Thread: KFX Format
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Old 03-18-2016, 01:13 AM   #402
cerem0ny
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Posts: 449
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Join Date: Jul 2014
Location: Australia
Device: Kobo Libra Colour, Kindle Scribe 2024
Quote:
Originally Posted by jhowell View Post
The Previewer (when it works) has allowed me to compare EPUBs with the resulting equivalent KDFs. I have also been able to use these results to see how different KDF data types appear in the Previewer's book renderer. That, combined with a few instances of unencrypted KFX files obtained from Amazon, has allowed me to have a pretty good idea of how KFX works, at least for reflowable e-books.

I have written some code to convert KDF/KFX back into EPUB in order to test my assumptions. That isn't anywhere near usable as a general function, just a proof of concept. I posted an example result earlier.

I don't see conversion of KFX to EPUB as being a very useful capability. First Amazon encrypts KFX books, even those that are available DRM-free in KF8. The only books that could be converted from KFX to EPUB are those you converted from EPUB to KFX in the first place. Even if decryption eventually becomes possible, KFX is far inferior to KF8 as a source for archival or conversion. The original EPUB internal HTML semantic markup is lost in the conversion of EPUB to KFX.

For example, in KFX conversion <p>, <div>, <h1>, and <blockquote> all produce the same 'text' data type with any differences reflected in the formatting style. The same goes for <b>, <em>, <i>, <small>, <span>, <strike>, <strong>, <sub>, <sup>, etc., which all become just the equivalent css styles applied to text. There is no way to tell from the result whether the original EPUB used these different tags or just used css for formatting. Also values expressed in px or pt units tend to be converted to roughly equivalent em units in KFX.
Hey mate. So I have found the temp directory with the converted book.kdf file but simply renaming this to book.kfx or book.azw8 or whatever and sideloading it to my kindle does not open the book, or list the book at all. Opening the file in calibre doesn't work either. A few pages back you listed a method where you would zip the file, and rename the zip file, but I'm unable to change the zip files file extension from.zip to.kfx or anything! Is this what I'm supposed to do to have a working sideloadable book? Please help, and thanks! Much love
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