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Re: Unsynchronised audio and video content


From: Patrick H. Lauke
Date: May 27, 2020 6:01AM

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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