[mythtv] Patch to autodetect 4:3 Zoom aspect ratio
mabo at mochc.net
Tue Feb 26 12:13:24 UTC 2008
On Mon, Feb 25, 2008 at 2:17 PM, Mårten Bohlin <mabo at mochc.net> wrote:
> On Fri, Feb 22, 2008 at 4:06 PM, Mark Kendall <mark.kendall at gmail.com> wrote:
> > 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.
> > Mårten
> > 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).
> I have not tested with content 2.35:1 content, but if it does not work
> as it is there is just som minor adjustments of the limits to get it
> to fill to full zoom.
> > 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.
> > Regards
> > Mark
> > _______________________________________________
> Yes it only looks at two lines on the screen for performance reasons,
> but it also checks that it seems to be vertical lines on the top and
> bottom of the screen before it makes a switch to the detected zoom mode. So yes
> I find it very robust, I have used it daily for over a week now and are happy with it.
I meant horizontal lines. Not vertical.
> It only switches if it finds out that it should switch in 3 frames in
> a row.
And here I meant three consecutive frames. ("in a row" is a Swedish expression)
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