[linux-dvb] Re: Aspect ratio on UK DVB-t

[Andrew de Quincey <adq_dvb@lidskialf.net>]

On Friday 25 July 2003 06:36, Robert Schlabbach wrote:
> From: "Andy carter" <fruit@ukgateway.net>
>
> > Virtually all images displayed as 4:3 on the monitor, but motv displays
> > some channels/images as widescreen. ISTR a post stating that the UK uses
> > a non-standard method for encoding ratio, but can't find it ATM.
> >
> > So, I'm just wondering if this is a dvb or vdr thing, and has anyone
> > watching UK TV any ideas about how to resolve this?
>
> From what I heard, the BBC (and only the BBC) has dreamt up their own
> method of indicating the aspect ratio, while other TV stations (including
> others in the UK) are using the standard MPEG-2 headers to indicate  the
> aspect ratio.
>
> The BBC method is called AFD and described here:
>
> http://www.dtg.org.uk/publications/books/afd.pdf
>
> I don't know if there is any AFD implementation for Linux yet...

This is actually part of the DVB-T standards now. Look at ETSI TR 101 154 
v1.41 Annex B.

AFD is in addition to the standard MPEG2 aspect ratio stuff.. basically, it 
lets the broadcaster describe which area within the frame is relevant, so you 
can a 14:9 picture within a "physical" 16:9 one.

Its quite easy to implement; I'd recommend using libmpsys to parse the MPEG 
transport stream.



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