[vdr] Aspect Ratio problems

Jon Burgess jburgess at uklinux.net
Fri Sep 2 21:47:13 CEST 2005


Mike Parker wrote:
> Thanks for the Help Darren.
> 
> By squashed I mean that the TV is showing a 'full' picture which is not in
> the correct aspect ratio, no pillar boxing.
> When a 4:3 is being transmitted I have to switch my TV into 4:3 mode and the
> tv puts in its own blank sides and the picture is correct.
> Watched bbc3 Apprentice last night, it shows pillar-boxing and no change is
> necessary, but surely that is 16:9 in stream (I did not check) so it should
> look ok anyway.

I recorded that program, it was broadcast as 16:9 stream containing 
pillar-boxed 4:3 content. If you have a 16:9 TV then you are correct, it 
will look OK without VDR or the TV doing any kind of proceeing on the video.

> The problem is when a 4:3 stream is being sent and dbv is set to 16:9, the
> 4:3 picture is sent to my tv in 16:9 format and the tv does not
> automatically switch.

I have a 4:3 TV and use a DXR3 card for my display so I can't be certain 
about the capabilities of the FF card, but here is what I can tell you 
about what I believe should happen.

A true 4:3 video stream obviously doesn't have the black borders to make 
it look right on a 16:9 TV so something needs to add them. I believe 
what is meant to happen is that the TV gets instructed to switch into 
the 4:3 mode in one of two ways:

- Signalling via SCART pin 8 which probably isn't applicable since even 
if you use some s-video to scart conveter then this pin will not be 
driven by the FF card. (see this link for some information on SCART 
http://en.wikipedia.org/wiki/SCART )

- Widescreen Signalling (WSS), which is a special signal embedded in one 
of the offscreen lines of the picture much like the old TeleText system. 
( see http://en.wikipedia.org/wiki/Widescreen_signaling ). I think this 
can either be delivered inside the original video stream by the 
broadcaster or be inserted by the playback card (I'm not sure if the FF 
is in this category).

> Is this a vdr / driver problem?

Sorry I can't help here. Other possibilities include the video stream 
not including the WSS signal or your TV perhaps not obeying the WSS. 
Occasionally broadcasters have even been known to flag 4:3 programs as 
16:9 by mistake.

	Jon



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