Perceivable · 1.2 Time-based Media
Prerecorded audio-only content, such as a podcast, needs a text transcript; prerecorded video-only content, such as a silent animation, needs a text alternative or an audio track conveying the same information. Media that is a clearly labeled alternative for text is exempt.
Live demo
The same task, done two ways: switch between the version that passes and the one that fails, or put them side by side. Everything in the box is live, so try it with a keyboard, a pointer or a screen reader.
Press play and listen. Then imagine you cannot hear it: in Passes you can read every word, in Fails there is nothing to read.
Priya and Daniel talk about saving for a first home.
Priya and Daniel talk about saving for a first home.
The tools follow the version you last used.
What happened
Why it passes
A person who cannot hear the clip reads the full transcript, with every word and the name of each speaker.
Why it fails
The clip is sound only. A deaf listener gets the title and one sentence, and misses the whole conversation.
Examples
Four examples, each one running: the usual ways this criterion fails, and code that passes. Listen to them, measure them, or copy the code.
Fails
Live preview
<h3>Money Matters, episode 12</h3><audio controls src="/audio/money-matters-12.mp3"></audio><p>Priya and Daniel talk about saving for a first home.</p>A one-line summary is not a transcript. People who cannot hear the episode miss everything that is said in it.
Passes
Live preview
<h3>Money Matters, episode 12</h3><audio controls src="/audio/money-matters-12.mp3"></audio><details> <summary>Transcript of episode 12</summary> <p>[Theme music plays, then fades.]</p> <p>Priya: Welcome to Money Matters. Today we talk about saving for a first home.</p> <p>Daniel: Start with one number: how much you can put aside each month.</p></details>The transcript names each speaker and includes meaningful sounds. It must cover the whole episode, not only the opening.
Fails
Live preview
<h3>How to assemble the bookcase</h3><video controls src="/video/bookcase-silent.mp4"></video>The video has no sound track and shows the steps only in pictures. A blind customer has no way to learn them.
Passes
Live preview
<h3>How to assemble the bookcase</h3><video controls src="/video/bookcase-silent.mp4"></video><h4>The same steps in text</h4><ol> <li>Lay the left side panel flat, with the holes facing up.</li> <li>Push the three shelves into the holes.</li> <li>Press the right side panel on top.</li> <li>Tighten the four screws with the key from the box.</li></ol>The numbered steps give everything the silent video shows, so people who cannot see it still learn each step.
Why it matters
People who are deaf or hard of hearing can read what is said in audio, and people who are blind or have low vision get the content of silent video through text or audio.
W3C: Understanding 1.2.1Level A
Level A is the minimum: failing it can shut some people out completely.
Where it is required
Required where the law names WCAG 2.0 or later at this level: the United States, Canada, the European Union, the United Kingdom, France, Germany, Italy, Spain, the Netherlands, Ireland, Norway, Switzerland, India, Japan, Australia, New Zealand and Israel.
How to test
A few concrete steps. Automated tools find some failures; most need a person.
Common failures