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Perceivable WCAG 1.2.1

1.2.1 Audio-only and Video-only (Prerecorded)

Prerecorded audio-only and video-only content must have text alternatives that convey equivalent information to users who cannot perceive the original media.

Level A Serious WCAG 2.0 (new) WCAG 2.1 WCAG 2.2
audio-caption

What this rule means

WCAG 1.2.1 requires that prerecorded audio-only content (such as podcasts or voice recordings) and prerecorded video-only content (such as silent animations or surveillance footage) each have a text-based alternative. For audio-only, this means a full transcript. For video-only, this means either a transcript or an audio track that describes the visual information.

The key distinction is that this criterion targets media that uses only one modality. If a video includes both an audio track and visual content, it falls under other 1.2.x criteria instead.

Why it matters

Users who are deaf or hard of hearing cannot access information delivered solely through audio. A transcript allows them to read the content at their own pace. Conversely, users who are blind cannot perceive visual-only content, so an audio description or descriptive transcript bridges that gap.

Transcripts also benefit users in noisy environments, non-native speakers who read more comfortably than they listen, and search engines that can index text but not audio or video streams.

Related axe-core rules

  • audio-caption — Ensures <audio> elements have captions or a transcript reference.

Note that automated tools can only detect the presence of certain elements. Manual review is always required to verify transcript accuracy and completeness.

How to test

  1. Identify all prerecorded audio-only and video-only content on the page.
  2. For each audio-only clip, confirm that a text transcript is provided nearby or linked directly.
  3. For each video-only clip, confirm that either a descriptive text transcript or an audio track describing the visuals is available.
  4. Verify the transcript or description accurately conveys all meaningful information present in the media.
  5. Check that the alternative is easy to locate — ideally adjacent to or directly linked from the media player.

How to fix

For audio-only content, provide a full transcript that includes speaker identification, all spoken words, and descriptions of meaningful sounds:

<audio controls>
  <source src="/podcast-ep-12.mp3" type="audio/mpeg" />
  Your browser does not support the audio element.
</audio>
<details>
  <summary>Read transcript</summary>
  <div class="transcript">
    <p><strong>Host:</strong> Welcome to episode twelve...</p>
    <p><strong>Guest:</strong> Thanks for having me...</p>
  </div>
</details>

For video-only content, provide either a descriptive transcript or an audio alternative:

<video controls>
  <source src="/assembly-instructions.mp4" type="video/mp4" />
  <track kind="descriptions" src="/assembly-desc.vtt" srclang="en" label="Audio Description" />
</video>
<a href="/assembly-transcript.html">Full text description of assembly steps</a>

Common mistakes

  • Providing auto-generated captions without reviewing them for accuracy.
  • Omitting non-speech sounds (e.g., applause, background music) from transcripts.
  • Placing the transcript on a separate page with no clear link from the media player.
  • Assuming video-only content does not need an alternative because there is no dialogue.
  • Using an image-based PDF as a transcript, which itself is not accessible to screen readers.

Resources