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Re: Transcript vs. Caption


From: John Foliot
Date: Dec 18, 2014 1:42PM

Patrick Burke wrote:
> We want to doublecheck our understanding of alternate content for media
> (Guideline 1.2).
> It appears that a transcript ("text alternative for time-based media)
> is sufficient if the content is audio-only or video-only, under section
> 1.2.1. Otherwise, captions/audio descriptions are necessary
> (1.2.2 & others).

First, you need to determine what compliance level you are going for. If it
is AA then you will need 3 "alternatives" - Captions, Transcript and Audio

The easiest way to think of this is via user-groups.

For the deaf and hard-of-hearing communities, captions are the necessary
accommodation (SC 1.2.2 - Level A)

For the blind and low-vision communities, the transcript can provide the
necessary accommodation, especially if the transcript combines both the
dialog and necessary explanation of what is on screen (SC 1.2.3 - Level a),
where the "transcript" serves as the Media Alternative called for:

"1.2.3 Audio Description or Media Alternative (Prerecorded): An
alternative for time-based media or audio description of the prerecorded
video content is provided for synchronized media, except when the media is a
media alternative for text and is clearly labeled as such. (Level A)"

For deaf/blind, or users with cognitive issues, then the Transcript (think
in terms of a screen play) will be their accommodation requirement.

WCAG recognizes that at Level A conformance, that Transcript can also serve
as an accommodation to the Audio-Description requirements, especially since
in practice most transcripts already serve a functionally similar equivalent

> We're preparing a report & want to strongly encourage captions, rather
> than transcripts.

Actually, you require both at a minimum, and if you are going for AA
conformance you also need "Audio Descriptions":

"1.2.5 Audio Description (Prerecorded): Audio description is
provided for all prerecorded video content in synchronized media. (Level

(* In my opinion this is now an unfortunate choice of wording, based upon
old-world tech - traditionally televisions and film - where the audio
description is tightly bound to the evolving timeline of the media
presentation. We have seen however PoC examples of providing the description
of on-screen activity and related important visual information as text files
that can be voiced by TTS engines, and that allow, for example, the ability
to speed up the 'voice' to be more in sync with what we know most daily
Screen reader users are accustomed to (e.g. 200+ words per minute). This of
course allows you to "cram" more information into the 'silence' between the
on-screen dialog (always a tricky requirement to meet, and one of the
reasons why traditional audio description is so hard at a professional

I have also seen a PoC that used popcorn.js to actually 'pause' the
pre-recorded media stream and render the "descriptive text" on screen, for
further end-user processing.

We are currently putting the finishing touches on a new W3C Note "Media
Accessibility User Requirements"
(http://w3c.github.io/pfwg/media-accessibility-reqs), which we hope will be
finalized and published early in the new year (January?? - seriously, that
close). This document recognizes this new means of providing video
description), but at this writing it is unclear whether or not WCAG will
move to accept text files as a functional replacement for "audio
description" (which is what WCAG explicitly requires)

At any rate Patrick, to be Level AA conformant, you will need all three.
Recognizing both the financial, production and technical limitations
inherent to this requirement (in plain language, this is *Really* hard to
accomplish today) the Canadian Federal Government has specifically issued a
'exemption' for this requirement at this time (with some limitations), with
a stated goal of revisiting this annually to assess the feasibility moving
forward (FWIW). See here: http://www.tbs-sct.gc.ca/pol/doc-eng.aspx?id=23601
Appendix B.


John Foliot
Web Accessibility Specialist
W3C Invited Expert - Accessibility
HTML5-a11y Task Force (Media SubTeam)
Co-Founder, Open Web Camp