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

Mårten Bohlin mabo at mochc.net
Mon Mar 17 11:45:49 UTC 2008


On Mon, Mar 10, 2008 at 9:20 PM,  <mythtv at longhome.co.uk> wrote:
>
> > On Sun, Mar 9, 2008 at 12:32 PM,  <mythtv at longhome.co.uk> wrote:
>  > > I've noticed that 2.39:1 letterboxed in a 16:9 stream also gets
>  > zoomed,
>  > >  meaning part of the broadcast picture is lost. I would have thought
>  > that
>  > >  only content in a 4:3 stream should be zoomed? Right?
>  > >
>  >
>  > That is strange because I test if width/height <= 1.5. And that is the
>  > width and the height of the frame I am processing. So it should not do
>  > anything about streams in 16:9.
>  >
>  > What kind of stream is it? Is it possible that it starts in 4:3 and
>  > then switches to 16:9?
>
>  [Martin Long]
>  Hmmm... it's interesting. As far as I know pixels in UK freeview are not
>  always square, but sometimes are.
>
>  So, sometimes the same resolution is used for 16:9 and for 4:3 - meaning
>  ratio is not a viable means of detecting aspect ratio. I'm not sure what the
>  signalling mechanism is that's used, but this must be available to myth, as
>  it seems to display at the correct aspect.
>
>  I'll see if I can dig around a bit in the code, and try and grab some
>  resolution examples for you. Unfortunately I'm working a lot of hours at the
>  mo, so it might be a little while.
>
>  Martin
>
>
>

Martin could you try the latest version of the patch (version 6). In
this version the width is never used for any boundaries.

This has changed some of the code, so those who has set the
"DetectLetterboxLimit" might need to adjust their settings.

Mårten


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