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Support report: video aspect ratio issue on satellite Sport service

  • Rob Hardy
  • 28 Jul 08, 5:20 PM

Like any IT service, we have a continuous flow of support issues for the live service (or incidents, if you're an ITIList).  Occasionally an issue is high profile enough to garner some outside interest, and I'll report on these here.  Here's the first report.

Symptom: Aspect ratio incorrect on certain video streams (16:9 displaying anomorphically - it looks squeezed).  This applies to the videos accessible under the Sport Multiscreen.

Diagnosis: The OpenTV middleware is responsible for handling the aspect ratio, taking into account the viewers' individual settings, and the aspect ratio of the broadcast video.  If the application uses any of the OpenTV API calls to manipulate the video, then the responsibility to maintain the aspect ratio moves to the application.  In this case our new OpenTV browser used for the sports service was overriding the middleware's automatic handling of the video aspect ratio.

Resolution: Code modified so that O_video_set_auto_mode is called with AUTO_ALL, and other video manipulation functions are inhibited for fullscreen video.  Code was released to live on 15th July.

Comments

  • 1. At 11:00am on 29 Jul 2008, hpengwyn wrote:

    I have a tangential question. Which BBCi things are different OpenTV applications? i.e. is the normal red button stuff one application and the sports stuff another etc. or is it one big application? What is the level of abstraction, does each of the applications essentially remain unchanged but the parameters e.g. the menus, the streams etc. change or do you have to rebuild the 'executable' every time?

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  • 2. At 4:51pm on 29 Jul 2008, Andrew Bowden wrote:

    The answer to this could be an entire post in itself!

    Where there's lots of generic, reusable code, we use OpenTV applications we call Browsers - the idea is along the lines you say - being that you feed XML into a core application and the core application needs not change much. So you can build a new template, or put some new content in without changing the core application. We call them browsers because there's a vague web browser parallel.

    We have a couple of these which do different things and support different applications and services, but the principles are always the same - keep a static application and feed it configurable data. That way you can crank the handle and get new stuff out quickly.

    We have a couple of completely static applications like the CBeebies games which don't change.

    Hope that answers your question

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  • 3. At 4:52pm on 29 Jul 2008, robhardy wrote:

    There are three in-house OpenTV applications:
    1) The 24/7 sport service
    2) The rest of the 24/7 text/video service
    3) Interactive TV programmes (quiz shows, gigs, karaoke etc)

    There are additional applications from 3rd parties used for games and other quizzes.

    Each app has pros/cons as to its flexibility vs speed, volume of content, etc.

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  • 4. At 5:11pm on 29 Jul 2008, hpengwyn wrote:

    Very interesting, thanks. I have always been very impressed at how stable the 'Sky' (or whatever you want to call it) DSAT platform is, certainly the BBC stuff which is more or less the only thing I ever use the red button for.

    It did occur to me that presumably the Freesat stuff has a multi-screen with more streams than Freeview but would look more like Freeview, so when on News 24 the presenter shows the interactive stuff they should be showing 3 things not 2 :-)

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  • 5. At 07:16am on 30 Jul 2008, Briantist wrote:

    It's not just the Sports service that suffer from this.

    All BBCi text services just overlay the broadcast image with no relation to the aspect ratio.

    This means on Satellite you get a fat-wide BBCi on 16:9 output and a thin-narrow one on 4:9.

    On Freeview and Freesat you also have the same problem with MHEG5 services, but with the 14:9 output as well.

    I can't understand why in 2008 the OpenTV and MHEG5 applications can't understand the aspect ratio of the "main picture" and adapt to fit.

    The most annoying thing is that the OpenTV/MHEG5 graphics cannot be integrated into the channel output as they can appear at three different locations.

    So you can't, even if you wanted to, put an alternative news ticker on the BBC News channel (say, regional news on Freeview) because you can't make it appear in the right place, even though it is pixel-perfect in the broadcast.

    I was forgiving about this back in 1998, but after a decade of OpenTV on satellite, and several years of MHEG5 on Freeview, it would be nice if someone could fix this.

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  • 6. At 10:52am on 31 Jul 2008, mangad the improbable wrote:

    This comment was removed because the moderators found it broke the House Rules.

  • 7. At 3:54pm on 31 Jul 2008, Andrew Bowden wrote:

    In reply to hpengwyn... Freesat doesn't yet have a multiscreen, but when it would probably look a bit like the Sky one when it does as there will be the same number of videos and things.


    In reply to Briantist - think you're spotting our graphical standards.

    The graphics are designed for 14:9 so that when viewed in 4:3 and in 16:9, they appear "less" wrong. The theory is that it looks better than a 4:3 graphic being stretched out ton 16:9.

    We don't detect aspect ratios of pictures, partially as we'd need to design and code everything twice - having a 4:3 version and a 16:9 version would take up a lot more data space and make the code more complex. It's a lot easier just to build one service that is used for both aspect ratios. Also, we don't actually know how the viewer is viewing a picture on TV - it may be cropped by the set top box, stretched by the TV or even cropped and stretched.

    We can line up application graphics with TV graphics - we've done it a few times for events like Test the Nation. It is tricky

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  • 8. At 09:32am on 15 Aug 2008, BigBadDaveB wrote:

    Interesting posts. I've been thoroughly enjoying the BBC interactive coverage of the Olympics and am just wondering what you've got in store for 2012!

    Anyway, two very minor grips about the technology side of it. I'm watching via a Sky system, by the way.

    1) Brilliant that you've fixed the aspect ratio but it still seems to switch into 4:3 when the multiscreen menu is displayed.

    2) Once a stream is selected, is there any way of making the blue button "MENU" prompt time-out? It's not the most annoying thing in the world but it does intrude on an otherwise uncluttered screen.

    That aside, congratulations once again on a fantastic technical achievement.

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  • 9. At 12:36pm on 22 Sep 2008, Andrew Bowden wrote:

    Hi BigBadDaveB - sorry no one has replied to this earlier.

    On the multiscreen aspect ratio - the video is produced in 4:3 hence the way it flips back to 4:3 when you view it. There's a combination of factors as to why we produce the multiscreen in 4:3 - mainly to do with avoiding video cropping, and to do with control of video within interactive applications.

    For the menu timeout - again there's a variety of reasons why the menu doesn't time out. It's a visible inidicator to help people remember how to change the video they're watching - so that they don't get stuck in a service, unsure of how to change it. Indeed, for reasons like that, Sky have a rule that says we have to make it known at all times that a user is in an interactive application rather than a normal TV channel.

    Obviously that's little compensation if you know what you're doing and you find menu icons annoying and distracting.

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