University of Tasmania, Australia

About live audio with video and accessibility

Making live audio with video (multimedia) accessible can benefit people with movement, visual, hearing, cognitive or seizure-related disabilties.

Single A

Making the multimedia

Starting with 'shooting' with a camera or capturing video, make sure that:

• If colour is an important part of the information, it is also combined with pattern - for people:
  • sitting where there is screen glare, or
  • using an old screen, or
  • who have low vision or colour blindness, or all or any of the above
• None of the content flickers rapidly, or if it does flicker, keep the flickering area safely small. There are formulas to help calculate the safest size of the flickering area for people who have photosensitive epilepsy

Making the purpose of your multimedia clear

Because a multimedia file is not text, it cannot be 'read' by a screen reader. Therefore, it must have a text alternative that serves the same purpose. This alternative must also be identified so people know it is non-text content. This alternative can be

• A short description, if it serves the same purpose
• A long description that serves the same purpose

Or, a brief description of the multimedia and:

• A long description as a link next to the multimedia, or
• A long description in the text near the multimedia, with a reference to the long description in the short description, or
• Adding a text alternative to the 'embed' tag with noembed when putting the multimedia in a webpage, as the noembed content is rendered if embed is not supported. Note: embed is widely supported by user agents and assistive technology but is not part of HTML or XHTML

Operating the multimedia in a webpage

People must be able to operate the multimedia by any input device. Therefore, just providing functionality for the mouse is not enough, although the mouse should be able to access any content on the page. The keyboard must be able to operate the all functionality of the multimedia. Also

• There must not be a time limit for interacting with the file, or any time limit should be able to be extended
• If the file contains blinking content, then it must be able to be paused or stopped
• The file must not trap the keyboard (not let people tab away from the file)

Double A

Making the multimedia

No specific requirements relating to pre-recorded multimedia production. Although if any text is included in the video, as screens or information added to preceed the viewing of the multimedia, such as credits or advertisements

• All text should have sufficent contrast with the background. There are tools to test the contrast between foreground and background of text

Making the purpose of your multimedia clear

Captions must be added to the audio in live multimedia to help people with hearing or cognitive impairments understand the content. They also help people understand content if the language of the captions is unfamiliar. Captions must be

• Synchronised with the audio and video displaying information that applies to the timeline
• Contain enough information to provide an alternative to the combined content of the video and audio
• Operable by the user (if closed)

Captions can be

• Open (always visible), OR
• Closed (opened by the user)

Operating the multimedia in a webpage

The controls to operate the multimedia should be accessible with a keyboard, and should be visible (highlighted) when they receive focus. Therefore it is best to keep it simple, so developers should keep the default 'focus' functionality of the browser, assistive technology or operating system.

Triple A

Making the multimedia

• The video content should not include any content that flashes more than three times in any one second period. There are tools to test videos for content that could trigger seizures
• When recording the foreground audio, for example, speech, must be 20 decibels louder that any background noise. This can be achieved during recording or by mixing the audio file to maximise the audibility of foreground sound

Making the purpose of your multimedia clear

• Tell the same 'story' in the multimedia in a separate document
• Include a sign language interpreter in the video stream
• Provide a synchronised video of a sign language interpreter, that can be displayed in a different window or overlaid on the image by the player