Re: Timed tracks

<chair hat off>

On May 6, 2010, at 3:01 PM, Sean Hayes wrote:

> When TTML was being defined, XSL:FO was ahead. And a lot of the CSS3  
> work was either in a very rough state or not there at all.
> When CSS3 gets a little more mature, in say 10 years. Then TTML  
> could migrate to it

TTML most recently went to CR in February of this year, first went to  
CR in 2006, and went FPWD in 2004. At which of those dates was XSL:FO  
ahead?

> But to be clear, TTML is *defined* in terms of the semantics of  
> XSL:FO, which is *defined* largely in terms of CSS; but it is its  
> own thing, and it does not require either a full XSL:FO processor or  
> a CSS one.

The implementation challenge is correctly implementing enough of the  
XSL:FO layout semantics to correctly process TTML. Standards experts  
will be *extremely* picky about whether the layout behavior in a  
browser precisely matches the spec, in a way they likely are not for  
uses of TTML in non-web contexts. There isn't really room to fudge it.

It's also incorrect to say that XSL:FO is trivially mappable to CSS.  
There are some shared styling properties, but they have subtly  
different definitions, and the fundamental layout model is different.

Regards,
Maciej

Received on Thursday, 6 May 2010 22:13:21 UTC