[matroska-devel] Re: a simple subtitle format

Pamel Paul at msn.com
Wed Feb 19 06:29:25 CET 2003


"John Cannon" <spyder482 at yahoo.com> wrote
> "Moritz Bunkus" <moritz at bunkus.org> wrote in message
> > After some reading on USF and a bit of discussion in #matroska I still
> > want a simple subtitle format like SubRip to be stored in Matroska in a
> > simple manner.
>
> I agree

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.

> > The duration must be stored somehow. Pamel proposed to store it in a
> > new 'KaxDuration' element for the Block (along with the Block's
> > timestamp). The duration could be used for other things as well. It can
> > be optional.
>
> Hmmm maybe a better idea :)

Errr.... What I said was there are three options.  But, I guess there are
four.

1.  Leave the duration time in the block as part of the text and let the
subtitle 'codec' parse it.  (Easy)

2.  Create a null block at the appropriate time to clear out the subtitle.
(Simple, yet elegant)

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)

4.  Change the block structure for subtitles to include a Timecode AND
Duration numbers.  (Does anyone really want another revision of the basic
Block design?)

I think what Moritz is refering to is method 3.  I actually meant to mention
this to someone quite awhile ago, but forgot.  It could be useful for many
things other than subtitles.  The main problem is how do we pass this info
to the subtitle filter in Windows?  (I realize it wouldn't be a problem with
mplayer in linux)  We would probably have to hardcode it into libmatroska
until something like UCI or gstreamer supported it.


Pamel



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