RE: Timed tracks

Tab Atkins Jr. wrote:
>
> SRT is the closest-to-ideal existing format,

Tab, with all due respect, what documented facts is this bold assertion 
based upon? <em>URLs would be most appreciated here, as the Media Sub-Group 
are assembling a needs requirement document at this time.</em>

As co-chair of the Media Sub-Group at the W3C Accessibility Task Force for 
HTML5, active participants (including, significantly, engineers from the 
related browser manufacturers) have been discussing Time Text formats for 
some time now, and a recent survey (2010-03-08 to 2010-03-11) of the larger 
a11y Task Force showed almost equal support for the minimal SRT format as 
well as a more robust format, likely DFXP/TTML and/or a profile of that.
- http://www.w3.org/2002/09/wbs/44061/media-text-format/results

The general consensus (and others are free to correct me) was that SRT was 
at best a minimal time-stamp format that could be used, but that it did not 
meet the 'robustness' test for all aspect of accessibility. Suggesting that 
it is the "closest-to-ideal" is pure folly and opinion at this time, and 
does not accurately reflect the opinion of those who are working closely at 
this subject (again, including engineers from Microsoft, Apple, Opera and 
Mozilla directly involved with <video> implementation in the browsers). In 
fact, Maciej himself suggested (in his survey response): "I don't think it's 
necessary to require a specific format for the initial proposal. It seems 
like requiring any one format will just make it more controversial."

Cue: Enter controversy...


> Even if were to just
> say "All right, we're just doing TTML", it would require us to still
> produce a spec explaining how TTML's layout primitives should be
> interpreted.  Potentially, of course, browsers could just implement
> XSL:FO directly, but initial feedback indicates that that's not an
> option they're willing to support.  So we'd have to define how all of
> that maps into CSS, which would be as much or more work.

And those types of discussions are on-going within the W3C Task Force 
charged with that requirement. As Matt May (and others) have pointed out 
(http://lists.w3.org/Archives/Public/public-html-a11y/2010Mar/0102.html), 
mapping the basic start and end times of any time-stamped document to a 
basic DFXP profile is not only quite easy, but significantly such a profile 
currently exists: 
http://www.w3.org/TR/ttaf1-dfxp/#profile-dfxp-presentation.

That DFXP profile (it should be noted) is also already supported by 
Flash-based video players such as JW-FLV (arguably the most widely deployed 
Open Source media player on the web today - http://longtailvideo.com), 
NCAM's CCforFlash player (http://ncam.wgbh.org/webaccess/ccforflash/) and 
Nomensa's Accessible Media Player 
(http://www.nomensa.com/web-accessibility/what-we-do/accessible-media-player). 
DFXP also has support within Silverlight-based media players which suggests 
that there is also existing DFXP content in the wild today.

Further, authoring tools already exist to create these DFXP time-stamp files 
today: For small and independent authors there is MAGpie* 
(http://ncam.wgbh.org/invent_build/web_multimedia/tools-guidelines/magpie) 
amongst others, and significantly, the Broadcast Industry is also creating 
tools to generate DFXP 
(http://broadcastengineering.com/automation/ninsight-unveils-dfxp-subtitling-mxf-ayoto-0901/)
Given that this class of content producer is likely going to be 
front-runners in captioned video on the web (especially if legislative 
initiatives such as H.R. 3101 - 
http://www.govtrack.us/congress/bill.xpd?bill=h111-3101 - come to fruition) 
I am curious to know if they were consulted on this new WebSRT format?

(*Funding for MAGpie was provided in part by the National Institute on 
Disability and Rehabilitation Research (NIDRR), the U.S. Department of 
Education, and the Mitsubishi Electric America Foundation)



Continue to expect significant and vocal opposition to this newly 
re-invented Time-stamp wheel, which apparently sprang to life earlier this 
week from the editor of the WHAT WG, as a complete and total surprise to 
Media Captioning experts and Accessibility specialists of all stripes within 
the W3C (such as Geoff, who's years of involvement within NCAM/WGBH - the 
'inventors' of captioning for television "video media" - carries significant 
weight, research and experience when it comes to understanding both user 
requirements, as well as an understanding of implementation issues).

JF

Received on Thursday, 6 May 2010 21:25:37 UTC