In Drupal 8 annotations for video and audio is achieved using the following two modules.
Open Video Annotation (OVA) Module allows rendering Video and Audio separate nodes with Field Formatters like OVA Video Formatter and OVA Audio Formatter. This module support Annotations by using VIDEOJS Plugin over video and audio. We can store the annotations by using Annotation Module in drupal 8 https://www.drupal.org/project/annotation_store. This module supports Textfield formatter which plays the video and audio as a link which will given in the textfields.
- Install this modules in modules/contrib folder.
- Create a 'text' fields for Audio and Video.
- Choose the formatters like Ova Audio Formatter & Ova Video Formatter.
- Allowable formats for Video: mp4, ogg, youtube, webm.
- Allowable formats for Audio: mp3
Annotation Store Module is mainly focused on storing the video annotation data [Open Video Annotation Library] locally in drupal. This modules creates the annotation data as an entity in drupal 8 in the name of "annotation_store". The entities which are created is listed at "/admin/annotation_store/list". Annotation list link is provided at '/admin/content'. Display date format at annotation list can be configures at/admin/config/media/annotation_store. This information includes Annotation text, type, URI, user, created and changed time stamp.
NOTE: To work around open video annotation and audio annotation in drupal 8 using OVA module and Annotation Store module, Refer the modules at https://www.drupal.org.