[FFmpeg-devel] [RFC] handling of subtitles

Michael Niedermayer michaelni
Mon Apr 7 02:00:19 CEST 2008


On Mon, Apr 07, 2008 at 01:12:09AM +0200, Dominik 'Rathann' Mierzejewski wrote:
> On Sunday, 06 April 2008 at 20:14, Michael Niedermayer wrote:
> > On Sun, Apr 06, 2008 at 12:02:15AM +0200, Benjamin Larsson wrote:
> > > Hi, the XBMC project is thinking of running a GSoC task of creating a
> > > unified subtitle handling lib:
> > > 
> > > http://xbmc.org/wiki/?title=GSoC_-_Unified_Subtitle_Parser
> > > 
> > > While the wiki page might not make sense, what support has FFmpeg for
> > > text subtitles and if there is none how should it be implemented ?
> > 
> > Well the first part is demuxing, dvb/dvd/text/ass/ssa/xsub and possibly others
> > are supported already. Adding more should be trivial matter of adding the
> > entries in the codec_tag/codec_id tables ...
> > 
> > Second is decoding, here the subtitle packets are converted into a common
> > and easy to digest format (AVSubtitle) we currently only have dvb
> > dvd ad xsub decoders. Adding text/ass/ssa/... will require AVSubtitle to
> > be extended to support text (with all the bells and whistles these formats
> > allow) in addition to bitmaps.
> > 
> > Third is rendering, the code in ffplay (which should be moved to avfilter)
> > supports what AVSubtitle supports currently.
> > 
> > Encoders which turn bitmap based AVSubtitles into their native format exist
> > for dvb and dvd subs.
> > 
> > No new library or other large scale redesign seem to be needed.
> 
> For rendering SSA/ASS, the libass code from MPlayer could be used. AFAIK it
> is almost self-contained and mostly feature-complete.

Well, if that is so ... then send a patch.

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Everything should be made as simple as possible, but not simpler.
-- Albert Einstein
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