Media alternatives findable

Functionality provided by assistive technology includes alternative presentations (e.g., as synthesized speech or magnified content), alternative input methods (e.g., voice), additional navigation or orientation mechanisms, and content transformations (e.g., to make tables more accessible).

Assistive technologies often communicate data and messages with mainstream user agents by using and monitoring APIs.

The distinction between mainstream user agents and assistive technologies is not absolute. Many mainstream user agents provide some features to assist individuals with disabilities. The basic difference is that mainstream user agents target broad and diverse audiences that usually include people with and without disabilities. Assistive technologies target narrowly defined populations of users with specific disabilities. The assistance provided by an assistive technology is more specific and appropriate to the needs of its target users. The mainstream user agent may provide important functionality to assistive technologies like retrieving web content from program objects or parsing markup into identifiable bundles.

For audiovisual media, audio description provides information about actions, characters, scene changes, on-screen text, and other visual content.

Audio description is also sometimes called “video description”, “described video”, “visual description”, or “descriptive narration”.

In standard audio description, narration is added during existing pauses in dialogue. See also extended audio description.

If all important visual information is already provided in the main audio track, no additional audio description track is necessary.

Closed captions are equivalents that can be turned on and off with some players and can often be read using assistive technology.

Open captions are any captions that cannot be turned off in the player. For example, if the captions are visual equivalent images of text embedded in video.

Audio descriptions can be, but do not need to be, captioned since they are descriptions of information that is already presented visually.

In some countries, captions are called subtitles. The term ‘subtitles’ is often also used to refer to captions that present a translated version of the audio content.

How a person or organization selects the set is not defined in WCAG3. There maybe informative guidance on selecting a suitable set in future (similar to WCAG-EM), but regional laws or regulations may provide a methodology.

This technique is only used when the sense of the video would be lost without the additional audio description and the pauses between dialogue or narration are too short.

See also sign language.

The mechanism may be explicitly provided in the content, or may be relied upon to be provided by either the platform or by user agents, including assistive technologies.

The mechanism needs to meet all requirements for the conformance level claimed.

This includes ASCII art (which is a pattern of characters), emoticons, leetspeak (which uses character substitution), and images representing text

Where a URI is available and represents a unique set of content, that would be the preferred conformance unit.

Platform software both makes it easier for subject software to run on different hardware, and provides the subject software with many services (e.g. functions, utilities, libraries) that make the subject software easier to write, keep updated, and work more uniformly with other subject software.

A particular software component might play the role of a platform in some situations and a client in others. For example a browser is a platform for the content of the page but it also relies on the operating system below it.

The platform is the context in which the conformance scope exists.

Video can be made up of animated or photographic images, or both.

A modal dialog box would constitute a new view because the other content in the viewport is no longer actively available.

The author has no control of the viewport and almost always has no idea what is presented in a viewport (e.g. what is on screen) because it is provided by the platform. On browsers the hardware platform is isolated from the content.

Content can be presented through one or more viewports. Viewports include windows, frames, loudspeakers, and virtual magnifying glasses. A viewport may contain another viewport. For example, nested frames. Interface components created by the user agent such as prompts, menus, and alerts are not viewports.