Originally Posted by davidfor
This is a little picky, but the "broken into smaller chunks" is wrong. The division of text into files in kepub is exactly the same as for epub. I have compared the kepub and epub versions of books I have bought from Kobo, and in general they are the same. None of the extra code is illegal. There are extra spans with a Kobo specific class and a sequential id.
You're right. I remembered wrong. It was a custom attribute in one of the meta files, in regard to the cover.
Originally Posted by davidfor
If you want to do this, go ahead, but I don't think it is very useful. While any non-DRM protected kepub can be treated as an ePub, the extras aren't useful anywhere outside a Kobo device. Kepubs can be read with the Kobo iOS or Android apps, but I think they can only read those download from Kobo by the app.
If you want to use an epub as a kepub on the devices, then all you need to do is rename it to have ".kepub.epub" as the extension. That gives most of the "advantages" of a kepub.
As for splitting, I was oversimplifying. Basically, Calibre splits stories at a size that gives HORRENDOUS performance on my Kobo. I assume this value is a sane default on most devices, and I know it's a sane default on my old Kindle, but on the Kobo, it sucks. I assume this is optimized for 95% of readers, so this isn't a bug in Calibre. I want to see what I can do here, and because the Kobo needs more breaks, I want to see if I can make the splitting smarter.
Also, I want to change the files into something that can take full advantage of the "kepub reader" that Kobos have. Mostly, adding the ids, adding a simple checkbox for the css needed to help the Kobo remember the correct page. No, that's not a typo. Formatting can make the Kobo not remember the page at all. So, you might think that those features aren't worth the effort, but I do.
> There is also no point in adding DRM protected kepubs to calibre.
> Finally, there is already a driver being developed to send epubs to the Kobo devices as kepubs. This is at https://github.com/jgoguen/calibre-kobo-driver
. This does the updates to the epubs when the book is sent to the device. I will be merging this into the current driver when I am happy that it works well and I have time. Last time I checked, it would handle at least 90% of the epubs out there. The ones it doesn't would probably work after a calibre conversion. This has been discussed in the Kobo forum.
My goal is to make this work with that plugin. I want the books per-converted and in my library, where it's easier to tweak them, and to make transferring to the Kobo faster after the first conversion, at the cost of some space.
So, to make a long story short, yes, you can use epubs on a Kobo, but if you want to make them work very well, you have to apply a lot of tweaks, including changing the file name. And, those changes makes the epub worst in most other readers. To me, that's justification for treating it as a separate format, considering that it already has a separate extension.
Edit: Yes, I understand that even if I do this, it will still need to be used with a custom driver.