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Picture Quality on BBC HD: a Viewers' Group Visit (part 1)

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Andy Quested Andy Quested | 17:00 UK time, Friday, 4 June 2010

As many of you know I contacted Paul a while ago to ask if he and a group of his choosing would like to visit me, Danielle and others involved with the BBC HD Channel. The debate about picture quality had met an impasse and we thought this might be a way to move it on and, for me at least, be a way of discussing quality as a whole and not just as a bit rate issue.

It took some time to arrange the meeting, mainly due to the move of all the test equipment from its old home in Surrey to a building in London W12. Have a look at the BBC R&D web site for some of the history of the buildings.

As soon as the new test room (even though it hadn't been re painted) and transmission test chain were ready and running, Paul and I set a date and the group duly arrived.

This is their blog, the content is Paul's and the rest of the group's. Just like the Hitch Hiker's Guide blog, it comes in episodes, this time over three days not five!

I will make comments where appropriate as posts and answer any other question I can in the usual way.

Just to keep you up to date, we had to stop all work as soon as the election was called. We don't allow any changes to hardware or software that's already in place and working in the run up to a major broadcast. We are also making some changes to the audio circuits in the playout chain to cope with the DTT HD service and these have caused a few bumps and mutes on the DTT output and to make sure we keep the sound running properly, I have had the channel locked in 5.1 mode. This means (for those who like to use pro-logic for stereo programmes) your AV systems will stay in surround mode with stereo on the front Left and Right only. We will revert back to switched mode as soon as possible. We obviously need to have the work finished and fully tested in time for the World Cup.

Stop Press (Thursday 3 June): We have just got the go-ahead to install the next software upgrade to the satellite service. This will include the first part of the mix-fade fix and a configuration change that means we will not need to add noise reduction as we have found a better way to handle noisy pictures. We will take the opportunity to change the way the Freeview encoders handle noise and remove the noise reduction we have been trying on the DTT service. The change went in this afternoon in time for the first programme. Unfortunately I couldn't get in touch with Paul in time as I wanted to let him (and the group) know as soon as possible. Other stages of the upgrade will go live as soon as we are sure they will not disrupt the output.

So I can now pass you to Paul and the group's HD Blog...

Blog 1: The Television Centre Visit

"Since August 2009, I have experienced noticeably worse picture quality (PQ) from the BBC HD channel. Well, after months of campaigning about this issue on BBC blogs and elsewhere I find myself in the rather strange position of being given my own series of blogs on the BBC Internet blog to write about it. For those who don't know, I made an appeal to the BBC Trust last year about the HD channel's PQ. Following this Andy Quested invited me to gather a small group of other concerned viewers to visit Television Centre for discussions and demos. That visit took place on 30 April 2010 and he has now asked me to put something together for these blogs to let you all know what we found out from the visit.

The first thing I'd like to say is a big thank you to Andy and the rest of the BBC staff for giving us the opportunity to visit them, for being so open with us, and for entering into such enthusiastic debate during our day. I'd also like to thank all those I took with me, and a few others who weren't able to make it on the day, for their help and assistance in preparing for the visit and compiling our thoughts after the event. I'm also grateful to many of you who will have known about this event from these Blogs, and from my own website and correspondence, for your patience while I put these thoughts together.

One of the key tenets in my appeal was that the 40% reduction in bit-rate, made by the BBC on 5 Aug 2009 (from 16 Mbps down to 9.7 Mbps), has had an adverse effect on the channel's PQ. Consequently a large part of the visit was spent with the BBC's Research and Development (R&D) team dealing with this issue. Because it is such a major one I'd like to discuss that aspect in detail in my next blog, which will be published tomorrow. For today, I intend to cover other aspects of the visit. Finally, since I get to write three, the last blog in the series will cover the group's conclusions from the whole visit and also give the BBC some recommendations from us, as discerning viewers, which they may wish to consider when developing their strategy for HD broadcasting.

So, onto Television Centre, and on a bright spring morning I found myself heading for reception with the rest of the group to meet Danielle and Andy and other BBC staff. What follows is a summary prepared by the group of what we did, and what we were told, during the day.

paul_and_group_large_high.jpg

[Back row, L to R: digital_elysium, tagmclaren, AYH20 Front row: paul_geaton, citizenloz, burnlea, mike, jtemplar Picture by HD_fan428]

Meeting with Danielle Nagler

Present were: Danielle Nagler (Head of BBC HD); Andy Quested (Head of Technology, BBC HD); Ian Potts (Executive Producer, BBC HD); Lauren Gildersleve (BBC Television Publicity, Daytime, BBC HD and BBC Films) and Umme Ali (PA to the Head of BBC HD).

danielle_paul_andy_high.jpg

[L to R: Danielle Nagler, Paul Eaton, Andy Quested]

First off, we were all welcomed to the BBC by Danielle Nagler who, as Head of BBC HD, gave us the opportunity to ask some of our more strategic questions regarding the channel. During this time she told us that:

  • There was no long-term strategy for BBC HD before she was appointed in July 2008. At that time, programmes were selected for transmission in HD having already been made. Now, they proactively commission programmes in HD and provide guidance to producers.
  • They are working hard with production companies to improve the PQ of their HD programmes. This includes giving advice on production techniques and recommendations regarding technology, such as camera choice. Without naming names she said they have themselves been critical of some of the programmes produced so far.
  • Danielle said "the need for another channel is very obvious and I'm fairly confident that that will happen, and certainly will happen by 2012", adding, "My expectation is that that would be a simulcast channel and, you know, the research that we've done and the logic, I don't think there's any particular secret, is that the most obvious channel to do it would be BBC1".
  • Transmission/playout costs are not within Danielle's BBC HD budget, so she isn't herself directly cutting bit-rates to save money, but she repeated that the BBC is required to use spectrum efficiently.
Some examples of production problems she (and Andy) mentioned included:
  • Inappropriate use of filters or effects like smoke/fog that softened the picture.
  • Incorrect gain, adding noise.
  • Focusing not critical enough; this would not have been noticed in SD.
  • Inappropriate use of the 25 frame progressive format.
  • Inappropriate lighting, in reference to programmes recorded in theatres etc. where the lighting director is more concerned about a small live audience than the greater TV audience.

After our time with Danielle, we were quickly whisked off to BBC R&D - a visit which deserves covering in detail so more of that tomorrow. On our return to TVC, our next destination was:


The Blue Room

Lunch was served in the Blue Room, which contains examples of the diverse range of devices on which BBC programming can be received and viewed, ranging from 65" plasma displays to mobile phones, and various set-top boxes and computers.
This was followed by an opportunity to discuss issues surrounding bit-rates, and also the freesat HD and Freeview HD services.
Present were: Andy Quested; Ian Potts; Stephen Baily (Acting Head of Distribution Technology) and Jo Gardiner (Project Manager for Freeview HD -and, previously, for freesat HD) from Distribution.

blue_room_595.jpg

Distribution, Bit-rates and Resolution

Stephen informed us that:
  • Cost of bandwidth is not a significant factor in reducing bit-rates. This was not the reason BBC HD bit-rates were reduced.
  • Platform neutrality has to be considered when reviewing transmission parameters.
  • Lack of spectrum, in particular with a UK footprint necessary to deal with rights issues, is a constraint. Even with additional capacity coming on-line in future, this will simply be taken up by additional demand for further HD channels.
  • Hence there is an obligation to always use the available spectrum efficiently.
  • Increasing the bit-rates for BBC HD now, using the spare satellite capacity, would only lead to disappointment when they are reduced again to make way for further channels. (NB: Take note of this statement - there is an inconsistent message here - Why would reducing the bit-rate lead to disappointment if, as we were told elsewhere, bit-rate has minimal effect on PQ?)
Andy claimed that:
  • TV Panels can't fully resolve the 1920 signal so he said it would be pointless to increase BBC transmissions to this resolution.

Red Bee Tour (Playout Suite)

Our time in the Blue Room was interspersed with a tour of the Red Bee playout suite accompanied by Andy Quested and Paul Murphy (Editor of the Internet blog) and given by Huw Hitchin, Playout Editor. Red Bee has a contract with the BBC and other broadcasters to "play out" live or recorded programmes, and the playout suite is where this is all controlled.

Though this was of little relevance to the real subject of the group's meeting with the BBC, as playout has no impact on BBC HD PQ, it was very interesting to see.

Comparison with Other Channels

For the final session of the day we returned to the Blue Room, where Andy Quested showed a series of clips from other HD channels which he believed highlighted similar problems to those the group has raised with regard to BBC HD. Examples included lack of definition, poor colour, or poor source material. These were viewed on a large 65" plasma display.

This was the most controversial aspect of the day for most of the group and, generally, we felt it fell short of achieving the effect that Andy had desired since the problems highlighted were primarily in the source material, not in the transmission. We all knew that other HD channels can suffer from poor source quality too, before being shown it.

Amongst those in the group who have access to subscription HD channels, the general feeling was that those which offer their viewers consistently superior PQ do so principally because of their higher bit-rate and, in some cases, their better source material.

Andy also made the point that some other channels use artificial means to enhance perceived PQ. Overall though, the group again felt such measures would be less significant contributors to perceived PQ than the basics of better source material and higher bit-rate.

At this point in our day we rounded-up and all adjourned to a nearby bar for a drink. This is an appropriate point to end today's blog on our visit to Television Centre. Tomorrow's will be about the visit to R&D, the PQ tests and what we learned from the highly qualified, skilled, personable and enthusiastic team of people we met there."

Ed's note: We'll be publishing part two tomorrow and part three the day after. (PM)


Comments

  • Comment number 1.

    Just back from a hot a sticky W12. The issues on the audio were limited to the DTT service but not easy to fix. Locking the channel kept DTT audio running properly and although an AV system would have said "Dolby Digital 3/2" or the like, stereo programmes would have come out front left/right only. Anyone wanting to use pro-logic would have had to set it manually.

    As I said in the preface I will comment as required but hope you enjoy the read


    Andy

  • Comment number 2.

    I'm getting really confused about BBC blogs now. TV things like BBC HD and the Red Button are posted on the internet blog. Computer things, such as the new Doctor Who computer game, get posted on the TV blog.
    Does this make sense to anyone?

  • Comment number 3.

    Dear lucas42 - I post on the Internet blog as it's primarily about technology and issues around technology. I know what you mean though and hope we get the navigation right so you can always find what you want no matter how you search.

    Let Nick or Paul (the moderators of this site) have your thoughts though as we (the BBC) should make sure you can be heard

    Andy

  • Comment number 4.

    Andy, I see your point, it probably is more appropriate to have posts about technology here than the TV blog. Perhaps its more the naming that is confusing, maybe calling it the BBC Tech blog would be clearer (though then it might get confused with dot.life).
    Personally, I'd love to see a more Web-focused blog. I think its a pity that so many of the smaller blogs are being merged to form larger blogs with less of an identity.

  • Comment number 5.

    Look forward to the rest of your posts.

    Andy said
    TV Panels can't fully resolve the 1920 signal so he said it would be pointless to increase BBC transmissions to this resolution.

    This is just not true. I have a Sony KDL-46x2000 which has a display resolution of 1920x1080 and I run it in pixel mode. This means that each pixel transmitted is mapped to one pixel on the screen if it is transmitted as 1920. Close up I can see each individule pixel. I must admit I have not counted them I just take Sony's word.

    With a viewing distance of 3 times the screen height a person with 20/20 vision can resolve 1920 horizontal pixels. I find it quite easy to see the difference between a 1920 and a 1440 picture. Most other broadcasters use 1920.

    The "disapointment" issue was a bit of an own goal wasn't it. Of cource the BBC have always been aware that the picture quality has deteriated. So we come to the "using the spectrum efficiently argument". The flaw in this argument is that spectral efficiency is not the primary requirement of HD. The essence of HD is high quality pictures and sound and this should be the primary requirement. Spectral efficiency is secondary. If you want spectral efficiency stick to SD or even go back to Baird's 32 line standard.

    The ITU has a definition for for HD. It says that at 3 times the screen height the picture should look the same as real life. Well that is the goal. As we know the even the best pannels cannot reproduce the full spectrum of colours visible to the human eye but this definition should be our goal.

    What the BBC realy mean by spectral efficiency is low cost. Unlike colour the BBC has not introduced an HD licence fee to fiance the increase cost of HD. So the BBC is trying to deliver an HD service within the existing budget. Something has to go and that something is called quality.

  • Comment number 6.

    Welcome Back Andy

    Very interesting,look forward to the other posts.

    Is todays software update/fix the first for the new (10 months old)encoders?

    It seems a long time to solve a problem that you were aware of from day 1.

    Please keep us updated on any further updates and fixes.

  • Comment number 7.

    Just a short comment for now until we red all three parts.

    Firstly thanks to all concerned for their efforts and input - I hope all posters will address the issues raised in the reports as they are made available.

    So my one comment is also about the 1920 issue.

    My 42 Toshiba Z3030 is a full 1920x1080 panel and it also offers 1 to Pixel Mapping.

    Cheers, daveac

  • Comment number 8.

    Dear trevorjharris thanks for the post.

    During the visit we quite clearly demonstrated that the uncompressed 30MHz grating fed via an HD SDI to HDMI convertor was not fully resolved and the displays demonstrated alias components (as described in the http://www.bbc.co.uk/blogs/bbcinternet/2009/03/bbc_hd_nyquist_limit.html blog).

    It is true the 25MHz grating is less defined at 1440 than 1920 but not substantially so. The difference between 1920 and 1440 is far more clearly demonstrated by cameras and reorders that do not record the full horizontal resolution of an image. By the time we get to the last point of conversion (the transmission encoder) the difference is far less clear. Even the Grade 1 32" HD CRT did not fully resolve the 30MHz grating.

    Dear SkyCaddie - thanks for the post, before we can up load any new software to the encoders, not only do we have to check the effect on pictures but we have to check it against all the set top boxes (on Freesat and Sky) and integrated TVs. This can take some time! If a STB cannot cope with a change, we have to give the manufacturer time to fix the problem and then to download it to ALL their STBs before we can put it to air.

    We also have to check the upgrade works correctly under all (we can conceive) operating conditions with subtitles, audio description, surround sound and stereo switching... And that it doesn't break in SD too.

    There are more upgrades to come - hopefully another next week that I will report on as soon as I can


    Andy

  • Comment number 9.

    Hi all, thanks for the comments so far, and I look forward to reading the rest following our other 2 Blogs. Sorry for the long wait too, there was a lot to discuss after our visit, all done by email in our respective spare time.

    I'm away now for a couple of weeks so you'll probably not see much comment from me during that time, if any. But I'll certainly read all of yours on return and I'm sure that, in the meanwhile, my fellow visitors will be monitoring and responding to your comments in my absence.

    Thanks too, Andy for being there to respond to comments, and for taking the time during a very busy week to do so.

  • Comment number 10.

    Just to check I’m understanding this right — “TV Panels can't fully resolve the 1920 signal so he said it would be pointless to increase BBC transmissions to this resolution.” is a little misleading, because it’s the source material and encoding process, rather than the panels themselves, that aren’t to “ideal” spec?

  • Comment number 11.

    Hi Andy, can we have this report/s posted on the main bbc blog as previously requested as well.

  • Comment number 12.

    A grating frequency is a concept associated with the sampling of an analogue signal. In digital television the picture is built from pixels and no analogue sampling is required througout the chain. However in a CRT the digital signal is converted to an analogue signal to modulate the electron intensity. So a grating frequency is relavent to a CRT display but not to a digital display.

    SDI and HDMI send the video as digital stream. Conversion should not affect the resolution. Please can you tell us how this was demonstrated.

    I point out that the colour difference streams are transmitted with only a quarter the number of pixels. Eg 960 x 540.

    I would add that a digital filter could mimic some of the effects of sampling. Subsampling at 1440 pixels is realy a form of digital filter. So to is the video codec which can lead to a loss in resolution which is so clearly demonstrated by the BBC. If the BBC were to increase to 1920 pixels they would also have to increase the bitrate for the same level of artifacts. The bottom line is that 1920 pixels could be clearly resolved if the bitrate was adequate.

    As I said before I can clearly see the difference between a 1920 and a 1440 picture.

  • Comment number 13.

    Just before I go, I'd like to make a clarification regarding Andy's introductory comments where he says: "This is Paul's blog, the content is his and the rest of the group's" In the final rounds of editing we'd missed the point that, when read in conjuction with the way I introduced the Blog, it could be deduced that I wrote most of it. That would be an incorrect deduction.

    The Blog was written by all of the visitors (pictured above + the photographer), with every one of us making contributions, some of them quite considerable, e.g. the entire account of the day's activites was written by citizenloz. The help and assistance of others not able to make the day should be acknowledged too and they may wish to step forward here and take due credit.

    I am grateful to them all, as I hope is made clear in the rest of the forthcoming Blogs.

  • Comment number 14.

    @12 Trevor, I agree. STV HD has been testing, with 1920x1080, and (when not upscaled) is definitely a clearer picture than ITV HD, which is at 1440, with the same source material. It is also running at slightly higher bandwidth. I guess some of it comes down to how well the TV comes with 'stretching' from 1440 to 1920. mine doesn't have any of the newer extra processing.
    @9, Paul, have a nice break!

  • Comment number 15.

    Re #13.

    Thanks Paul for clarifying that.

  • Comment number 16.

    The main issue in all this has been ignored once which is the quality of the encoder that is being used. Just like a car, the performance of encoders varies dramatically amongst different manufacturers.

    It is interesting that both the British and the Germans are complaining about mediocre picture quality on public-broadcasters' HD services. Complainants on both sides of the North Sea are pointing to incorrect solutions. Us Brits are saying that the bit-rate should be increased and the Germans want 1080i. Both are missing the actual reason which has let do picture quality problems around the world - the encoders are poor. Virtually all of them are optimising for metrics like PSNR instead of actually bothering to produce a picture that is pleasing to the human eye. It is possible for PSNR to increase and visual quality to decrease.

    For example I have seen a case in which only 4 out of a possible 16 intra-prediction modes were used - consider this H.264 intra-prediction done very lazily.

    It is also worth pointing out that the quality of the distribution encoders are poor too. There was severe blocking during some of the tougher scenes during this year's and last year's Eurovision. Some of the playout server encoders I have seen also are poor too.

    Having said that, throughout Europe there are many broadcast engineers who share my concerns. It is the fault of some people in the industry for merely accepting such issues and drinking too much "manufacturer kool-aid". (3-5mbit 1080i comes to mind as a good example of this)

    Frankly, it is becoming silly to read all the various "explanations" for picture quality deficiencies that are posted on this blog and in the comments every week. Some of them are valid but in relative terms are mere drops in the ocean.

    It doesn't matter much anyway because in a few years we will be at the level of American HDTV, which shouldn't even be called HDTV. A few channels on the continent are already not far from that level.

  • Comment number 17.

    "•Platform neutrality has to be considered when reviewing transmission parameters"

    I'm really concerned and disappointed by this statement by the BBC as this amounts to nothing less than an admission that Freesat is being dumbed down in quality of transmission so as to match Freeview HD which is much more bandwidth restricted.

    This to me is totally wrong.

    Its not biased to have one platform of better quality than another when that is caused by a restriction on the available tranmsission space on the other that simply cannot be avoided. This situation is entirely different to that where both platforms are equal but one is given favourable treatment.

    It is however, morally wrong to deliberately dumb down the other broadcast channel and spoil people's viewing pleasure simply to match the restricted one.

    The BBC owes a duty to deliver the best possible quality to its viewing audience and licence payers and is failing to deliver that where it reduces quality deliberately for these reasons.

    To put it simply, why should the viewing audience of one medium suffer a deliberate low quality picture simply because it cannot be avoided on another channel?

    Also, I briefly make the point I've been making for a long time on all of this.

    Freesat and Freeview need to be seperated out and allowed to play to their own strengths.

    There's room for both platforms to co-exist simply in different roles. Freeview as the easy to get cheap option and Freesat as the ultra high quality, max content enthusiasts / frequent viewer option for those who put picture quality over and above cheap reception. That way everyone is happy and the public are given a clear choice over which medium to choose according to their viewing habits, pockets and installation preferences.

  • Comment number 18.

    I think I wrote "distribution encoder" in the comment (can't see it yet) above when I actually meant "contribution encoder".

  • Comment number 19.

    Hi Andy,

    Can you expand a bit on your comments about not requiring noise reduction and "as we have found a better way to handle noisy pictures". Sounds intriguing.

    NR is not something I remember us talking about in much detail during the visit so it would be interesting to find out what you are doing to handle it with this latest change.

    Thanks

  • Comment number 20.

    "•Platform neutrality has to be considered when reviewing transmission parameters"

    Why?

  • Comment number 21.

    “Why?”

    that’s a bloody good question.

  • Comment number 22.

    re #10, Mo, “TV Panels can't fully resolve the 1920 signal so he said it would be pointless to increase BBC transmissions to this resolution.” I'd just like to point out that the first half of this sentence is Andy's suggested formulation, though the second is ours. I only say this to clarify whence any response might come.

    The incorrect capital P is all mine. :/

  • Comment number 23.

  • Comment number 24.

    •Cost of bandwidth is not a significant factor in reducing bit-rates.

    If it is no issue, then why has bitrate been stuck at a mere 9.7Mbps for 10 months, when there is so much free space on that transponder?

    •Platform neutrality has to be considered when reviewing transmission parameters.

    WHY? Why then does the BBC HD satellite feed to Europe transmit at much higher bitrate & resolution?

    •Hence there is an obligation to always use the available spectrum efficiently.

    Then why have we had half a transponder transmitting nullbytes for the last 10 months?

    •Increasing the bit-rates for BBC HD now, using the spare satellite capacity, would only lead to disappointment when they are reduced again to make way for further channels.

    ROTFL, what a feeble rationale, & an own-goal too

    Andy claimed that:
    •TV Panels can't fully resolve the 1920 signal so he said it would be pointless to increase BBC transmissions to this resolution.

    Oh really, in that case why do manufacturers persist with their 1920*1080 FULL HD panels, with their 'full pixel' setting? Surely they should be making 1440*1080 panels to reduce manufacture costs?
    And why are all those other HD channels transmitting 1920 - could it be that they all are wrong to do so?

    Andy Quested showed a series of clips from other HD channels which he believed highlighted similar problems to those the group has raised with regard to BBC HD. Examples included lack of definition, poor colour, or poor source material. These were viewed on a large 65" plasma display.

    Interesting to see that shows from competitor channels that were selected for poor PQ purposes were demonstrated on such an enormous panel. Was the viewing at the correct distance for this size of panel? I take it that the visitors were also shown BBC HD's Ashes 2 Ashes & Survivors on this same screen?

    Andy Q
    During the visit we quite clearly demonstrated that the uncompressed 30MHz grating fed via an HD SDI to HDMI convertor was not fully resolved.

    Sorry, what is this 30MHz grating with its SDI to HDMI converter? In reality we have a viewer (not a grating!) watching via a Full HD panel 1920, connected to STB via HDMI lead, watching full-pixel mode at the recommended viewing distance - where does the SDI to HDMI conversion come in?

  • Comment number 25.

    Dear nur0 - thanks for the post - I hope this covers your questions:

    WHY? Why then does the BBC HD satellite feed to Europe transmit at much higher bitrate & resolution?

    (AQ) They do not use the same encoder as we do and the decision re 1440 or 1920 is up to the commercial suppliers of the channel. At some point in the future we will go to 1920 horizontal if we believe it is necessary.


    Then why have we had half a transponder transmitting nullbytes for the last 10 months?

    (AQ) Turning bit rate up and down to fit space in transponder capacity is not a good idea. The Sat service can't use VBR yet (but it is one of the things we are working on) so we selected a CBR that gave us (yes I know you all hate this) a picture quality "better than or at least as good as across the majority of the output" than the old encoder.

    DTT (Freeview) HD is VBR as it's in the same mutliplex as other HD channels. VBR on satellite will be the first step in what will become a two channel stat mux.

    An increased bit rate would not have led to an overall increase in quality where the encoder was not directly responsible for a specific quality issue.



    ROTFL, what a feeble rationale, & an own-goal too ( AQ - see above)

    Oh really, in that case why do manufacturers persist with their 1920*1080 FULL HD panels, with their 'full pixel' setting? Surely they should be making 1440*1080 panels to reduce manufacture costs?
    And why are all those other HD channels transmitting 1920 - could it be that they all are wrong to do so?

    (AQ) A 1920 x 1080 display may well produce a 1920 x 1080 image if fed with a digitally created image.



    Andy Quested showed a series of clips from other HD channels which he believed highlighted similar problems to those the group has raised with regard to BBC HD. Examples included lack of definition, poor colour, or poor source material. These were viewed on a large 65" plasma display.

    (AQ) We also showed BBC content on the same screen - also as viewing distance was around 3-4 times picture hight in our demo room i.e. not a critical viewing set-up.


    Sorry, what is this 30MHz grating with its SDI to HDMI converter? In reality we have a viewer (not a grating!) watching via a Full HD panel 1920, connected to STB via HDMI lead, watching full-pixel mode at the recommended viewing distance - where does the SDI to HDMI conversion come in?

    (AQ) HD SDI is the full 1.5Gbs signal and the connectivity used for broadcast equipment. It therefore contains all the information in an image - the HD SDI to HDMI convertor, converts the signal to the standard HDMI signal directly so it can be displayed on a standard display. As it is a direct conversion the HDMI signal contains all the information in the original HD SDI image (or as much as the HDMI specification allows)

    The test card gratings are quite important as (unlike computer generated graphics) they test the systems ability to pass specific frequencies (i.e.resolution) and allow you to measure peaking or attenuation of frequencies - so you can tell if a display boosts some frequencies (try changing the sharpness when the Testcard is on) or looses detail by filtering. On a waveform monitor the gratings on the test card are all the same level.


    Andy

  • Comment number 26.

    Andy Q, thank you for the detailed reply - can't say as I agree with it all though ;-)

  • Comment number 27.

    Dear nur0 - thank you anyway!! Any particular piece you disagree with?

    Andy

  • Comment number 28.

    Andy #25

    When you say

    "On a waveform monitor the gratings on the test card are all the same level."

    is thatbefore or after encoding?

  • Comment number 29.

    Dear ALL - especially the group who visited. With the rush on Friday and the fact that the blog was posted when I was "in transit" I haven't had a chance to comment on the visit in general.

    I can say the few days prior to the visit were busy and very nerve racking, we had to get everything right and we had to be seen to get it right. It was however a pleasure to meet the group and very nice to be able to put a personality to the comments on the blogs. I had spoken to Paul several times during the weeks before to arrange the housekeeping for the day so it was very good to finally meet face to face.

    One very interesting result of the meeting was the clips the group had chosen to examine in detail. I had added some other material and we had mixed the whole lot up into one roll. For some time R&D has been collecting material to test encoders but looking for examples takes a lot of time and you don't necessarily get everything you need (and you miss a lot too).

    Having a relatively large group of people collecting not just programmes but specific shots or sequences in programmes has produced a test roll we will be able to use for some time to come - it represents not necessarily the worst but more importantly what the group (audience) doesn't like.

    Coming to the ITU test, this was very interesting to set up and to watch happen. There were concerns on both sides as to the implications of such an open test but I hope you all appreciate how impartial the test is and that the results are not only reliable but repeatable.

    As you may have gathered I stopped posting after the trip was set-up (I was reading though and noticed the comments on the impending visit) - one thing I didn't want to do was start a debate or comment on anything either we (the BBC) or the group wanted to discuss or look at. This meant, when everyone arrived there had been no discussion about the material or the tests that could have influenced or distracted from the fact this was your visit.

    I will continue to post on parts 1 & 2 but after tomorrow's final part it would be good to keep all the comments on part 3 - I will forget or miss comments on parts 1 & 2 if they continue and grow at the same rate

    Andy


  • Comment number 30.

    Surely the issue is not whether a Full HD consumer panel can display the full 1920x1080 broadcast or not, but whether it can display better resolution than when fed with a 1440x1080 broadcast.

    Whilst Andy did demonstrate to us that there were indeed inadequacies in the handling of the 1920 broadcast - in comparison with a very expensive HD CRT - we didn't see a comparison of a 1920 vs 1440 broadcast.

    So like so many things, it seems Andy is able to prove his point (that 1920 displays cannot display the full resolution) but not actually addressing the real point that viewers are making - namely that 1920 is better than 1440.

  • Comment number 31.

    Of course a 1920 panel can display 1920 pixel resolution, that is its native res - the res at which it performs optimally. 1 broadcast 1920 pixel = 1 display 1920 pixel.

    Contrast with 1440 broadcast res. - how many panels are manufactured at this res? None that I know of, so ALL panels have to interpolate the BBC HD signal.

  • Comment number 32.

    25 Andy Quested wrote:
    At some point in the future we will go to 1920 horizontal if we believe it is necessary.

    But why don't you believe it is necessary now, give the almost universal use of 1920 by other UK HD channels, BBC HD abroad, the notes about the need for 1920 that have been made by the BBC themselves to the trust, preferences by the BBC for source material to be in 1920, etc, etc, etc, - all of which have been pointed out in the blogs many times typically without reply.

    What people find so infuriating is that the BBC just can't simply accept this, do it, and move on, when even one man and a dog HD channels can.

    Or at least offer a valid reason - instead of obfuscation such as "panels can't display it" - or at least a time frame rather than a vague "when necessary".

  • Comment number 33.

    Andy no disrespect meant by this as I know your a busy man, but I couldn't help but notice that you skipped around my point in post 17 above.

  • Comment number 34.

    #29 Andy Quested

    "Coming to the ITU test, this was very interesting to set up and to watch happen. There were concerns on both sides as to the implications of such an open test but I hope you all appreciate how impartial the test is and that the results are not only reliable but repeatable."

    Reliable and repeatable maybe, but not conclusive as our third blog tomorrow will show.

  • Comment number 35.

    Sorry Alsone - yes missed it going through the other posts. I am pleased to say on Friday Sat HD actually reached the quality of Freeview HD! One change was made to Freeview HD at the same time as the fist of the sat upgrades - mentioned in the stop press, we removed the noise reduction. I hope the upgrades to come will keep the two platforms in sync but there are bound to be leap frog moments.

    Dear burnlea - I will comment tomorrow if asked but please add comments too - it is your blog and you (all) have very valid and good points to raise

    Andy

  • Comment number 36.

    Fascinating reading this folks. A big thankyou to everyone involved. Only one comment to make so far, HD_fan428 - love the suit and sunglasses! :D

  • Comment number 37.

    #36, hdblogger, glad you like it so far. But it's jtemplar in the cool outfit--I stayed behind the camera! :)

  • Comment number 38.

    Dear HD_fan24 - Now someone else has mentioned it - send a picture in and I will try and pursued Paul (blog moderator Paul that is) to put it in the post

    Andy

  • Comment number 39.

    HD_fan428,

    Sorry my mistake. Still, looks like an audition for a Crimewatch identity parade.

    Seriously though, I'm still of the opinion that it's down to the source material. I've seen some pretty outstanding stuff on BBC HD as with other channels and I've also seen some really poor stuff on other channels. I'll wait until the next installment though before I'm convinced either way. It's a shame Paul is away for two weeks. That guy has more holidays than Judith Chalmers.

  • Comment number 40.

    Jonatham Ross, last Night
    Andy, lets get to the point of all this, why then does BBC HD look
    so bad then, i still can see sub standand HD Broadcasting all the
    time on BBC HD, and the ture fact is that ITV HD looks so much better
    most of the time, But there broadcast is at the higher Resolution,
    which I CAN SEE LOOKS BETTER and sharper and cleaner looking,
    The very sad fact to me is that ITV HD Picture Quality is still
    very badly let down by a Bit Rate that is far to low, Yes and the
    same old fact , a lack of bandwith on the Freeview HD Platform.

    Andy
    I still remember the Winter Olympics, so much better on Eurosport HD,
    has you no it was Broadcast at the best quality, ie 1920 x 1080i with
    a higher bit rate of 16 to 18 mbps.
    it was so easy to see the difference, my point is to you Andy it was
    in a class of its own, not second class HD i keep seeing on BBC HD...

  • Comment number 41.

    @Andy, #35 that wasn't actually my point.

    I was seeking comment on the point that Freesat is being deliberately dumbed down so as to match Freeview quality and the fact that, that isn't being "platform neutral" at all.

    I've copied the post down here to avoid you having to search the blog:

    "•Platform neutrality has to be considered when reviewing transmission parameters"

    I'm really concerned and disappointed by this statement by the BBC as this amounts to nothing less than an admission that Freesat is being dumbed down in quality of transmission so as to match Freeview HD which is much more bandwidth restricted.

    This to me is totally wrong.

    Its not biased to have one platform of better quality than another when that is caused by a restriction on the available tranmsission space on the other that simply cannot be avoided. This situation is entirely different to that where both platforms are equal but one is given favourable treatment.

    It is however, morally wrong to deliberately dumb down the other broadcast channel and spoil people's viewing pleasure simply to match the restricted one.

    The BBC owes a duty to deliver the best possible quality to its viewing audience and licence payers and is failing to deliver that where it reduces quality deliberately for these reasons.

    To put it simply, why should the viewing audience of one medium suffer a deliberate low quality picture simply because it cannot be avoided on another channel?

    Also, I briefly make the point I've been making for a long time on all of this.

    Freesat and Freeview need to be seperated out and allowed to play to their own strengths.

    There's room for both platforms to co-exist simply in different roles. Freeview as the easy to get cheap option and Freesat as the ultra high quality, max content enthusiasts / frequent viewer option for those who put picture quality over and above cheap reception. That way everyone is happy and the public are given a clear choice over which medium to choose according to their viewing habits, pockets and installation preferences.

  • Comment number 42.

    In #35 Andy Q states 'I am pleased to say on Friday Sat HD actually reached the quality of Freeview HD!'

    Was this said tongue-in-cheek, or are you really claiming this is worthy of celebration? That a platform of many years standing with much greater potential bitrate - DSat - has actually just managed to achieve equality with an inferior transmission platform - DTT - that's merely a few months old, bitrate-constrained & hardly out of the testing phase?

  • Comment number 43.

    Dear nur0 - thanks for the post. DTT is by no means an inferior platform - limited but by no means technically inferior - in fact at the moment the reverse is true.

    andy

  • Comment number 44.

    #43 Andy Quested

    I was hoping after our visit that you would engage in all aspects of our visit report and not be selective in your responses, but that appears not to be the case.
    The fact that you have ignored Alsone's post (#41) completely and only picked up on a secondary point in nur0's post (#42) just confirms that platform neutrality is a policy being pursued by the BBC for HD transmissions.

  • Comment number 45.

    The third section of our visit report, containing conclusions and recommendations, has now been posted here:

    http://www.bbc.co.uk/blogs/bbcinternet/2010/06/picture_quality_on_bbc_hd_a_vi_2.html

  • Comment number 46.

    Dear burnlea

    Thanks for the post - Post 41 suggests one service is being deliberately "dumbed down" to match another - as this is not the case, there is nothing more I can say that isn't on my post 43.

    Andy

  • Comment number 47.

    #46 Andy Quested,

    But that contradicts the statement from Stephen Baily, acting Head of Distribution technology. Perhaps Alsone's choice of the term 'dumbing down' was wrong, but clearly a policy of not using any more resources on satellite than is available for DTT would leave capacity for a second HD channel on satellite, albeit at the same unacceptable picture quality as the current BBC HD channel

  • Comment number 48.

    Dear burnlea thanks for the post - there is a great deal of difference between reducing quality due to bandwidth constraints than reducing services due to bandwidth constraints. Freeview cannot at the moment offer the same number of services or channels than the satellite platforms but it offers quality for its HD services.

  • Comment number 49.

    My point Andy is simple, the BBC ISN'T pursuing a policy of platform neutrality, what they're doing is a CLEAR BIAS TOWARDS FREEVIEW.

    A policy of platform neutrality is quite simply to look at the best bit rate available for optimum transmission quality eg 16 mbs.

    Then apply that that equally to all of the platforms eg. Freesat, BBC on Sky, BBC on cable, Freeview.

    Where a platform cannot through bandwidth restrictions accomodate the optimimum bit rate chosen for the BBC HD medium, then bit rate on that platform should be reduced to the maximum level that can be accomodated along with a pledge to increase the bit rate as and when extra bandwidth ever becomes available.

    That is platform neutrality. Where you have one standard and apply it across the board to all platforms without any bias, with only platforms that cannot accomodate it having a reduced bit rate.

    What the BBC have done however, is entirely different and shows a CLEAR BIAS TOWARDS FREEVIEW.

    They have taken a standard and set it, then looked at Freeview and said Freeview can't accodate this bit rate so all other platforms will have to suffer as a result as we can't have other platforms exibiting a better picture than Freeview, and then thrown the chosen standard out of the window and dumbed all of the other platforms down to Freeview's restricted bandwdith level irrespective of the orginal standard's optimum encoding or the poor picture quality for all that results.

    That isn't neutrality. That is a clear bias towards Freeview and ensuring that other mediums don't exceed Freeview quality.

  • Comment number 50.

    Dear Alsone - thanks for the post but now I am lost - are you saying the picture are worse or better on freeview HD? Up until last week Freeview HD was slightly better than Freesat but we were trying noise reduction on Freeview that did give a softer look. Or are you suggesting we use 16Mbs just because it's there?

    Andy

  • Comment number 51.

    What I'm suggesting Andy is that the bit rate shouldn't be reduced just to accodate Freeview's bandwidth failings but rather if you are pursuing platform neutrality, what should be being done is a bit rate set which maintains high quality HD and then apply this to all available platforms. If that bit rate falls above Freeview's available space then Freeview should be transmitted at the reduced bit rate alone (but at the maximum level available for that platform). That is platform neutrality, not reducing every platform just so as to avoid others looking better than Freeview.

    Astra commented a while ago that below 12mbs they get complaints about HD quality. Therefore this begs the question as to why the BBC haven't set 12 mbs or above as the BBC HD standard? There can only be one answer here from your answer above, because Freeview can't accomodate 12mbs.

    However, the point I've been trying to make is reducing all service below the optimium level just to make Freeview look good isn't platform neutrality but rather bias towards Freeview.

    What the BBC should be doing is applying the optimum bit rate, be that 12mbs or more, then applying it to all platforms and in the case of Freeview where it can't be accomdated, instead applying the highest possible level that can. That is neutrality.

  • Comment number 52.

    Thanks for the blog one of the visit.

    Key points:

    Have BBC admitted that the reduction in bit-rate has resulted in a reduction in PQ from what we got at the end of the Trial Period. [you reported them as saying they can not temporally increase the bit-rate as we will be disappointed when they have to reduce it]

    I do not understand the statement that TV panels can not process 1920. I have a Full HD 1080 by 1920p panel that is used in unscaled mode!

  • Comment number 53.

    #52 Bill-Taylor

    "Have BBC admitted that the reduction in bit-rate has resulted in a reduction in PQ from what we got at the end of the Trial Period"

    Not in so many words. What Andy said was that an increase in bitrate (presumably using the spare capacity on satellite) would only produce a small improvement in picture quality

    What Stephen Baily (Acting Head of Distribution Technology) said was that increasing the bitrate now (on satellite), only to have to reduce it in the future (when the spare capacity was needed for another channel?) would lead to disappointment. This suggests there would be a noticeable improvement in picture quality, and that viewers would be disappointed when that picture quality wasn't maintained.

    "I do not understand the statement that TV panels can not process 1920. I have a Full HD 1080 by 1920p panel that is used in unscaled mode!"

    Join the club which no doubt also includes 1920 x 1080 TV manufacturers!

  • Comment number 54.

    Dear all - see post 59 in part 3. More to follow tomorrow

    Andy

  • Comment number 55.

    Further to the discussion on the reduced quality of freesat transmission.(not HD). Freesat signal strength on BBC channels seems to have reduced in the last week. We are in North West Wales, we now get "no satellite signal" on BBC1 Wales and BBC2 Wales but can get a reasonable picture on BBC West Midlands and BBC North West.
    The same problem occurred late last year and then mysteriously went away again.
    Our neighbours on freesat experienced the same issues.

  • Comment number 56.

    Dear john - I will pass this to the people in distribution, can you let me know if the signal strength of any of the SD channels has changed?

    Andy

  • Comment number 57.

    Hi Andy
    They are all SD channels, we do not have HD.
    When we had the problem last year and again now the best reception
    is on S4C. BBC1 West Midlands and North West are OK but Wales and London
    are very poor/ non-existent.
    Cheers
    John

  • Comment number 58.

    Dear john - thanks for the post. I missed a viral fact in your first post (Freesat not Freeview). As it happened at the same time of year and a neigbour has the same problem, can you check for trees in the line of sight of the dish? You may have a bit of "leaf fade!!" especially id the trees are wet too. It is not unknown for trees to grow into the path over a year or tow or for dishes installed when there are fewer (or no) leaves to have problems in late spring and summer!

    If this is the case there are several options ranging from a bit of pruning to a larger dish. The company that installed it should be able to measure signal strength.

    Andy

  • Comment number 59.

    The BBC HD bitrate and has recently dropped again. Last nights (10th June 2010) Opera Italia part 3 was broadcast at 7Mbps MBAFF 25fps instead of the usual 9.256Mbps PAFF 50fps.

    TSReader showed the real-time bitrate hovering between 6.5Mbps and 7.5Mbps. TS Packet Editor showed an average bitrate of 7.156Mbps and a peak of 15Mbps. Just thought you'd like to know.

    Just in case you're not aware upscaled SD on ITV 1 HD uses 9.8Mbps and looks fuzzy as you'd expect. The 7Mbps MBAFF 25fps still looks ok but not as good as 9Mbps PAFF 50fps. If the bitrate drops any further (to say 5Mbps) then BBC HD will start looking looking fuzzy like upscaled SD on ITV HD.

  • Comment number 60.

    Dear Barry Warburton - thanks for the post. We are now using VBR so the encoder is "choosing" bit rates. I am not sure where the 50fps came from unless you are converting the output to 720p/50. We have always transmitted 1080i/25! Glad to see TS PE is working though!

    Andy

  • Comment number 61.

    Hi Andy
    re post 58
    Our neighbour is 500 metres away over a hill.
    This evening the picture on BBC1 West Mids and ITV1 London are perfect, whereas BBC1 Wales, BBC2 Wales and ITV1 Wales get No Satellite Signal. Is this a Welsh problem?
    John

  • Comment number 62.

    Dear Andy Quested - yes, I suspected that you might be using VBR. A week or so ago you where broadcasting PAFF 50fps at 9.256Mbps. Picture quality was superb in this format. No movement between interlace fields gave a BluRay 1080p style picture - well almost.

    When viewing a PAFF 50fps TS file with MediaInfo you'll see 2 frame rates. MediaInfo reports:
    Frame rate: 50.000 fps
    Original frame rate: 25.000 fps

    If you strip the .264 video and .ac3 from the TS container and mux into a MKV container you have to use 50fps for the video and audio to be in sync. If you use 25fps the video is played in slow motion and out of sync with the audio.

    The MBAFF 25fps is noticeably more blurred when viewed frame by frame because of the interlacing and the movement between fields. This is a bit of a step back into the past in my opinion. Admittedly when viewed in real-time (rather than frame by frame) no one is likely to see the difference unless you watch in slow motion.

    As for the reason for VBR I assume this is to squeeze 3 or 4 HD streams into the one 36Mbps terrestrial multiplex that'll probably appear this Christmas. After the 6 terrestrial multiplexes were moved around last year to leave one multiplex reserved for HD I assume that you're now trying to squeeze BBC HD, ITV HD and Ch4 HD into this slot. Channel 5 have also said they'll be starting HD broadcasts on satellite sometime in the future so maybe you're trying to squeeze a forth HD channel into this one multiplex.

    It would be better to get OFCOM to reserve at least 4 more frequencies to be used for future multiplexes and limit the number of HD channels per multiplex to 3x12Mbps HD broadcasts per 36Mbps slot. Then you'll have some spare capacity for the future. If all the spare frequencies are sold off it'll only cause problems in future.

    Maybe you could find out if VBR is possible with PAFF 50fps but I realise that the aim of the exercise is to use the absolute minimum bandwidth so I understand why MBAFF 25fps is being used.

  • Comment number 63.

    Dear Barry Warburton thanks for the post - one bit of (vital) information missed between us when I replied last. As you mentioned a recent change, I assumed DSat not Terrestrial. We have recently change DSat modes but I was unaware of local DTT changes - I will ask and (unfortunately Monday now) and get back to you. DTT is as you say Stat Mux not VBR on its own.

    As for Ofcom and frequencies, please feel free to approach them to discuss it - although most of the details are on their web site.

    Andy

  • Comment number 64.

    Dear Barry Warburton - a PS, can I ask what your local transmitter is?

  • Comment number 65.

    Sorry, I got the incorrect terminology with fields and frames.

    PAFF at 50 fields per second with 2 fields per frame gives 25 frames per second. PAFF can be configured to have no movement (so I understand) between the 2 fields so the receiver can re-construct a 25 frames per second image or 1080p 25. The image quality can be made to be similar to BluRay 1080p. It's also possible to display the image or create files at 50 frames per second which is useful for fast moving stuff - sport, nature - that kind of thing but I assume that movement between fields must be allowed in this mode to give flow of movement. Most of the NRK Beta files is 50fps nowadays but it does increase CPU usage on playback and lower the quality factor which means using more bitrate.

    MBAFF 25fps is like the traditional interlacing technique where you mix frames from different points in time giving the blurred image when viewed a frame at a time. When viewed in real time the human eye isn't quick enough to see the difference and software algorithms in the receiver can reduce the interlace effects but fast moving stuff is blurred.

    That's how I understand it. As far as I can see 50 fields per second is the future for broadcasting in Europe. I've read that many American HD channels now use 60fps (I don't know if that's fields or frames) for broadcasts because of the improved picture quality for fast moving stuff.

    My local transmitted is Waltham.

  • Comment number 66.

    "Increasing the bit-rates for BBC HD now, using the spare satellite capacity, would only lead to disappointment when they are reduced again to make way for further channels. (NB: Take note of this statement - there is an inconsistent message here - Why would reducing the bit-rate lead to disappointment if, as we were told elsewhere, bit-rate has minimal effect on PQ?)"

    To play Devil's advocate - couldn't he just be referring to disappointment amongst viewers monitoring the bit rate and being pleased it had increased then disappointed it had decreased rather than saying it would be due to a change in PQ? I'm not saying whether that would/wouldn't be the case, just that the statement can be read in more than one way.

  • Comment number 67.

    #66 Alan Robertson

    "couldn't he just be referring to disappointment amongst viewers monitoring the bit rate and being pleased it had increased then disappointed it had decreased rather than saying it would be due to a change in PQ"

    An interesting perspective, but I was present when that statement was made and the context of the discussion around it was picture quality.

    That statement has now been vindicated. With the introduction of VBR, the encoder has been utilising bitrates 70% higher than when it was fixed at 9.7 Mbps and viewers have been reporting improved picture quality coincident with that higher use of bitrates. Those picture quality improvements being sharper definition, improved clarity and less motion blur.

  • Comment number 68.

    Dear burnlea and Alan Robertson - thanks for the posts - burnlea, please remember VBR was only one of several upgrades, yes it has improved quality as we promised otherwise R&D would not have put the time and intensive effort. We have a PQ that is noticeable better than the August upgrade and considerably better than anytime since the start of the trial. There is still more to come too.


    Alan Robertson. I don't think you need be a devil here. Transparent compression starts around 200Mbs - and even at these rates the compression tools are vital, not just the raw bit rate. As bit rates fall the codec type become more important - so around 200+Mbs not much (if anything) between MPEG2 and H.264.

    At contribution rates (50 - 120Mbs) MPEG2 tends to be used at the moment as there is a lot of equipment out there, it is a mature technology and it had relatively low latency. Below 100Mbs long GOP is preferred but at 100+Mbs, i-frame is good news.

    Between 30 and 50Mbs the new H.264 seem to be doing a better job (long GOP) but the latency is fairly high. OK for when everything comes "down the line" but there could be problems for 2-way conversations!

    Down at the lower transmission rates it is assumed no further processing will occur, HD MPEG2 is OK 17 - 24Mbs (lets assume CBR) and H.264 efficiency becomes far more apparent up to around 2:1. Also the toolset (or implementation of the codec) is now as, if not more important than the actual bit rate. Latency however has gone through the roof!

    So at around 9Mbs with a good implementation (generation 3 encoding as some people refer to it) H.264 CBR does a very good job. However the latency is around 4-6 seconds by now!

    In a stat mux you can take advantage of the fact the mean bit rate will be lower than required for CBR and if done efficiently a stat mux offers a very good use of available spectrum, picture quality and number of channels.

    Of course if you only measure quality by bit rate, any decrease in numbers will cause disappointment as the comments about the "average" bit has done, even though everyone acknowledges the quality has improved.

    Thanks again

    Andy

  • Comment number 69.

    #68 Andy Q

    Thank you for your comment on my post.

    I am well aware that several changes were introduced over a short period of time, for which we all appreciate the efforts of the BBC HD team in introducing them and the improved picture quality resulting from them.

    The fact that the encoder, in VBR mode, now uses bit rates as high as 16.5 Mbps for challenging scenes is proof in itself that an increase in bit rate was necessary and that the increased bit rate is indeed playing its part in improving HD picture quality, which is what we have been maintaining all along would be the case.

  • Comment number 70.

    Dear burnlea - thanks for the post - happy to agree the pictures have improved and we can move on

    Andy

  • Comment number 71.

    #70 Andy Q

    Thanks Andy.

    A suggestion. Can parts 1 & 2 of the blogs be closed for further comment with redirection to blog 3 for all future comments?

  • Comment number 72.

    Dear burnlea - would be a good idea I will ask if we can mark up the last comment with a link - however as it's your group's blog can you get confirmation from the others before I do?

    Andy

  • Comment number 73.

    #72 Agreed

  • Comment number 74.

    Thanks for all the comments, folks - didn't expect so many on a Sunday! All the talk about statmuxing, etc. takes me back to the days of ONdigital! (I had one of the first boxes and received it via a small set-top aerial thanks to being in a flat on a hill with a clear view of Black Hill) - even remember BBC Choice and BBC Knowledge (as they were called in those days) sending out some researchers to hold a focus group with me and my flatmates! Things have certainly moved on leaps and bounds since then :-)

  • Comment number 75.

    #72 Andy Quested

    The viewers group are happy for blogs 1 & 2 to be closed for comment, with a final post on each redirecting to blog 3.

  • Comment number 76.

    Just to let you know that I'm closing this post for comments. Please go to blog 3 should you wish to comment.

 

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