Embedding metadata into epub files

steve1977 · 06-15-2021, 12:03 AM

First of all, I am new to the forum. Big thanks to the development of Calibre. I have been an active user and really love it. It's an excellent tool, which I use for tagging.

My ebooks (largely epub, some pdf) are all tagged using Calibre. I use the goodreads plugin and my metadata is complete.

I only use Calibre for metadata scraping, but a different tool to serve the ebooks via opdf to my IOS devices. That's my preferred workflow.

I have a few questions:

1) Is it possible to embed the metadata within the epub file rather than in a separate opf file (or both)? I did quite some googling and it seems that the "Polish books" plugin is supposed to do so? I installed this, but doesn't seem to work (getting an error message that epub not supported). Any thoughts how I can embed the metadata within an epub file?

2) It seems that Calibre uses a a custom tag for series (<meta content="xxx" name="calibre:series"/>). This does not seem to be the official tag per epub specification (should be "belongs-to-collection"). Is there a way to add the epub tag "belongs-to-collection". This will be better supported as it is in line with official specification.

3) I'd like to change the "title" tag to combine "calibre:series" and "calibre:series_index" (i.e., Title tag reads "series name [series number]". Is there a way for me to create / override this tag and embed it in the epub file?

kovidgoyal · 06-15-2021, 01:28 AM

1) Preferences->Toolbars->add the embed metadata tool

2) EPUB 2 has no series metadata. For EPUB 3 calibre does use spec compliant series metadata

3) Preferemces->Metadata plugboards-> create a plugboard for the content server and get your books on your device via the content server

steve1977 · 06-15-2021, 03:49 AM

Thanks for your quick reply.

Are you saying that I am using epub 2? If so, can I convert all my ebooks automatically to epub 3?

Is there a way not to do #3 via the content server, but create a revised tag that is embedded within the epub 3 format.

kovidgoyal · 06-15-2021, 05:22 AM

The polish books tool has an option to auto-convert to epub 3. And no, the embed metadata tool will embed the same metadata as is in calibre into the file.

steve1977 · 06-15-2021, 12:02 PM

When using the plugin on an ebook, I get the message "calibre, version 5.21.0
ERROR: Cannot polish: Polishing is only supported for books in the AZW3 or EPUB formats. Convert to one of those formats before polishing".

DNSB · 06-15-2021, 03:22 PM

Quote:

Originally Posted by steve1977

When using the plugin on an ebook, I get the message "calibre, version 5.21.0
ERROR: Cannot polish: Polishing is only supported for books in the AZW3 or EPUB formats. Convert to one of those formats before polishing".

I would say that the error message is pretty self-explanatory. If your ebooks are not in EPUB or AZW3 format, convert them to one of those two formats before polishing.

If you think the file is already in epub for example, you might want to try opening it in calibre's editor and error checking it. I'd recommend installing the epubcheck plugin for the editor and use it instead of the builtin error check. Another choice might be to do an epub to epub conversion which will often clear up many errors.

theducks · 06-15-2021, 08:39 PM

Also Calibre can not polish DRM infested books. You need to be sure they are clear.

steve1977 · 06-18-2021, 07:56 AM

Thanks for your help. I got the issue now. Somehow, Calibre does not longer see my books (at least not most of them). I may have changed the folder or something? It's very odd though as the covers are shown and I can see the metadata. Also when I click "Path - click to open", I am brought to the right folder with the epub inside. Any ideas?

calibre, version 5.21.0
ERROR: Cannot view: xxx has no available formats.

steve1977 · 06-18-2021, 07:58 AM

When I try to open the book, I get the error message "has no available formats". There is a epub file though in the folder (and I can open it manually with the viewer).

kovidgoyal · 06-18-2021, 07:59 AM

Use the library maintenance tool

steve1977 · 06-18-2021, 08:08 AM

I just did and no errors were found. Any other idea?

steve1977 · 06-18-2021, 08:22 AM

Oh no :-( Now Calibre deleted by books...

I ran the libary tool and selected "delete extra book formats". And now the epub files are all gone and no trace of my ebooks left (except the jpg and opf files). Also nothing in my trash.

Can this be undone or the ebooks otherwise recovered?

kovidgoyal · 06-18-2021, 08:38 AM

If you tell it to delete the extra books, it will do just that. And no there is no way to recover if you dont have a backup of your library.

steve1977 · 06-18-2021, 11:16 AM

Ok... That's a pity. I still have the ofp files though, so I hope I don't need to rescrape the metadata? I just copy the ebook file back into the folder?

theducks · 06-18-2021, 11:26 AM

Quote:

Originally Posted by steve1977

Ok... That's a pity. I still have the ofp files though, so I hope I don't need to rescrape the metadata? I just copy the ebook file back into the folder?

NO! Never touch the contents of a folder EXCEPT by using Calibre. Calibre logs all files it deals with.
That is probably what got you in this mess to begin with.

OTOH since you DO have your metadata set (as you wanted):
Open the metadata editor: Drop the (correct) file into the FORMATS section and move on to the next.

06-15-2021, 12:03 AM	#1
steve1977 Member Posts: 14 Karma: 10 Join Date: Jun 2021 Device: Ipad	Embedding metadata into epub files First of all, I am new to the forum. Big thanks to the development of Calibre. I have been an active user and really love it. It's an excellent tool, which I use for tagging. My ebooks (largely epub, some pdf) are all tagged using Calibre. I use the goodreads plugin and my metadata is complete. I only use Calibre for metadata scraping, but a different tool to serve the ebooks via opdf to my IOS devices. That's my preferred workflow. I have a few questions: 1) Is it possible to embed the metadata within the epub file rather than in a separate opf file (or both)? I did quite some googling and it seems that the "Polish books" plugin is supposed to do so? I installed this, but doesn't seem to work (getting an error message that epub not supported). Any thoughts how I can embed the metadata within an epub file? 2) It seems that Calibre uses a a custom tag for series (<meta content="xxx" name="calibre:series"/>). This does not seem to be the official tag per epub specification (should be "belongs-to-collection"). Is there a way to add the epub tag "belongs-to-collection". This will be better supported as it is in line with official specification. 3) I'd like to change the "title" tag to combine "calibre:series" and "calibre:series_index" (i.e., Title tag reads "series name [series number]". Is there a way for me to create / override this tag and embed it in the epub file?

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06-15-2021, 01:28 AM	#2
kovidgoyal creator of calibre Posts: 43,992 Karma: 22669822 Join Date: Oct 2006 Location: Mumbai, India Device: Various	1) Preferences->Toolbars->add the embed metadata tool 2) EPUB 2 has no series metadata. For EPUB 3 calibre does use spec compliant series metadata 3) Preferemces->Metadata plugboards-> create a plugboard for the content server and get your books on your device via the content server

06-15-2021, 03:49 AM	#3
steve1977 Member Posts: 14 Karma: 10 Join Date: Jun 2021 Device: Ipad	Thanks for your quick reply. Are you saying that I am using epub 2? If so, can I convert all my ebooks automatically to epub 3? Is there a way not to do #3 via the content server, but create a revised tag that is embedded within the epub 3 format.

06-15-2021, 05:22 AM	#4
kovidgoyal creator of calibre Posts: 43,992 Karma: 22669822 Join Date: Oct 2006 Location: Mumbai, India Device: Various	The polish books tool has an option to auto-convert to epub 3. And no, the embed metadata tool will embed the same metadata as is in calibre into the file.

06-15-2021, 12:02 PM	#5
steve1977 Member Posts: 14 Karma: 10 Join Date: Jun 2021 Device: Ipad	When using the plugin on an ebook, I get the message "calibre, version 5.21.0 ERROR: Cannot polish: Polishing is only supported for books in the AZW3 or EPUB formats. Convert to one of those formats before polishing".

06-15-2021, 08:39 PM	#7
theducks Well trained by Cats Posts: 29,944 Karma: 55705602 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	Also Calibre can not polish DRM infested books. You need to be sure they are clear.

06-18-2021, 07:56 AM	#8
steve1977 Member Posts: 14 Karma: 10 Join Date: Jun 2021 Device: Ipad	Thanks for your help. I got the issue now. Somehow, Calibre does not longer see my books (at least not most of them). I may have changed the folder or something? It's very odd though as the covers are shown and I can see the metadata. Also when I click "Path - click to open", I am brought to the right folder with the epub inside. Any ideas? calibre, version 5.21.0 ERROR: Cannot view: xxx has no available formats.

06-18-2021, 07:58 AM	#9
steve1977 Member Posts: 14 Karma: 10 Join Date: Jun 2021 Device: Ipad	When I try to open the book, I get the error message "has no available formats". There is a epub file though in the folder (and I can open it manually with the viewer).

06-18-2021, 07:59 AM	#10
kovidgoyal creator of calibre Posts: 43,992 Karma: 22669822 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Use the library maintenance tool

06-18-2021, 08:08 AM	#11
steve1977 Member Posts: 14 Karma: 10 Join Date: Jun 2021 Device: Ipad	I just did and no errors were found. Any other idea?

06-18-2021, 08:22 AM	#12
steve1977 Member Posts: 14 Karma: 10 Join Date: Jun 2021 Device: Ipad	Oh no :-( Now Calibre deleted by books... I ran the libary tool and selected "delete extra book formats". And now the epub files are all gone and no trace of my ebooks left (except the jpg and opf files). Also nothing in my trash. Can this be undone or the ebooks otherwise recovered?

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06-18-2021, 08:38 AM	#13
kovidgoyal creator of calibre Posts: 43,992 Karma: 22669822 Join Date: Oct 2006 Location: Mumbai, India Device: Various	If you tell it to delete the extra books, it will do just that. And no there is no way to recover if you dont have a backup of your library.

06-18-2021, 11:16 AM	#14
steve1977 Member Posts: 14 Karma: 10 Join Date: Jun 2021 Device: Ipad	Ok... That's a pity. I still have the ofp files though, so I hope I don't need to rescrape the metadata? I just copy the ebook file back into the folder?