Custom metadata command line for a fixed layout comic

[nylnook]

Hi Calibre community !

I'm new to to world of ebooks, and I try to publish my first comic as an ebook...
I'm also a Linux user, so I created a really simple bash script to convert a serie of jpg files to a CBZ file and then an ePUB :

zip $joinedfilename.cbz *.jpg
ebook-convert $joinedfilename.cbz $joinedfilename.epub --authors "$creator" --publisher "$creator" --title "$title" --isbn "$ebookIsbn" --pubdate "$pubDate" --no-default-epub-cover --dont-grayscale --keep-aspect-ratio

And It work like a charm, thanks to Calibre !

but I discovered today than Amazon want more metadatas :
"Error Description :Your book content appears to be fixed-format layout, but it is missing a fixed-format metadata tag. Please consult sections 4.1 and 5.1 of the Kindle Publishing Guidelines to determine the best formatting choice for your content."
So, it's required I add :
<meta property="rendition:layout">pre-paginated</meta>
and
<meta name="original-resolution" content="584x754"/>
to my epub ...

But with ebook-convert and ebook-meta, I can't find a way to add them...

I can edit the ebook withe the graphical client, but I'd like to automate the process...

Any Idea ?
Thanks a lot in advance !

[eschwartz]

I don't think you can, not with ebook-convert or ebook-meta.


ebook-meta is for setting user-facing metadata, like title, series, author, publisher, etc.
You cannot set formatting metadata with it.

As for ebook-convert, it relies on calibre's Input/Output plugins, which do not understand Fixed-Format.
The fact that they sort-of-resemble Fixed-Format books is incidental.


It should be easy to unzip the epub though and insert the right meta tags with awk or sed.
You can also use a vimscript, since if your EDITOR=vim then

calibre-debug --explode-book $joinedfilename.epub

will open directly with vim.

Now, even if you do that, I'd still want to check the book to make sure it works as expected.

[nylnook]

Thanks for your quick answer eschwartz !

To be more precise, I founded that converting to CBZ first will force ebook-convert to set up a fixed format ePub... so I sort of cheated the fixed layout

So ... with your suggestion... maybe a script which unzip the epub, edit the content.opf file with the correct metadata, and zip it again would work ?

EDIT : with an additional epub check ?

[eschwartz]

Yeah, should work.

Rezipping an EPUB is tricky, of course, because you have to deal with the mimetype file -- "can't be compressed, multiple passes to zip" garbage.
That's why I like calibre-debug --explode-book or alternatively the Editor, but they are geared toward human oversight not scripting.
I'm not really sure how you'd find the exploded ebook directory via a script in order to modify it. Usually it pops up the File Browser. Or opens vim of course.

That's why I suggested a vimscript, you could probably load it automatically via a filetype plugin, apply the changes, save and exit without touching a single key...
... or maybe I enjoy making things harder, because it's more fun.

[eschwartz]

And yes, I caught the fact that you converted to CBZ to trick it into "sort-of-resemble Fixed-Format books" in an incidental way.
Nice trick, but of course calibre doesn't know to add explicit Fixed-Format references.

[nylnook]

I just tested it out...

Googling around, I ended up with this little script (called edit.sh):

----------
#!/bin/sh

mkdir edit
mv "$1" edit
cd edit
unzip "$1"
CONTENT='\t\t<meta property="rendition:layout">pre-paginated</meta>\n\t\t<meta name="original-resolution" content="584x754"/>'
sed -i '/<\/metadata>/i\'"$CONTENT" content.opf
zip -r "$1" .
mv "$1" ..
cd ..
rm -r edit
----------

and surprisingly, it seem to work ! Not sure it's really solid...
Thanks a lot for showing me the way eschwartz !

[eschwartz]

Not exactly.

I think you need to pass the `-D` switch as well.
Otherwise you can see you have a listing for the actual directories as well, which I *think* might be a problem, and if you take a look at the raw file, the mimetype is moved over.
I have no idea how exactly the mimetype is read, but apparently it's very fragile!
Must be right at the beginning, blah blah blah...

#!/bin/bash

epub="$(realpath "$1")"
tmp_epub=$(mktemp -d)

unzip "$epub" -d $tmp_epub
pushd $tmp_epub
CONTENT='\t\t<meta property="rendition:layout">pre-paginated</meta>\n\t\t<meta name="original-resolution" content="584x754"/>'
sed -i '/<\/metadata>/i\'"$CONTENT" content.opf
zip -X0 "$epub" mimetype
zip -rDX9 "$epub" * -x mimetype
pushd
rm -rf $tmp_epub

My script doesn't do as much moving around, which is like a total waste of a CPU cycle or two.
And it's "cleaner" to put the extracted files in /tmp - right?

You can also redirect most of the output to /dev/null if you want to make it really professional and distribute it.

[nylnook]

Thanks again eschwartz

Yes, your version seem much more solid and clean !
I'm a drawer, not a coder, so I admit my scripts are far from perfect...

If I publish my whole script on github, which is meant to generate .cbz, .epub, .pdf for ebooks and print from individual .svg files, are you interested in reviewing it ?
I'm sure you will give it a valuable clean up and boost

[nylnook]

Actually, it make me decide to publish my work.... So here it is : https://github.com/nylnook/climate-frogs-comic

and the export script in particular if you are curious :
https://github.com/nylnook/climate-f...xport-comic.sh

Cheers !

[nylnook]

After some more tests, the best way to avoid mimetypes errors is to not touch the mimetype at all...
So here is the updated script :

epub="$(realpath "$joinedfilename.epub")"
tmp_epub=$(mktemp -d)
unzip "$epub" -d $tmp_epub
pushd $tmp_epub
CONTENT='\t\t<meta name="fixed-layout" content="true"/>\n\t\t<meta name="original-resolution" content="584x754"/>'
sed -i '/<\/metadata>/i\'"$CONTENT" content.opf
zip -r "$epub" * -x mimetype
pushd
rm -rf $tmp_epub

Cheers !