[FFmpeg-devel] [RFC] handling of subtitles

Dominik 'Rathann' Mierzejewski dominik
Mon Apr 7 01:12:09 CEST 2008

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.


MPlayer developer and RPMs maintainer: http://mplayerhq.hu http://rpm.livna.org
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