Re: Proposed extension to HTML5.1 for rollup captions

Hi Glenn,

On Thu, Feb 21, 2013 at 9:52 AM, Glenn Adams <glenn@skynav.com> wrote:

>
> On Wed, Feb 20, 2013 at 1:46 PM, Travis Leithead <
> travis.leithead@microsoft.com> wrote:
>
>> > From: Silvia Pfeiffer [mailto:silviapfeiffer1@gmail.com]
>> >
>> > I'm looking for feedback on this feature here. If there are no
>> objections
>> > and sufficient support for these features, I suggest adding them to the
>> > HTML5.1 specification.
>>
>> I'm very cautious about immediately merging this feature back into
>> HTML5.1. I believe the best course of action is to keep this feature
>> separate from the HTML5.1 spec (as a stand-alone document) as it allows
>> easier review, as well as time to get consensus and develop the proposal
>> based on feedback.
>>
>> Given that there is some time elapsed between now and when you can get
>> sufficient support, then I don't object to merging it in. I would prefer to
>> have at least a month or two to have time to gather all the right people
>> together, perform the review, summarize and submit (and have time for you
>> to incorporate any feedback).
>>
>> Finally, just a quick "thank you" for putting this together. I really
>> like that extension specs are starting to be developed and I want to
>> encourage folks to continue to submit these and get them started as
>> reviewable documents.
>>
>
> A few questions of clarification:
>
>    - does this rollup caption extension depend on
>    https://dvcs.w3.org/hg/text-tracks/raw-file/default/608toVTT/region.html? if the answer is yes, then these TextTrackRegion interface extensions
>    need to be renamed to WebVTTTextTrackRegion or otherwise made more generic
>    to accommodate use of TTML instead of WebVTT
>
>
No, they don't depend on WebVTT. It's a generic concept that builds on
CEA708 windows and should thus similarly be able to present TTML rollup
captions.


>
>    - does the mechanisms defined as extensions to the current HTML5
>    TextTrack and related interface types take into account use of TTML instead
>    of WebVTT? if the answer is no, then it should be reviewed and modified as
>    needed to permit use of TTML as well, or at least support future
>    integration with TTML
>
>
Yes, it does just as much as TextTrackCue also permits use of TTML. I
actually mentioned that in my email, but maybe not explicitly enough.


>
> Overall, we need to keep in mind that TTML will be used by commercial
> video content providers for captioning HTML5 media elements, and any
> features defined to support TextTracks needs to separate generic
> functionality|usage from text track format specific functionality|usage.
>

Exactly. Which is why we have defined a mechanism that closely matches the
existing CEA708 window concept.

HTH.

Regards,
Silvia.