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Re: [WebVTT] It's not easy being green

From: David Singer <singer@apple.com>
Date: Tue, 17 Mar 2015 12:11:43 -0700
Cc: public-tt@w3.org
Message-id: <153BDD3C-BDEB-4F9E-A8BF-8F1366F2F0F7@apple.com>
To: Michael Dolan <mdolan@newtbt.com>
I think we already discussed this…

see thread starting <https://lists.w3.org/Archives/Public/public-texttracks/2014Mar/0031.html>

> On Mar 16, 2015, at 17:03 , Michael Dolan <mdolan@newtbt.com> wrote:
> I received an email from someone studying SMPTE-TT and WebVTT who wrote and presented a paper about 18 months ago titled, “'It's not easy being green - a closed captioning for web case study'”.  Among other things, he observed that we map CEA 608 “green” to SVG/CSS3 “green”.
> FYI, the SVG/CSS3 RGB value of “green” is 008000, not 00FF00 you might expect (which is the color “lime”):
> http://www.w3.org/TR/css3-color/#html4
> Note in contrast that “red” and “blue” are both full brightness.
> Of the various 608 mapping documents….SDP-US uses only RGB values (no color names) and explicitly defines “green” to be 00FF00.  However both SMPTE-TT (RP2052-10) and WebVTT say to map 608 “green” to TTML “green” which is minimally inconsistent with SDP-US. The same would be true for 708 mappings, of course.
> Of historical note, CSS1 says the color palette came from the “Windows VGA palette”, which seems to have come from the CGA text color palette:
> http://en.wikipedia.org/wiki/Color_Graphics_Adapter
> (although the above  defines the brighter green as “light green”).
> We could assume it is supposed to be maximum brightness like “red” and “blue” (i.e. 00FF00), but on the off chance that “green” text overlay is actually handled differently in the billion TV’s out there I’ll ask a couple of set manufacturers….
> Regards,
>                 Mike
> -------------------------
> Michael A DOLAN
> TBT, Inc. PO Box 190
> Del Mar, CA 92014
> (m) +1-858-882-7497

David Singer
Manager, Software Standards, Apple Inc.
Received on Tuesday, 17 March 2015 19:27:42 UTC

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