[mythtv] [PATCH] Specify aspect ratio cycle

[Kristof Pelckmans]

Quoting Hamish Moffatt <hamish at cloud.net.au>:

> On Fri, Jun 04, 2004 at 06:15:57PM +0100, Jon Burgess wrote:
> > Yes are correct, but there is some info transmitted in the MPEG stream
> > of the UK DVB broadcasts that can help determine the correct mode.
> >
> > The AFD field contains further information describing the transmission
> > format, for example one of the codes indicates "4:3 picture transmitted
> [...]
>
> Interesting stuff Jon. Do you have any information on whether this has
> been implemented outside of the UK?
I'm still in the old league : using plain pal(plus), so that would not work.
You can try and do this for dvb though.

Another solution would be to get this from the programinfo. My xmltv source
indicates whether the original format is 16:9 or 4:3. The broadcast signal is
always palplus, which means 4:3 (with some extra information for 16:9 footage,
but there is no tv capture card that can decode this). I capture on a bt8x8
card, so 4:3 format and I am displaying on a 16:9 format.

So :
16:9 -> 4:3 (black bars top and bottom) -> 4:3 (black bars top and bottom) ->
16:9 (4:3 MythTV zoom) for 16:9 footage
4:3 -> 4:3 -> 4:3 -> 16:9 (4:3 MythTV : black bars left and right) for 4:3
footage

Detection for these two cases is feasible : detect whether the 4:3 image on the
bt8x8 card has black bars on top and bottom. However, this does not work when
you get 16:9 -> 4:3 (shrinked) -> 4:3 -> 16:9 and I have no idea how you are
going to detect such an image distortion without some sort of metadata.

One last remark : I don't know of a schema where you would have 4:3 -> 4:3 ->
16:9 -> 16:9, which means that the capture device cannot capture 4:3 format.
Can this sort of situation exist ?

Cheers,

Kristof