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Re: Timed tracks

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Thu, 6 May 2010 15:35:15 -0700
Message-ID: <o2wdd0fbad1005061535y41b4efcete8a15b579c51a913@mail.gmail.com>
To: Frank Olivier <franko@microsoft.com>
Cc: Geoff Freed <geoff_freed@wgbh.org>, Maciej Stachowiak <mjs@apple.com>, Philippe Le Hegaret <plh@w3.org>, "Edward O'Connor" <hober0@gmail.com>, Ian Hickson <ian@hixie.ch>, "public-html@w3.org" <public-html@w3.org>
On Thu, May 6, 2010 at 3:02 PM, Frank Olivier <franko@microsoft.com> wrote:
> " Flash and Silverlight aren't concerned with being interoperable.  They can rely on hacking something together that works well enough.  The open web works somewhat differently."
> I'll rewrite my point...
> Some existing web runtimes* use TTML. XSL:FO is not in those web runtimes. People who author web experiences using those web runtimes seem to be able to create something that meets their needs with that level of TTML support. We should learn from that.
> *Those-plugins-who-must-not-be-named ;)

I'm not actually meaning to disparage the plugins here.  ^_^  What I
mean is exactly what I said, though - people aren't going to care that
Flash and Silverlight don't treat the same files precisely the same.
They just use whichever one they happen to care about, tweak the file
until it works sufficiently, and then deploy on the plugin across all
platforms that support it.  It's nearly the same problem that people
have changing their mental outlook from desktop applications to
webapps.  In desktop apps, you're in a place where strict parsing is
okay and versioning works ok because you only care about the version
of the tools that you personally are using, and you just compile to a
fairly agnostic machine code.  Whereas in webapps, the user is the one
who's tools matter, and so you need to design the ecosystem in such a
way that is tolerant to "errors" (because future changes are errors to
yesterday's tools) and limits versioning (because data never really
disappears, so every version has to be supported forever).

The analogy is very similar here.  When you're targetting a single
runtime like Flash, you can depend on everyone working similarly.
Thus, the Flash creators don't actually have to support XSL:FO or
similar; they can just create some ad hoc "good enough" mapping.
Silverlight can do the same thing for itself.  If anyone were to
migrate from Flash to Silverlight, they might have problems, but that
is rare enough that it's not an important deal for either plugin.

On the open web, though, you can't target a single runtime, and you
have no control over what your users will use to receive your data.
So you have to make sure that everyone supports everything in the same
way, which is a ton more work.

So, that's why the fact that some plugins support TTML without XSL:FO
isn't necessarily relevant to the discussion at hand.  ^_^

Received on Thursday, 6 May 2010 22:36:11 UTC

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