[ogg-dev] video chapters and subtitles in ogg containers

Hans J. Koch hjk at linutronix.de
Fri Nov 14 12:25:06 PST 2008

On Fri, Nov 14, 2008 at 11:40:18AM -0800, Ralph Giles wrote:
> On Fri, Nov 14, 2008 at 3:43 AM, ogg.k.ogg.k at googlemail.com
> <ogg.k.ogg.k at googlemail.com> wrote:
> > If the use of these is seeking, chaining doesn't fit the bill as you have to
> > parse the stream to know which chains you have, no ? This kind of defeats
> > the purpose of skipping to a known place.
> You don't have to parse the whole file, just enough to find all the
> chain boundaries. That can still take some time, of course.
> Prohibitively so for many segments over a high-latency interface.
> We have resisted doing a seek table in the past. One of the design
> goals of Ogg has always been that it be not just consumable as a
> stream, but writable as well. This requires that everything be single
> pass, which isn't true of a seek table. If the chapter index only
> references time as Hans has described, and not byte offsets, then when
> transcoding of course you could put it in at the beginning with the
> expectation that the complete encode would include all the targets.

Yes, that's what I mean. When encoding such a file, you usually pass in
a text file containing the chapter entry times and optionally chapter
names. That's how dvdauthor or ogmmerge do it. The fisbone element of
ogg skeleton might be a good place to store such data, maybe simply as
name/value pairs, like CHAPTER01=00:00:00.000;CHAPTER02=00:00:58.240;...


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