W3C home > Mailing lists > Public > public-texttracks@w3.org > September 2012

Re: Yet Another Scroll-Up Idea (YASUI) in VTT

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Fri, 21 Sep 2012 11:25:12 +1000
Message-ID: <CAHp8n2nmB8a3kJwBp_-VPyzvWQJGeM4qBD1KxHW7gip_gV-A0A@mail.gmail.com>
To: Simon Pieters <simonp@opera.com>
Cc: public-texttracks <public-texttracks@w3.org>, David Singer <singer@apple.com>
On Fri, Sep 7, 2012 at 8:02 AM, Simon Pieters <simonp@opera.com> wrote:
> On Thu, 06 Sep 2012 23:02:20 +0200, David Singer <singer@apple.com> wrote:
>>> CSS allows several selectors per ruleset.
>>> ::cue-region(#foo), ::cue-region(#bar) { background:blue }
>> I think I am failing to explain myself.  I need it to be possible that
>> there is a 'general purpose' spreadsheet that defines "this style gives you
>> a window with a red fill color", "this style gives you a window with a blue
>> fill color" and so on, and then be able to apply those styles to regions,
>> and that two distinct regions with the same fill color have distinct names,
>> Why?  That general-purpose stylesheet can be embedded, in effect, in UAs
>> that don't implement CSS, so that it can be used -- just like the red text
>> in the example here
>> http://www.w3.org/community/texttracks/wiki/608_to_WebVTT#4._CHARACTER_STYLE_CONVERSION
> Woah! I was unaware of that wiki page.

It's  a bit outdated and replaced by
 now. I have emailed the group about this before and asked if it can
become part of what we're working on.

> Why can't such UAs just support the subset of CSS that they want to support,
> like 'color' and 'background-color'? WebVTT already subsets which CSS
> properties apply, so full CSS support is not needed for WebVTT. Sure, you
> need a CSS parser, but that's pretty easy and even has a state machine
> tokenizer and parser spec now. http://dev.w3.org/csswg/css3-syntax/

That spec was created for offline players in particular. The default
CSS style sheet is not one that I would bake into the browsers, but
one that I would supply the browser with when given a WebVTT file that
uses 608 features. Thus, from the browser's point of view nothing

>>> I imagine the scrolling mechanism and the WebVTT positioning rules would
>>> have a messy interaction. It would also mean we can't use CSS rules for
>>> laying out the cues within the region, thus maybe can't use CSS transitions.
>> I don't follow you at all here.  What I suggest seems pretty much like
>> laying out nested divs, doesn't it, and then putting text into those divs?
> The WebVTT rendering rules don't really work like "divs" at all.
> The rendering rules do things like avoid overlapping. What happens if a
> rollup cue and a positioned cue within a region overlap?

The browser should just let that happen it's the responsibility of the
author to deal with that. If they intended them to overlap, then so be

Received on Friday, 21 September 2012 01:26:00 UTC

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