Converting on-device EPubs to Kepubs but keeping their Calibre links?

iandol · 02-22-2022, 06:36 PM

I have a Kobo Nia, and have used Calibre to sync about 100 EPubs onto the Nia, a workflow that works amazingly well (Calibre really is wonderful!).

I saw this great tool: https://pgaskin.net/kepubify/ which does super fast conversion of EPubs to Kepubs. I do NOT want to convert the original EPubs on my desktop machine, but want to convert the EPubs on the Nia. I have tried to use

Code:

kepubify --update --inplace 'MyBook.epub'

Which creates a MyBook.kepub.epub. BUT this breaks the link back to the Calibre library. I tried to edit the calibre metadata file that is on the device to now point to the new file, but Calibre still seems to have forgotten the book when reconnected. I am completely new to this all and just wondered:

If I just rename 'MyBook.kepub.epub' to 'MyBook.epub' on the device, will the kobo still use the "enhanced" kepub engine (I realise it is an internal format difference, but don't know what heuristic kobo software uses, maybe it is dumb and uses filename?).
How can I tell if the kobo is in kepub vs epub reading mode?
Do kepubs also benefit other readers like KOReader?

And finally, a massive thank you to Patrick Gaskin for this tool, and also NickelMenu and the patching system, it is all very cool!!!

DNSB · 02-23-2022, 12:52 AM

Quote:

Originally Posted by iandol

1. If I just rename 'MyBook.kepub.epub' to 'MyBook.epub' on the device, will the kobo still use the "enhanced" kepub engine (I realise it is an internal format difference, but don't know what heuristic kobo software uses, maybe it is dumb and uses filename?).

The .kepub.epub and .epub extensions are used to decide which renderer to use. .epub uses the Adobe RMSDK renderer while .kepub.epub uses a webkit based renderer. Basically, you need to know which renderer to use before opening the ebook and the filename makes for very simple and fast code.

Quote:

Originally Posted by iandol

2. How can I tell if the kobo is in kepub vs epub reading mode?

If you look in the library view, you'll see EPUB or KOBO EPUB. When reading, if you tap the middle of the screen, you'll notice a bar graph looking icon between the As and gear wheel icons. If you tap on an image, you'll get the 4 headed arrow to allow zooming, rotating, etc. the image. I've found that to be of little use since very few images in commercial ebooks have the resolution to make it worth zooming the image. I also prefer the RMSDK's font handling but that is likely only of interest to my fellow typography geeks.

Quote:

Originally Posted by iandol

3. Do kepubs also benefit other readers like KOReader?

The basic change in kepubs are not visible in other renderers so you would see no difference in how KOReader rendered the ebook.[/LIST]

ZodWallop · 02-23-2022, 12:59 AM

If you add the KoboTouchExtended plug-in to Calibre, when you send books to the Nia, it will convert them from ePub to kepub as it transfers them. So you will have epub in your Calibre library, but will have kepub on your Nia.

This won't work for books you have already sent, though you can delete them from the Nia and send them again.

iandol · 02-23-2022, 04:53 AM

Many thanks to both of you for your helpful and informative responses!

@DNSB — I would certainly consider myself part of typography geekdom; I have installed my favorite book font, Dolly Pro from the Underware Type foundry, which works quite well on the Nia's screen. There are many things I still don't quite understand: (1) What advantages does the EPub render offer typographically? (2) On my desktop I tend to stick to OTF, but is there any disadvantage to OTF on device? (3) Standard ligatures are enabled as far as I can tell, but is there a mechanism to enable discretionary ligatures or other opentype features (I assume this has to be a patch of some sort)?

Thanks again!

ps67 · 02-23-2022, 06:53 AM

With Kobe ereader there are no ligatures for Kepub so I use Epub when there aren't images or notes. Otherwise I use Kepub. This is reason why with kepub I use fonts that fit good also without ligatures like Bitter, Lexia Dama or Roboto Serif. Or I read them with Koreader so I have great typography, the choice of sharpness of fonts, pop up notes and images enlargement (and many other features).

About otf fonts: if You use the patch "Enable advanced settings for all fonts" it works only with ttf font with Epub, it doesn't work with otf fonts.

I don't know any way to have discretionary ligatures but using css:

Code:

font-variant: discretionary-ligatures

I don't know if it works with epub in Kobo (may be epub 3?) It should work with Koreader.

ZodWallop · 02-23-2022, 11:08 AM

Quote:

Originally Posted by iandol

Standard ligatures are enabled as far as I can tell, but is there a mechanism to enable discretionary ligatures or other opentype features (I assume this has to be a patch of some sort)?

By default, kepub does not display ligatures. There is a patch you can use to enable ligatures on kepub. Enabling ligatures in kepub does mess with spacing. Installing JSWolf's Better Hyphenation dictionary can help there.

iandol · 02-24-2022, 05:49 AM

Thanks to both of you. Understanding the trade-offs I think I'll generally stick to EPubs for the moment (I don't use any of the things kepubs are better for, so it is only a general performance improvement that I can apply selectively).

Given the possible downsides with patch support for OTF, I converted my OTF fonts to TTF (using https://github.com/shermp/ReadifyFont.git), merci!

Thanks for the feedback and knowledge shared!

02-22-2022, 06:36 PM	#1
iandol Enthusiast Posts: 36 Karma: 216612 Join Date: Feb 2022 Device: Kobo Nia	Converting on-device EPubs to Kepubs but keeping their Calibre links? I have a Kobo Nia, and have used Calibre to sync about 100 EPubs onto the Nia, a workflow that works amazingly well (Calibre really is wonderful!). I saw this great tool: https://pgaskin.net/kepubify/ which does super fast conversion of EPubs to Kepubs. I do NOT want to convert the original EPubs on my desktop machine, but want to convert the EPubs on the Nia. I have tried to use Code: kepubify --update --inplace 'MyBook.epub' Which creates a MyBook.kepub.epub. BUT this breaks the link back to the Calibre library. I tried to edit the calibre metadata file that is on the device to now point to the new file, but Calibre still seems to have forgotten the book when reconnected. I am completely new to this all and just wondered: If I just rename 'MyBook.kepub.epub' to 'MyBook.epub' on the device, will the kobo still use the "enhanced" kepub engine (I realise it is an internal format difference, but don't know what heuristic kobo software uses, maybe it is dumb and uses filename?). How can I tell if the kobo is in kepub vs epub reading mode? Do kepubs also benefit other readers like KOReader? And finally, a massive thank you to Patrick Gaskin for this tool, and also NickelMenu and the patching system, it is all very cool!!!

02-23-2022, 06:53 AM	#5
ps67 Guru Posts: 739 Karma: 7025494 Join Date: Aug 2017 Location: Italy Device: Kindle Paperwhite, Kobo Elipsa, Pocketbook Inkpad 4, Inkpad Color	With Kobe ereader there are no ligatures for Kepub so I use Epub when there aren't images or notes. Otherwise I use Kepub. This is reason why with kepub I use fonts that fit good also without ligatures like Bitter, Lexia Dama or Roboto Serif. Or I read them with Koreader so I have great typography, the choice of sharpness of fonts, pop up notes and images enlargement (and many other features). About otf fonts: if You use the patch "Enable advanced settings for all fonts" it works only with ttf font with Epub, it doesn't work with otf fonts. I don't know any way to have discretionary ligatures but using css: Code: font-variant: discretionary-ligatures I don't know if it works with epub in Kobo (may be epub 3?) It should work with Koreader.

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02-23-2022, 12:59 AM	#3
ZodWallop Gentleman and scholar Posts: 11,359 Karma: 110455811 Join Date: Jun 2015 Location: Space City, Texas Device: Clara BW; Nook ST w/Glowlight, Paperwhite 3	If you add the KoboTouchExtended plug-in to Calibre, when you send books to the Nia, it will convert them from ePub to kepub as it transfers them. So you will have epub in your Calibre library, but will have kepub on your Nia. This won't work for books you have already sent, though you can delete them from the Nia and send them again.

02-23-2022, 04:53 AM	#4
iandol Enthusiast Posts: 36 Karma: 216612 Join Date: Feb 2022 Device: Kobo Nia	Many thanks to both of you for your helpful and informative responses! @DNSB — I would certainly consider myself part of typography geekdom; I have installed my favorite book font, Dolly Pro from the Underware Type foundry, which works quite well on the Nia's screen. There are many things I still don't quite understand: (1) What advantages does the EPub render offer typographically? (2) On my desktop I tend to stick to OTF, but is there any disadvantage to OTF on device? (3) Standard ligatures are enabled as far as I can tell, but is there a mechanism to enable discretionary ligatures or other opentype features (I assume this has to be a patch of some sort)? Thanks again!

02-24-2022, 05:49 AM	#7
iandol Enthusiast Posts: 36 Karma: 216612 Join Date: Feb 2022 Device: Kobo Nia	Thanks to both of you. Understanding the trade-offs I think I'll generally stick to EPubs for the moment (I don't use any of the things kepubs are better for, so it is only a general performance improvement that I can apply selectively). Given the possible downsides with patch support for OTF, I converted my OTF fonts to TTF (using https://github.com/shermp/ReadifyFont.git), merci! Thanks for the feedback and knowledge shared!