Captions (Live)
Tier 1 · The normative floor
Baseline compliance
What the normative text of WCAG 2.2 requires, and nothing more. Only a failure of this tier is a WCAG failure.
The bare minimum
Live audio in synchronized media, such as a live-streamed event with video, has captions.
Normative text
Verbatim from WCAG 2.2, W3C Recommendation 12 December 2024. Underlined terms are defined below.
Captions are provided for all live audio content in synchronized media.
Known failures
These fail this criterion or a related one named in the text. Log them as WCAG failures.
- Live captions that leave out speech or sounds needed to understand the content don't meet WCAG's definition of captions.
Not required by the normative text
Common claims that this criterion does not support. Don't log these as WCAG failures.
- Captions for live audio-only streams. Those aren't synchronized media; 1.2.9 (AAA) covers them.
Definitions used (4)
Glossary definitions are normative. Their notes are informative.
- captions
-
synchronized visual and/or text alternative for both speech and non-speech audio information needed to understand the media content
Informative notes (6)
Captions are similar to dialogue-only subtitles except captions convey not only the content of spoken dialogue, but also equivalents for non-dialogue audio information needed to understand the program content, including sound effects, music, laughter, speaker identification and location.
Closed Captions are equivalents that can be turned on and off with some players.
Open Captions are any captions that cannot be turned off. For example, if the captions are visual equivalent images of text embedded in video.
Captions should not obscure or obstruct relevant information in the video.
In some countries, captions are called subtitles.
Audio descriptions can be, but do not need to be, captioned since they are descriptions of information that is already presented visually.
- live
-
information captured from a real-world event and transmitted to the receiver with no more than a broadcast delay
Informative notes (2)
A broadcast delay is a short (usually automated) delay, for example used in order to give the broadcaster time to cue or censor the audio (or video) feed, but not sufficient to allow significant editing.
If information is completely computer generated, it is not live.
- audio
-
the technology of sound reproduction
Informative notes (1)
Audio can be created synthetically (including speech synthesis), recorded from real world sounds, or both.
- synchronized media
-
audio or video synchronized with another format for presenting information and/or with time-based interactive components, unless the media is a media alternative for text that is clearly labeled as such
Tier 2 · The gap
Usability & user impact
Where content can meet this criterion and still make things harder for people with disabilities. These are not failures of SC 1.2.4, so raise them as usability defects. Known failures, including failures of related criteria, are listed in Tier 1.
Complete live captions that lag well behind the speaker are hard to follow alongside the video.
Tier 3 · The golden path
Recommended best practice
The pattern that meets the floor, closes the gap, and avoids audit disputes. A recommendation, not a requirement.
Book human real-time captioning (CART) for important live events. Correct the captions before publishing the recording.
W3C's Understanding document and techniques for SC 1.2.4 ↗ are informative: sufficient techniques show ways to pass, and documented failures show common ways to fail, but neither changes what the criterion requires.
How SC 1.2.4 maps to the WCAG 3 draft
From this site's reviewed map to the WCAG 3 editor's draft. It's an interpretation: W3C has not published a mapping.
Successor provisions
From WCAG 2.2, section 5.1: “The main content of WCAG 2.2 is normative and defines requirements that impact conformance claims. Introductory material, appendices, sections marked as "non-normative", diagrams, examples, and notes are informative (non-normative). Non-normative material provides advisory information to help interpret the guidelines but does not create requirements that impact a conformance claim.”