Multimedia with synchronized alternative |
Section 508 1194.22(b); WAI / WCAG 1.0 checkpoint 1.4
Issue Description The page contains elements such as OBJECT or EMBED tags embedding multimedia files or elements referring directly to them (such as A or AREA tags). Make sure equivalent alternatives such as captions or auditory descriptions of the visual track are synchronized with the multimedia presentation.
How to check The page contains elements such as OBJECT or EMBED tags embedding multimedia files or elements referring directly to them (such as A or AREA tags). Make sure the following requirements are met:

- For any multimedia content, text captioning is provided for all audible output
- All audio descriptions and text captions are synchronized with their associated dynamic content

Issue Explanation Auditory presentations must be accompanied by text transcripts or textual equivalents of auditory events. When these transcripts are presented synchronously with a video presentation, they are called captions and are used by people who cannot hear the audio track of the video material.

Some media formats such as QuickTime 3.0 and SMIL allow captions and video descriptions to be added to the multimedia clip. SAMI allows captions to be added.

Until the format you are using supports alternative tracks, two versions of the movie could be made available - one with captions and descriptive video, and one without. Technologies such as SMIL and SAMI allow separate audio/visual files to be combined with text files through a synchronization file to create captioned audio and movies.

Some technologies also allow the user to choose from multiple sets of captions to match their reading skills. For more information see the SMIL 1.0 specification at http://www.w3.org/TR/1998/REC-smil-19980615/.