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Under the Hood and Behind the Curtains of the FB3 eBook Format

When news broke earlier this week that the Russian media retailer LitRes was adopting the FB3 ebook format, all we had to go on were the sparse details in the official press release.

That release lacked important info like the technical differences between FB2 and FB3, why the format has sat unused for four years, how readers will benefit, and why there was so little coverage of the announcement on Russian ebook blogs.

I still haven’t found an answer to the last question, but I do have information to share. I reached out to Nikolay Pultsin, developer of the FBReader ebook app, and he clued me in.

Nikolay has known about the FB3 format for years, but FBReader has not supported it because no one was using it. "There is no sense to support a format if there are no books in this format," Nikolay told me.

FB3 and its predecessors were developed by Dmitry Gribov, I was told. Gribov, is now the technical director at LitRes, and while in that role he led the development of the FB3 format. (Judging from news coverage and GitHub commits, this project has been going on for five or more years.)

And starting way back in 2005, Gribov developed the Fictionbook, or FB, format and its successor, FB2.

FB2 and FB3 are quite different ebook formats, Nikolay told me. FB3 is based on a ZIP file, while FB2 is structured more like the older Mobipocket format:

One technical example: in fb2 all images are encoded in base64 and embedded into single XML file. This means that eReader has to read all images during opening the book.

FB3, on the other hand, is a ZIP file similar to Epub albeit with simpler formatting:

As for ePub, I’m sure it’s too complicated for most real books. Like html, ePub is a mess of content and styles/formatting. In fb2 (and fb3, as far as I understand) content and styles are clearly separated. Styles in fb2 (and in fb3?) are not as rich as in ePub, but this is enough for usual books.

FB3 is not widely supported at this time by either apps or ereaders, but Nikolay says that he expects "FB3 support will be added to all readers that want to be on the Russian market."

That is going to present a problem, though; many ereaders have been released in Russia over the past decade, and none support the newer FB3 format.

Russian publishers will need to treat FB3 much like American publishers handle Epub3 and that many ereaders that support Epub: build in the better format, but plan on many readers using the older format.

image by generalantilles



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