Re: [TTML2] Issue-228: Ruby text support

On Thu, Sep 25, 2014 at 3:48 AM, Nigel Megitt <nigel.megitt@bbc.co.uk<mailto:nigel.megitt@bbc.co.uk>> wrote:
I've added the following review note to Issue-228:


Alignment with the proposed approach for Rubys in HTML5 has been achieved semantically but not syntactically with the current draft proposal.

That (syntactic equivalence) has never been a goal or a requirement for any TTML feature adopted from other specifications.

Agreed it's not a requirement or a goal, but it's certainly an option.


One of the impacts of this is that, in order to support Rubys, processors must also support #nested-span.

Correct. I don't see that as a problem.

Okay, others might, or might not – I've noted it because it's a subtlety that some might miss. Some profiles of TTML1 do not support #nested-span but may want to adopt Rubys, so it's possible that the chosen syntax would be problematic.

 Another is that an extra level of translation is needed to create an HTML5 equivalent ISD including Rubys.

What do you mean by "extra level"? I don't see any extra level: it would simply be part of the same single translation layer.

I mean that a converter would not be able simply to duplicate the elements but would need to have a mapping from TTML span to HTML 'destination element' that's dependent on the value of the style attributes, specifically for Rubys. That would be part of a general translation requirement that's already not a direct 1:1 element mapping; by choosing not to duplicate the HTML5 syntax we should recognise that we're not choosing the simplest possible translation scenario for this incremental feature, and we should understand the reasons why the chosen syntax is better in the context of TTML than the pre-existing HTML syntax.



Nigel