Preparing your ePUB files to sell via Snapplify

This article is for CONTENT OWNERS. 

One of the many formats supported by Snapplify is ePUB.    

In order for your content to display correctly, you will need to ensure that the file requirements meet the required specifications.

The specifications and requirements for ePUB files are:

We subscribe to IDPF ePub standards. 
For more information on best practices for creating accessible digital publications, see the Accessible Publishing Knowledge Base.	

Video

When including video clips, ensure that the native reading system controls are enabled by default (i.e. by setting the controls attribute on the video element). 

This practice ensures that the controls are accessible, even if scripting is not available. If custom controls are provided and supported by the reading system, the native controls can be disabled by JavaScript.

Although the video element allows child content for fallback purposes, this content is not intended to serve as an accessible alternative. It is only made available to the reader if the video element is not supported by the reading system, which typically only occurs in EPUB 2 reading systems.

The following methods for making video content accessible are instead recommended in the HTML5 specification:

• Using the track element to include subtitles, captions and descriptions.
• Embedding subtitles and captions directly in the video.
• Providing navigation by scene using the track element (i.e. using the chapters track type).
• Providing a link to a transcript.

The video element also includes the poster attribute to allow a default image to be set for display while no data is available. There is currently no way to describe this image, however, so text fallbacks should be preferred.

Agreement on universal support for a video codec and container could not be reached in HTML5, and there is a similar issue for EPUB 3. Although the EPUB 3 specification technically allows any format (without fallback), the IDPF recommends one or both of the MP4 and WebM formats be included. While this might not seem like an accessibility issue, consider that it means that many more readers might be relying on fallbacks than you might at first anticipate.

Example 1: Enabling native controls with the controls attribute

<video controls="controls">

  <source

      src="video/the_general.webm"

      type="video/webm"/>

  <source

      src="video/the_general.mp4"

      type="video/mp4"/>

  …

</video>

Example 2: Including more than one video option using the source element

<video controls="controls">

 
  <source

      src="video/the_general.webm"

      type="video/webm"/>

  <source

      src="video/the_general.mp4"

      type="video/mp4"/>

  …

</video>

Example 3: Including timed tracks

<video controls="controls">

      src="video/big-hollywood-blockbuster.mp4"

      controls="controls">

  <track

      kind="subtitles"

      src="subtitles.en.vtt"

      srclang="en"

      label="English"/>

  <track

      kind="captions"

      src="captions.en.vtt"

      srclang="en"

      label="English"/>

</video>

Example 4: Including a poster image

<video

  src="video/the_general.mp4"

  poster="graphics/the_general.jpg"

  controls="controls">

  …

</video>

Example 5: Including a fallback error message

<video

      src="video/the_general.mp4"

      controls="controls">

  …

  <div class="err">

     <p>

        Sorry, it appears your system

        either does not support video

        playback or cannot play the

        MP4 format provided.

     </p>

  </div>

</video>

Learn how to prepare other types of files.
Next, learn how to compile your metadata by understanding metadata format options and digital rights management (DRM).

Need help? Reach out to us by emailing marketplace@snapplify.com.