36 replies to this topic

[alanh]

DVB-T2: An Update from the UK Rollout

Alanh

[mtv]

alanh, on Mar 20 2010, 10:01 PM, said:

DVB-T2: An Update from the UK Rollout

Alanh

Update?... it's over a year old.

[DrP]

It does make you wonder.

Anyway, reading the aged document reveals an interesting and already commented on issue.  Where to put DVB-T2.  In the UK they have a shared transmission system so they can shuffle programs between tranport streams to free up a transmitter for DVB-T2.  We do not have this luxury and with the impending reshuffle of Australian transmissions (to allow the sell off of higher frequencies) one has to wonder exactly where Australia would put its DVB-T2 transmissions.  I think the answer is clear.  It will not put them anywhere until all (yes, thats all) receivers can manage DVB-T2 at which point it may be turned on.

It is also interesting to note that the document states that DVB-T2 works quite well, which contrasts quite starkly with what 'others' have said.  In fact it works so well (and the document so outdated) that the UK has put it into operation.

I have no doubt that 'others' will have differing opinions and that's fine, but rather than just differ perhaps they could explain precisely where the DVB-T2 transmission would be put.

Edited by DrP, 20 March 2010 - 11:15 PM.

[alanh]

MTV,
This is the title of the article!
If you have found a newer one then post it

The update is that Sony has a large range of DVB-T2 receivers on the market, check their website. This includes some 3D receivers.
The London transmitters are operating under the banner of Freeview HD+


AlanH

[MLXXX]

alanh, on Mar 20 2010, 10:01 PM, said:

DVB-T2: An Update from the UK Rollout

Alan, I've noticed you begin a great many threads (perhaps more than anyone else on the forum).  And that you frequently do so by no more than providing a brief title and a hyperlink.  Many of these threads evoke no posts beyond your opening post.  They become part of archived threads in due course, but by then the link is so old it may no longer be a valid url. If so, the thread becomes even more cryptic.  

You appear to be unaware of standard practice when commencing a thread:-

It is usual protocol when commencing a thread to supply a brief explanation of its purpose.

If supplying a link, it is usual practice to explain what content the link points to, e.g. by providing a one paragraph précis of the content.

Such explanations are a courtesy to other members. It may save them the time and trouble of reading a link that is of no relevance to them.  Conversely, it may alert them to an aspect of the content being linked to that is of relevance.

[alanh]

MLXXX,
I am only posting a link because if I make any comment the topic is redirected to insults rather than discussing the content.

For example the first comment on this post was the age of the article. Well it has not been posted here before and it is the reasonning behind the planning for the current rollout which will continue until the whole country is covered.

I would be happy to comply with what you request, however it seems pointless when the points I bring up are "doubted" and worse.

There is currently a DBCDE green paper (Digital Dividend) discussion how to introduce DVB-T2 into Australia. This is now being considered by the DBCDE. Question 3.21

Having just stated this, you watch what happens. (DrP has already attacked this link)

AlanH

[DrP]

Bad link!  Bad link!  Go sit in the corner.  

No alanh, I have not attacked the document and you will find, no doubt to your dismay, that you can not find any post where I have attacked the document.  All I've ever said WRT the document is read it, specifically this part which you seem to have so much difficulty with

Quote

The Government does not propose to move to a new standard in the foreseeable future, at least prior to switchover being completed.

As for doubting your posts, doubt is with good reason.  The Big Red book of alanh facts atests to this.

Edited by DrP, 21 March 2010 - 02:55 AM.

[MLXXX]

alanh, on Mar 21 2010, 02:31 AM, said:

I would be happy to comply with what you request, however it seems pointless when the points I bring up are "doubted" and worse.

I was conscious when I made my remarks that it could prove very difficult to create a précis that would not itself be challenged.

But I guess that in preparing any brief explanation "forewarned is forearmed".

[alanh]

DrP,
If you read the rest of the post it was not you this time. You didn't have much to attack because I did not say anything.

MLXXX
I predicted he attacks the man every time to take the posts away from the content to himself.

AlanH

[Basil]

The 1080p comments are interesting,i guess Freeview Oz. will be looking at a similar model to where Freeview UK is heading,i doubt Conroy will be around to see it even if Labor is re-elected.

[DrP]

alanh, on Mar 21 2010, 08:37 AM, said:

If you read the rest of the post it was not you this time. You didn't have much to attack because I did not say anything.

alanh, on Mar 21 2010, 02:31 AM, said:

There is currently a DBCDE green paper (Digital Dividend) discussion how to introduce DVB-T2 into Australia. This is now being considered by the DBCDE. Question 3.21

Having just stated this, you watch what happens. (DrP has already attacked this link)

Really?  That's not how it looks from your posts.  In the context of your post it looks pretty clear that you are stating that I have attacked the link (ie, the government document).  I have done no such thing and I challenge you to produce any posts where you think that I have.

What have I 'attacked'?  Your unique intrepretation of what the document quite clearly says - 'no changes for the foreseeable future, at least until analogue switch off'.

You'll notice a theme here too alanh.  The only posts I am 'attacking' (its not really attacking but I see you do like a bit of the dramatic) are your posts where you are posting information that is clearly false or directly contradictory to the evidience offered.  Don't expect me to stop 'attacking' these posts either.

Edited by DrP, 21 March 2010 - 11:21 AM.

[DrP]

Basil, on Mar 21 2010, 11:01 AM, said:

The 1080p comments are interesting,i guess Freeview Oz. will be looking at a similar model to where Freeview UK is heading,i doubt Conroy will be around to see it even if Labor is re-elected.

The UK's freeview is considerably removed from Australia's freeview.  I can't see the FTA networks here giving up their own transmission and joining a shared transmission system such as the UK has.  WRT 1080p50 in Australian television it would require the use of both MPEG-4 AVC and DVB-T2 unless the number of programs transmitted falls.  Its not possible to implement T2 in the Australian context until all receivers are T2 capable or additional RF space is 'pulled out of a hat' and a whole new transmission network rolled out (that's another 5 TXes per region).

[Basil]

DrP, on Mar 21 2010, 12:28 PM, said:

The UK's freeview is considerably removed from Australia's freeview. I can't see the FTA networks here giving up their own transmission and joining a shared transmission system such as the UK has. WRT 1080p50 in Australian television it would require the use of both MPEG-4 AVC and DVB-T2 unless the number of programs transmitted falls. Its not possible to implement T2 in the Australian context until all receivers are T2 capable or additional RF space is 'pulled out of a hat' and a whole new transmission network rolled out (that's another 5 TXes per region).

Yes it will be interesting to see what happens after analogue is shut down but i was referring more to the marketing side of Freeview such as the "signposting" HD logos,i can see Oz Freeview running with that when we migrate to MPEG4.

[alanh]

Basil,
The only way we can go DVB-T2 is to only sell DVB-T2 receivers from now on.
If we do this it will bring forward the time FTA broadcasters can transmit 3-D. This could be the carrot for the retailer to get togther to only import receivers which are DVB-T2 capable. The displays should all be capable of accepting 24, 25, 48 and 50 frame/s progressive. For current compatibility they need to be able to accept 25 frame/s interlaced. For full HD TVs this will be a small firmware change.

It is not worth duplicating 5 national transmission networks to allow time for viewers to buy DVB-T2 receivers.

DVB-T2 requires a more sophisticated error correction and MPEG-4 decompression.
MPEG-4 decompressors MPEG-2 capable and are in very wide spread use in manufacturing of receivers Terrestrial & HD satellite) and Blu-ray players. The more sophisticated error correction will no doubt have some royalites to be paid. The receiving section of a TV is only a small proportion of the manufacturing cost of a TV.

AlanH

[DrP]

alanh, on Mar 22 2010, 10:59 PM, said:

The only way we can go DVB-T2 is to only sell DVB-T2 receivers from now on.

And this simply isn't happening.  Not all sets are even capable of MPEG-4 AVC (your previous hobby horse).

Quote

It is not worth duplicating 5 national transmission networks to allow time for viewers to buy DVB-T2 receivers.

Absolutely.  Meaning T2 isn't happening any time soon, in fact I'd go so far as any time in the next 10 years.

[Malich]

alanh, on Mar 22 2010, 10:59 PM, said:

DVB-T2 requires a more sophisticated error correction and MPEG-4 decompression.

Does it require MPEG-4? Not according to the spec; DVB-T2 is simply a "Frame structure, channel coding, and modulation for a second generation digital terrestrial television broadcasting system" (to quote the title). No mention of compression schemes inside either - you'll search in vain for any mention of MPEG-2, MPEG-4, or H264.

The fact that the UK etc have mandated MPEG-4 for DVB-T2 transmissions is quite aside from DVB-T2 itself. To quote the technology director of UK's DTV group (p2 of that PDF) : "What's being considered for the delivery of HDTV is an MPEG-4 box, so you may as well add DVB-T2 to make that jump as far as possible and avoid lots of mini switchovers. That's why the tie between DVB-T2 and MPEG-4 is made. It makes it more attractive to the consumer, as you can't really sell technology for technology's sake."

So "DVB-T2 requires MPEG-4" is wrong; changing over to DVB-T2 is just a convenient time to add MPEG-4.

[alanh]

Malich,

The DVB -T2 and DVB-T are specification for the modulation of an RF channel as you say. MPEG-4 and MPEG-2 are a compression standards.

DVB-T2 and DVB-S2 are both designed to increase the efficiency of an RF Channel. Since these systems have been designed after MPEG-4 was specified which provides a reduction in data rate of 30 % every system specifies the use of MPEG-4. The overseas HD satellite broadcasters all use DVB-S2 with MPEG-4 compresssion to keep the transmission costs down. Now that the Digital Dividend is going to sell off the channels made available with the the analog switchoff there will be no more RF channels for TV transmission. So if you want to transmit 3-D which is already MPEG-4 MVC compressed with enough data rate you need DVB-T2 with MPEG-4 compression.

Note also the quote they want displays capable of 1920 x 1080 @ 50 frame/s progressive. They are obviously are going to wait until there are many more displays can run at this rate. It must be remembered that until the end of last year there has been no terrestrial HD broadcasts.

We have full HD TVs which are capable of 1920 x 1080 at 24 frame/s progressive. To change these displays to take 50 frame/s a firmware change is required and an HDMI1.4 input.

Alanh

[digitalj]

alanh, on Mar 23 2010, 10:50 PM, said:

every system specifies the use of MPEG-4

MPEG-4 might be the recommended compression method, but it doesn't mean they have to use MPEG-4.

alanh, on Mar 23 2010, 10:50 PM, said:

We have full HD TVs which are capable of 1920 x 1080 at 24 frame/s progressive. To change these displays to take 50 frame/s a firmware change is required and an HDMI1.4 input.

Full HD TV's in Australia support the following at 1080x1920:

24 Frames/S
50 Frames/S
60 Frames/S
50 Fields/S
60 Fields/S

as you can see 50 Frames/S is already there, so there is no need for a firmware upgrade to gain 50 Frames/S

[DrP]

alanh, on Mar 23 2010, 09:50 PM, said:

The overseas HD satellite broadcasters all use DVB-S2 with MPEG-4 compresssion to keep the transmission costs down.

Making blanket sweeping statement usually leads to embarassment.

[Malich]

alanh, on Mar 23 2010, 09:50 PM, said:

The DVB -T2 and DVB-T are specification for the modulation of an RF channel as you say. MPEG-4 and MPEG-2 are a compression standards.

Aware of that.

Quote

Since these systems have been designed after MPEG-4 was specified which provides a reduction in data rate of 30 % every system specifies the use of MPEG-4.

My point is that your statements "DVB-T2 requires ... MPEG-4 decompression" and "every system specifies the use of MPEG-4" are wrong. Now, if you were to say "current implementations of DVB-T2 specify the use of MPEG-4", I'd be more inclined to agree.

(Not quite sure what to make of the first part of your sentence either - it's accepted that DVB-T2/S2/C2 has ~ 30% increase in available bandwidth over DVB-T/S/C, while the usually accepted figures for MPEG-4 AVC are a 40%~60% reduction in bitrate over MPEG-2 for the same quality. You seem to be conflating the two; it may pay to be clearer about the specific point you're trying to make, and quote the appropriate figures.)

Quote

It must be remembered that until the end of last year there has been no terrestrial HD broadcasts.

Again, be clear. I presume you're talking about DVB-T2? Then say that.

Not gonna touch your comments on 3D because in the context of the point I'm making - that DVB-T2 does not require MPEG-4, and that MPEG-4 does not require DVB-T2 - they're a furphy.

[alanh]

Malich,
All Freeview Aust products are DVB-T and MPEG-4 and MPEG-2 capable.

There is only 3 countries using DVB-T2, the UK, Finland and one other European country which has slipped my memory. The UK has specified MPEG-4 as stated above, and all broadcasting in Finland is MPEG-4.

The BBC says that the increase in usable data rate through the use of better error correction and other techniques is 30 %. This of course depends on the number of states transmitted as 256 levels is not available in DVB-T, the transmitter power and the likelyhood of interference. All the UK transmissions are UHF where impulse interference is less of a problem than at our mostly VHF transmissions.

MPEG-4 compression ratios which are acceptable depends on the quality of the encoder, the type of vision being transmitted and the critical perception of the viewers.
For example the comparison should be made of a reasonably rapid pan of the audience at a sporting event or a wide shot a very large flock of birds taking off.

The point I am making is to take the uncompressed data rate from a camera compared displayed image from a receiver with imperceptable artifacts. The channel band width is reduced until artifacts appear. The percentage is calculated between the RF channel width divided by the data rate from the camera. Quite a number of different test pieces need to be shown using a standardised measurement technique for subjective testing in standard viewing room conditions.

Yes I am talking of DVB-T2. DVB-S2 has been going much longer.

I have never thought that on its own that DVB-T2 requires it from the standards, but from the broadcasters themselves pushing regulators.

DigitalJ,
I have not said they cannot show 50 frame/s @ 1920 x 1080p, its just that all receivers must be able to show 50 frame/s progressive including those of lower resolution and refresh rates. Otherwise a set top box will be required to halve the frame rate and probably split the frames in to fields. Most people do not like STBs.

AlanH

[digitalj]

alanh, on Mar 24 2010, 08:17 PM, said:

DigitalJ,
I have not said they cannot show 50 frame/s @ 1920 x 1080p

AlanH

yes you have:

alanh, on Mar 23 2010, 10:50 PM, said:

We have full HD TVs which are capable of 1920 x 1080 at 24 frame/s progressive. To change these displays to take 50 frame/s a firmware change is required and an HDMI1.4 input.

Alanh

What you're implying here is that there aren't any that accept 50 Frames/S.

[MLXXX]

I don't think there would be any Full HD TVs on sale in Australia that don't accept 1080p50 through HDMI.

alanh, on Mar 24 2010, 07:17 PM, said:

MPEG-4 compression ratios which are acceptable depends on the quality of the encoder, the type of vision being transmitted and the critical perception of the viewers.
For example the comparison should be made of a reasonably rapid pan of the audience at a sporting event or a wide shot a very large flock of birds taking off.

The point I am making is to take the uncompressed data rate from a camera compared displayed image from a receiver with imperceptable artifacts. The channel band width is reduced until artifacts appear. The percentage is calculated between the RF channel width divided by the data rate from the camera. Quite a number of different test pieces need to be shown using a standardised measurement technique for subjective testing in standard viewing room conditions.

It is not a question of MPEG4 artifacts being imperceptible, but being tolerable/acceptable.

For example "a wide shot [of] a very large flock of birds taking off" is very challenging for any video codec at terrestrial broadcast bitrates.  There is too much chaotic change.  Even at peak permissible bitrate in a DVB-T[2] mux where bitrate is dynamically apportioned based on instantaneous need of individual streams ["stat mux"], such a scene could be expected to look noticeably poor; based on current typical practice by broadcasters.  Broadcasting is not at Blu-ray quality, either for the video, or the audio.

Edited by MLXXX, 24 March 2010 - 09:13 PM.

[alanh]

MLXXX,
If you wish to minimise the artifacts, we need to get the highest RF data rate and the most efficient compression system because of the huge data rate produced by the video sources. An increase in the Australian data rate to around 31 Mb/s (up about 30 %). We need extra data capacity for the future transmission of 3-D which will require 50 % more for the depth signal.

Stat Mux should not be used during testing because the idea is to test the relationship between data rate and visual degridation so you can see the effects on different types of pictures.

Another way of increasing the data available is to stop simulcasting HD and SD content. Any new programs should be in MPEG-4 minimise the amount of data generated.

Who knows when this will occur, this is upto the decision makers in the DBCDE and the Broadcasters.

AlanH

[digitalj]

alanh, on Mar 24 2010, 11:06 PM, said:

MLXXX,
If you wish to minimise the artifacts, we need to get the highest RF data rate and the most efficient compression system because of the huge data rate produced by the video sources. An increase in the Australian data rate to around 31 Mb/s (up about 30 %).

Increasing the multiplex's bitrate will just result in more channels being offered as the majority of people seem to care only about content and not about quality. So don't expect any PQ improvement by moving to DVB-T2 or MPEG-4 AVC

alanh, on Mar 24 2010, 11:06 PM, said:

Another way of increasing the data available is to stop simulcasting HD and SD content.

AlanH

have you not heard?

they will stop this year.