[mythtv] Ticket #4872: Detect if video is letterboxed and switch to corect fill mode

Mårten Bohlin mabo at mochc.net
Tue Apr 1 07:10:41 UTC 2008


On Mon, Mar 31, 2008 at 4:33 PM, Petr Stehlik <pstehlik at sophics.cz> wrote:
> Willy Boyd wrote:
>  >>  For me, the "default zoom: half" does not work as expected because it is
>  >>  zooming even contents that would fit perfectly on screen without any
>  >>  black bars - i.e. 16:9 movie on 16:9 screen is zoomed as well. The
>  >>  default zoom should IMHO zoom to half (if enabled) only if the movie is
>  >>  4:3 and screen is 16:9 (not sure about 16:9 movie on 4:3 screen).
>  >
>
> > I thought that "half" only specified how much to zoom?  Even if the
>  > video is 4:3, it may be displaying a 16:9 movie or show with the black
>  > bars encoded into the stream.  Zooming in on this is what this feature
>  > enables.
>
>  Well, I meant it differently - normally the "remove black bars" function
>  never "overscans" but with 4:3 movie on 16:9 screen there is a lot of
>  wasted screen space due to the black bars so I thought it would be cool
>  to automatically zoom in to 14:9 (called also half zoom) to partially
>  overscan and partially remove the black bars.
>
>  I realize it has not much common with the autodetect function but it
>  fits under the feature "remove black bars" :-)
>
>  So it would work as follows:
>
>  if (black bars in stream detected)
>      zoom as much as possible to remove the black bars;
>  else
>      if (video aspect ratio != screen aspect ratio)
>          if (half zoom allowed)
>              set half zoom to remove at least part of the black bars;
>
>
>  Currently it seems to miss the aspect ratio compare condition.
>
>  Petr
>

Petr could you try this patch together with my autodetection patch.
And see if the combination give the behavior that you are desiring.

Theoretically there is cases when this is wrong. What if you have a
16:9 display and watches a lot of 4:3 content that is pillar boxed in
a 16:9 video? But that is theoretically.

Mårten
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