jloutsch/kfxgen v5.19.0

on GitHub

kfxgen is a Calibre plugin that turns EPUB books into Amazon's KFX format, with a working Kindle table of contents.

What's new in 5.19.0

This release brings kfxgen's output in line with Kindle Previewer 4.0.3, Amazon's own converter.

• The parts of kfxgen never reviewed before were compared, piece by piece, with what Previewer writes for the same book.
• Every difference found was fixed or filed.
• The fixes were then checked on real Kindles: a Paperwhite (firmware 5.19.2) and a Voyage (5.13.6). All passed except one known gap.

What readers will notice

• Navigation:
  • the contents pane keeps the book's chapter order;
  • chapter skipping stops at the book's real headings;
  • web and email links work;
  • links land on the right word.
• Pictures:
  • pictures are sized as Previewer sizes them, and very large ones are scaled down;
  • pictures inside a line of text stay in the line;
  • pictures saved in print colours show their true colours;
  • a damaged picture no longer stops the conversion.
• Tables: cells are aligned as in Previewer, including right-to-left tables, and cell background colours show.
• Text: line spacing, hanging indents, quotation marks, and headings styled by the book all match the book's own styles.
• Library:
  • the book's own description and every author carry over;
  • the language is written correctly, so Japanese shows Japanese letter forms and look-ups use the right dictionary.

Tech debt paid down

• Audit: the code that had never had a review was audited against Amazon's own output.
• Dead code: code that could never run, and an old navigation fallback Amazon never uses, were removed.
• Duplicate data: each paragraph with a picture or equation now stores its words once, not twice, which also fixes an error some books reported.
• Failure reports: when the converter fails, the log says what went wrong and where, even if the fallback fails too.
• Safer saving:
  • a failed save cleans up after itself;
  • an overwritten book keeps its file permissions;
  • the Kindle Previewer fallback checks what it needs before it starts.
• Speed: each picture is decoded once instead of twice.
• Tests: each fix's tests were checked by breaking the code on purpose, and tests were added where none failed.

Still open:

• A subscript inside a superscript is drawn raised (#536).
• Print page numbers and one table-of-contents link that Previewer adds are not written yet (#578, #579).
• Right-to-left page turning (#246) and vertical Japanese text (#247) are not supported.

The full list, with issue numbers, is in CHANGELOG.md.

Install (Calibre)

1. Download kfxgen-plugin-5.19.0.zip from the Assets below.
2. In Calibre, open Preferences → Plugins → Load plugin from file, and choose the zip.
3. Restart Calibre.

Or from the command line:

calibre-customize -a kfxgen-plugin-5.19.0.zip

Then convert any book to KFX.