[whatwg] Introduction of media accessibility features

Silvia Pfeiffer silviapfeiffer1 at gmail.com
Wed Apr 14 21:00:06 PDT 2010

On Thu, Apr 15, 2010 at 1:08 PM, Jonas Sicking <jonas at sicking.cc> wrote:
> On Wed, Apr 14, 2010 at 5:59 PM, Silvia Pfeiffer
> <silviapfeiffer1 at gmail.com> wrote:
>> On Thu, Apr 15, 2010 at 3:19 AM, Tab Atkins Jr. <jackalmage at gmail.com> wrote:
>> If TTML creates specs that cannot be mapped, then those are ignored.
>> All we are basically committing to would be that a best effort is done
>> on the mapping. Just like with SRT we would do a best effort on the
>> mapping - there are SRT files now that have more than just plain text
>> in them. But we would not commit to interpreting every special markup
>> that some author came up with that worked in his particular player.
>> I think the dependencies between external timed text formats and HTML5
>> are much less than e.g. the dependency on SVG. TTML is not supposed to
>> be a native Web format in my eyes. It is just interpreted for the Web.
> I'm not sure I understand what you mean by "TTML is not supposed to be
> a native Web format"? Once browsers add support for it, it becomes a
> native web format.

Would you call SRT a native Web format, too? Are RSS and ATOM native
Web formats?

> No matter if the implementation behind the scenes
> map xsl:fo to CSS or through some other means. Netscape 4 implemented
> CSS by mapping it to JSSS [1], however for all any web developer ever
> knew, Netscape 4 supported CSS. Poorly.

CSS is much tighter linked to HTML than a timed text format. If your
UA happens to not support TTML, only one feature will be missing, i.e.
timed text on your video. That doesn't destroy your Web page. But lack
of CSS support does.

> I really do hate to come up with a new format. But I think TTML is
> severely off the mark for what we want. Am I wrong in that marking up
> dialogue vs. sound effects vs. narrator vs. descriptions is important?
> Or at least more useful than for example the ability to set the text
> outline blur radius?

I don't think your requirement is off the mark. I think it is
something that current caption formats don't do, since there hasn't
been a need and nobody has really looked at them from a Web
background. Therefore it wasn't included in TTML. I also have multiple
requirements that are not satisfied by TTML. I was under the
impression that we can fix up TTML with such extensions. But if people
prefer to develop a new format, that's fine by me.

That doesn't mean though that we can ignore TTML. For what it has been
developed - for use in captions in all sorts of environment, which
include for example digital TV and mobile devices - it has been good
and its use is spreading.


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