Section 3.3: Relevant accessibility standards and guidelines

All 3 of the major accessibility standards and guidelines refer to some aspect related to multimedia. The need to provide equivalents for non-text content is one of the most important, but there are other areas to consider as well.

Section 508

• (a) A text equivalent for every non-text element shall be provided (e.g., via "ALT", "longdesc", or in element content).
• (b) Equivalent alternatives for any multimedia presentation shall be synchronized with the presentation.
• (j) Pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz.
• (m) When a web page requires that an applet, plug-in or other application be present on the client system to interpret page content, the page must provide a link to a plug-in or applet that complies with §1194.21(a) through (l).

Web Content Accessibility Guidelines 1.0

Guideline 1. Provide equivalent alternatives for auditory and visual content.

• Checkpoint 1.1: Provide a text equivalent for every non-text element (e.g., via "ALT", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ascii art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
• Checkpoint 1.3: Until user agents can automatically read aloud the text equivalent of a visual track, provide an auditory description of the important information of the visual track of a multimedia presentation. [Priority 1]
• Checkpoint 1.4: For any time-based multimedia presentation (e.g. a movie or animation), synchronize equivalent alternatives (e.g., captions or auditory descriptions of the visual track) of a multimedia presentation. [Priority 1]

Guideline 7. Ensure user control of time-sensitive content changes.

• Checkpoint 7.1: Until user agents allow users to control flickering, avoid causing the screen to flicker. [Priority 1]

Guideline 8. Ensure direct accessibility of embedded user interfaces.

• Checkpoint 8.1: Make programmatic elements such as scripts and applets directly accessible or compatible with assistive technologies. [Priority 1 if functionality is important and not presented elsewhere, otherwise Priority 2]

Guideline 9. Design for device-independence.

• Checkpoint 9.3: For scripts, specify logical event handlers rather than device-dependent event handlers. [Priority 2]

Guideline 14. Ensure that documents are clear and simple.

• Checkpoint 14.2: Supplement text with graphic or auditory presentations where they will facilitate comprehension of the page. [Priority 3]

(WCAG 1.0)

Web Content Accessibility Guidelines 2.0 (Working Draft, 27 April 2006)

Guideline 1.1: Provide text alternatives for all non-text content

• Level 1 Success Criterion 1.1.1: For all non-text content, one of the following is true:
  • If non-text content presents information or responds to user input, text alternatives serve the same purpose and present the same information as the non-text content. If text alternatives cannot serve the same purpose, then text alternatives at least identify the purpose of the non-text content.
  • If non-text content is multimedia; live audio-only or live video-only content; a test or exercise that must use a particular sense; or primarily intended to create a specific sensory experience; then text alternatives at least identify the non-text content with a descriptive text label. (For multimedia, see also Guideline 1.2: Provide synchronized alternatives for multimedia.)
  • If the purpose of non-text content is to confirm that content is being operated by a person rather than a computer, different forms are provided to accommodate multiple disabilities.
  • If non-text content is pure decoration, or used only for visual formatting, or if it is not presented to users, it is implemented such that it can be ignored by assistive technology.

Guideline 1.2: Provide synchronize alternatives for multimedia

• Level 1 Success Criteria for Guideline 1.2
  • Success Criterion 1.2.1: Captions are provided for prerecorded multimedia.
  • Success Criterion 1.2.2: Audio descriptions of video, or a full multimedia text alternative including any interaction, are provided for prerecorded multimedia.
• Level 2 Success Criteria for Guideline 1.2
  • Success Criterion 1.2.3: Audio descriptions of video are provided for prerecorded multimedia.
  • Success Criterion 1.2.4: Captions are provided for live multimedia.
• Level 3 Success Criteria for Guideline 1.2
  • Success Criterion 1.2.5: Sign language interpretation is provided for multimedia.
  • Success Criterion 1.2.6: Extended audio descriptions of video are provided for prerecorded multimedia.
  • Success Criterion 1.2.7: For prerecorded multimedia, a full multimedia text alternative including any interaction is provided.

Guideline 2.3: Allow users to avoid content that could cause seizures due to photosensitivity

• Level 1 Success Criterion 2.3.1: Content does not violate the general flash threshold or the red flash threshold.
• Level 3 Success Criterion 2.3.2: Web units do not contain any components that flash more than three times in any 1-second period.