Re: Conversion of 608/708 captions to WebVTT - how to map the colour green

On Thu, Mar 27, 2014 at 4:40 AM, David Singer <singer@apple.com> wrote:
> Thanks Michael

Ineed! Thanks for digging into this!


> yes, you are right, we should map to colors of the same or close chromaticity.  I think we weren't thinking straight when we wrote that.

Thanks - that had nothing to do with thinking straight. ;-)
I merely wasn't aware of the color issues and CSS colors seemed to be
the most direct mapping. So let's fix it.


>  We probably need a table of the named colors in 608 and their matching CSS colors.

That is codified in
https://dvcs.w3.org/hg/text-tracks/raw-file/default/608toVTT/608toVTT.html#browsers.

However, I would appreciate any patches to this listing.

Michael: Is green the only color with problems or are any of the other
colors problematic, too?

These are the relevant rules:

::cue(c.green) {
  color: green;
}

::cue(c.bg_green) {
  background-color: green;
}

What should we change them to? You're suggesting "lime", but it's
possible to pick any CSS color spec, so if there is anything more
appropriate than "lime" please provide that code.

Also, if you have any other suggestions of improvement, do share! It's
a wiki and easy to change at this point!

Cheers,
Silvia.



> We could really do with moving this document along; it sounds as if you have direct experience with the conversion of 608.  Are there other areas of the document you can suggest changes to?
>
>
> On Mar 24, 2014, at 18:16 , Michael Borthwick <mb@michaelborthwick.com.au> wrote:
>
>> Dear List Members,
>>
>> I am Australian media engineer who wrote a technical paper, presented last year at the SMPTE 2013 Conference in Sydney, entitled "It's not easy being green - a closed captioning for web case study'.
>> This dealt with the making some hundreds of closed captioned video clips available on a client web site in 2011 using DFXP format and JW player.
>> One of a number of hurdles that were overcome in that project was gaining an understanding of, and overcoming, an apparent semantic difference between the colour green when used for closed captions and subtitles in the broadcast industry and that on the web.
>>
>> To speak to the essence of a 5 page technical paper I formed the opinion that it is the intention in the broadcast world, in standards such as CEA608/708 and the European DVB standard (used in Australia) that the colour green means that the green value be at its maximum ie in 8 bit RGB (decimal) 0 255 0.
>>
>> Colour captions are commonly used in Australia to distinguish between speakers and are particularly relevant to clarify meaning for the Deaf or hearing impaired viewer when the speaker is off screen - although green is arguably the least common of the four colours used.
>>
>> Literally translating the occurrence of 'green' from a broadcast standard into a web caption standard that leverages CSS specifications for green of RGB  (hexadecimal) 008000 yields a darker green with inadequate contrast as the green channel is not at its maximum.
>>
>> I would therefore respectfully suggest that the WebVTT Community Group, in common with others developing cross-domain conversion standards, revisit the assumption that CEA608 and 708 colours 'map to CSS colors of the same name' as suggested in Clause 1.6 of the Draft of the conversion document at https://dvcs.w3.org/hg/text-tracks/raw-file/default/608toVTT/608toVTT.html
>>
>> If the desire is to map to a named colour then a more appropriate named colour might be 'lime' in order to more accurately capture what I believe to be the broadcast intent.
>>
>> it is my understanding, based on personal communication with engineers from the BBC undertaken after the conclusion of my project, that this is the parsing used when caption files in broadcast formats are mapped for web display on the BBC's many public-facing platforms.
>>
>> While the slides from my presentation are available from my LinkedIn profile, and the paper was made available to conference to attendees, is not publicly available on the web.
>> However I am happy to respond to requests off-list should it be of interest to individual members of the Community Group.
>>
>> Thankyou for your interest in this important area of web accessibility.
>>
>>
>>
>> Thanks,
>>
>> Michael
>>
>>
>>
>>
>> Michael Borthwick Consulting Pty. Ltd.
>> GPO Box 1950, 380 Bourke Street, Melbourne Australia 3001
>> Level 1, 384 Bridge Road, Richmond
>> Mobile Ph: + 61 418 345 800
>> http://www.michaelborthwick.com.au
>>
>>
>>
>>
>>
>
> David Singer
> Manager, Software Standards, Apple Inc.
>
>

Received on Tuesday, 8 April 2014 02:56:34 UTC