HTML and CSS Reference
In-Depth Information
Note the
width
and
height
values specified in order to set the dimensions of the video,
and the addition of
controls
attribute to give the user access to the traditional video-
player buttons for controlling playback. For increased web browser compatibility, two
video files are made available: one in MPEG-4 format and one in Ogg format.
If you're planning to embed
<video>
content in EPUB, however, at this
time, I'd recommend limiting video files to MP4 format, which is cur-
rently supported by both iBooks and NOOK Color. Ogg files are not
supported by either of these ereaders, and may interfere with video dis-
play.
Additionally, when embedding video in EPUB, you may want to opti-
mize for file size, as large video files can quickly bloat your EPUB docu-
ment—another good reason to stick with just one video format.
Take a look at the
video clip in your browser
. The code and video clips are available
for
download in GitHub
.
EPUB 3 Media Overlays
The preceding examples are well suited to situations in which you want to intersperse
audio and video throughout your content, but what if you want to incorporate more
comprehensive functionality—say, provide an audio track for an entire book? For cases
like these, EPUB 3 provides a
specification for media overlay documents
that allows
you to sync audio with text:
Books featuring synchronized audio narration are found in mainstream e-books, educa-
tional tools and e-books formatted for persons with print disabilities. In EPUB 3, these
types of books are created by using Media Overlay Documents to describe the timing for
the pre-recorded audio narration and how it relates to the EPUB Content Document
recommendation for representing synchronized multimedia information in XML.
The Media Overlays feature is designed to be transparent to EPUB Reading Systems that
do snot support the feature. The inclusion of Media Overlays in an EPUB Publication
has no impact on the ability of Media Overlay-unaware Reading Systems to render that
Publication as a “regular” EPUB Publication.
Although future versions of this specification may incorporate support for video media
(e.g., synchronized text/sign-language books), this version supports only synchronizing
audio media with the EPUB Content Document.
*
As stated above media overlays are currently limited
only to audio
content (no support
for syncing video to text at the present time), and furthermore, support for overlays is
optional
, so EPUB 3-compliant ereaders are allowed to ignore them.
* From 8 September 2011 draft of “EPUB Media Overlays 3.0” specification:
http://idpf.org/epub/30/spec/
