Proposed Audio or video element that plays automatically has no audio that lasts more than 3 seconds

Description

audio or video that plays automatically does not output audio for more than 3 seconds.

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 that contains audio.

Expectation

For each test target the total audio output does not last more than 3 seconds.

Note: This rule does not cover single audio instances that play repeatedly for more than three seconds, or multiple audio instances for more than three seconds. The WCAG Understanding documentation for 1.4.2 Audio Controls is ambiguous about how to handle these scenarios.

Assumptions

There are currently no assumptions

Accessibility Support

There are no major accessibility support issues known for this rule.

Background

Bibliography

Accessibility Requirements Mapping

G60: Playing a sound that turns off automatically within three seconds
- Learn more about technique G60
- Not required for 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

Input Aspects

The following aspects are required in using this rule.

DOM Tree
CSS Styling
Audio output (no link available)
Visual output (no link available)

Test Cases

Passed

Passed Example 1

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This audio element does not play automatically for more than 3 seconds.

<audio src="/test-assets/moon-audio/moon-speech.mp3#t=25" autoplay></audio>

Passed Example 2

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This video element’s audio output does not last 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>

Failed

Failed Example 1

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This audio element plays automatically for more than 3 seconds.

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

Failed Example 2

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This video element plays some audio automatically for more than 3 seconds.

<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 has audio that 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 refers to a source file that 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 autoplay.

<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.

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.

Implementations

There are currently no known implementations for this rule. If you would like to contribute an implementation, please read the ACT Implementations page for details.

Changelog

This is the first version of this ACT rule.