The Sound and the Fury: Audio and Video

The new built-in support for audio and video in EPUB 3 has its pros and cons from both mainstream and accessibility perspectives. The elements simplify the process of embedding multimedia, but come at the expense of complicating interoperability, and by extension accessibility—specifically as relates to video.

There is currently no solution for the general accessibility problem of video, namely that not all reading systems may natively play your content. The video element permits any video format to be specified, but not all reading systems will support all formats. Support for one or both of the VP8 codec (used in WebM video) and H.264 codec is encouraged in the EPUB specification to improve interoperability, but you still have to be aware that if you have an EPUB with WebM video and a reading system that only supports H.264 you won’t be able to view the video.