Link to audio in XHTML/EPUB

I'm looking into synchronizing an ebook in epub format (so the content is in XHTML) to an audio file. I'm thinking of putting something along the lines of:

<a class="audiolink" href="sound.ogg?t=1093"></a>

into the body of the document, and then have a custom epub reader that recognizes those tags and synchronizes the audio accordingl开发者_如何转开发y. That does seem like a bit of a hack to me though, especially the use of a special class name.

Does anyone have any pointers to how this may be done in a more standards-compliant manner (or somewhere where it has been done before)? Ebooks with audio annotation seem like an idea that may already be out there.

Yes, it's an old idea, and yea-- it's a lot of work. See the DAISY Talking Book (DTBook) specification:

A subset of the DAISY format has been adopted by law in the United States as the National Instructional Material Accessibility Standard, and K-12 textbooks and instructional materials are now required to be provided to students with disabilities.

The EPUB spec includes the Open Publication Structure (OPS) spec which describes the content markup, which can be either XHTML, or ... wait for it... DTBook. The good thing for you is that DTBook is based on HTML, XHTML, and SMIL.

So you could use DTBook and some of the publishing toolchains that are available for authoring DTBooks, and then just wrap it up into an epub.

Synchronized reading is being pursued by an iphone startup, Enhanced Editions: http://www.enhanced-editions.com/blog/2010/02/enhancing-the-ebook/, so you'll have company.

Good luck.