On the Interoperability of eBook Formats
Prof. Christoph Bläsi / Prof. Franz Rothlauf
Johannes Gutenberg-Universität Mainz – Germany
It is widely seen as a serious problem that European as well as international customers who have bought an ebook from one of the international ebook retailers implicitly subscribe to this retailer as their sole future ebook sup- plier, i.e. in effect, they forego buying future ebooks from any other sup- plier. In particular, this is a threat to the tight and qualified European book distribution infrastructure and hence to the European book culture, since subscribers to one of these ebook ecosystems cannot buy future ebooks from privately owned community-located brick & mortar booksellers engag- ing in ebook retailing. This view is completely in line with the European Commission: the Digital Agenda of the European Commission calls in pillar II (interoperability and standards) for an “effective interoperability between IT products and services to build a truly digital society. Europe must ensure that new IT devices, applications, data repositories and services interact seamlessly anywhere – just like the Internet.”
It is the task of this report to study whether convincing technological or functional reasons on the side of the international ebook retailers can be identified to justify non-interoperable ebook formats. Moreover, we study the digital rights management (DRM) measures employed by those retailers and question the necessity to build up additional walls between the ecosys- tems with the help of such measures. In the process, we will also address the challenge to protect intellectual property adequately across ebook eco- systems. And we evaluate the potential of the proposal for a common ebook format standard covering multimedia and interactivity features, EPUB 3 (as proposed by the IDPF in October 2011), and also dwell on interoperable options regarding the DRM protection of intellectual property.
Major players in the ebook market, especially Amazon or Apple, have built up closed ebook ecosystems in the last few years. eBooks that are distributed via one of these ecosystems are formatted using ecosystem-specific ebook formats like KF8 (Amazon) or Fixed Layout EPUB/.ibooks (Apple). As well as using incompatible ebook formats, Apple and Amazon fence their eco- systems with the help of DRM measures of various kinds. These measures prohibit the export and import of files to and from other ecosystems. Some of these measures are restrictive software-based methods using encryption. Thus, ebooks can only be read on ecosystem-specific end-user devices (or reader applications) such as the Kindle readers (in the case of the Amazon ecosystem) or iPads or iBooks (for the Apple ecosystem). The transfer of ebooks from one ecosystem into another is not possible (or, at least, requires measures that are not legal).
The main results of our study are the following:
1. eBook Formats: Having gone through the features of the different ebook formats (EPUB 3, KF8, Fixed Layout EPUB, and .ibooks) from page layout aesthetics to multimedia and interactivity, we conclude that EPUB 3 clearly covers the superset of the expressive abilities of all the formats.
Therefore, we cannot see a technological or functional reason to go on using proprietary ebook formats. A possible move from proprietary ebook formats to EPUB 3 on the side of Amazon and Apple would be facilitated by the fact that all formats have a common predecessor, namely EPUB 2 (from 2007 on). KF8, Fixed Layout EPUB, and .ibooks do not only share the underlying basic concepts for ebook production and distribution with EPUB 3, but also parts of the data structures. Moreover, Apple was actively engaged in the definition of the EPUB 3 standard; with Amazon’s KF8, it can be observed that more recent versions converge with EPUB 3 with respect to a growing number of features.
2. Digital Rights Management Measures: The general use of EPUB 3 as an interoperable ebook format would not in itself lead to full interoperability of ebooks for customers. The reason for that is that Apple and Amazon additionally fence their ecosystems with the help of DRM measures of different types and robustness. To overcome some of these obstacles to full interoperability, unilateral decisions of the enterprises in question would suffice, e.g. by offering data file import and export on the inter- faces of their reader applications. For others – software-based methods using encryption, mostly at the request of the copyright holders – more fundamental measures would have to be taken, including multi-lateral agreements on using compatible or identical encryption solutions, e.g. open (source) solutions.
To sum up, there is no technical or functional reason not to use and establish EPUB 3 as an/the interoperable (open) ebook format standard. One short- term obstacle is the non-availability of reader applications able to display all EPUB 3 features. However, this problem should be fixed soon by the IDPF Readium initiative which is developing an open source reference system and rendering engine for EPUB 3. Given the will to do so on the side of Amazon and Apple, the DRM barrier between the ecosystems could be partly over- come by simple changes to the respective store and reader applications, and partly only by more demanding agreements between different players on interoperable DRM solutions. The latter is only necessary if copyright holders continue insisting on having their intellectual property protected by highly restrictive measures.