Is your feature request related to a problem? Please describe.

EN 301 549 7.1.5 requires spoken subtitles. Able Player already has the ability to voice audio description, which can be used to mock up spoken subtitles, but it's not a supported option otherwise.

Describe the solution you'd like

Add an option to enable voiced captions in the caption settings. If enabled, pass the caption string to voice synthesis or set aria-live attributes on the caption container.