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[Bug 28257] [webvtt] start/end linked to left/right [I18N-ISSUE-422]

From: <bugzilla@jessica.w3.org>
Date: Tue, 16 Feb 2016 10:13:54 +0000
To: www-international@w3.org
Message-ID: <bug-28257-4285-AX6cPRerZx@http.www.w3.org/Bugs/Public/>

--- Comment #36 from Simon Pieters <simonp@opera.com> ---
(In reply to Silvia Pfeiffer from comment #35)
> Yeah, I think it has to stay where it would when it's LTR text. Basically,
> we're saying that LTR determines the box position. If you have RTL, you have
> to put explicit positioning on it with the offset.

I don't like baking in LTR semantics for this one thing when the rest of WebVTT
is agnostic to LTR vs RTL. I think we should either be *clearly* LTR-by-default
and require something explicit to opt into RTL semantics, or have *everything*
be agnostic about the direction. Going half-way seems like it would be
difficult to reason about what's going on.

> Yeah, it does seem unfair between LTR and RTL text. But maybe that's ok? I'd
> be curious about thoughts from actual RTL captioners!

WebVTT has clearly tried from the start to be agnostic about directionality.
Personally I'd like to maintain that, it seems like a missed opportunity for a
new format not to.

> I'd suggest moving it to the left. For a LTR box this is the natural thing
> to do and what captioners expect. This also covers the case where you're
> captioning in a LTR language and then add translations automatically. If the
> captioner instead starts captioning in RTL, the box is so obviously in the
> wrong position that they will probably explicitly position it anyway.

The last sentence is this bug exactly. :-)

> Leaving it centered is also wrong, too. For RTL text that is in a 50% box
> and start aligned, it should be positioned at the right edge if there was
> not the translation use case.

I'm not really convinced it's wrong. A cue can contain *both* LTR and RTL text,
on different lines. Which side is the correct one in such a case?

Also consider if we were to add align:justified. Then text is aligned on both
sides, regardless of directionality. Where should the box be?

Since center is the default, and there's no clear right answer, I still think
center is the best choice. It might not be what the captioner wants, but it's
not like it can't be set to something else. This is a heuristic to give a
useful default, but we don't need to apply the heuristic for everything; we can
avoid applying for ambiguous cases (like align:start).

> 'align:start' still makes the text inside the box align correctly. It's just
> the box position that is confusing.


> > Bidi is confusing as it is, we shouldn't make
> > it worse.
> Yeah, I worry about that, too.
> Alternatively, we could ignore the translation use case and say that if you
> have intended to explicitly position the box on the left, you have to put a
> 'position:0%' on it, too, otherwise the box might move if the text
> directionality changes. A validator could even raise a warning in this case.

I think if we want captioners to explicitly position their boxes, it is better
to let the default position be center for all alignment values. Having
heuristics and then advice against using it makes little sense to me.
Translations seems like a very common use case, and sometimes it will be
automated; if we go this route I would expect the net result will be that users
see translated subtitles where the cues' positions are on the opposite side.

I could live with dropping the heuristic completely and always having center
position by default, if it's confusing that align:left and align:start have
different positions.

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Received on Tuesday, 16 February 2016 10:13:57 UTC

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