Creating Accessible LibGuides

Audio and video content is considered a time-based media option because the information presented is revealed over time. It is important to provide alternatives to time-based media. 

Level A

• Include a text alternative for all non-text content. See the criteria for a list of exceptions  (Success Criterion 1.1.1)
• Audio-only and video-only content offer the same information in non-media form (e.g. transcript) (Success Criterion 1.2.1)
• Provide synchronized captions (Success Criterion 1.2.2)
• Provide an audio description or text alternative (Success Criterion 1.2.3)
• Audio tracks that play automatically for more than 3 seconds must include a way to pause/stop the audio or allow for volume control (Success Criterion 1.4.2)

Level AA

• All pre-recorded videos include an audio description (Success Criterion 1.2.5)

Level AAA

• Provide a sign language alternative for prerecorded videos (Success Criterion 1.2.6)
• For videos that do not have enough time in between pauses to add audio description, provide a version with extended pauses and audio description (Success Criterion 1.2.7)
• Provide non-media options for all pre-recorded audio and video (Success Criterion 1.2.8)
• Background sounds must be four times quieter than foreground sounds (Success Criterion 1.4.7)

Non-text Content

All non-text content has a text alternative that serves the same purpose, except for:

• Input Controls - If non-text content has a description within its name, then alt text is not necessary. For example, a box in a form where a last name will be entered, and “Last Name” is next to the box.
• Time-Based Media - When non-text content such as video or audio is used (media that relays information over a period of time), alternative descriptions can be provided for identification. (for Level A)
• Test - If the non-text content is in a test and directly naming it in the alt text would give away the answer, provide a useful description. For example, people are asked to identify a picture of Chris Hadfield and his name is the answer. The alt text can be “A famous Canadian astronaut”.
• Sensory - Non-text content that presents information to make people feel a certain way upon viewing/listening, a descriptive text can be used instead of a transcript.
• CAPTCHA - Captcha is strongly discouraged by the accessibility community. However, if it is necessary, consider more than two captcha options or a sign-in that allows registered users to avoid having to use it.
• Decoration - Non-text content can be ignored by assistive technology if it is just decoration and can be marked so with ARIA.

Images that do not convey content, are decorative, or contain content that is already conveyed in text are given empty alternative text (alt="") or implemented as CSS backgrounds. All linked images have descriptive alternative text.

WCAG 2.2 example:

The link to an audio clip says, "Chairman's speech to the assembly." A link to a text transcript is provided immediately after the link to the audio clip.

Audio-only and Video-only (Prerecorded) (Level A)

Provide a non-media alternative to prerecorded audio and video, for example a text transcript (audio) or a description of the media (video), unless the audio or video is already an alternative to text. 

Captions (Prerecorded) (Level A)

Include synchronized captions with prerecorded audio or video materials, unless the audio or video is already an alternative for text.

Audio Description or Media Alternative (Prerecorded) (Level A)

Prerecorded video should include audio description (added during gaps in dialogue) or another non-media option, unless the video is already an alternative for text.

*Note: if all of the information in the video track is already provided in the audio track, no audio description is necessary.

WCAG example:

A company purchases a Training video for use by its employees and puts it on the companies intranet. The video involves explaining use of a new technology and has a person talking and showing things at the same time. Since there is no place to insert audio description of the visual demonstrations during gaps in dialogue, the company provides an alternative for time-based media that all employees, including those who cannot see the demonstrations, can use to better understand what is being presented.

Audio Description (Prerecorded) (Level AA)

All prerecorded video includes audio description.

*Note: if all of the information in the video track is already provided in the audio track, no audio description is necessary.

WCAG example:

A movie with audio description.

• Describer: A title, "Teaching Evolution Case Studies. Bonnie Chen." A teacher shows photographs of birds with long, thin beaks.
• Bonnie Chen: "These photos were all taken at the Everglades."
• Describer: The teacher hands each student two flat, thin wooden sticks.
• Bonnie Chen: "Today you will pretend to be a species of wading bird that has a beak like this."
• Describer: The teacher holds two of the sticks to her mouth making the shape of a beak.

Transcript of audio based on the first few minutes of " Teaching Evolution Case Studies, Bonnie Chen" (copyright WGBH and Clear Blue Sky Productions, Inc.)

Sign Language (Prerecorded) (Level AAA)

All prerecorded audio includes sign language or a sign language alternative.

Extended Audio Description (Prerecorded) (Level AAA)

For videos that do not have enough time in between pauses to add audio description, a version with extended pauses and audio description is provided. 

WCAG example:

Video of a lecture - A physics professor is giving a lecture. He makes freehand sketches on the whiteboard, speaking rapidly as he draws. As soon as he has finished discussing one problem, he erases the drawing and makes another sketch while continuing to speak and gesture with his other hand. The video is paused between problems, and extended audio description of the professor's drawings and gestures is provided; the video is then resumed.

Alternative (Prerecorded) (Level AAA)

For all prerecorded audio and video, non–media alternatives are provided.

*Note: if all of the information in the video track is already provided in the audio track, no audio description is necessary.

WCAG 2.2: 1.2.3, 1.2.5, and 1.2.8 overlap with each other to give the author some choice at the minimum conformance level, and to provide additional requirements at higher levels.

Audio Control (Level A)**  

Automatic audio on a website that plays for more than 3 seconds must include a way to pause/stop the audio or allow for volume control.

**This is a non-interference requirement. See Conformance Requirement 5: Non-Interference

Low or No Background Audio (Level AAA)

For prerecorded audio when:

1. The foreground is speech
2. It is not an audio CAPTCHA option or logo
3. It is not any kind of singing/rapping/musical, must include one of the following:

• No background -  The background is silent.
• Turn off  - The volume of the background can be turned off.
• 20dB  - The background decibel level is 20< than the foreground speech, unless the sound is shorter than 2 seconds.

*Note - The meaning of decibel in this case is that the foreground is 4 times louder than the background.

"Copyright © 2020 W3C® (MIT, ERCIM, Keio, Beihang). This software or document includes material copied from or derived from Web Content Accessibility Guidelines (WCAG) 2.2."