgrade the tv
Its like watching vhs when i tune to normal tv

 

[spiney]

Going back to sampling ...


Nyquist sampling frequency with filtering is not a sufficient condition to prevent aliasing, as there are many other types of "patterning" effects, eg interlace conversion problems, standards conversion, etc ......

 

[Analoguesat]

Have to say this poll is remarkably close so far....

 

[BGonaSTICK]

Indeed. It's going to be even more interesting to see how it flies in reality.

I'd love it, but won't pay extra for it. AFAIC it should not attract a premium - TV costs enough these days and technological advancements and overheads of such should be factored into long-term fee structures.

OK so we know that won't happen in the modern world, but I'm taking a moral standpoint here

Other than the $ky launch, I'll just watch it as it becomes FTA/compromised.

More interesting than that even is if it's possible to use the same flavour of ND$.

Wonder if the card authorisations will happen more frequently?

Will they be using the same cards does anyone know?

Sorry, I have to admit to not having read the entire thread. My brain was fried after the second post!

 

[gameboy]

BSkyB reminds me of Apple Computers with its silent progression to its ultimate goal. We know its high definition service is coming, we know that the reasons for it are to do with factors like subscriber saturation, FreeView competition, share price and achievable innovation - but we don't know much more.

Apple Computers uses the trickle of information to cause a torrent of interest from consumers - the same is happening to BSkyB with its HD news, but the public doesn't care... yet. All the noise is coming from the trade and its competitors.

The BBC has announced that it will have total HD production by 2010 and in the same breath has claimed an interest in how BSkyB gets on with its HD strategy. Most of the other channels have a 'wait and see' attitude - some of the advertising agencies are dealing in mixed messages and ignorance by saying things like 'HD costs more to shoot' so they won't be recommending it to their clients.

more...

 

[EgyptDUDE]

I will buy it when it gets cheaper

 

[gameboy]

If you have your computer linked up to your HDTV you can download some files from the Apple Quicktime library here...

The BBC one looks great on a standard monitor - goodness know how it will look on a HDTV...

 

[BarMoo]

I'd love it, but won't pay extra for it. AFAIC it should not attract a premium .....

This is true BGonaSTICK, since its conception only the broadcasters have benefitted from actual 'bottom-line' cheapness of MPEG-2; i,e, six+ channels for the price of one analogue one - ten if you are ITV or Discovery Channel - or twelve if you are a religious/shopper type.

Meanwhile.

After five full years of UK widescreen madness (think about it: 14:9, cut-out, zoom, 16:9 fits into 4:3, LCD/Plasma HD-Unready displays, et al) the UK now wants to rush you into HD.

I never understood why the UK sucked consumers into/manipulated them into dead technologies like SD widescreen in the first place ;) The US and Japan already had HD at that time and it was only the ad agencies in the UK that ultimately got broadcasters fully into SD 16:9. Saying that, I actually liked the PAL+ transmissions on Channel Four way back in 1687.

Funny - to this day, 16:9 transmissions still have to be compatible with full screen? Doh! Meanwhile, HD is ONLY 16:9 - which will be fun for those onscreen logo maker's and bad graphic designers.

SKY say that there will not be a premium on HD - save for the usual sub stuff. The trick is telling Joe Public that satellite is/will always offer more than Freeview (until analogue switch-off). Technically, SKY-HD will leave the BBC kicking themselves for not implementing MPEG-4 when they had the chance (i.e. when they took over from OnSquigital).

Whatever, SKY will benefit from the jump to MPEG-4 before the terrestrial broadcaster's get their chance in a hundred years time.

Have Fun

Mark.

 

[gameboy]

mljgmljg did Berlin not go from analogue to digital TV in a few months?