audio or video avoids automatically playing audio

  • Rule Type:composite
  • Rule Id: 80f0bf
  • Last modified: Jun 25, 2021
  • Accessibility Requirements Mapping:
    • 1.4.2 Audio Control (Level A)
      • Learn More about 1.4.2 Audio Control
      • Required for conformance to WCAG 2.0 and later on level A and higher.
      • Outcome mapping:
        • Any failed outcomes: success criterion is not satisfied.
        • All passed outcomes: success criterion needs further testing.
        • An inapplicable outcome: success criterion needs further testing.
    • WCAG Non-Interference
      • Learn More about WCAG Non-Interference
      • Required for conformance to WCAG 2.1.
      • Outcome mapping:
        • Any failed outcomes: WCAG 2 conformance requirement is not satisfied.
        • All passed outcomes: WCAG 2 conformance requirement needs further testing.
        • An inapplicable outcome: WCAG 2 conformance requirement needs further testing.
    • G60: Playing a sound that turns off automatically within three seconds
      • Learn More about technique G60
      • Not required to conformance to any W3C accessibility recommendation.
      • Outcome mapping:
        • Any failed outcomes: technique is not satisfied.
        • All passed outcomes: technique needs further testing.
        • An inapplicable outcome: technique needs further testing.
    • G170: Providing a control near the beginning of the Web page that turns off sounds that play automatically
      • Learn More about technique G170
      • Not required to conformance to any W3C accessibility recommendation.
      • Outcome mapping:
        • Any failed outcomes: technique is not satisfied.
        • All passed outcomes: technique needs further testing.
        • An inapplicable outcome: technique needs further testing.
    • G171: Playing sounds only on user request
      • Learn More about technique G171
      • Not required to conformance to any W3C accessibility recommendation.
      • Outcome mapping:
        • Any failed outcomes: technique is not satisfied.
        • All passed outcomes: technique needs further testing.
        • An inapplicable outcome: technique needs further testing.

Description

This rule checks that audio or video that plays automatically does not have audio that lasts for more than 3 seconds or has an audio control mechanism to stop or mute it.

Applicability

This rule applies to any audio or video element for which all the following are true:

  • autoplay: the element has an autoplay attribute value of true; and
  • not muted: the element has a muted attribute value of false; and
  • not paused: the element has a paused attribute value of false; and
  • duration: the element has a media resource lasting more than 3 seconds and that contains audio.

Expectation

For each test target, the outcome of at least one of the following rules is passed:

Assumptions

  • This rule assumes that it is not possible to satisfy Success Criterion 1.4.2 Audio Control if the total length of the automatically playing audio is more than 3 seconds, even if there are pauses in the sound and no more than 3 seconds in a row with actual sound.
  • This rule assumes that the mechanism to control the sound must be located in the same web page. Mechanisms located on other pages can still create accessibility issues for users relying on sound to navigate (e.g. screen readers users) since the autoplaying sound will interfere with their ability to find and activate the mechanism. If a mechanism external to the web page is provided, it is possible to fail this rule but still satisfy Success Criterion 1.4.2 Audio Control.
  • This rule assumes that the mechanism to control the sound must be visible and accessible in order to be effective and usable by all kinds of users. If the mechanism is hidden to some users, it is possible to fail this rule but still satisfy Success Criterion 1.4.2 Audio Control.

Accessibility Support

The native video and audio controls in several browser and assistive technology combinations are not keyboard accessible and the video or audio element itself may not be announced. Authors are recommended to use custom controls for keyboard navigation and cross browser accessibility support in general.

Background

The instruments used to pass this rule (if any), must meet all level A Success Criteria in order to fully satisfy Success Criterion 1.4.2 Audio Control. These extra requirements are left out of this rule, and should be tested separately.

Test Cases

Passed

Passed Example 1

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This audio element has an instrument to pause, stop, or turn the audio volume off.

<audio src="/test-assets/moon-audio/moon-speech.mp3" autoplay controls></audio>

Passed Example 2

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This video element does not play for longer than 3 seconds.

<video autoplay>
	<source src="/test-assets/rabbit-video/video.mp4#t=8,10" type="video/mp4" />
	<source src="/test-assets/rabbit-video/video.webm#t=8,10" type="video/webm" />
</video>

Passed Example 3

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This video element autoplays and has an instrument to pause, stop, or turn the audio volume off.

<head>
	<style>
		button {
			color: #000;
		}
		button:hover {
			cursor: pointer;
			cursor: pointer;
			background-color: grey;
			color: white;
		}
	</style>
</head>
<body>
	<div id="video-container">
		<!-- Video -->
		<video id="video" autoplay>
			<source src="/test-assets/rabbit-video/video.mp4" type="video/mp4" />
			<source src="/test-assets/rabbit-video/video.webm" type="video/webm" />
		</video>
		<!-- Video Controls -->
		<div id="video-controls">
			<button type="button" id="play-pause" class="play">Play</button>
			<button type="button" id="mute">Mute</button>
		</div>
	</div>
	<script src="/test-assets/80f0bf/no-autoplay.js"></script>
</body>

Failed

Failed Example 1

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This audio element autoplays, lasts for more than 3 seconds, and does not have an instrument to pause, stop, or mute the audio.

<audio src="/test-assets/moon-audio/moon-speech.mp3" autoplay></audio>

Failed Example 2

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This video element audio autoplays for longer than 3 seconds, and does not have an instrument to pause, stop, or mute the audio

<video autoplay>
	<source src="/test-assets/rabbit-video/video.mp4" type="video/mp4" />
	<source src="/test-assets/rabbit-video/video.webm" type="video/webm" />
</video>

Inapplicable

Inapplicable Example 1

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This video element audio autoplays for longer than 3 seconds but is muted.

<video autoplay muted>
	<source src="/test-assets/rabbit-video/video.mp4" type="video/mp4" />
	<source src="/test-assets/rabbit-video/video.webm" type="video/webm" />
</video>

Inapplicable Example 2

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This video element has no audio output.

<video autoplay>
	<source src="/test-assets/rabbit-video/silent.mp4" type="video/mp4" />
	<source src="/test-assets/rabbit-video/silent.webm" type="video/webm" />
</video>

Inapplicable Example 3

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This audio element does not play automatically.

<audio src="/test-assets/moon-audio/moon-speech.mp3" controls></audio>

Glossary

Attribute value

The attribute value of a content attribute set on an HTML element is the value that the attribute gets after being parsed and computed according to specifications. It may differ from the value that is actually written in the HTML code due to trimming whitespace or non-digits characters, default values, or case-insensitivity.

Some notable case of attribute value, among others:

  • For enumerated attributes, the attribute value is either the state of the attribute, or the keyword that maps to it; even for the default states. Thus <input type="image" /> has an attribute value of either Image Button (the state) or image (the keyword mapping to it), both formulations having the same meaning; similarly, "an input element with a type attribute value of Text" can be either <input type="text" />, <input /> (missing value default), or <input type="invalid" /> (invalid value default).
  • For boolean attributes, the attribute value is true when the attribute is present and false otherwise. Thus <button disabled>, <button disabled="disabled"> and <button disabled=""> all have a disabled attribute value of true.
  • For attributes whose value is used in a case-insensitive context, the attribute value is the lowercase version of the value written in the HTML code.
  • For attributes that accept numbers, the attribute value is the result of parsing the value written in the HTML code according to the rules for parsing this kind of number.
  • For attributes that accept sets of tokens, whether space separated or comma separated, the attribute value is the set of tokens obtained after parsing the set and, depending on the case, converting its items to lowercase (if the set is used in a case-insensitive context).
  • For aria-* attributes, the attribute value is computed as indicated in the WAI-ARIA specification and the HTML Accessibility API Mappings.

This list is not exhaustive, and only serves as an illustration for some of the most common cases.

The attribute value of an IDL attribute is the value returned on getting it. Note that when an IDL attribute reflects a content attribute, they have the same attribute value.

Instrument to achieve an objective

An HTML element that when activated allows an end-user to achieve an objective.

Note: Any rule that uses this definition must provide an unambiguous description of the objective the instrument is used to achieve.

Background About Instrument for Instrument to achieve an objective

This definition is a more restrictive version of WCAG's definition of mechanism, notably restricting it to the current document. WCAG has a note that "The mechanism needs to meet all success criteria for the conformance level claimed." This includes all the level A criteria such as Success Criterion 2.1.1 Keyboard (the mechanism must be keyboard accessible) or Success Criterion 4.1.2 Name, Role, Value (the mechanism must be exposed to assistive technologies and have an accessible name). This definition, and the rules using it, leaves these extra requirements out. This avoids reporting the same component twice for the same reason (e.g., missing an accessible name) under two different rules and Success Criteria, and helps pinpoint the error related to each Success Criterion. Instruments should nonetheless be fully accessible at the correct conformance level (depending on the rule using them).

Outcome

An outcome is a conclusion that comes from evaluating an ACT Rule on a test subject or one of its constituent test target. An outcome can be one of the three following types:

  • Inapplicable: No part of the test subject matches the applicability
  • Passed: A test target meets all expectations
  • Failed: A test target does not meet all expectations

Note: A rule has one passed or failed outcome for every test target. When there are no test targets the rule has one inapplicable outcome. This means that each test subject will have one or more outcomes.

Note: Implementations using the EARL10-Schema can express the outcome with the outcome property. In addition to passed, failed and inapplicable, EARL 1.0 also defined an incomplete outcome. While this cannot be the outcome of an ACT Rule when applied in its entirety, it often happens that rules are only partially evaluated. For example, when applicability was automated, but the expectations have to be evaluated manually. Such "interim" results can be expressed with the incomplete outcome.

Web page (HTML)

An HTML web page is the set of all fully active documents which share the same top-level browsing context.

Note: Nesting of browsing context mostly happens with iframe and object. Thus a web page will most of the time be a "top-level" document and all its iframe and object (recursively).

Note: Web pages as defined by WCAG are not restricted to the HTML technology but can also include, e.g., PDF or DOCX documents.

Note: Although web pages as defined here are sets of documents (and do not contain other kind of nodes), one can abusively write that any node is "in a web page" if it is a shadow-including descendant of a document that is part of that web page.


Useful Links


Implementations

This section is not part of the official rule. It is populated dynamically and not accounted for in the change history or the last modified date. This section will not be included in the rule when it is published on the W3C website.

ToolConsistencyCompleteReport
axe-coreconsistentYesView Report
QualWebconsistentYesView Report
SortSiteconsistentYesView Report

Acknowledgments

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