[Bug 24129] [WebVTT] Support for bidi

https://www.w3.org/Bugs/Public/show_bug.cgi?id=24129

Martin Dürst <duerst@it.aoyama.ac.jp> changed:

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--- Comment #2 from Martin Dürst <duerst@it.aoyama.ac.jp> ---
(In reply to Silvia Pfeiffer from comment #1)

Hello Silvia,

> Also, we don't actually
> want to repeat the full set of HTML bidi markup in WebVTT, but only do as
> little as absolutely necessary given that we always have a UTF-8 document.
> 
> Given this background, what directional controls are you missing in VTT?
> 
> I was under the impression that Unicode covered all features that bidi text
> requires, seeing as it is used for much more than just HTML. If people are
> capable of creating fully functional bidi documents with using only Unicode,
> I don't think we need to replicate any Unicode functionality with duplicated
> markup.

Let me give you some historical background. The spec that introduced bidi
markup in HTML is RFC 2070 ("Internationalization of the Hypertext Markup
Language" http://tools.ietf.org/search/rfc2070). As one of its authors, I can
tell you with confidence that when we worked on it, questions like the above
were exactly what we considered. (Bidi features have been significantly
increased in Unicode 6.3, but essentially stayed the same before that since way
before 1997.)

What we realized when working on RFC 2070, and what has stood the test of time
since then, is that there is a strong correlation between document structure
and bidi structure. Using Unicode bidi controls in a markup language obscures
this correlation and complicates things. Making bidi controls available in
markup (i.e. HTML and WebVTT) exposes and strengthens this relationship.

As simple examples, bidi embeddings (and the newer isolates) usually correlate
with changes in language, quotations, changes in emphasis or other style
changes, and so on.

So indeed Unicode bidi control characters and HTML bidi controls cover the same
features, but from a markup point of view, the Unicode bidi controls are just
there for cases where markup isn't available, and definitely not the solution
of choice if markup is available.

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Received on Monday, 23 December 2013 07:16:05 UTC