Re: CEA-608/708 and WebVTT

On Thu, Aug 30, 2012 at 9:39 AM, David Singer <singer@apple.com> wrote:
> Silvia
>
> thanks for taking the lead on starting this.

Note that the up-to-date spec is at
http://dvcs.w3.org/hg/text-tracks/raw-file/default/608toVTT/608toVTT.html
.

>  I think making it a CG document makes a lot of sense, and unless someone objects (I can't think why), we should take it on.  You should also indicate when you're ready to have others contribute and help.

At any time. We could even ask for a separate component to be opened
in the bug tracker if that helps.

I've already received feedback that the spec didn't adhere to the
proposed format for headers, so I recently changed that.

And just now I adapted the referencing of external stylesheets to the
way proposed in bug
https://www.w3.org/Bugs/Public/show_bug.cgi?id=18530.


> Some points:
>
> Suggest we define some styles that are clearly 608/708 specific with names that clue us in to that (e.g. s708 for Style from 708, or CEAx08, or somesuch).
>
> In that vein, how about s708cXYZ, where X, Y and Z are 0 thru 3, for the CEA 708 64 standard colors?  We should also have names for the 8 named colors (R G B, C M Y and L, and White).

The named CEA608 colors have been given class names and are
identifiable: .red, .green, .blue etc.
Are you suggesting a different approach?

As for the cEA708 colors, yes, I think that makes sense.


> The biggest issue I see is that 708 has the concept of 'windows' -- rectangular areas into which text gets painted.  We can land text in the right place, I think, but 708 has *3* colors -- the window, the text background, and the text foreground.  I don't see a way to identify the rectangular region to paint with the window color, in WebVTT, right now.  The 'size' and 'position' on a cue effectively define the left/right extent, but we don't have a line-range, just a line number.  (I am researching when the window gets painted with that color in 708.)

That is a fundamental problem of WebVTT - you should register a bug on
this. I don't think we can solve this for the 708 spec until we
introduce the concept of a "window" (or "cue box").


> Your example of metadata in the file header uses key=value, and though I originally suggested key=value, Ian and you both proposed key: value, and that's what's in the most recent write-ups. Suggest we change the example to use colons.

Agreed. I had changed that recently, but the link only pointed to the
very first commit. Check out the new link given above.


> More as I see it, but thanks for catalyzing this important work!

No worries. We need to move forward - the lack of common caption
features in WebVTT is causing me massive headaches.

Cheers,
Silvia.

Received on Thursday, 30 August 2012 01:02:26 UTC