Web Access Centre

Audio and video - Web Access Centre

Summary: Audio and video are really helpful to a number of people who use the web but need to have an accessible alternative.

• Rationale
• Techniques
• Testing techniques
• Website Accessibility Initiative compliance
• Other pages about multimedia

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Rationale

Audio and video are great tools for communicating information to your audience. If used correctly they can also enhance the accessibility of a website by becoming additional means of providing information. Audio and video can also be great for learning.

The problem is that, without text alternatives, audio and video is inaccessible to people who are deaf, blind or both deaf and blind. In addition to this not all users will have a media player or support for a media player such as Real, QuickTime or Media Player.

Providing audio and video content should be thought of as a visual aid, and not the primary means of presenting content. When used alongside an accessible alternative, audio and video can considerably enhance the accessibility of a page. For example people with cognitive or language problems will find it easier to absorb information when they can hear or see it.

Techniques

• Text transcripts to the audio or video must be provided in HTML format. This can be just a text transcript on the page where the audio is linked to or it can be static images (with good descriptive ALT text) and accompanying text on a web page. If the audio track contains speech, provide a text transcript. This is fairly straightforward for speeches or news pieces.

If the video is more conceptual good judgement is required as to what information is included in the transcript. For example video of a dance would need a transcript detailing who, time, place and a conceptual overview of what is happening rather than a word for word description.

• Alternative content should be provided within the OBJECT element. This should be a brief description or title of the content and instructions of where else it can be accessed. This will be picked up by assistive technologies and text-based browsers (which do not support audio or video) as well as by some search engines.

• Controls such as on and off buttons should be provided in video and Flash movies that have sound. Sound in a movie can conflict with a screen reader so the user should be given the ability to start and stop it.
  
  
• Link to media player downloads so that a user can download a player or update an older version player, if they have browser support for one.
  
  
• Provide captioning where possible for video. A transcript should be provided in closed captions and encoded into the audio or video track itself. Where possible this should be synchronised with the audio or video track.
  
  
• Web casts are very difficult to provide alternatives to in real time. WAI (Website Accessibility Initiative) guidance states that alternatives do not have to be presented in real time and can be added retrospectively.

Testing techniques

Verify that audio and video has alternative text content and all OBJECT elements have alternative content.

• Automated tools - Automated tools should flag presence of multimedia files. Manually assess whether alternative links are present.
  
  
• Accessibility toolbar - Go to Doc Info - Identify Multimedia Files.
  
  
• Browser - View all content and manually assess pages to see if there is an alternative to the video and audio content. Check that content is available to a user who is blind or has a hearing impairment.

Check in the <object> tag for alternative content. Go to View - Source - Edit - Find "<obj".

Website Accessibility Initiative compliance

• 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
  
  
• 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

For more information on techniques visit the Web Accessibility Initiative techniques page.

Other pages about multimedia

• Audio and video
• Flash
• PDFs

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Content author: webaccess@rnib.org.uk

Last updated: 06/03/2008 15:41