MobileRead Forums - View Single Post - Certain books only transferring as epub, not kepub

davidfor · 10-10-2021, 08:57 PM

The KoboTouchExtended driver does not actually convert books. It takes the epub and makes changes to that to make it a kepub. The distinction is that if you use calibre to convert a book from one format to another, calibre runs it through the complete conversion pipeline which means a lot more changes are made to the book. The driver pretty much just adds the spans to each internal file. It doesn't rebuild the ToC, update the metadata and cover or one of the many other things that happen during a conversion. And it doesn't add the resulting book to the library.

If you don't have format in the library that the device supports, when sending to the device, calibre will convert the book to the first format in the supported list that it can convert to. The default for the KoboTouch and KoboTouchExtended drivers is to have kepub first and epub second. And PDF third. So, if you send a AZW to the device, it will try to convert to kepub, but, if it cannot, it will convert to epub. To do those conversions, it is not the driver. Calibre runs the full conversion, adds the result to the library and then sends that book to the device. For a book to be converted to kepub in this way, you need to have the conversion output plugin for this format. And as that is not happening, you do not have the Kepub Output plugin installed. But, you may not want that.

Without the Kepub Output plugin, the AZW should be converted to epub and the extended driver should do the transformation to kepub when sending the book to the device. If that is not happening, then it suggests that there is something in the epub that was produced that meant the extended driver could not do what it was supposed to. When this fails, the driver will send the epub to the device. And there is an option in the driver whether to report this error or not.

All that means is that I believe there is a problem with the epub that is created when calibre does a conversion of the AZW file. If you run calibre in debug mode and post the log from when you send the book, it may show what is happening. The calibre editor or Sigil might show the error when you use their checking. That will depend on exactly what the problem is. Otherwise, I would need to see the book and try it myself.

10-10-2021, 08:57 PM	#2
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	The KoboTouchExtended driver does not actually convert books. It takes the epub and makes changes to that to make it a kepub. The distinction is that if you use calibre to convert a book from one format to another, calibre runs it through the complete conversion pipeline which means a lot more changes are made to the book. The driver pretty much just adds the spans to each internal file. It doesn't rebuild the ToC, update the metadata and cover or one of the many other things that happen during a conversion. And it doesn't add the resulting book to the library. If you don't have format in the library that the device supports, when sending to the device, calibre will convert the book to the first format in the supported list that it can convert to. The default for the KoboTouch and KoboTouchExtended drivers is to have kepub first and epub second. And PDF third. So, if you send a AZW to the device, it will try to convert to kepub, but, if it cannot, it will convert to epub. To do those conversions, it is not the driver. Calibre runs the full conversion, adds the result to the library and then sends that book to the device. For a book to be converted to kepub in this way, you need to have the conversion output plugin for this format. And as that is not happening, you do not have the Kepub Output plugin installed. But, you may not want that. Without the Kepub Output plugin, the AZW should be converted to epub and the extended driver should do the transformation to kepub when sending the book to the device. If that is not happening, then it suggests that there is something in the epub that was produced that meant the extended driver could not do what it was supposed to. When this fails, the driver will send the epub to the device. And there is an option in the driver whether to report this error or not. All that means is that I believe there is a problem with the epub that is created when calibre does a conversion of the AZW file. If you run calibre in debug mode and post the log from when you send the book, it may show what is happening. The calibre editor or Sigil might show the error when you use their checking. That will depend on exactly what the problem is. Otherwise, I would need to see the book and try it myself.