RE: Right usage of TTML for video

Indeed and the links you cite are so called polyfills using client side script to emulate the <track> and <video> elements for browsers that don’t support them and wrap up plugins for the video where that is not supported. It was written against a slightly earlier version of the HTML specification, and so there may be changes required.

From: Glenn Adams [mailto:glenn@skynav.com]
Sent: 24 June 2013 14:28
To: Eunice Yu
Cc: public-tt
Subject: Re: Right usage of TTML for video


On Mon, Jun 24, 2013 at 4:42 PM, Eunice Yu <yonhee.yu@gmail.com<mailto:yonhee.yu@gmail.com>> wrote:
Hello people.
I'm very new to TTML and FCC regularion brought me here. after short surveying, still very confused about how to deal with TTML in modern browser implementation.

I can see several links which seem to demonstrate TTML.
http://www.cwmwenallt.com/ttml/ttml-demo.htm

http://www.html5labs.com/HTML5CaptionDemo/


and they are all something like using track element.

<video width="640" height="480" controls>
  <source src="video.mp4" type="video/mp4" />
  <track src="ttml.xml" kind="subtitles"srclang="en" label="English" />
</video>

this is correct on the surface syntax, the real issue is whether the browser directly supports rendering TTML or not; some do, some don't; it is sort of like SVG, at one point, many browsers didn't support SVG format directly, but now most do, at least on desktop browsers

there is some work afoot to add TTML support to some of the browsers that don't support it today, so I expect the level of support to improve over time; in the mean time, you may find it necessary to use client side scripting to parse TTML into HTML/CSS for rendering purposes on the browsers that don't yet support it;


but I am not sure if that is right implementation based on current standard. if it is, it's wired that track does not have mime type. and if it's not, I don't see any HTML element who requires TTML as text subtitles.

this is similar to the <video/> and <img/> elements that similarly don't require support for any specific video or image format; the <track/> element doesn't dictate which text track formats are to be supported either;


so my question is where web developers are suppose to put TTML and on which element should browser work to make it happen?

on second thought, javascript can request and parse specific xml(TTML here) and display them being styled somewhere on the web page. can I say TTML is only for this?

Any comments would be very helpful.

Thank you in advance.
Eunice