Playing a sign language video from a video element's video track list



  • New technique.

This technique would be an Advisory Technique in Understanding 1.2.6 (Sign Language). Once there is sufficient user agent support, it would be a Sufficient Technique in the list under "G81: Providing a synchronized video of the sign language interpreter that can be displayed in a different viewport or overlaid on the image by the player".


  • HTML5 and client-side scripting

This technique relates to:

User Agent and Assistive Technology Support Notes

  • Jan 2014: Per the HTML5 spec, these features are all ready for first implementation.


It is clear that the HTML5 spec intends that this functionality be supported by playing multiple video objects together. There are several references to this, and an example in the description of video tracks.

However, there is no kind attribute for a video element; it only occurs in the API describing the VideoTrack object, and it is not clear what the source of the kind should be. Selecting specific audio and video tracks declaratively may be saying that the kind is specified as in the fragment identifier of the src URL, e.g., <video src="myvideo#track=sign"></video> Assigning a media controller declaratively shows such an example when discussing the mediagroup attribute.

References to supporting sign-language videos in the HTML5 spec Media resources with multiple media tracks Media resources with multiple media tracks starts with the explanation: "A media resource can have multiple embedded audio and video tracks. For example, in addition to the primary video and audio tracks, a media resource could have foreign-language dubbed dialogues, director's commentaries, audio descriptions, alternative angles, or sign-language overlays." It includes an example of script that loads a video, and, once it is loaded, checks to see if there is a sign-language track available. If there is, it also displays that track. Synchronising multiple media elements Synchronising multiple media elements starts with "Each media element can have a MediaController. A MediaController is an object that coordinates the playback of multiple media elements, for instance so that a sign-language interpreter track can be overlaid on a video track, with the two being kept in sync." Assigning a media controller declaratively shows an example where a sign-languge interpreter track from a movie file is overlaid on the primary video track of that same video file using two video elements, some CSS, and an implicit MediaController.



Related Techniques



Expected Results

  • Check that #1 is true