Missing media alternative (AAA)

media-alt

WCAG success criterion: 1.2.8 (level AAA)
Outcome class: Manual. A tool cannot decide this check. The audit only points a person at it; it is never counted as automatically verified.
Area: Accessibility, Content & Alternatives
Default severity: medium
axe-core rule: media-alt

Why we flag this

Users who cannot play video or audio receive no text alternative.

Missing transcript or audio description.

What the rule checks

Scope. Every page (page-wide manual note, enriched when <video> / iframe embeds and a transcript link are found).

Expectation. Always one UNTESTED note: on pages with video it names the video and, when a nearby link mentions a transcript, quotes it as evidence (presence, not completeness); without detected media it is the general 1.2.8 reminder. Never a pass, never a violation.

Why a person has to decide. Whether prerecorded media has a full text alternative or audio description is a judgement about the content of the media; the DOM can only show that media (or a transcript link) exists. The note stands on every page because custom players are not reliably detectable.

Source. WCAG 2.2 SC 1.2.8 Media Alternative (Prerecorded) (AAA), G69, G159

Detection: page; needs dom.

Failing example

The check flags this for review. Corpus case content_plain_article. The page may contain further findings for other rules.

content_plain_article.htmlHTML

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Opening hours and visiting rules</title>
    <style>
        nav a, .skip-link { display: inline-block; min-width: 44px; min-height: 44px; }
    </style>
</head>
<body>
    <a class="skip-link" href="#main">Skip to main content</a>
    <header>
        <p>City Library</p>
        <nav aria-label="Main"><a href="/" aria-current="page">Home</a> <a href="/catalogue">Catalogue</a> <a href="/visit">Visit</a></nav>
    </header>
    <main id="main">
        <h1>Opening hours and visiting rules</h1>
        <p>The reading room opens at nine and closes at six on weekdays.</p>
        <h2>Borrowing</h2>
        <p>Members may borrow up to ten books for three weeks. Renewals are possible twice, online or at the front desk.</p>
        <h2>Quiet zones</h2>
        <p>The upper floor is a quiet zone. Phone calls are welcome in the foyer.</p>
    </main>
    <footer><p>City Library, 1 Market Square</p></footer>
</body>
</html>

This page is generated from the rule catalogue and the rule contracts; see therule overview for how the outcome classes are derived.