This respository contains a test file with an automatically generated word-by-word media overlay.
Sources of the original files:
The EPUB was downloaded from the Gutenberg project at https://www.gutenberg.org/ebooks/11
The audio book was downloaded from the librevox project at https://librivox.org/alices-adventures-in-wonderland-by-lewis-carroll/
The automatically created media overlay is far from perfect, but it illustrates some problems with the current media overlay implementation of the Readium R2 javascript reader and can be used for other test purposes.