Re: VTT/CSS (was RE: Evidence of 'Wide Review' needed for VTT)

On Wednesday, January 21, 2015, Simon Pieters <simonp@opera.com> wrote:

> On Wed, 21 Jan 2015 17:27:25 +0100, Jeroen Wijering <jeroen@jwplayer.com>
> wrote:
>
>  Hey David, John,
>>
>>  when you say inline CSS, you mean both of
>>>> a) style-sheets in the header?
>>>> b) styling in the cues themselves, using CSS snippets?
>>>>
>>>> Have you looked at the old threads on this question?  I think we got
>>>> close to a number of possible designs, but held off until it was really
>>>> needed and we had real implementers on hand.
>>>>
>>>
>> Style rules in the header are most important IMO. They allow CC
>> authors to style:
>>
>> *) All cues in a VTT
>> *) Specific cues (using classes or ids)
>> *) Specific persons or snippets (using voices or ids)
>>
>> I see inline styling as largely redundant to styling rules in the
>> header (most can be achieved with classes, id's and voices).
>>
>>  This should be achievable through UA configuration or even through
>>> something
>>> like a greasemonkey script or user CSS which can override styles
>>> dynamically
>>> in the browser."
>>> (source: Media Accessibility User Requirements -
>>> http://www.w3.org/WAI/PF/media-a11y-reqs/#VP-2)
>>>
>>> From a practical perspective, it is significantly easier for third
>>> parties to
>>> write scripts and/or user style-sheets if the content is all located in
>>> one-place. For this reason, I would suggest that CSS be contained in a
>>> linked
>>> style sheet, and *NOT* written in-line in the VTT file.
>>>
>>
>> This is absolutely important, but I also see this also as a separate
>> step. Overall there seem to be 3 tiers:
>>
>> First, there's the styling rules from the environment (HTML5 browser),
>> which apply to all VTT files played. They're the baseline. General use
>> cases are to make the captions look good and read well within the
>> site/player design.
>>
>> Second, there's the styling from the VTT author, which apply to only
>> that single file. Use cases include emphasis on certain types of cues
>> (music, voiceover, etc) and certain ranges of cues (e.g. repositioning
>> when the default region overlaps with in-video text).
>>
>
> VTT doesn't allow CSS to reposition cues, other than by changing the
> line-height.
>
>  It's preferred
>> to have these rules live inside the VTT, as it makes for easier
>> authoring, file management, conversion to other formats and
>> implementation of parsers (outside of HTML browsers).
>>
>> Third, the end user can override the styles an author has set (or,
>> more common, set additional rules). This is specific to the individual
>> user and relates to the FCC options end users can set in video
>> players. As David said, through CSS but more importantly system-wide
>> menus (iOS/Android/etc) or options in the video player
>> (YouTube/JWPlayer/etc).
>>
>> In short, style rules in the header of a VTT file is what we (our
>> publishers) would like to have. Styling rules inside the cues and
>> links to external CSS are less relevant.
>>
>
> CSS can link to external CSS with @import, so VTT doesn't need a dedicated
> mechanism for that.


This does not solve the problem of keeping all of the authored information
in a single file. I agree with Jeroen on the desirability of style rules in
the header.

Loretta Guarino Reid
Google


> --
> Simon Pieters
> Opera Software
>
>

Received on Thursday, 22 January 2015 06:17:09 UTC