Adhere is an ES6 implementation of the audio features of TTML2 built using the Web Audio API and the Web Speech API, with timing events cued using Text Track Cues.
The project includes both library code and a web page demonstrating the code in use.
TTML2-based audio description files can support the entire audio description workflow from scripting to mixing, and include the timed script to be voiced, markup to trigger text to speech, or the recorded audio alongside audio mixing instructions to adjust the pan and gain to match current audio description user experiences on broadcast television.
The project was written to support standardization work and is not intended in itself to be used in production environments.