Extracting and repacking epub (as zip) shows missing container.xml file

bendtherules · 09-13-2021, 02:07 AM

I am trying to batch process (say, sharpen) most images in a epub and keep everything else as it is.

Approaches -
1.The in-built editor allows me to export all images, but only replace one-by-one. So, that won't work.
2. I thought since epub is just zipped folder - I'll extract all content, process files, then zip it up again. This sort of works, but I am facing this problem.

On mac, using in-built archive tool and Keka both - if i rename epub to zip, extract it as a folder, again zip it and rename to epub, the edit epub tool then does not recognise this epub. The error is - "No META-INF/container.xml in epub". I have verified that this file exists in the zip. Both ebook conversion and ebook-viewer still works with this file but not ebook-edit.

What can be a possible reason for this? Is there a unpack and repack tool for epub within calibre (or plugin)?
I saw some old post about tweak epub/unpack book functionality, but I can't find it.

Sample file - https://www.swisstransfer.com/d/6ba0...f-eed865eaacd8

kovidgoyal · 09-13-2021, 02:08 AM

Preferences->Toolbars->add the unpack book tool to the main toolbar

retiredbiker · 09-15-2021, 09:54 PM

If I remember correctly, that container.xml file has to go into the archive uncompressed for an epub.

DNSB · 09-16-2021, 12:43 AM

Quote:

Originally Posted by retiredbiker

If I remember correctly, that container.xml file has to go into the archive uncompressed for an epub.

Not quite right. The mimetype file must be the first file in the archive, must be stored uncompressed and must contain only "application/epub+zip" (without the quotes).

The container.xml file must be stored in a META_INF directory.

See EPUB Open Container Format (OCF) 3.2 for more information (and possibly a decent insomnia cure

)

bendtherules · 10-27-2021, 01:55 PM

I forgot to check back on this thread, so sorry for the late reply.

About the issue - I figured out my stupidity in just few hours after trying unpack. So, after changing the content - I was earlier trying to zip the whole folder again - and most zip creators create a zip with literally that folder inside it (instead of taking its contents which i wanted).
The simple fix was to select all contents in the folder and compress them and then manually name the zip from the folder name.

09-13-2021, 02:07 AM	#1
bendtherules Junior Member Posts: 6 Karma: 10 Join Date: Jul 2021 Device: Kobo Aura One, Kindle android	Extracting and repacking epub (as zip) shows missing container.xml file I am trying to batch process (say, sharpen) most images in a epub and keep everything else as it is. Approaches - 1.The in-built editor allows me to export all images, but only replace one-by-one. So, that won't work. 2. I thought since epub is just zipped folder - I'll extract all content, process files, then zip it up again. This sort of works, but I am facing this problem. On mac, using in-built archive tool and Keka both - if i rename epub to zip, extract it as a folder, again zip it and rename to epub, the edit epub tool then does not recognise this epub. The error is - "No META-INF/container.xml in epub". I have verified that this file exists in the zip. Both ebook conversion and ebook-viewer still works with this file but not ebook-edit. What can be a possible reason for this? Is there a unpack and repack tool for epub within calibre (or plugin)? I saw some old post about tweak epub/unpack book functionality, but I can't find it. Sample file - https://www.swisstransfer.com/d/6ba0...f-eed865eaacd8

10-27-2021, 01:55 PM	#5
bendtherules Junior Member Posts: 6 Karma: 10 Join Date: Jul 2021 Device: Kobo Aura One, Kindle android	I figured out that it creates a folder inside the zip I forgot to check back on this thread, so sorry for the late reply. About the issue - I figured out my stupidity in just few hours after trying unpack. So, after changing the content - I was earlier trying to zip the whole folder again - and most zip creators create a zip with literally that folder inside it (instead of taking its contents which i wanted). The simple fix was to select all contents in the folder and compress them and then manually name the zip from the folder name.

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09-13-2021, 02:08 AM	#2
kovidgoyal creator of calibre Posts: 44,397 Karma: 23798586 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Preferences->Toolbars->add the unpack book tool to the main toolbar

09-15-2021, 09:54 PM	#3
retiredbiker Evangelist Posts: 420 Karma: 2737916 Join Date: May 2013 Location: Ontario, Canada Device: Kindle KB, Oasis, Pop_Os!, Jutoh, Kobo Forma	If I remember correctly, that container.xml file has to go into the archive uncompressed for an epub.

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