- From: David Singer <singer@apple.com>
- Date: Tue, 29 Nov 2011 18:05:45 +0100
- To: Christian Vogler <christian.vogler@gallaudet.edu>
- Cc: public-texttracks@w3.org
At the moment, I can't think of a way of doing even jump-scroll without repeating text, unless (as is very likely) I am being dense. Maybe someone could correct me if the best practice on jump-scroll is something other than repeat? On Nov 29, 2011, at 17:40 , Christian Vogler wrote: > This is not quite true if the text is duplicated in the WebVTT file. > This would present serious accessibility issues for people who use > screenreaders (and that includes the deaf-blind population). It also > would make searching and indexing harder if text were duplicated. > > Christian > > On Tue, Nov 29, 2011 at 11:33 AM, David Singer <singer@apple.com> wrote: >> I think a fundamental question that needs addressing is whether we expect roll-up to be (a) 'part of' the core VTT vocabulary or (b) a presentational issue that is 'optional'? >> >> I tend to think the latter. Yes, maybe smooth roll-up is easier on the eye than jump-scroll, but the same information is presented. >> >> If that is the case, I think using CSS transitions is a good candidate. Alas, we don't use CSS positioning (for obvious reasons -- positioning DOES have to be part of the core of VTT). But that doesn't hose us. >> >> Consider a stream that has Line1, Line2, …. LineN, showing in a three-line area. A simple way to jump scroll that is simply to repeat each line, every time it 'moves' in the 3-line display. >> >> <blank> >> <blank> >> Line1 >> >> then >> >> <blank> >> Line1 >> Line2 >> >> Line1 >> Line2 >> Line3 >> >> Line2 >> Line3 >> Line4 >> >> displayed simply, the lines appear to jump. >> >> If we can convince the CSS engine that Line1 in the first cue is the same as Line1 in the second, we could ask for a transition on, say, 'y'. That's pretty easy to do with markup -- if a line of text in two consecutive cues has the same marked-id, then it's the same, and any CS transitions declared on its class apply, if you use CSS. >> >> Saying CSS transitions can be used to smooth out display transitions also allows for fade-in/fade-out (transition on color), and so on. >> >> >> David Singer >> Multimedia and Software Standards, Apple Inc. >> >> > > > > -- > Christian Vogler, PhD > Director, Technology Access Program > Department of Communication Studies > SLCC 1116 > Gallaudet University > http://tap.gallaudet.edu/ > VP: 202-250-2795 David Singer Multimedia and Software Standards, Apple Inc.
Received on Tuesday, 29 November 2011 17:06:18 UTC