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Re: Unsynchronised audio and video content


From: Tim Harshbarger
Date: May 27, 2020 6:47AM

I would also considered them synchronized if the video and audio are part of
the same file. If they are separate and not synchronized, I think the
success criteria for video-only and audio-only media would apply.

Tim Harshbarger
Senior Accessibility Consultant
Deque Systems

-----Original Message-----
From: WebAIM-Forum < <EMAIL REMOVED> > On Behalf Of Steve
Sent: Wednesday, May 27, 2020 7:17 AM
To: WebAIM Discussion List < <EMAIL REMOVED> >
Subject: Re: [WebAIM] Unsynchronised audio and video content

My interpretation of WCAG's definition of "synchronised media" is that the
audio and video do need to be synchronised, such as when you have a talking
head i.e. the relative timing of the audio and video is important. I don't
believe that merely having audio and video present at the same time is
sufficient to constitute "synchronised media" if their relative timing does
not matter. It would simply be "multimedia". The word "synchronised" has a
very specific meaning and I don't think we can simply ignore it.

In the videos I am currently dealing with, the audio track contains all the
important information. The video content is entirely decorative fluff except
for a medical disclaimer that is displayed for a few seconds.


-----Original Message-----
From: WebAIM-Forum < <EMAIL REMOVED> > On Behalf Of
Patrick H. Lauke
Sent: 27 May 2020 13:01
Subject: Re: [WebAIM] Unsynchronised audio and video content

On 27/05/2020 11:13, Steve Green wrote:

> I am encountering a lot of videos that contain both audio and video, but
they are not synchronised.

A file that has both audio and video together is "synchronised media", where
the audio and the video are synchronised. Or am I missing what you mean? (I
don't believe WCAG makes any more subtle distinction about whether the audio
component and video component of an a/v file need to make sense even if they
weren't in time or not here...the mere fact that playing the video you get
both the audio and the video happening at the same time is sufficient to
class that as "synchronised media").

But, assuming that what you meant is that you have pages that have both
audio-only files and video-only files. In that case, the reason why WCAG
doesn't allow captions for the audio-only files is that the assumption here
is there's no "place" for those captions to show ... i.e. if it's an
audio-only file, it would have a play/pause button, maybe a scrub bar, but
no actual large "player" area where captions would then show.
If you do somehow provide some captions (e.g. using some extra container
with automatically injected captions), then those would probably count as a
"transcript" of sorts and pass the requirement for audio-only.

Patrick H. Lauke

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