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


--- Comment #38 from Simon Pieters <simonp@opera.com> ---
(In reply to Silvia Pfeiffer from comment #37)
> Yeah, I tend to agree. Maybe here consistency should go ahead of the
> translation use case. If a box is not expected to move, it has to be
> explicitly positioned.

> That's a third use case: LTR, RTL, and then mixed. If it was just RTL, right
> edge alignment would be correct.
> Mixed text with 'align:start' is Example 15 and we haven't really made an
> example for when the size is restricted also. I guess mixed text should be
> center aligned.

OK... I'm not sure it's great to have the position change depending on the text
in the cue. It would make the cues jump around if streaming pop-on is supported
(which can be done today with the DOM API).

Since mixed directionality is presumably very rare, it also seems bad to add
complexity to handle it (recording the base direction of all lines and have
that influence the positioning).

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


> Only for mixed directionality. I think for purely RTL, center is as wrong as
> for purely LTR.


> Not advising against them. Only advising that in one particular case they
> have to be careful that it has the expected consequence.
> > 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.
> We are optimising for a small part of the translation problem though: one
> where we have 'align:start' and LTR text initially and then RTL text after
> translation.


> As a consequence of optimising for this, we are making the default rendering
> of the common "align:left/right size:50%" case very confusing and forcing
> extra markup onto it:
> * "align:left size:50% position:0%" or
> * "align:right size:50% position:100%".

Right, I agree it would be good to keep the heuristic for align:left and

> This is in contrast to merely adding position to the 'align:start/end' case
> like this:
> * "align:start size:50% position:0%"
> * "align:end size:50% position:100%"
> If we keep the heuristic, we could even go as far as requiring 'position' to
> be added when 'align:start/end' is used - at least then there's a
> conformance error and we require explicit expression of intent by the
> captioner.

How do you feel about align:start and align:end having center position by
default and have an authoring conformance requirement that the position setting
must be present when align:start/align:end? (And keep the heuristic for

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Received on Tuesday, 16 February 2016 13:29:42 UTC