[MPlayer-dev-eng] [PATCH] libass improvements and fixes

[Evgeniy Stepanov]

On Friday 06 February 2009 09:56:03 Grigori G wrote:
> Hello,
>
> libass is starting to get old. This patch fixes various problems and
> adds support for new stuff.
>
> In detail it
> adds stubs for most features introduced in vsfilter 2.39,
> implements \blur and \be > 1 (often used in more recent anime fansubs),

OK

> corrects fix_outline_and_shadow() for transparency + anti-aliasing,

It's not a fix, it's a regression. It adds a little transparency between the 
border and the actual glyph. It happens because in current implementation 
bitmaps are blitted one by one to a video frame. Suppose for some pixel 
opacity(glyph) = opacity(border) = 1/2. After blitting first bitmap we have 1/2 
glyph color and 1/2 background color. After blitting the second one we have 
1/4 glyph color, 1/4 background color and 1/2 border color. That looks ugly.

The correct way is to build a composite, multicolor bitmap of a glyph with its 
border, and then blit it into video frame.

> fixes first-tag-wins for \pos and \move.

OK

>
> There's more to come...
>
> Grigori