Section 3.1: Defining accessible video and audio

Video and audio are accessible when you are "not relying on a single sensory capability to receive important information" [ 7, p.360 ]. Basically, this means that the content available in the audio track is also available for those who are hard-of-hearing or deaf, and the content in the video is available for those who are have low or no vision. Accessible video and audio can also make information easier to understand for those with learning disabilities or cognitive impairments because the information is presented in multiple modalities, such as being able to read the transcript as well as listen to the audio.

Like images, video and audio are considered to be non-text content that needs some type of alternative presentation of the content. There are several strategies and techniques for making multimedia accessible.

Accessible Video (with audio)

Alternative content for video will include one or both of the following, as appropriate:

• Captions for spoken word (visual presentation of auditory information)
• Audio descriptions of relevant action taking place on the screen (auditory presentation of visual information)

Both of these "alternatives should be synchronized with the action taking place on the screen. Modern video players support captioning and allow users to turn the caption on or off." [ 2 ]

Written words that are part of the video content should be included in the audio description; examples include the names of actors, directors and other credits presented at the beginning or end of the video; place-names, dates, etc., shown on screen during the video to indicate changes of location or passages of time; important signage that establishes a new scene (e.g., "Doctor's office"). If such information is available from the sound track, then it does not have to be included in the audio description. For example, if the receptionist can be heard saying, "Doctor's office" when answering the phone, the words "Doctor's office" on the sign don't need to be included in the audio description.

The audio description does need to include subtitles-words (usually at the bottom of the screen) that translate foreign dialogue into the language of the audience. These are essential to understanding the video, and are not read by screen readers.

Captions do not need to be included in the audio description. Users who are blind can hear the dialogue and other sounds in the video and do not require the captions. This is why screen readers do not read captions.

Accessible Audio (no video)

Alternative content for audio will include:

• Text transcription in HTML form (visual presentation of auditory information)

Rather than listening to the content in the audio file, the user will read it as they would any other content.

"This text transcription needs to be placed in the vicinity of the audio file. Ideally, the link to the audio file is accompanied by a second link that transports users to a web page where they can read the text transcription." [ 2 ]