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Old 01-11-2020, 09:31 AM   #15
JSWolf
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Posts: 55,497
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Join Date: Nov 2006
Location: Roslindale, Massachusetts
Device: Kobo Aura H2O, Sony PRS-650, Sony PRS-T1, nook STR, iPad 4, iPhone 5
Quote:
Originally Posted by jxall View Post
OK, I just conducted some tests.
  1. I downloaded the .epub and the .kepub.epub editions of David Copperfield from Standard Book website. I'll call these files E and KE.
  2. I copied-pasted E and KE to the Kobo main folder.
  3. I duplicated the original E file, added it to Calibre library, and converted it to .kepub.epub via KoboTouchExtended and sent it to Kobo. I'll call this file E>KE.
  4. I duplicated the original KE file and added it to Calibre. Calibre detected it as an epub, so I had to convert it to .kepub.epub via KoboTouchExtended and send it to the device. I'll call this file KE>(E)>KE.
  5. I duplicated the original KE file, shortened its name to .kepub, added it to Calibre library and sent it to Kobo (no KoboTouchExtended conversion took place). I'll call this file K.

[Please note that in KoboTouchExtended driver I ticked "Cleanup ePub markup" and "Hyphenate Files". I have always kept those configurations like that because the developer himself prefers them to be ticked.]

Then I opened all these files on my Kobo one after another. I didn't change font and any other settings - and started to take pictures to them. Then I used the pictures to visually compare the formatting of the same bunch of pages.

Here are the comparative results:
  • The text from E - as it happens with any epub file - looks a lot bigger than the text from kepub files, using the same nominal font size.
  • KE and K are identical.
  • E>KE and KE>(E)>KE are identical between themselves, but they have a noticeably different formatting from KE and K, taking up more lines per page.

So, Standard Books kepubs are indeed optimized and they do require the manual editing .kepub.epub > .kepub) in order to work in a Calibre library. I guess I'll really a tool to do that in big scale.

Many thanks @JSWolf and @DNSB for the help.




Thanks for pointing out about the upcoming feature in Kepubify.

Even if I do understand the general sense of your answer, kepubs have been around for a while. AZW3 are Amazon-specific files just like KEPUBS are Kobo-specific files, so - considering that both formats have been around for many years now - why do AZW3 files have native support and KEPUBs don't?

Kobo is the 2nd most popular producer after all. And as I have shown, it is very useful for backup-restore / practical reasons to have Standard Books' native kepubs in Calibre library instead of epubs in my library.

Couldn't you try to normalize this situation through your plugins? (Allow Calibre to recognize .kepub.epub files just like .kepub files?
One reason there is no native KePub support is that most KePub are created on-the-fly when you send ePub to your Kobo using the KoboTouchExtended driver. The KePub is not kept in Calibre. Just the ePub.

As for the font size, there are some patches to allow you to have ePub and KePub font settings to be the same. So you do not have to go from one to the other and have different font sizes. I have applied the patches and I no longer have different font sizes for ePub and KePub. Here is the link to the patch thread for the 4.19.x firmware.

https://www.mobileread.com/forums/sh...d.php?t=325572
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