We have posted some ePub samples on the AZARDI resource page to enable publishers to possibly understand and evaluate the various transition issues when making decisions about when to move to ePub 3, and how.
The samples include four Gutenberg books processed as ePub2, ePub3+2 (transitional) and ePub3 directly out of IGP:Digital Publisher. I could have added a KF8 mobi as well but that would have been showing off, and AZARDI doesn't like them.
The most interesting issue with these ePub variants is how they work on various readers - the reason for this evaluation set. It helps to set a baseline of understanding the issues.
Cover treatment is probably the biggest issue, but ePub 3 also has a cute little landmarks section that will only be seen in AZARDI right now.
The results were pretty much as expected. Covers were a big issue in ePub2 as they were not explicitly handled in the specification.
The ePub 3 spec has addressed that ommission enthusiastically, with the cover-image property marking the cover loud and clear so Reader applications can locate this explicitly. AZARDI uses that for thumbnail and dedicated cover in TOC presentation.
In principle it is not necessary to put a cover in the spine with ePub 3, but we have to wait and see what comes out when the trade readers are updated or released.
Obviously no ePub 2 reader is going to understand, load, and read the ePub3 Landmarks and TOC.xhtml. But there was a surprise with iPad.
All files were validated with the epubcheck 3.04B version released Monday.
This is what we have done:
Packaging: ePub2 gets the standard ePub2 packaging treatment. The cover HTML is inserted in the spine and the cover image ID is inserted into the metadata.
ADE iPad. Both display cover thumbs and cover page which you would expect. This is the baseline for readers today.
Packaging: Our ePub3 package currently contains a cover HTML file and cover image in the manifest, but does not insert the cover HTML into the spine. The cover image has the properties attribute cover-image="coverID".
An ePub 3 reader is meant to be able to decide what it wants to do with the cover. AZARDI extracts and uses the image only (JPG, SVG or PNG) and ignores the HTML page. However if it had been inserted in the spine it would have presented fine, but there would be two covers - the Reader managed one, and the one inserted into the spine.
ADE. The ePub3 content pages load and no TOC is shown. There is no cover thumb or page.
iPad. The Reader squeals "This book cannot be opened because the format is not recognized, or is invalid." A nice politically correct message.
Packaging: The transitional ePub is the same packaging as the ePub3 but also contains the ePub2 guide and ncx. That means no cover.html in the spine.
ADE. Pages and TOC load OK but no cover is seen in either.
iPad. Pages and TOC load. It manages to display a thumbnail in the library which is nice.
With the promise/hype/threat of Apple announcing ePub 3 support on 19th January 2012 it is useful to have a few samples of these ePub variants available to see how it all runs.
We put up a small variety set. The same but different. People of the Abyss is lavishly illustrated! The covers are the same but the ePub version is included in the title of each ePub variant so they stand out in table/list library view in any reader.
- A Christmas Carol - Charles Dickens Released early for Xmas 2012.
- Siddharth - Herman Hesse - Part Chapter structure.
- People of the Abyss - Jack London - Images.
- Hound of the Baskervilles - Arthur Conan Doyle. A ripping good yarn.