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+---
+title: "How I convert PDFs to EPUB semi-automatically"
+slug: how-i-convert-pdfs-to-epub
+description: "A guide to clean EPUBs from PDFs using Calibre, Emacs and time."
+date: 2021-03-15T04:12:00+01:00
+type: posts
+draft: false
+tags:
+- epub
+- e-books
+- emacs
+---
+
+:source-highlighter: pygments
+
+:url-calibre: https://calibre-ebook.com/
+:url-calibre-convert: https://manual.calibre-ebook.com/conversion.html#pdfconversion
+:url-emacs: https://www.gnu.org/software/emacs/
+:wp-pdf: https://en.wikipedia.org/wiki/PDF
+:wp-epub: https://en.wikipedia.org/wiki/EPUB
+:wp-xhtml: https://en.wikipedia.org/wiki/XHTML
+:wp-css: https://en.wikipedia.org/wiki/CSS
+
+Sometimes e-books come only in link:{wp-pdf}[PDF] format. Almost always PDFs are
+a pain to read on e-book readers. You can use link:{url-calibre}[Calibre] to
+automatically convert it, but link:{url-calibre-convert}[the results are
+okay-ish at best]. If the PDF has footnotes, forget it. Unfortunately, the type
+of books that most often come only as PDFs are science books and these usually
+have a lot of footnotes.
+
+One option is to use Calibre to convert and then fix the result, but I have
+found that I get better results in less time when I create a new
+link:{wp-epub}[EPUB], copy the PDF's content into link:{url-emacs}[Emacs], clean
+it up there and then copy it over to Calibre. This process is what I'd like to
+share with you here. You will need Calibre, Emacs or another editor with
+keyboard macros and some knowledge of link:{wp-xhtml}[XHTML] and
+link:{wp-css}[CSS] to follow this recipe. It will take long and is boring, but
+the result is a clean and enjoyable book.
+
+== Create a new book in Calibre
+
+Click on “Add books” → “Add empty book”. Then fill in the metadata and select
+“EPUB” as format. You can add more metadata and a cover image by right-clicking
+the book and then selecting “Edit metadata”. Open Calibre's editor by right
+clicking on the book and selecting “Edit book”. You start with a single XHTML
+file, `start.xhtml`. I always use that for the title page, the copyright notice
+and so on. You can force a page break to separate the title and the copyright
+notice with CSS: Add `style="page-break-after: always;"` to the last element of
+the virtual “page” or use a CSS class. To add a CSS file click “File” → “New
+file” and enter a filename ending with `.css`. Add the CSS file by right
+clicking on `start.xhtml` in the file browser and selecting “Link
+stylesheets…”. Note that the in-built preview does not show page breaks.
+
+Your files should look similar to this:
+
+.`start.xhtml`
+[source,html]
+--------------------------------------------------------------------------------
+
+
+
+
+ Meine zwei Jahre in Russland
+
+
+
+
+
+
+
+
Emma Goldman
+
+
Meine zwei Jahre in Russland
+
+
+
+
1. Auflage
+ München, Januar 2020
+
+
Anti-Copyright (siehe S. 362)
+
+
Die englische Originalausgabe erschien 1921 und 1925 in den
+ USA aufgrund eines Versehens in zwei Teilen unter den Titeln
+ My Disillusionment in Russia und My Further Disillusionment in
+ Russia.
+
+
+
+
+--------------------------------------------------------------------------------
+
+.`style.css`
+[source,css]
+--------------------------------------------------------------------------------
+.pagebreak {
+ page-break-after: always;
+}
+.center {
+ text-align: center;
+}
+--------------------------------------------------------------------------------
+
+I added the IDs “title” and “copyright” to add semantic links to them later.
+
+=== Some styling advice
+
+Please refrain from using CSS too much. Most people have configured their e-book
+readers the way they like, with the right font, font-size, margins and so on. If
+you override their settings, they will be annoyed. I usually only style the
+title page and headlines.
+
+Do not use `` or `` tags to emphasize, do not use `font-style: italic` or
+`font-style: bold`. Use `` for emphasis and `` for
+importance so screen readers will be able to pronounce the text differently.
+
+== Add text to the book
+
+Add a new `.xhtml` file in Calibre and write in the heading of the first
+chapter. Then switch to Emacs and copy the first paragraph from the PDF into a
+`text-mode` buffer. The emphasis will not be copied over, so you'll have to
+re-add it. We ignore (but keep) the footnote numbers for now. Repeat with the
+rest of the paragraphs of the chapter, leaving 2 blank lines between each
+paragraph. The paragraphs will be broken and likely be full of hyphens at the
+end of the lines.
+
+.elisp function to add HTML tags easily
+[source,elisp]
+--------------------------------------------------------------------------------
+(defun my/html-surround-with-tag (beg end)
+ "Surround region with HTML tag."
+ (interactive "*r")
+ (if (region-active-p)
+ (let ((tag (completing-read "Tag: "
+ '("blockquote" "em" "strong"))))
+ (insert (concat "<" tag ">"
+ (delete-and-extract-region beg end)
+ "")))
+ (message "No active region")))
+--------------------------------------------------------------------------------
+
+Make sure that `auto-fill-mode` is disabled. Position the cursor at the start of
+the buffer and press `` to start recording a macro. Press ``
+`` `SPC` (space bar) and then `` to stop recording. If there is
+a hyphen at the end of the current line, press `` 2 times. Press
+`` to call the macro and repeat until you are at the end of the
+paragraph. Move the cursor to the first line of the next paragraph and repeat.
+
+Now you should have a text file with 1 paragraph per line. We need to wrap all
+lines in `
` tags, except block quotes and sub-headlines. Either use another
+macro (“
” `` “
” `` `` ``) or this elisp function:
+
+[source,elisp]
+--------------------------------------------------------------------------------
+(defun my/html-paragraphify-buffer ()
+ "Wrap every line not beginning with < or a newline in
")))
+--------------------------------------------------------------------------------
+
+Once you are done, copy the result into Calibre.
+
+== Add footnotes
+
+Use the method from above to copy the footnotes into the now empty Emacs buffer
+and clean them up until you have 1 paragraph per line. Footnotes need to be
+hyperlink-able, so we can't just wrap them in plain `
` tags, they need IDs. I
+like to use `1
[…]
` if there is only one
+footnote-section or `1
[…]
` for
+chapter-footnotes. We are going to use a macro with a counter to generate
+consecutively numbered IDs. First, set the counter to 1 with `C-x C-k
+C-c` “1”. Then, record this macro:
+
+“” `C-x C-k` `` `C-u` “-1” `C-x C-k C-a` “
” `` “
” `` `` ``
+
+`C-u` “-1” `C-x C-k C-a` “adds” -1 to the counter, so that we can use the same
+number again.
+
+Call the macro until every footnote is wrapped and copy them to Calibre.
+
+=== Add references to footnotes
+
+The footnotes are probably superscript numbers in the PDF but normal numbers in
+the EPUB right now. I found that the footnote-numbers are usually preceded by a
+space and followed by a space or `<`. I use the find & replace function in
+Calibre in Regex-mode to convert them to hyperlinks.
+
+Find: `` ([0-9]{1,3})([ <])`` (note the leading space) +
+Replace: `\1\2`
+
+Press `` to search through the text and `C-r` to replace.
+
+== Finishing touches
+
+Click “Tools” → “Table of Contents” → “Edit table of Contents”, remove the
+existing entry and click “Generate ToC from major headings” or “Generate ToC
+from all headings”.
+
+Click “Tools” → “Set semantics” and set the location of the title page,
+copyright page, beginning of text and so on.
+
+Select “Tools” → “Check book” and fix the errors.
+
+You're done! Enjoy your cleanly formatted book. 😊
+
+
+// LocalWords: Calibre