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

From: John Foliot <john@foliot.ca>
Date: Wed, 21 Jan 2015 08:56:48 -0800
To: "'Jeroen Wijering'" <jeroen@jwplayer.com>
Cc: "'David Singer'" <singer@apple.com>, "'Steve Heffernan'" <steve@zencoder.com>, "'John Luther'" <jluther@jwplayer.com>, <philipj@opera.com>, <public-texttracks@w3.org>, "'Richard Eyre'" <rick.eyre@hotmail.com>, "'Gary Katsevman'" <gkatsevman@brightcove.com>, <w3c-wai-gl@w3.org>, "'HTML A11Y TF Public'" <public-html-a11y@w3.org>
Message-ID: <01f601d0359b$3fb405f0$bf1c11d0$@ca>
Jeroen Wijering wrote:
> 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).


As authoring guidance (and I will ensure that the WCAG WG is brought into the 
loop) large organizations *could* (RFC 2119 MAY) provide information about 
those (reusable) classes as part of their larger site's "Accessibility Info" 
documentation, so that for those users who need/want to author custom CSS 
style sheets, they have the 'hooks' provided to them.

> > 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.

+1  Modifications at this level SHOULD be handled via UA user-settings. 
Question: should this be conveyed in the VTT spec, or elsewhere? David? 

> 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). 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).

Scenarios 2 & 3 SHOULD be modifiable by the end user. The means to make these 
modifications would likely best be integrated with the 'player', but could 
also be achieved through user style-sheets. However, given the complexity of 
creating user style-sheets, good players should offer a simpler means of 
making some basic changes (I am thinking, for example of font size, font-face, 
foreground and background colors as the most basic sub-set). While I can 
follow up with the appropriate WAI groups (likely WCAG WG and UAAG WG - the 
User Agent Accessibility Guidelines WG) I wonder again out loud whether this 
type of basic authoring guidance should be provided in the VTT spec itself. If 
there is a general feeling that this isn't a bad idea, David I would be 
willing to try my hand on a first-pass paragraph or two as non-normative 
content for the spec. Thoughts?

> 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.

Thanks Jeroen, I think that a consistent approach to providing styling 
information will be critical, and this approach seems quite workable to me 
(for whatever that's worth LOL).


Received on Wednesday, 21 January 2015 16:57:29 UTC

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