Adobe Digital Editions

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Adobe Digital Editions, ADE, is a eBook reader for Windows and MacOS X. It can read ePUB documents, PDF documents, and Adobe Flash® SWF. There is also a Mobile Edition for specific eBook Readers.

Contents

[edit] Features

  • Adobe Digital Editions (ADE) is a new, rich Internet application (RIA) built from the ground up for digital publishing. It is a simplified, engaging way to acquire, manage, and consume eBooks and other kinds of digital publications.
  • It focuses on Reading and managing eBooks, unlike Acrobat Reader that is intended to read all kinds of eDocuments, not just eBooks.
  • The Reader is free and requires less that 3 MegaBytes to install.
  • Formats supported include: PDF/A and an OPS (enhanced OEBPS, which is a profile of XHTML 1.1 with OCF packaging) are the two publication-level content types, basically ePUB with limitations.
  • SWF content and common image file types can be referenced within PDF- and XHTML-based publications.
  • Common DRM format called ADEPT for supported file types. This is used by some publishers and in Libraries. Both DRM and non-DRM files are supported by the product.
  • A version is available for developers to use to provide ADE on portable devices.
  • PDF support includes a somewhat limited reflow ability to permit reading large format PDF documents on the smaller screens present on mobile devices.

[edit] acsm

When you download an encrypted DRM file such as one from a library you might see a .acsm file instead of the file you wanted. Generally this is invisible if everything is set up correctly.

The .acsm file is a small transfer file that contains the encryption codes necessary for downloading the actual eBook. All you should need to do is open the .acsm file using Adobe Digital Editions. Usually, when you install ADE it tells your web Browser to do this automatically when it sees an .acsm file.

[edit] ePUB extensions

Adobe has a number of extension to the ePUB standard.

[edit] Page-map

Adobe can add a page-map to provide mapping between the hardcopy book page numbers and the eBook. In the absence of a page-map ADE computes an arbitrary page number for each file in the spine using 1024 unicode characters as the page size. The last page in the file contains whatever overflow is needed.

If a page map is included the TOC entry in the content.opf file is modified to add a reference to the page map file: 

<spine page-map="map" toc="ncx">

The map needs an entry in the manifest section of the content.opf file as well. 

<item href="page-map.xml" id="map" media-type="application/oebps-page-map+xml"/>

A page-map file is an XML file that looks like: 

<?xml version="1.0" ?>
<page-map xmlns="http://www.idpf.org/2007/opf">
 <page name="" href="cover.html"/>
 <page name="i" href="halftitle.html"/>
 <page name="ii" href="other.html"/>
 <page name="iii" href="title.html"/>
 <page name="iv" href="copyright.html"/>
...
 <page name="1" href="part1.html"/>
 <page name="3" href="chapter1.html"/>
 <page name="4" href="chapter1.html#page_4"/>
 <page name="5" href="chapter1.html#page_5"/>
 <page name="6" href="chapter1.html#page_6"/>
 <page name="7" href="chapter1.html#page_7"/>
...
</page-map>

Most if not all of the portable devices supporting ADE use this page number as the eBook page number. Since most eBooks pages are not capable of showing 1024 readable characters on a screen there is usually multiple screens with the same page number. Sony, for example, displays page numbers on the status line that is the ADE number and a sub-number. If the Sony Reader showed 3-7 you see 3 ADE page number and a sub-number of 7 within that main number. The number of available sub-numbers varies since it is a virtual page number based in the screen and font size. Images will also increase the screen number but not the ADE number. The idea of the ADE number is to have a single number that can be referenced like a book reference you sometimes see in academic works so it should not change based on font size or screen size.

[edit] Layout Template

Adobe Digital Editions viewer implements several layout extensions to EPUB format which are collectively referred to as an XML page template (XPGT). These include:

  • Page Masters – specify XSL:FO page masters to add headers, footers and sidebars as well as multicolumn layout.
  • Dynamic Page Master Selection – choose the right page master based on the environment.
  • Dynamic Styling – style the document based on the environment (viewing area dimensions, default font size, device resolution, etc.)

These changes are all added to an additional stylsheet that is referenced from the XHTML file like any other stylesheet or import from another stylsheet: 

@import url(template.xpgt);

The XPGT file is also declared in the OPF manifest and assigned media type 

 “application/adobe-page-template+xml”.

XPGT uses XML rather than CSS-like syntax. This is further described in the Adobe ePUB Best Practices guide.

[edit] SWF

Since SWF is supported by ADE it is possible to Use Flash Video in ePUB.

[edit] obfuscated fonts

Both ADE and IDPF support obfuscated fonts which use and XOR (exclusive or) technique to obscure the fonts in an embedded font set so that it cannot be extracted and used by itself. This is done to meet the copyright requirements imposed by the font designer. Unfortunately the methods documented and used by ADE and idpf are different! Idpf defines the standard but ADE defines the way their SDK used by most eBook Readers actually work. Most eBooks using obfuscated fonts use the Adobe method.

[edit] Page numbers

Synthetic page numbers are used when the page map is not available in the document, Adobe Digital Editions will synthesize a page-map based on the document content. The approach used is the following:

  1. Determine a compressed byte length of each resource which is referenced in the spine, subtracting any known encryption overhead (IV size)
  2. Assume that there is a page for each 1024 bytes in each resource, rounding up to the nearest whole number of pages for each resource.
  3. To map page breaks into a resource, use the number of pages for the resource as determined in step 2, count the number of Unicode characters in the resource; distribute synthetic page breaks in the resource evenly between the characters by dividing the number of characters by the number of pages; if the number of characters don’t divide evenly among the pages, round the number of characters per page up and let the last “page” contain less characters than the rest.

[edit] Device Support

ADE also has a mobile edition called Adobe Reader Mobile SDK (RMSDK). It supports a number of mobile devices now exceeding 50 devices. Note that portable devices may not have all of the features of the full PC/Mac version. Typically SWF is not supported. The DRM used on ADE has been adopted by Overdrive for use in its library software to permit Library checkout of ePUB and PDF books. For the official list see: Adobe's blog which may not be up-to-date. Some devices have PC versions that match their mobile product. There are now so many devices that it is hard to keep a complete list. Check the descriptions of the individual devices in this wiki to determine if the device uses ADE or not. If it supports DRM then it is likely it uses ADE unless it is from Apple.

Some of the devices supported include:

[edit] For more Information

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