[matroska-devel] Re: a simple subtitle format

Steve Lhomme steve.lhomme at free.fr
Wed Feb 19 09:39:01 CET 2003


En réponse à Moritz Bunkus <moritz at bunkus.org>:

> Hi.
> 
> > I always figured that people who made the 'codecs' for subtitles would
> store
> > the subtitles in Matroska however they like.  I really think that this
> is
> > outside of the spec of the container.  However, giving a few
> recommendations
> > would be good so that things are done a little more universaly across
> the
> > board.
> 
> Well as I am the person who creates the mplayer support for the
> complete Matroska format I'll also have to handle the subtitle formats
> it can transport ;) And so far Christian has not listed a CodecID for
> such a simple format, so I just wanted to ask if we couldn't add it
> right now and define it the way we like it (mostly how to store the
> duration and the CodecID).
> 
> > 3.  Create a new element "BlockDuration" under "BlockAdditional" that
> tells
> > the duration of the block.  (Adding yet another element to matroska? 
> Well,
> > thats why it uses EBML.  This is the coolest method)
> 
> This is fine with me. And what I meant, yes. But if you want to store
> it in the text so that the Windows subtitle filter can read it easily
> it's no problem either, just chose
> 
> -----[cut]-------------------------------
> 1200
> The quick brown fox jumped
> over the lazy dog.
> A third line is also present.
> -----[cut]------------------------------
> 
> The first line is the duration in ms, the rest are the text lines.
> Each
> line is terminated by either DOS style line breaks (\n\r?) or by UNIX
> style line breaks (only \n, so the filter would just have to ignore
> \r).
> 
> Very easy to parse, hopefully solves your Windows API problem, trivial
> to implement, no changes to the Matroska specs necessary (apart from
> the CodecID - I still suggest 'S_SIMPLE').

I'm undecided on the BlockDuration field. But it could make sense, even for
video (remember the Diaporama codec I was talking about ?). So I think it can be
added. That would allow to cut a movie (with Diaporama) at the duration
bondaries (keeping the audio in the correct area, since the image transitions
could be linked to audio transitions).

> By the way. So far there's only KaxTrackVideo and KaxTrackAudio, but
> no
> KaxTrackSubtitles. Why? I guess it's just about priorities and/or lack
> of time :)

Exactly :) The same way there was no EbmlDate until yesterday :)
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