[vlc-devel] Re: [patch] Fixed source aspect ratio calculation

[Marian Durkovic]

On Tue, Oct 18, 2005 at 02:07:49AM -0700, Michel Lespinasse wrote:
> On Tue, Oct 18, 2005 at 09:44:51AM +0200, Marian Durkovic wrote:
> > This IMHO means, that VLC needs to immplement 1088->1080 fix, otherwise
> > the users will still complain about HDTV greyline bug on considerable amount
> > of HDTV content (claiming their STB played it fine so there must be a "bug"
> > in VLC). The problem is so widespread, that it's not possible to ignore it,
> > and if the situation changes in the future there's nothing easier than to
> > remove this ugly fix.
> 
> In my opinion it'd be much better to teach the rescaling code to do
> nothing if the pixel aspect ratio is within 1% of being square. That way
> you have a more general way of preserving quality without having to
> mess with the stream parameters. (you still get the 8 gray lines though).

Michel,

  my primary focus is to get rid of those 8 grey (green, alternating) lines 
which look terrible during dark scenes.

  Also, the output format of 1920x1080 with aspect ratio 16:9 could be
encoded in several ways, e.g.

-  1920x1080, pixel aspect ratio 1:1 (square)
-  1440x1080, pixel aspect ratio 4:3
-  1280x1080, pixel aspect ratio 3:2  

  All those formats break and loose quality, if display_height says 1088 
instead of 1080.  

  On the other hand, I'm not aware of any single reasonable format really 
utilising 1088 lines and maintaning sane aspect ratios at the same time. 
Thus I think that my 1088->1080 fix couldn't harm anything in real life,
although I agree it's an ugly fix (to a common encoder bug, though).


	With kind regards,

		M.

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