Re: Captioning verbiage for the Text Spacing Understanding doc

Hi John,

Thank you very much for the detailed explanation and excellent text for
the  understanding document. I'll incorporate it soon as I get a chance.

Kindest Regards,
Laura

On Jan 4, 2018 10:58 AM, "John Foliot" <john.foliot@deque.com> wrote:

> Hi Laura,
>
> I had to go back and figure out what this was about, but after reading
> [2] http://rawgit.com/w3c/wcag21/master/understanding/21/text-spacing.html,
> it comes back to me now. Note that my concern/issue is similar to
> @steverep's issue (canvas = images of text).
>
> At issue is that not all captions are provided as stand-alone text files,
> and as such, not all captions will have the technical ability to be
> 'reformatted' because they are, for all intents and purposes, "images of
> text" burned into the "moving pictures" video file (in a similar way that
> text may be part of a JPEG or PNG file).
>
> In effect, there are multiple ways of providing captions. The most common
> are:
>
>    1. The caption file is and remains a stand-alone text file (using a
>    timed-text markup language, either TTML or WebVTT), and the caption file is
>    supplied via the @track element, like this:
>          <video poster="myvideo.png" controls>
>              <source src="myvideo.mp4" srclang="en" type="video/mp4">
>              <track src="myvideo_en.vtt" kind="captions" srclang="en"
>    label="English">
>          </video>
>    (This is often referred to as out-of-band captions)
>
>    2. The caption file (again, similar to above, a time-stamped text
>    file) is "bundled" inside of the video wrapper (i.e. .mp4 or .mkv) - these
>    are file formats that are wrappers or containers that traditionally include
>    the H.264 encoded video stream, the AAC encoded audio stream, and the
>    wrapper formats can also include other associated data files such as the
>    WebVTT file. Here, the user-agent "looks inside" the video wrapper for text
>    files that correspond to caption files, and when present exposes them to
>    the end user. See https://www.w3.org/TR/2011/WD-html5-20110113/video.
>    html#sourcing-in-band-text-tracks
>    <https://www.w3.org/TR/2011/WD-html5-20110113/video.html#sourcing-in-band-text-tracks>
>    for more specifics, but the key thing to remember is that the captions are
>    still being supplied via a seperate time-stamped text file, it's just that
>    the delivery method (in-band) is different: the caption file is 'embedded'
>    into the video wrapper, and not referenced via the stand-along @track
>    attrribute.
>
>    3. A third method of providing captions is done at the post-production
>    level, where text is 'burned' directly into the moving image files. While
>    less common today than in the past, for certain languages and under certain
>    conditions this remains a valid and viable option (as it meets the
>    functional need of providing captions). These types of captions are also
>    traditionally known as "Open Captions" as they are present and
>    persistent to all users, and cannot be disabled or hidden, as the text
>    rendered on screen is actually part of each individual frame of the video
>    asset itself.
>
> It is this third condition that, due to technical limitations, needs to be
> exempted from the SC - there is no way for the end user to manipulate the
> on-screen 'text', because it isn't text, it's a special type of image. The
> core difference is that there is no "text file" being used to provide the
> captions, so there is nothing that can be further modified by the
> user-agent(s).
> (The following video may help better explain the production process:
> https://www.youtube.com/watch?v=WzADacd7NMo)
>
> To wrap things up, perhaps the following may meet your need?
>
> Examples of text that are typically not affected by style properties
> <https://www.w3.org/TR/WCAG21/#dfn-style-properties> are images of text
> <http://rawgit.com/w3c/wcag21/master/guidelines/index.html#dfn-images-of-text> and
> video captions embedded directly into the video frames, and not provided
> as an associated caption file, which are not expected to adapt.
>
> ​HTH.
>
> JF​
>
>
>
>
>
>
> On Thu, Jan 4, 2018 at 6:32 AM, Laura Carlson <laura.lee.carlson@gmail.com
> > wrote:
>
>> Hi John,
>>
>> At the November 13, 2017 AGWG teleconference, you mentioned that the Text
>> Spacing Understanding doc should have verbiage to explain what types of
>> captions are not expected to adapt to the SC's metrics [1].
>>
>> I put a place holder in the document [2] so it wouldn't fall through the
>> cracks. Would it be possible for you please suggest appropriate verbiage to
>> use?
>>
>> We are very fortunate that you have deep expertise in captioning. Thank
>> you very much for your consideration.
>>
>> Kindest Regards,
>>
>> Laura
>>
>> [1] http://rawgit.com/w3c/wcag21/master/guidelines/index.htm
>> l#text-spacing
>> [2] http://rawgit.com/w3c/wcag21/master/understanding/21/tex
>> t-spacing.html
>>
>
>
>
> --
> John Foliot
> Principal Accessibility Strategist
> Deque Systems Inc.
> john.foliot@deque.com
>
> Advancing the mission of digital accessibility and inclusion
>