[mythtv] [PATCH] Add AFD support for aspect 'magic'

William Uther willu.mailingLists at cse.unsw.edu.au
Sun Jun 5 02:53:09 UTC 2005

On Sat, 04 Jun 2005 15:16:03 +0100, Neale Swinnerton wrote:

> The Active Format Descriptor (AFD) is set by some broadcasters like  
> ITV1
> and CH4 in the UK in their DVB-T streams. This signals what the format
> of the video is, and along with the aspect ratio of the video  
> stream and
> your display it can resize the video 'better'.
> This patch adds support for this to myth. To enable it go to
> Utilities/Setup->Settings->TV Settings->Playback and set aspect  
> override
> to AFD.

I have no idea if AFD is supported in Aus, but I've been thinking of  
re-working the aspect ratio override stuff for a while.  Here are my  

Aus DVB broadcasts are usually 16:9, but that is often an already  
pillarboxed 4:3 image.  My TV is 4:3.  For many shows you want the  
aspect override set to 'Fill' to remove the pillarboxing, otherwise  
you end up with an image that is first pillarboxed remotely, then  
letterboxed locally.  For signals that really are 16:9, you want to  
switch the aspect ratio override to 'off'.  Switching between 'Fill'  
and 'Off' can require cycling through a whole list of other 'aspect  
ratio' settings - something that I find a little annoying at times.

It seems that there are really three settings here which are being  

i) The aspect ratio of the incoming signal.  This is usually correct  
for DVB in Aus, but I can imagine people wanting to over-ride it.  I  
don't know how often this changes however - it should be set and  
forget, shouldn't it?
ii) The aspect ratio of the display.  This should also be set and  
forget (if it isn't already correct from your X setup).
iii) How to handle aspect ratio mismatch when i) and ii) are not  
equal.  This is the setting that I want to change somewhat  
regularly.  I can imagine switching between 'Zoom in' == 'Fill', and  
'Zoom out' == 'letterbox/pillarbox'.  Is this what AFD is for?

With this arrangement, I could set the 'w' key to just change the  
last setting.  I get a much simpler interface.

Can anyone see any reasons not to split things up this way?


Will           :-}

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