[MEncoder-users] Generating switchable binary subtitles with MEncoder

[Giacomo Comes]

On Mon, Oct 29, 2007 at 05:12:46PM +0100, Nicolas George wrote:
> L'octidi 8 brumaire, an CCXVI, Giacomo Comes a écrit :
> > spumux (part of dvdauthor) is able to convert text subtitles to spu format
> > since forever. After uou have them in spu format you can extract them to 
> > vobsub format if you like.
> 
> I mentioned spumux, but I also mentioned that it does not handle font
> subtleties: you can not have italic, for example.

Ok, it does not handle automatically <italic> </italic> etc.,
but it's not that difficult to split your source subtitle file
in several files each one for a different font style and mux them
in separate passes.

> 
> > Well actually ALL dvd subtitles uses the alpha channel because the region 
> > surrounding the subtitle text is transparent.
> > Otherwise you would see a rectangle of some opaque color surrounding the
> > subtitle text.
> 
> I know, that is the reason I wrote "non-trivial alpha channel": the DVD use
> only opaque black, opaque white and completely transparent. It is possible
> to have half-transparent black, which gives a nice anti-aliasing for
> example.

Semitransparent subtitles are supported and I have seen some DVDs using them.
It's just that most of the commercial DVD do not use such feature.

Giacomo