[theora-dev] using Kate for WebVTT encapsulation

ogg.k.ogg.k at googlemail.com ogg.k.ogg.k at googlemail.com
Fri Apr 15 13:53:20 PDT 2011


sorry for the delay, I haven't been checking mail for a few days.

> My idea is that - because WebVTT is so similar to SRT - it would be
> simple to support WebVTT in Ogg by encapsulating it in a Kate track
> and making sure that it can be extracted again without loss of
> information through the kate libraries.

This would seem easily doable.
However, since WebVTT seems to define all layout/styling, it seems like
shoehorning it, and adding baggage that will be left unused. It is easy to
ignore the decoding of the Kate styling information though, as timing and
text were placed first to allow for simple text only decoders to work like this.
The category present in the header is also meant for decoders to know the
type/purpose of the stream, which would allow a player to know whether a
track is a WebVTT track or not.

> There would only be a few changes necessary:
> * WebVTT has a header which needs to be parsed and re-created.

While I haven't looked at it, it doesn't sound much different from, say,
LRC, which kateenc/katedec can import/export.

> * Also, there is a suggestion for inclusion of name-value Metadata at
> the top right after the header, which we'd want to retain (maybe in a
> header or a first packet).

The second header packets is a Vorbiscomment packet, which is used
for the same thing.

> * Then there are cue settings, which are position modifiers on each
> cue (segment of timed text). They need to be recreated, too.
> The marked-up text inside cues needs to be retrieved unchanged.

I don't know what these are, so I can't say offhand whether it would match.
I'll have a look at those in the URL you quoted.

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