Other Multimedia
Other Accessibility Guidelines for Multimedia
The following are some other guidelines that should be validated for accessibility compliance for multimedia found on the Web site:
- Audio Control
- No Keyboard Traps
- Pause, Stop, Hide
- Pausing Time-based Media
- Summary Text
- Three Flashes or Below Threshold
Audio Control
If background audio automatically plays for more than 3 seconds, provide a means to pause, stop or lower the volume of the audio.
WCAG Guidelines referenced:
- Guideline 1.4 Distinguishable: Make it easier for users to see and hear content including separating foreground from background.
- 1.4.2 Audio Control: If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level. (Level A)
Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether or not it is used to meet other success criteria) must meet this success criterion.
- 1.4.2 Audio Control: If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level. (Level A)
No Keyboard Traps
Ensure all page functions are accessible from the keyboard. Avoid instances in which focus cannot be moved away from a page element such as an embedded multimedia file.
WCAG Guidelines referenced:
- Guideline 2.1 Keyboard Accessible: Make all functionality available from a keyboard.
- 2.1.2 No Keyboard Trap: If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys or other standard exit methods, the user is advised of the method for moving focus away. (Level A)
Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion.
- 2.1.2 No Keyboard Trap: If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys or other standard exit methods, the user is advised of the method for moving focus away. (Level A)
Pause, Stop, Hide
For moving, blinking, scrolling or auto-updating information, provide a mechanism to pause, stop or hide the content.
WCAG Guidelines referenced:
- Guideline 2.2 Enough Time: Provide users enough time to read and use content.
- 2.2.2 Pause, Stop, Hide: For moving, blinking, scrolling, or auto-updating information, all of the following are true: (Level A)
Moving, blinking, scrolling: For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential; and
Auto-updating: For any auto-updating information that (1) starts automatically and (2) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it or to control the frequency of the update unless the auto-updating is part of an activity where it is essential.
Note 1: For requirements related to flickering or flashing content, refer to Guideline 2.3.
Note 2: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.
Note 3: Content that is updated periodically by software or that is streamed to the user agent is not required to preserve or present information that is generated or received between the initiation of the pause and resuming presentation, as this may not be technically possible, and in many situations could be misleading to do so.
Note 4: An animation that occurs as part of a preload phase or similar situation can be considered essential if interaction cannot occur during that phase for all users and if not indicating progress could confuse users or cause them to think that content was frozen or broken.
- 2.2.2 Pause, Stop, Hide: For moving, blinking, scrolling, or auto-updating information, all of the following are true: (Level A)
Pausing Time-based Media
Make sure that time limits are adjustable.
Some users may take longer to read through content.
WCAG Guidelines referenced:
- Guideline 2.2 Enough Time: Provide users enough time to read and use content.
- 2.2.1 Timing Adjustable: For each time limit that is set by the content, at least one of the following is true: (Level A)
Turn off: The user is allowed to turn off the time limit before encountering it; or
Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or
Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times; or
Real-time Exception: The time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or
Essential Exception: The time limit is essential and extending it would invalidate the activity; or
20 Hour Exception: The time limit is longer than 20 hours.
Note: This success criterion helps ensure that users can complete tasks without unexpected changes in content or context that are a result of a time limit. This success criterion should be considered in conjunction with Success Criterion 3.2.1, which puts limits on changes of content or context as a result of user action.
- 2.2.1 Timing Adjustable: For each time limit that is set by the content, at least one of the following is true: (Level A)
Summary Text
Provide summary text descriptions of interactive content.
If embedded interactive content cannot be made completely accessible, provide a text description summarizing the description and purpose of the interactive content.
WCAG Guidelines referenced:
Three Flashes or Below Threshold
Some people with seizure disorders can have a seizure triggered by flashing visual content. The objective of this guideline is to ensure that content that is marked as conforming to WCAG 2.0 avoids the types of flash that are most likely to cause seizure when viewed even for a second or two.
WCAG Guidelines referenced:
- Guideline 2.3 Seizures: Do not design content in a way that is known to cause seizures.
- 2.3.1 Three Flashes or Below Threshold: Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds. (Level A) Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion.