bnc tech forum 2010: designing ebooks for epub reading engines

Open source ePub: Digital Books

Liza DalyThreepress Consulting Inc.

Thursday, April 1, 2010


This is the collection of ereaders and mobile devices I have at the office. I use them to test ebooks as well as report on the capabilities of the various hardware readers out there.

TextPlus one netbook, two Macs, one Windows laptop, and an iPad (on order).


That doesn’t even count the most popular ereading devices today: the multiple computers, netbooks and tablets.

?Thursday, April 1, 2010

The challenge: How do book designers and publishers effectively design ebooks for large screens, small screens, and screen dimensions and platforms that haven’t launched yet?

Thinking about devices


Thinking about devices

Thinking about reading engines


I’d like to propose that we change the conversation from thinking about specific devices (which multiply every day) to thinking about “reading engines.”

Reading engines put text on the screen


A reading engine is the part of the ereading software that actually places text on the screen. It’s the most basic, primitive component of any ereader.

Mobi: fail

AdobeReader Mobile SDK

WebKit


Fortunately for ebook producers, there are far fewer reading engines than devices. This talk will focus on the two most popular reading engines for ePub books: Adobe Reader Mobile SDK (RMSDK) and WebKit.

Adobe Reader Mobile SDK

Software that is licensed to device-makers and software partners to provide Adobe’s

EPUB support and DRM.




RMSDK doesn’t technically power Adobe Digital Editions, but it’s very close in terms of its behavior.



RMSDK includes both the reading engine and the DRM server. Licensees get both, so in most cases if a reader supports Adobe EPUB DRM, it uses the RMSDK reading engine.

With great power...

• Limited CSS support•No support for foreign

characters (without font embedding)•Narrow default margins•Multimedia only via Flash•Adobe-only extensions

•Almost industry- standard DRM•Consistent rendering

across devices• SVG support• Flash support•More precise pagination

and layout controls


There are some advantages and disadvantages to this approach. I’m going to focus on how to turn the disadvantages into cost savings during ebook production.

...at least the bugs are consistent


Once you understand what uses RMSDK, it’s possible to see the same issues across many different software programs and devices.

Readers using the RMSDK:

•Digital Editions• Sony Reader• Sony desktop reader•Barnes & Noble nook• IREX

• txtr• Spring•PlasticLogic•Kobo Reader (device

only)


WebKit


WebKit powers a number of different web browsers and mobile browsers. If you’ve used Google Chrome, Safari, the iPhone/iPad/iPod Touch, Android or Palm Pre/Pixi, you’ve used WebKit.

WebKit


Though there are other browser engines on the desktop web (IE, Firefox’s Gecko, Opera), WebKit has quickly dominated the mobile web.

WebKit


and it’s expected to grow as other kinds of mobile devices replace their own browsers with it.

Ereaders using WebKit


Although WebKit isn’t technically a reading engine, because ePub is so similar to web technologies, it makes an excellent tool for building an ereader. Most mobile ereaders use WebKit, and any browser-based solution (Bookworm, Ibis Reader) will be using it on the right browser. iBooks is almost certainly WebKit-based.

Ereaders using WebKit


Some devices are hybrids. The Spring Design Alex ereader uses both RMSDK and WebKit, via its built-in Android browser.

WebKit vs. Mobile SDK(Barnes & Noble vs. itself)


Some ecosystems are also hybrids. Kobo also follows this pattern, where they have a custom WebKit-based software for computers and mobile devices, but RMSDK on hardware devices.

Designing for 99 devices


Designing for 99 devicesDesigning for 2 reading engines


So thinking about reading engines can really simplify issues around ebook design.

Avoid Adobe-specific extensions...

...except to solve Adobe-specific problems

Surviving Digital Editions


Here are some techniques for optimizing for the Adobe ecosystem without affecting the validity of your ebooks.

Page templates (XPGT) control the layout and flow of pages in ADE-related reading engines

Mostly harmless

http://blogs.adobe.com/digitaleditions/template.html





Mostly harmless

XPGT lets you control page breaks and widths of columns in RMSDK software, and still produce valid ePubs




Mostly harmless

Work around RMSDK’s poor international font support with embedded open-source fonts.

http://blog.threepress.org/2009/09/16/how-to-embed-fonts-in-epub-files/




Considered harmful

InDesign font obfuscation isn’t compatible with other systems and isn’t in the ePub spec.





Considered harmfulADE will only display the first dc:author - don’t work around by adding multiple authors in a single field. That’s bad metadata!

http://blog.threepress.org/2009/11/27/practical-epub-metadata-authorship/




Considered harmful

Adobe’s page-map, mapping print pages to ebook “pages,” is not in the ePub spec and won’t work anywhere else.

http://blog.threepress.org/2009/11/26/adobe-page-map-versus-ncx-pagelist/




Designing for the future of ePub

Keep markup minimal and semantic.



Specifying the spacing between a header and body text is presentational.

Specifying some spacing between a scene change is semantic.

Keep markup minimal and semantic.


Some tips that will work well in WebKit and all future ePub implementations include being thoughtful about what design elements are specified in the book. Try to keep to purely semantic markup and styling.


Prefer padding to margin.

Use Adobe’s extensions to handle page breaks and margins; let other readers decide for “themselves.”

Restrict CSS to inside the content.


Test and preview in:

RMSDKBig WebKitLittle WebKit


My recommended testing paradigm: test in one RMSDK device/software (usually ADE), one “big WebKit” like a web browser or iPad, and one “small WebKit”, or mobile device or browser.

Multimedia?

No HTML5 in ePub...

...but no Flash on the iPad


Designing for the future of ePub: what about multimedia? Unfortunately Flash is no longer the easy answer. HTML5 <video> adoption will come to ePub eventually, but for now it will produce invalid ebooks in most case.

These companies are betting HTML5:

and provide significant resources for WebKit development...


However, looking ahead, I think the smart money is on what Google and Apple are doing.


...means designing for WebKit


This doesn’t mean that you should ignore the Adobe ecosystem! It’s the most significant part of the marketplace right now. And don’t design two different ebooks -- all these techniques can be used in the same ePub file successfully. But in my opinion, the future will be browser-like reading engines.

Thanks!

Liza DalyTwitter: @[email protected]

http://threepress.org


mailto:[email protected]

mailto:[email protected]



bnc tech forum 2010: designing ebooks for epub reading engines

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