Now that the iBooks application is available on the iPhone and iPod touch under iOS4 as well as on the iPad, ePub has just become that much more important. Just as it did with RSS, Apple is finding and implementing ways to extend that standard. Including MPEG-4 audio and video in the text of an ePub document is a recent example. To be sure, these ePub documents won't play on very many devices other than iPad, iPhone and iPod touch via the iBooks application. At least not yet.

The technique employed by Apple is a straightforward one. Using the HTML 5 audio and video tags, these new elements appear and play as the following screen shot images illustrate. The first example involves adding audio to Lewis Carroll's classic "Alice in Wonderland" which is now in the public domain. Here, we see the table of contents:

Then, as we click on Chapter 2, we see the audio playback controller:

In another ePub title, we can see how video becomes a part of the ePub document. Here's the table of contents:

Clicking on Chapter 2, we see both chapters two and three, each with a video to accompany the text.

Clicking the "play" icon, the various control mechanisms appear. These quickly fade until a tap on the video brings them back.

Here's a closeup. Note the full screen option:

And here's the full screen view with controls visible. These controls also quickly fade until a tap on the video brings them back.

So there we are, audio and video in an ePub document and playing on iPad, iPhone and iPod touch. We should note the fact that this is not necessarily exclusive to Apple products. HTML 5, MPEG-4 and ePub are all open standards. Anyone building an eReader device or application should be able to follow Apple's lead.

You can check this out yourself by subscribing to my eBooks test channel and downloading these two examples. Look for these titles: "Video in ePub" and "Audio in ePub." Using a desktop or laptop computer, click here to subscribe.

Using this method, the eBooks will show up in both the Podcast and Books libraries in the iTunes application. The Podcast Library listing will look something like this:

The Books Library will look something like this:

New eBooks should be selected for synchronization by default but it is a good idea to check. Here's what that should look like in the iTunes app:

Now that we know that it can be done and that broad audiences can actually experience what we create, the next question is, "How do I do that?" I'll cover that in a future blog so stay tuned and keep those cards and letters coming.