Add informative note to tts:fontStyle recommending use of tts:shear instead of tts:fontStyle="italic" for Japanese text.

w3c / imsc

TTML Profiles for Internet Media Subtitles and Captions (IMSC)

https://w3c.github.io/imsc/

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Add informative note to tts:fontStyle recommending use of tts:shear instead of tts:fontStyle="italic" for Japanese text. #495

Closed jmccrossan-fox closed 4 years ago

jmccrossan-fox commented 5 years ago

Per CSS

"italic" selects a particular version of the font, which might not exist.
when an "italic" version of the font does not exist, CSS silently converts "italic" to "oblique", which, by default, maps to a recommended shear of 14 deg.

Many Japanese fonts do not have an "italic" version.

Consider adding an informative note in the definition of tts:fontStyle highlighting the above and recommending that, to avoid indeterministic results, the content author specify tts:shear on Japanese text instead of tts:fontStyle="italic".

nigelmegitt commented 5 years ago

@jmccrossan-fox Thank you for raising this issue!

skynavga commented 5 years ago

To date, we have not made stylistic recommendations in TTML2; nor have we singled out treatment of content from specific languages. Rather, we have defined features that are useful across a range of languages usage. Finally, suggesting the use of just tts:shear is problematic, since it doesn't apply to span, which is what tts:fontStyle applies to. So overall, I am opposed to this suggestion, both in general and in its particulars.

skynavga commented 5 years ago

I should add that it is the responsibility of the content author to select fonts that correspond to the styles they employ, and that, if they want to specify an "italic" form of a CJK font, then they are free to do so. They can always embed the font directly or reference it as an external resource using the font element.

palemieux commented 5 years ago

@cconcolato Any input on italic vs oblique vs shear?

skynavga commented 5 years ago

I would not object to moving this issue to IMSC, which does have precedent for making author recommendations. Also, as a point of note, CAP2TT [1] maps inline shear to oblique style when generating imsc11 output from Lambda CAP (a popular Japanese subtitle format) since imsc11 does not support tts:fontShear.

[1] https://github.com/skynav/ttt/issues/239

palemieux commented 5 years ago

Also, as a point of note, CAP2TT [1] maps inline shear to oblique style when generating imsc11 output from Lambda CAP (a popular Japanese subtitle format) since imsc11 does not support tts:fontShear.

Presumably tts:shear could be used if "oblique" is applied to all text within a paragraph, including ruby text.

skynavga commented 5 years ago

@palemieux yes, in Lambda CAP, one can apply 斜め (i.e., obliquing) with a specified angle to either (1) a "screen" (= paragraph in TTML) or (2) inline text (= span in TTML); CAP2TT translates the former to tts:shear and the latter to tts:style='oblique' when generating imsc11 output; for ttml2 output, it translates both to tts:fontShear;

cconcolato commented 5 years ago

I'm fine with adding the note to IMSC.

cconcolato commented 5 years ago

@palemieux would you be ok moving this issue to IMSC?

skynavga commented 5 years ago

Do we have consensus to move it? If so, then one of the editors can do the mechanics of the move.

nigelmegitt commented 5 years ago

@skynavga I think we have consensus, but I haven't tested that yet. Will add to agenda for this week, and we can action it after then if need be.

nigelmegitt commented 5 years ago

Since it is unclear looking at the thread, I'm noting that this issue arrived in this repository after being transferred from ttml2, with TTWG consensus.