Error message: Following books are virtual

RobertJSawyer · 10-30-2012, 12:50 AM

When trying to import books from my Kobo Glo into the Calibre Library, I get a message that says, "The following books are virtual and cannot be added to the calibre library." I can't find any reference in the help to that message. What does it mean? The books are on the device; I can read them there without difficulty. They are purchased Kepub (Kobo ePub) copies, direct from the Kobo online bookstore. Thanks!

theducks · 10-30-2012, 01:02 AM

Kepub = Proprietary format
EPUB = standard format

RobertJSawyer · 10-30-2012, 01:08 AM

In what sense, though, does that make them "virtual" books? NOTE: these are DRM free books, as provided by the publisher. They are Tor Books titles and do NOT have DRM -- I'm not asking Calibre to strip the DRM; there is none. I'm simply asking it to convert formats ... and I was given to understand that that was one of the things Calibre CAN do.

davidfor · 10-30-2012, 07:31 AM

It is because calibre doesn't know exactly what the kepub format is. Yes, it is basically an epub, but it does have some extras in the file. Adding it is something I have thought about, but haven't looked at that side of the calibre code much.

Agama · 10-30-2012, 08:19 AM

I've bought quite a few books from Kobo, both DRM'd and non-DRM'd but they are all 100% ePub - no sign of this Kepub format, so I don't know why the OP's are different. Perhaps it's country specific or purchased directly from an eReader rather than downloaded to a computer.

Do Kepubs work on non-Kobo readers? If not then this sounds like another nasty proprietry tie-in. One reason I like ePub is that I can buy them from anywhere and they all work on my reader.

davidfor · 10-30-2012, 08:53 AM

Quote:

Originally Posted by Agama

I've bought quite a few books from Kobo, both DRM'd and non-DRM'd but they are all 100% ePub - no sign of this Kepub format, so I don't know why the OP's are different. Perhaps it's country specific or purchased directly from an eReader rather than downloaded to a computer.

Do Kepubs work on non-Kobo readers? If not then this sounds like another nasty proprietry tie-in. One reason I like ePub is that I can buy them from anywhere and they all work on my reader.

As your device is a Sony, I am guessing you have bought the books from the Kobo site and downloaded them via the browser. If that is this case, you will have gotten an epub.

kepubs only work in Kobo devices or their reader apps. The advantages of using them is that they can be synced to the device from the Kobo server and the current reading position will also be synced. If you buy a book through a Kobo device, it will automatically download the kepub to the device. But, you can go to the shop later and download the epub.

You can look at them as "nasty proprietry tie-in". But, as far as I can see, Kobo also offer the epub version of all the books.

Agama · 10-30-2012, 04:21 PM

Yes, I bought mine via a browser. I've not come across the idea of syncing a reading position but I guess it could be useful for some people.

At least the OP can go back to the Kobo shop and download the ePub, so this could be a solution for the OP's problem.

RobertJSawyer · 10-31-2012, 02:31 PM

Hi, Agama. And that's what I did: downloaded the plain ePubs from the Kobobooks site to Adobe Digital Editions, then imported them to Calibre. But it WOULD be nice if Kobo books could be imported directly into Calibre from the Kobo device just as Kindle books -- which are also in a proprietary format -- can be.

Thanks, everyone!

PeterT · 10-31-2012, 04:53 PM

The problem is that the Kindle books have a format that has been reverse-engineered. The kEpub format has not been; it is similar (if not identical) to an ePub, just with it's own encryption applied to it.

davidfor · 11-01-2012, 12:17 AM

And if someone does reverse-engineer it, I'll be happy to add the code necessary. I might do it myself, but it is very low on my priorities.

Agama · 11-01-2012, 08:13 AM

I'll take a look at the format if someone can post a non-DRM'd kEpub without violating copyright.

davidfor · 11-01-2012, 11:26 PM

Quote:

Originally Posted by Agama

I'll take a look at the format if someone can post a non-DRM'd kEpub without violating copyright.

I've found a couple. I'll send a PM with the location.

I looked at them before but had another look now. The only differences to a standard epub that I can see are a a javascript and CSS that have "android" as part of the names. Then in the text, each sentence is wrapped with a div with an id. There has been some discussion on this in the Kobo forum. The ids seem to be used as part of the bookmarking and syncing with the Kobo server.

Agama · 11-02-2012, 05:17 AM

Thanks, I'll have a look and I'll also check the discussion in the Kobo forum.

Agama · 11-08-2012, 07:49 AM

@davidfor: Thanks for the 2 links: the first downloaded a kepub file but the second failed with some sort of xml error.

Using a file extension of .epub, the downloaded kepub was added to calibre with no errors. It works in calibre viewer and can be converted to other formats.

It is essentially an ePub, with mimetype, content.opf and toc.ncx all conforming to the ePub standard.

The stylesheets referenced in the xhtml documents are not declared in the OPF manifest although they still seem to get applied by calibre's reader. (CSS font sizes are defined in PTs: whilst not an error this does stop zooming from working.)

There is also a javascript file, (also omitted from the OPF), which deals with Kobo specifc styling, paginating and bookmarks.

The individual xhtml documents have a <style> element which is referenced from the javascript and therefore aimed specifically at the Kobo reader, (though it may also work with other reading systems that support javascript.) These xhtml documents also contain an empty <span> element for every sentence in every paragraph, each having a unique ID. I can only guess that these may be used by Kobo devices somehow.

RobertJSawyer is also going to send me a kepub so I'll see how it compares.

davidfor · 11-08-2012, 08:19 AM

@agama: I don't know what happened with the second link. It works here, so I don't know. But, other than the text, they are the same.

For some other reason I also pulled one apart since I sent them to you. I can see what you mean about there being very few differences to an ePub. I thought there were more differences, but I suspect I have learnt a bit more since the last time I looked.

The spans with the id are used for Kobos bookmarking system. These get synced between devices. I don't know if they are used for anything else.

An annoying thing with this is the file names. On the devices, the file names are just a GUID without an extension.

With all that, it should be possible to bring kepubs without DRM into calibre. A conversion to epub would be basically just dropping the extra files. Or adding them to the manifest. A conversion to kepub is only complicated by the ids and whether to add the other files in.

10-30-2012, 12:50 AM	#1
RobertJSawyer Guru Posts: 730 Karma: 3871570 Join Date: Jun 2006 Location: Toronto Device: Kobo Libra 2, Clara 2E, and Clara HD; Kindle PaperWhite	Error message: Following books are virtual When trying to import books from my Kobo Glo into the Calibre Library, I get a message that says, "The following books are virtual and cannot be added to the calibre library." I can't find any reference in the help to that message. What does it mean? The books are on the device; I can read them there without difficulty. They are purchased Kepub (Kobo ePub) copies, direct from the Kobo online bookstore. Thanks!

10-30-2012, 01:08 AM	#3
RobertJSawyer Guru Posts: 730 Karma: 3871570 Join Date: Jun 2006 Location: Toronto Device: Kobo Libra 2, Clara 2E, and Clara HD; Kindle PaperWhite	In what sense, though, does that make them "virtual" books? NOTE: these are DRM free books, as provided by the publisher. They are Tor Books titles and do NOT have DRM -- I'm not asking Calibre to strip the DRM; there is none. I'm simply asking it to convert formats ... and I was given to understand that that was one of the things Calibre CAN do. Last edited by RobertJSawyer; 10-30-2012 at 01:10 AM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Error message when auto adding books	Rachel	Library Management	3	04-08-2012 12:27 PM
Calibre Error Message - Now I have NO BOOKS	SmiLynnLady	Calibre	10	07-14-2011 05:12 AM
error message: ERROR ITMS-4099: "Invalid ISBN: [#] at Book (MZItmspBookPac	NewDay	ePub	3	10-07-2010 01:47 PM
error message when I delete books	ficbot	Calibre	0	01-20-2010 06:31 PM
Error Message - can't add books	davidwat	Calibre	4	03-01-2009 11:25 PM

10-30-2012, 01:02 AM	#2
theducks Well trained by Cats Posts: 29,800 Karma: 54830978 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	Kepub = Proprietary format EPUB = standard format

10-30-2012, 07:31 AM	#4
davidfor Grand Sorcerer Posts: 24,907 Karma: 47303748 Join Date: Jul 2011 Location: Sydney, Australia Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos	It is because calibre doesn't know exactly what the kepub format is. Yes, it is basically an epub, but it does have some extras in the file. Adding it is something I have thought about, but haven't looked at that side of the calibre code much.

10-30-2012, 08:19 AM	#5
Agama Guru Posts: 776 Karma: 2751519 Join Date: Jul 2010 Location: UK Device: PW2, Nexus7	I've bought quite a few books from Kobo, both DRM'd and non-DRM'd but they are all 100% ePub - no sign of this Kepub format, so I don't know why the OP's are different. Perhaps it's country specific or purchased directly from an eReader rather than downloaded to a computer. Do Kepubs work on non-Kobo readers? If not then this sounds like another nasty proprietry tie-in. One reason I like ePub is that I can buy them from anywhere and they all work on my reader.

10-30-2012, 04:21 PM	#7
Agama Guru Posts: 776 Karma: 2751519 Join Date: Jul 2010 Location: UK Device: PW2, Nexus7	Yes, I bought mine via a browser. I've not come across the idea of syncing a reading position but I guess it could be useful for some people. At least the OP can go back to the Kobo shop and download the ePub, so this could be a solution for the OP's problem.

10-31-2012, 02:31 PM	#8
RobertJSawyer Guru Posts: 730 Karma: 3871570 Join Date: Jun 2006 Location: Toronto Device: Kobo Libra 2, Clara 2E, and Clara HD; Kindle PaperWhite	Hi, Agama. And that's what I did: downloaded the plain ePubs from the Kobobooks site to Adobe Digital Editions, then imported them to Calibre. But it WOULD be nice if Kobo books could be imported directly into Calibre from the Kobo device just as Kindle books -- which are also in a proprietary format -- can be. Thanks, everyone!

10-31-2012, 04:53 PM	#9
PeterT Grand Sorcerer Posts: 12,166 Karma: 73448616 Join Date: Nov 2007 Location: Toronto Device: Nexus 7, Clara, Touch, Tolino EPOS	The problem is that the Kindle books have a format that has been reverse-engineered. The kEpub format has not been; it is similar (if not identical) to an ePub, just with it's own encryption applied to it.

11-01-2012, 12:17 AM	#10
davidfor Grand Sorcerer Posts: 24,907 Karma: 47303748 Join Date: Jul 2011 Location: Sydney, Australia Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos	And if someone does reverse-engineer it, I'll be happy to add the code necessary. I might do it myself, but it is very low on my priorities.

11-01-2012, 08:13 AM	#11
Agama Guru Posts: 776 Karma: 2751519 Join Date: Jul 2010 Location: UK Device: PW2, Nexus7	I'll take a look at the format if someone can post a non-DRM'd kEpub without violating copyright.

11-02-2012, 05:17 AM	#13
Agama Guru Posts: 776 Karma: 2751519 Join Date: Jul 2010 Location: UK Device: PW2, Nexus7	Thanks, I'll have a look and I'll also check the discussion in the Kobo forum.

11-08-2012, 07:49 AM	#14
Agama Guru Posts: 776 Karma: 2751519 Join Date: Jul 2010 Location: UK Device: PW2, Nexus7	@davidfor: Thanks for the 2 links: the first downloaded a kepub file but the second failed with some sort of xml error. Using a file extension of .epub, the downloaded kepub was added to calibre with no errors. It works in calibre viewer and can be converted to other formats. It is essentially an ePub, with mimetype, content.opf and toc.ncx all conforming to the ePub standard. The stylesheets referenced in the xhtml documents are not declared in the OPF manifest although they still seem to get applied by calibre's reader. (CSS font sizes are defined in PTs: whilst not an error this does stop zooming from working.) There is also a javascript file, (also omitted from the OPF), which deals with Kobo specifc styling, paginating and bookmarks. The individual xhtml documents have a <style> element which is referenced from the javascript and therefore aimed specifically at the Kobo reader, (though it may also work with other reading systems that support javascript.) These xhtml documents also contain an empty <span> element for every sentence in every paragraph, each having a unique ID. I can only guess that these may be used by Kobo devices somehow. RobertJSawyer is also going to send me a kepub so I'll see how it compares.

Advert

Advert

11-08-2012, 08:19 AM	#15
davidfor Grand Sorcerer Posts: 24,907 Karma: 47303748 Join Date: Jul 2011 Location: Sydney, Australia Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos	@agama: I don't know what happened with the second link. It works here, so I don't know. But, other than the text, they are the same. For some other reason I also pulled one apart since I sent them to you. I can see what you mean about there being very few differences to an ePub. I thought there were more differences, but I suspect I have learnt a bit more since the last time I looked. The spans with the id are used for Kobos bookmarking system. These get synced between devices. I don't know if they are used for anything else. An annoying thing with this is the file names. On the devices, the file names are just a GUID without an extension. With all that, it should be possible to bring kepubs without DRM into calibre. A conversion to epub would be basically just dropping the extra files. Or adding them to the manifest. A conversion to kepub is only complicated by the ids and whether to add the other files in.