EPUB 3 defines an implementation of synchronized media known as Media Overlays. This specification defines a profile of the SMIL grammar for synchronizing text rendering with audio playback.
Media Overlays documents are built using the following elements:
In order to synchronize a publication, each content document in a publication must have its own overlay
associated with it. Overlays are tied to content documents in the package document manifest using a
media-overlay attribute with the ID of the
item that defines the
The EPUB Samples Project contains the following publications that implement Media Overlays: