kepub vs epub render engines

[hobnail]

Why does Kobo use two different rendering engines? Or, why can't they use the kepub rendering engine for epubs? I did a little experiment and changed an epub's extension to .kepub and side loaded it on my Forma and it worked. I don't know what all of the features are for a kepub to test it, I only tested that the fast scrolling worked.

[Sirtel]

Because they want people to buy books from their store and not from their competitors? Kepub rendering is faster and you can do things like image zooming. I'd guess they keep the epub rendering somewhat crippled, to encourage people to buy books directly from Kobo. I may be wrong, of course.

[JSWolf]

Originally Posted by Sirtel

Because they want people to buy books from their store and not from their competitors? Kepub rendering is faster and you can do things like image zooming. I'd guess they keep the epub rendering somewhat crippled, to encourage people to buy books directly from Kobo. I may be wrong, of course.

RMSDK is not crippled. It's just different. There are good and bad points to both. ePub has better typography. With ePub ou don't have to have a wider line hight to avoid splitting the last/first line the screen. The highlighting is no longer an issue with ePub as that's been fixed. Yes, ePub may turn the page a fraction slower, but it's not too slow. ePub does not zoom images, but if you aren't reading an image heavy eBook or the images are not needing zoomed, then ePub is not a problem.

I go for ePub when I don't need to zoom images because I want the better typography. I suggest trying both and seeing which is preferred,

[davidfor]

For epubs, they use the RMSDK. That gives support for books with Adobe DRM including books from lots of libraries. And it includes PDF support. But, they are restricted to how and what Adobe wants to implement.

Kepub rendering exists so that they have control on the books from their store with their own DRM. And they don't have to pay any license fee to Adobe if you don't download the epub version. It also gives them control over the rendering and features they implement.

And what you did is exactly what Kobo recommends to authors. And I occasionally recommend for anyone to who wants to test things without actually converting the book. The .kepub.epub extension triggers the choice of the rendering engine. About the only thing that doesn't work properly is the reading location and bookmarks. These require the spans to be added.

[Sirtel]

Originally Posted by JSWolf

RMSDK is not crippled. It's just different. There are good and bad points to both. ePub has better typography. With ePub ou don't have to have a wider line hight to avoid splitting the last/first line the screen. The highlighting is no longer an issue with ePub as that's been fixed. Yes, ePub may turn the page a fraction slower, but it's not too slow. ePub does not zoom images, but if you aren't reading an image heavy eBook or the images are not needing zoomed, then ePub is not a problem.

I go for ePub when I don't need to zoom images because I want the better typography. I suggest trying both and seeing which is preferred,

No need to preach to the choir , I use epub myself. But still, I think it is more crippled than kepub. Mostly because of image zooming (or lack thereof). I read many fantasy novels with maps, which I can't zoom on my Kobo. Also searching within the book is much slower with epub (again a feature I use often). Of course I could use kepub, but I like the epub layout more.

[JSWolf]

Originally Posted by davidfor

For epubs, they use the RMSDK. That gives support for books with Adobe DRM including books from lots of libraries. And it includes PDF support. But, they are restricted to how and what Adobe wants to implement.

Adobe has implemented more ePub 3 features in RMSDK but Kobo hasn't updated to the latest version.

[JSWolf]

Originally Posted by Sirtel

No need to preach to the choir , I use epub myself. But still, I think it is more crippled than kepub. Mostly because of image zooming (or lack thereof). I read many fantasy novels with maps, which I can't zoom on my Kobo. Also searching within the book is much slower with epub (again a feature I use often). Of course I could use kepub, but I like the epub layout more.

I posted that so others would know what some of the differences between ePub & KePub.

I don't find searching with ePub to be slow. Most books i read don't have graphics that need any sort of zooming. If I do read an eBook that has a map, I'll fix the map to rotate it so it's sideways and fix the code so it displays full screen. If need be, I'll even try to find another higher resolution map if I can if need be. Sometimes, if the map is big enough, I'll cut it in half. I've seen some books do that.

[Sirtel]

Originally Posted by JSWolf

I posted that so others would know what some of the differences between ePub & KePub.

I don't find searching with ePub to be slow. Most books i read don't have graphics that need any sort of zooming. If I do read an eBook that has a map, I'll fix the map to rotate it so it's sideways and fix the code so it displays full screen. If need be, I'll even try to find another higher resolution map if I can if need be. Sometimes, if the map is big enough, I'll cut it in half. I've seen some books do that.

The longer the book, the slower the search. It's practically impossible to search anything within the epub version of The Wheel of Time omnibus (the longest book I have, over 4 million words). So I have to read that on my Kindles or use the kepub version. Of course most books are nowhere near as long. Still, searching within a kepub is much faster.

As to maps, it's easier to grab my tablet and look at the map there. I really don't feel like fixing all the maps in my library one by one. I spend enough time fixing metadata and formatting as it is.

[hobnail]

Originally Posted by davidfor

For epubs, they use the RMSDK. That gives support for books with Adobe DRM including books from lots of libraries. And it includes PDF support. But, they are restricted to how and what Adobe wants to implement.

Kepub rendering exists so that they have control on the books from their store with their own DRM. And they don't have to pay any license fee to Adobe if you don't download the epub version. It also gives them control over the rendering and features they implement.

Thanks, now I get it.

[RobertJSawyer]

Originally Posted by JSWolf

With ePub ou don't have to have a wider line hight to avoid splitting the last/first line the screen,

JSWolf, if I read you correctly (there's a word missing in what you wrote, so I'm not sure I am), you're suggesting that Kepubs sometimes show only part of a line at the bottom and top of the screen, yes? I've never encountered that, except very rarely when someone has botched the coding of superscripted or subscripted numbers in the ebook.

Are there any other ways in which RMDSK typography is better, in your view?

Thank you!

[JSWolf]

Originally Posted by RobertJSawyer

JSWolf, if I read you correctly (there's a word missing in what you wrote, so I'm not sure I am), you're suggesting that Kepubs sometimes show only part of a line at the bottom and top of the screen, yes? I've never encountered that, except very rarely when someone has botched the coding of superscripted or subscripted numbers in the ebook.

Are there any other ways in which RMDSK typography is better, in your view?

Thank you!

RMSDK has proper kerning and hyphenation as well as any line hight you prefer without the split line bug that KePub has.

Oh and there is a better English hyphenation dictionary at https://www.mobileread.com/forums/sh...d.php?t=325081 It'v#se what I use. I posted it. You can set up the patches to auto install this every time you patch.

[davidfor]

Originally Posted by RobertJSawyer

JSWolf, if I read you correctly (there's a word missing in what you wrote, so I'm not sure I am), you're suggesting that Kepubs sometimes show only part of a line at the bottom and top of the screen, yes? I've never encountered that, except very rarely when someone has botched the coding of superscripted or subscripted numbers in the ebook.

With some combinations of font size, line spacing and font, the descenders of the last line show at the top of the next page, and the ascenders of the first line appear at the bottom of the previous page. Patching the firmware to allow lower line spacing can trigger it. And I've always though that some fonts had their metrics set in a way to cause it. Most times I have seen it, the book had Charis SIL or one of it's derivatives embedded.

[DNSB]

Originally Posted by hobnail

Why does Kobo use two different rendering engines? Or, why can't they use the kepub rendering engine for epubs?

The simple answer is that when Kobo moved into the Japanese market, they needed an epub3 renderer to handle Japanese typography. Their answer was to use the "ACCESS NetFront™ BookReader v1.0 EPUB Edition" to open epub3 ebooks with the file extension .kepub.epub. OTOH, they needed to keep using RMSDK to be compatible with Adobe ADEPT DRMed epubs and pdfs.

So two renderers became part of Kobo's firmware. RMSDK is still not close enough to a full featured epub3 renderer to allow sole use.

[ps67]

The other advantage of epub in Kobo is that it handles ligatures while kepub doesn't do.
Of course Kepub is indispensable if there are images or notes. In epub notes are very badly handled, most times You tap in the note but the only result is to go to the next or previous page.

[Sirtel]

Originally Posted by ps67

The other advantage of epub in Kobo is that it handles ligatures while kepub doesn't do.
Of course Kepub is indispensable if there are images or notes. In epub notes are very badly handled, most times You tap in the note but the only result is to go to the next or previous page.

You can disable changing pages by tapping and only go to to the next page by swiping or by buttons (if you have the Forma or the Libra). No more problems with notes.