Synchronised audio description (time-based media)

Narration added (via a sound file) to an audio track to describe important visual details that cannot be understood from the main audio track alone. The audio description must be synchronised with the time-based media by a feature of the player itself or provided by the developer, for example with JavaScript.

Note 1: the audio description of a video provides information about actions, characters, scene changes, on-screen text and other visual content.

Note 2: in a standard audio description, narration is added during pauses in the dialogue.

Note 3: when all the information in the video is already given in the audio track, no additional audio description is required.