Proposed Test Rule: audio or video that plays automatically has a control mechanism

Description

audio or video that plays automatically must have a control mechanism.

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 1

For each test target, there is at least one instrument in the same web page to pause or stop the audio, or turn the audio volume off independently from the overall system volume control.

Expectation 2

The instrument to pause or stop or turn the audio volume off is visible, has an accessible name that is not only whitespace, and is included in the accessibility tree.

Assumptions

There are currently no assumptions

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

Bibliography

Accessibility Requirements Mapping

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 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

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

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

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

Passed Example 3

This video element has a custom instrument to pause or 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">Pause</button>
			<button type="button" id="mute">Mute</button>
		</div>
	</div>
	<script src="/test-assets/80f0bf/no-autoplay.js"></script>
</body>

Failed

Failed Example 1

This audio element does not have an instrument to pause, stop, or turn the audio volume off.

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

Failed Example 2

This video element autoplays and does not have an instrument to pause, stop, or turn the audio volume off.

<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>

Failed Example 3

This video element has an instrument to pause, stop, or turn the audio volume off but the instrument is not visible.

<head>
	<style>
		button {
			color: #000;
			display: none;
		}
		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">Pause</button>
			<button type="button" id="mute">Mute</button>
		</div>
	</div>
	<script src="/test-assets/80f0bf/no-autoplay.js"></script>
</body>

Failed Example 4

This video element has an instrument to pause, stop, or turn the audio volume off but its button elements do not have accessible names.

<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"></button>
			<button type="button" id="mute"></button>
		</div>
	</div>
	<script src="/test-assets/80f0bf/no-autoplay.js"></script>
</body>

Failed Example 5

This video element has an instrument to pause, stop, or turn the audio volume off but the instrument is not included in the accessibility tree.

<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" aria-hidden="true">
			<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>

Inapplicable

Inapplicable Example 1

The audio of this video element 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

The src file of this video element has no audio output.

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

Inapplicable Example 3

This audio element does not autoplay.

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

Glossary

Accessible Name

The accessible name is the programmatically determined name of a user interface element that is included in the accessibility tree.

The accessible name is calculated using the accessible name and description computation.

For native markup languages, such as HTML and SVG, additional information on how to calculate the accessible name can be found in HTML Accessibility API Mappings 1.0, Accessible Name and Description Computation (working draft) and SVG Accessibility API Mappings, Name and Description (working draft).

For more details, see examples of accessible name.

Note: As per the accessible name and description computation, each element always has an accessible name. When no accessible name is provided, the element will nonetheless be assigned an empty ("") one.

Note: As per the accessible name and description computation, accessible names are flat string trimmed of leading and trailing whitespace. Notably, it is not possible for a non-empty accessible name to be composed only of whitespace since these must be trimmed.

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.

Focusable

Elements that can become the target of keyboard input as described in the HTML specification of focusable and can be focused.

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs are exposed to assistive technologies. This allows users of assistive technology to access the elements in a way that meets the requirements of the individual user.

The general rules for when elements are included in the accessibility tree are defined in the core accessibility API mappings. For native markup languages, such as HTML and SVG, additional rules for when elements are included in the accessibility tree can be found in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

For more details, see examples of included in the accessibility tree.

Programmatically hidden elements are removed from the accessibility tree. However, some browsers will leave focusable elements with an aria-hidden attribute set to true in the accessibility tree. Because they are hidden, these elements are considered not included in the accessibility tree. This may cause confusion for users of assistive technologies because they may still be able to interact with these focusable elements using sequential keyboard navigation, even though the element should not be included in the accessibility tree.

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.

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.

Programmatically Hidden

An HTML element is programmatically hidden if either it has a computed CSS property visibility whose value is not visible; or at least one of the following is true for any of its inclusive ancestors in the flat tree:

has a hidden attribute; or
has a computed CSS property display of none; or
has an aria-hidden attribute set to true

Note: Contrarily to the other conditions, the visibility CSS property may be reverted by descendants.

Visible

Content perceivable through sight.

Content is considered visible if making it fully transparent would result in a difference in the pixels rendered for any part of the document that is currently within the viewport or can be brought into the viewport via scrolling.

Content is defined in WCAG.

For more details, see examples of visible.

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.

Whitespace

Whitespace are characters that have the Unicode “White_Space” property in the Unicode properties list.

This includes:

all characters in the Unicode Separator categories, and
the following characters in the Other, Control category:
- Character tabulation (U+0009)
- Line Feed (LF) (U+000A)
- Line Tabulation (U+000B)
- Form Feed (FF) (U+000C)
- Carriage Return (CR) (U+000D)
- Next Line (NEL) (U+0085)

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.