Kepub format and Koreader

gontofe · 08-19-2014, 03:09 AM

Hi all,

I experienced much better performance on my Kobo Touch by converting my epub files to Kepub with Calibre when transferring them to my reader when I was using Nickel, but wondered if I still needed to when using Koreader? I gather its something to do with having the book broken down into smaller parts inside the file that speeds up page flips etc for Nickel...

WS64 · 08-20-2014, 03:57 AM

I think (but might be wrong here) that kepubs are after all normal epubs. As long as they are DRM-free and the extension ends with epub they should work fine in Koreader. We could even allow the extension .kepub (maybe we have already, not sure, I don't have any .kepubs at all)

gontofe · 08-20-2014, 05:08 AM

Kepubs do work fine in Koreader I can confirm (I think there is some text splitting and other changes), its more a question of whether Koreader handles plain epubs better than Nickel, and if I can dispense with the epub -> kepub conversion in Calibre...

davidfor · 08-20-2014, 06:44 AM

I have no idea whether Koreader handles epubs better than nickel, but it's handling of kepubs will be worse than for the equivalent epub. But only by a tiny bit.

As WS64 said, a kepub is really just an epub with some extras. Most of those extras a spans wrapping each sentence with an id. These are use by the ACCESS reader for bookmarking. Some purchased kepubs have javascript and some extra CSS that is used by ACCESS.

Because of this, any kepub converted from an epub will be bigger. Any renderer will take more time with the size and all the extra spans and use more memory. Hence, it will be a little slower. But, you probably won't notice the difference.

Also, the extended driver does not break the files down in size. Each file within an epub is processed to add the spans and are otherwise unchanged. If you use convert to kepub using a calibre conversion, you can break the files down, but converting to epub will do exactly the same thing. If ACCESS is handling sideloaded kepubs better than the RMSDK handles epubs, it probably means that ACCESS is better written. It is likely that it is adapted to the hardware better than RMSDK.

My opinion is:

If you are swapping between nickel and Koreader and prefer kepubs in nickel, then sideload as kepubs.

If you have decided only to use Koreader, don't bother with kepubs. But, don't worry about removing them and replacing them with the original epubs.

And if you are not using nickel, you probably should stop using the KoboTouch drivers in calibre. These read the database created by nickel. If you don't use nickel, it won't be populated and calibre won't show any books on the device. You would be better to use the "Folder device". This will scan the folder for books and find everything under that folder.

gontofe · 08-20-2014, 09:10 AM

Ah, I knew there was a thing.

Thanks for the useful info, @davidfor.

I imagine I will stick with Koreader, so will stop using the Kobo driver and switch back to epubs (I don't have all that many, and there's no reason to have them converted). I prefer this option mainly in case I buy a different reader in future, and there will be no reason to use the kepub format.

Thanks again for your help!

08-19-2014, 03:09 AM	#1
gontofe Enthusiast Posts: 30 Karma: 19606 Join Date: Sep 2013 Device: Kobo Touch	Kepub format and Koreader Hi all, I experienced much better performance on my Kobo Touch by converting my epub files to Kepub with Calibre when transferring them to my reader when I was using Nickel, but wondered if I still needed to when using Koreader? I gather its something to do with having the book broken down into smaller parts inside the file that speeds up page flips etc for Nickel...

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08-20-2014, 03:57 AM	#2
WS64 ♫ Posts: 660 Karma: 506380 Join Date: Aug 2010 Location: Germany Device: Kobo Aura / PB Lux 2 / Bookeen Frontlight / Kobo Mini / Nook Color	I think (but might be wrong here) that kepubs are after all normal epubs. As long as they are DRM-free and the extension ends with epub they should work fine in Koreader. We could even allow the extension .kepub (maybe we have already, not sure, I don't have any .kepubs at all)

08-20-2014, 05:08 AM	#3
gontofe Enthusiast Posts: 30 Karma: 19606 Join Date: Sep 2013 Device: Kobo Touch	Kepubs do work fine in Koreader I can confirm (I think there is some text splitting and other changes), its more a question of whether Koreader handles plain epubs better than Nickel, and if I can dispense with the epub -> kepub conversion in Calibre...

08-20-2014, 06:44 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	I have no idea whether Koreader handles epubs better than nickel, but it's handling of kepubs will be worse than for the equivalent epub. But only by a tiny bit. As WS64 said, a kepub is really just an epub with some extras. Most of those extras a spans wrapping each sentence with an id. These are use by the ACCESS reader for bookmarking. Some purchased kepubs have javascript and some extra CSS that is used by ACCESS. Because of this, any kepub converted from an epub will be bigger. Any renderer will take more time with the size and all the extra spans and use more memory. Hence, it will be a little slower. But, you probably won't notice the difference. Also, the extended driver does not break the files down in size. Each file within an epub is processed to add the spans and are otherwise unchanged. If you use convert to kepub using a calibre conversion, you can break the files down, but converting to epub will do exactly the same thing. If ACCESS is handling sideloaded kepubs better than the RMSDK handles epubs, it probably means that ACCESS is better written. It is likely that it is adapted to the hardware better than RMSDK. My opinion is: If you are swapping between nickel and Koreader and prefer kepubs in nickel, then sideload as kepubs. If you have decided only to use Koreader, don't bother with kepubs. But, don't worry about removing them and replacing them with the original epubs. And if you are not using nickel, you probably should stop using the KoboTouch drivers in calibre. These read the database created by nickel. If you don't use nickel, it won't be populated and calibre won't show any books on the device. You would be better to use the "Folder device". This will scan the folder for books and find everything under that folder.

08-20-2014, 09:10 AM	#5
gontofe Enthusiast Posts: 30 Karma: 19606 Join Date: Sep 2013 Device: Kobo Touch	Ah, I knew there was a thing. Thanks for the useful info, @davidfor. I imagine I will stick with Koreader, so will stop using the Kobo driver and switch back to epubs (I don't have all that many, and there's no reason to have them converted). I prefer this option mainly in case I buy a different reader in future, and there will be no reason to use the kepub format. Thanks again for your help!

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