[vlc-devel] Re: VCD OGT subtitles and rescaling
d.hartman at student.utwente.nl
Tue Dec 23 23:32:53 CET 2003
Why not just take it one step at a time.
Don't try to make it too perfect. This is low level stuff you want to do,
and in these cases it is better to first work with what is available so at a
later stage where you enhance the backend, you know what you DO want and
what you DON'T want. It seems like double work, but it probably produces a
more refined end result. And it allows you to make improvements over time,
instead of doing it all at once.
----- Original Message -----
From: "R. Bernstein" <rocky at panix.com>
To: <vlc-devel at videolan.org>
Sent: Tuesday, December 23, 2003 8:34 PM
Subject: [vlc-devel] Re: VCD OGT subtitles and rescaling
> > I don't understand what you mean by antialiasing here.
> Subtitles in SVCD OGT, CVD (and I think also DVD's) are pretty limited
> in the number of colors that they can use. For SVCD, the palette is 4
> colors. However one color, (usually color 0 which allows for a length
> 1-4 RLE), is transparent. So you have 3 colors: white, black and
> something in between. The text bitmaps that you get appear
> jagged. However the underlying chroma (I'm using YUV) doesn't suffer
> such limitations. Hence antialiasing may be a win.
> > I also still don't
> > understand why you want to reuse the dvd rendering procedure.
> The state of developer documentation (and as I am learning, useful
> support routines) are not to the stage where one (or at least not me)
> would be able to do much than take existing working code, and read
> that in order to infer how things work. In such an environment, one
> may as well modify the code since one has to dig deeply in to it
> anyway. No, it's not the way I prefer to work.
> > Why not write
> > a little function what does this directly, and not encode/decode an
> > time.
> Antialiasing is a separable filter. Scaling is a separable filter. It
> might be possible to interpret OGT and CVD-specific format, antialias
> it, scale it and encode into the right chroma in one step. However for
> me right now, it would be too complex to understand and difficult to
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