[mythtv] Patch to autodetect 4:3 Zoom aspect ratio

Mark Kendall mark.kendall at gmail.com
Fri Feb 22 15:06:25 UTC 2008

On 22/02/2008, Mårten Bohlin <mabo at mochc.net> wrote:
> Hi!
>   I have written a patch for the release-0-20-fixes branch (svn
>   revision: 16162) that detects black bars on the top and bottom of the
>   frames. When that is detected it toggles to "Letterbox 4:3 Zoom". And
>   if no bars is detected it toggles back to "Letterbox Off".

>   Comments are welcome.


What about material that is (for example) 2.35:1 displayed on a
widescreen (16:9) display? (i.e. 'super' widescreen dvds) If you
updated your patch for trunk, you would apply the correct 'zoom'
(either half or full) but the scan lines you're using may not work
(i.e. they might still fall within the actual content - though I
haven't checked).

Also, is the letterbox detection robust enough? As far as I can tell,
it's taking a very  limited sample set and doesn't check for
consistency within the 'actual' frame content. So how would it react
to a dark sequence for example? Would it be better to check for 'dark'
letterboxing and 'non-dark' content?

My apologies if my quick scan of your code has missed something.



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