WebAIM - Web Accessibility In Mind

E-mail List Archives

Re: Transcript vs. Caption


From: Jonathan Avila
Date: Dec 18, 2014 6:15PM

> 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 Descriptions(*).

John, I'm trying to figure out what success criteria you are saying would require transcripts for WCAG Level AA multimedia conformance if audio description was available. My read is that SC 1.2.3 and SC 1.2.5 can both be met via audio description. SC 1.2.2 and 1.2.4 can be met through captions. The requirement for transcripts when audio description and captions is present is something that doesn't appear to be clear.


-----Original Message-----
From: <EMAIL REMOVED> [mailto: <EMAIL REMOVED> ] On Behalf Of John Foliot
Sent: Thursday, December 18, 2014 3:43 PM
To: 'WebAIM Discussion List'
Subject: Re: [WebAIM] Transcript vs. Caption

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 Descriptions(*).

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 already.

> 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 AA)"

(* 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 level).

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