- From: John Foliot <john.foliot@deque.com>
- Date: Fri, 28 Apr 2017 19:31:16 -0500
- To: "White, Jason J" <jjwhite@ets.org>
- Cc: Alastair Campbell <acampbell@nomensa.com>, David MacDonald <david100@sympatico.ca>, WCAG <w3c-wai-gl@w3.org>
- Message-ID: <CAKdCpxybq4Yavp96fiZAg9t9umujoKiCeHYb6dxEu2tOpTXkNA@mail.gmail.com>
Jason wrote: > *This is a good point. If the video is embedded in an HTML-based Web page, then whether the Web page conforms or not presumably depends on whether or not the video conforms, so it’s covered. However, if (assuming this is possible) it’s linked to rather than embedded, then it’s more of a separate resource and questions arise.* Video formats can be delivered over the network using a number of different protocols, including both streaming protocols (see here: http://www.streamingmedia.com/Articles/Editorial/What-Is-.../What-Is-a-Streaming-Media-Protocol-84496.aspx) as well as more 'packet' based protocols (http, ftp, gopher <smile>, whatever). However, with the second category of protocols, you need to download the entire file to the local host before the video will play properly, which often causes serious buffering issues. Streaming protocols (and as I recall there is even a pseudo streaming hack) do not wait for all of the packets to arrive before rendering on screen. HTML5's <video> element supports either streaming or packet-based protocols however, and so in some ways I'd argue that either would be "in scope" especially when we start to discuss packaging the required accessibility support files in-band of the video wrapper; so for example your .mp4 file might have an H.264 encoded video, AAC encoded audio description files, and WebVTT text (caption) files all wrapped up inside of the .mp4 file. If you crafted such a file, and then linked it from a web page *<a href="http://video.mp4 <http://video.mp4>>See the video</a>* all of the support content (mandated by WCAG today) would be included in the .mp4 file (even thought that file is not a "web page") and *I* would report that link and file as being "compliant" to WCAG. If I linked the same file like this instead: *<a href="rtsp://video.mp4>See the video</a>* as an evaluator I'd still expect to find the captions, described audio/video description file, and perhaps even the transcript made available to the end user before i could report compliance. *HOW* you do that I'm less concerned with, only that you *DO* do so. All which further suggests to me that the http protocol as an identifier of "content" (or even "Web Content") is a red herring. JF On Fri, Apr 28, 2017 at 12:38 PM, White, Jason J <jjwhite@ets.org> wrote: > > > > > *From:* Alastair Campbell [mailto:acampbell@nomensa.com] > *Sent:* Friday, April 28, 2017 1:30 PM > > Well, most connections are now over httpS, and behind the scenes that is > becoming http2, so it doesn't work from that point of view. > > *[Jason] I agree, and it obviously depends on whether you treat HTTP as > including all of the variants (whether TLS is used or not, whether it’s > HTTP 1.1 or HTTP 2, etc.).* > > > > I'm less certain of this but i believe that a lot of video is delivered by > UDP or RTSP, have you checked to see if a particular video is covered by > WCAG based on the protocol it uses? > > > > *[Jason] This is a good point. If the video is embedded in an HTML-based > Web page, then whether the Web page conforms or not presumably depends on > whether or not the video conforms, so it’s covered. However, if (assuming > this is possible) it’s linked to rather than embedded, then it’s more of a > separate resource and questions arise.* > > > If we want to widen it for future versions that is another matter... but > as far as clarity, the definition of web page is very clear in the > standard. It says exactly what the working group intended it to say. > > > > And there are plenty of people who can't work out what that means anymore.. > > *[Jason] I agree there are issues; I agree the definition should be > widened (we have an open issue on that question).* > > > > ------------------------------ > > This e-mail and any files transmitted with it may contain privileged or > confidential information. It is solely for use by the individual for whom > it is intended, even if addressed incorrectly. If you received this e-mail > in error, please notify the sender; do not disclose, copy, distribute, or > take any action in reliance on the contents of this information; and delete > it from your system. Any other use of this e-mail is prohibited. > > Thank you for your compliance. > ------------------------------ > -- John Foliot Principal Accessibility Strategist Deque Systems Inc. john.foliot@deque.com Advancing the mission of digital accessibility and inclusion
Received on Saturday, 29 April 2017 00:31:51 UTC