[mythtv-users] Skipping adverts in UK using DVB-T - supported ?

[Andy Whitworth]

My TV when in 'auto' mode often switches to/from 16:9 when the ad break appears
so I guess there is a physical change ?  I think this would be a
useful detection
trigger to add to the list!

Andy.


On Thu, 20 Jan 2005 00:00:05 GMT, Tom Hughes <tom at compton.nu> wrote:
> In message <200501192307.j0JN7Wcd007133 at panther.bc2va.org>
>           "Chris Pinkham" <cpinkham at bc2va.org> wrote:
> 
> > > Haven't updated my cvs version yet to try the new detection, but does
> > > it also monitor for aspect ratio changes?  Just noticed while watching
> > > tv yesterday quite a few channels change aspect ratio when they switch
> > > to the adverts (I'm in the UK).
> > >
> > > In this situation it could be a very accurate way for detecting ads.
> >
> > Is this a physical aspect ratio change or does the frame stay the same
> > ratio and have black bars on the top/bottom?  I have a sample of a UK
> > broadcast that uses the black bars and will be trying to code up something
> > to detect that transition so it can be used to determine where commercials
> > start/stop.  If you mean a physical frame aspect ratio change, then I'd
> > like to detect this at some point but don't have any sample recordings
> > to test with right now (I'm in the U.S. with analog cable).
> 
> Well it would be black bars on the side of the program if anything
> rather than black bars on the top and bottom of the adverts.
> 
> In a DVB-T stream there are two ways of handling aspect ratios. For
> simple 4:3 vs 16:9 it can be done with a simple flag. In that case
> then the transmitted data is always the full picture area and the
> flag tells the receiver what aspect ratio to use when displaying
> the data - the resolution doesn't change, so would be 720x576 or
> 704x576 in the UK depending on the channel.
> 
> The other option is to use an AFD where a 16:9 picture is transmitted
> and if the content is 4:3 then there are black bars on each side. There
> is then an Active Format Descriptor (AFD) which indicates which part
> of the transmitted picture to display. That allows more choice of
> ratios but in the UK at least only 4:3 and 16:9 are used.
> 
> Some channels use AFDs in the UK and some use the simple flag. Most
> of the AFD channels don't have adverts however, but I think there is
> one that does - certainly Five was, but it may have changed recently.
> 
> I'm not sure how Myth handles those two cases however, or what you
> see in the stream when you read it back from disk.
> 
> Tom
> 
> --
> Tom Hughes (tom at compton.nu)
> http://www.compton.nu/
> 
> 
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