The work done here on adpt has been used at least in part as the basis for DAPT, under development by the Timed Text Working Group. DAPT's scope additionally includes the creation of dubbing scripts.
No further work is expected on ADPT.
The Audio Description Profile of TTML2, by the Timed Text Working Group is a profile of TTML2 suitable for the scripting, voicing and audio mixing of audio descriptions for videos. This work was originally made by the Audio Description Community Group, and contributions can be made also via the W3C Audio Description Community Group.
It is intended to meet the requirements set out in the Requirements for Audio Description, currently residing in the TTML2 repo's wiki space.
The Editor's Draft can be viewed at https://w3c.github.io/adpt/