Kobo Epub Compatibility?

[davidfor]

Originally Posted by ZodWallop

Could that be related to the 'Use Adobe page numbers' option in the settings? I never understood what that did.

The numbers in the margins with that option are where the page starts. The page number at the bottom can cover multiple screens, or multiple pages on the same screen. This number is the line where the new page starts.

[wingmongyee]

Originally Posted by ZodWallop

You could do that. Or you could go into settings and change 'Display progress for:' from 'Current chapter' to 'Entire book'

Which is exactly what I do...

[JSWolf]

Originally Posted by chrisridd

I'd also add that Kobo sells both ePub 2 and ePub 3 books, so your "any ePub reader" will likely need to be able to handle ePub 3.

I don't think the Kobo store says what version each book uses.

The ePub 3 being sold is really ePub 2 in ePub 3 clothing. It's backwards compatible with ePub 2 Readers and if not, it's a problem with that particular program. You can read the ePub 3 sold at Kobo with RMDSK (ADE) no problem or you can read as kepub. So the choice is yours as to which renderer you want to use.

[JSWolf]

Originally Posted by jackie_w

No, I don't believe that's true, either. Whatever the page count algorithm for kepub entire book is, it's not the same as the ADE algorithm for plain epub.

The problem is that kepub has all those spans and javascript and extra css. All that makes the page numbers different then the same eBook without all the kepub code. So even using ADE, ePub and kepub will have different page numbers. The longer the eBook, the more the page numbers will differ with even more spans.

[wingmongyee]

Originally Posted by ZodWallop

I guess. I didn't know that and I'd guess wingmongyee doesn't either. It's close enough for government work.

You're right. I didn't know that! Damn!

I just tested this with a book, and the total number pages of the book doesn't indeed change when the font size changes. Well, at least the number of pages per chapter is proportional to the size of the font. That's good enough for me as I display the number of pages per chapter.

As for letting friends (who read only paper books) know the number of pages of an eBook, back to approximate figures, or the total number of pages as indicated with a caveat concerning the size of the pages.

[wingmongyee]

Originally Posted by davidfor

To get that number, you need to open each chapter, see how many pages are in each and add them up. Then change the font size, margins, line spacing or even the justification and do it again. You actually do that? That's going to take a fair amount of time for a 30 chapter book.

(...)

Of course, I think the chapter graph in kepubs is great, and it is almost enough to convert me, but, I'm not that great a fan of the per-chapter page numbering.

I don't actually do that (checking each chapter's number of pages and adding them all up). From now on, I might suggest to friends to check the book in a bookshop if they really want to have a true idea of its size

The graph is fun, yes, but it's the per-chapter page numbering that is the real advantage, so if you're not using it, I can see why you wouldn't switch to KePubs, however aren't you bothered about the slower page turns (you said they're faster after all the firmware updates, but still slightly slower than KePub)?

I find that the general responsiveness of the reader is the most important factor in the reading experience, much more than any page numbering or other details.

Anyhow, each to his own. The main thing we all share is the love of reading...

[davidfor]

Originally Posted by JSWolf

The ePub 3 being sold is really ePub 2 in ePub 3 clothing. It's backwards compatible with ePub 2 Readers and if not, it's a problem with that particular program. You can read the ePub 3 sold at Kobo with RMDSK (ADE) no problem or you can read as kepub. So the choice is yours as to which renderer you want to use.

You might want to look at the example I pointed to. That is definitely an epub3 and uses epub3 only tags. Just opening it an epub2 only app has some formatting problems. For most of the epub3 books I have found, changing the version from 3.0 to 2.0 is enough. But, this needed more work. And I couldn't reproduce some of the style in epub2, so I left as epub3 and a kepub.

[jackie_w]

Originally Posted by davidfor

I've always assumed it was the same algorithm, but possibly with a different factor than Adobe uses. With all the extra spans, it probably makes sense to use a number a little higher than 1024. But, the page count is always higher than for epubs. Of course, there are other issues such as compression ratios affecting these counts.

I might have a little play the Count Pages plugin to see a comparison between epubs and kepubs.

Here are the results of my little experiment using a random single plain epub from my calibre library:

1. Create 4 "versions" of the same book:
   
   

   book1.epub       - the original plain epub (it's epub2 not epub3)
   book2.kepub.epub - book1 format-shifted to kepub using KoboTouchExtended not a calibre full conversion
   book3.epub       - copy of book2 with file ext manually changed to .epub
   book4.kepub.epub - copy of book1 with file ext manually changed to .kepub.epub

2. Drag-drop all 4 into calibre and run Count Pages on all of them to get ADE page count and word count.
   
3. Drag-drop all 4 onto my KA1. I deliberately avoided using calibre to do the transfer to avoid any auto file changes calibre might make in-transit.
   Open all 4 on the KA1 to see total page count.
   Books 1 & 3 open in the Adobe epub renderer.
   Books 2 & 4 open in the Kobo kepub renderer.

Results:

                            <-Count Pages ->  <--- Kobo entire book --->
File             Filesize   Pages      Words  Adobe Pages   Kepub Pages
book1.epub       1614709    277        98574  277           -
book2.kepub.epub 1665258    321        98574  -             325
book3.epub       1665258    321        98574  321           -
book4.kepub.epub 1614709    277        98574  -             325

Conclusions:

• Comparing books 1 & 3. The extra Kobo spans/divs inflate the ADE page count from 277 --> 321
• Comparing books 2 & 3. These are the same file with 2 different file extensions. ADE pages 321, kepub pages 325. Not the same value, so algorithms are different.
• Similarly, comparing books 1 & 4. The same file with 2 different file extensions. ADE pages 277, kepub pages 325. Not the same value, so algorithms are different.
• Comparing books 2 & 4. The "true" kepub (book2) and the "fake" kepub (book4) have exactly the same kepub page count, 325. The lack of Kobo spans/divs in the "fake" kepub does not affect the kepub page count, so I surmise filesizes are not a factor in calculating kepub page count. My guess is that the algorithm uses wordcount rather than filesizes.

If you're still reading ... thanks for staying awake and feel free to disagree! I'll be interested to read any of your own test results.

[davidfor]

Originally Posted by jackie_w

Here are the results of my little experiment using a random single plain epub from my calibre library:

1. Create 4 "versions" of the same book:
   
   

   book1.epub       - the original plain epub (it's epub2 not epub3)
   book2.kepub.epub - book1 format-shifted to kepub using KoboTouchExtended not a calibre full conversion
   book3.epub       - copy of book2 with file ext manually changed to .epub
   book4.kepub.epub - copy of book1 with file ext manually changed to .kepub.epub

2. Drag-drop all 4 into calibre and run Count Pages on all of them to get ADE page count and word count.
   
3. Drag-drop all 4 onto my KA1. I deliberately avoided using calibre to do the transfer to avoid any auto file changes calibre might make in-transit.
   Open all 4 on the KA1 to see total page count.
   Books 1 & 3 open in the Adobe epub renderer.
   Books 2 & 4 open in the Kobo kepub renderer.

Results:

                            <-Count Pages ->  <--- Kobo entire book --->
File             Filesize   Pages      Words  Adobe Pages   Kepub Pages
book1.epub       1614709    277        98574  277           -
book2.kepub.epub 1665258    321        98574  -             325
book3.epub       1665258    321        98574  321           -
book4.kepub.epub 1614709    277        98574  -             325

Conclusions:

• Comparing books 1 & 3. The extra Kobo spans/divs inflate the ADE page count from 277 --> 321
• Comparing books 2 & 3. These are the same file with 2 different file extensions. ADE pages 321, kepub pages 325. Not the same value, so algorithms are different.
• Similarly, comparing books 1 & 4. The same file with 2 different file extensions. ADE pages 277, kepub pages 325. Not the same value, so algorithms are different.
• Comparing books 2 & 4. The "true" kepub (book2) and the "fake" kepub (book4) have exactly the same kepub page count, 325. The lack of Kobo spans/divs in the "fake" kepub does not affect the kepub page count, so I surmise filesizes are not a factor in calculating kepub page count. My guess is that the algorithm uses wordcount rather than filesizes.

If you're still reading ... thanks for staying awake and feel free to disagree! I'll be interested to read any of your own test results.

Thanks for doing that so that I don't have to.

When I saw the 321 an 325 for book 2, I figured that was close enough for it to be rounding or something. The algorithm is to divide the compressed file sizes by 1024 (from memory) and then add that up. For a book with multiple chapters, a five page difference wouldn't be enough to worry my.

But, as the kepub pages for book 2 and 4 are the same, that suggests they are using something else. It's probably just the character count when the tags are stripped. But, I wonder if they are actually using the word count and an average word length factor. They calculate the word count for each chapter when the kepub is first opened. Using that would mean they don't need to reprocess each chapter later to get the full book size.

[davidfor]

Originally Posted by wingmongyee

I don't actually do that (checking each chapter's number of pages and adding them all up). From now on, I might suggest to friends to check the book in a bookshop if they really want to have a true idea of its size

There are lots of page count source including Goodreads and some of the stores.

The graph is fun, yes, but it's the per-chapter page numbering that is the real advantage, so if you're not using it, I can see why you wouldn't switch to KePubs,

The graph tells me a lot more that the chapter page count. As well as where I am in the current chapter, it tells me length of the next and where I am in the book overall.

however aren't you bothered about the slower page turns (you said they're faster after all the firmware updates, but still slightly slower than KePub)?

I've never considered the epub page turning to slow. My requirement is basically that the next page needs to be displayed by the time my eyes get to the top left corner of the page. And recent versions of the firmware have improved the performance of the epub page turning enough that I don't see a difference between the two

I find that the general responsiveness of the reader is the most important factor in the reading experience, much more than any page numbering or other details.

Strangely enough, responsiveness of the device is a very low factor in my reading experience. There is probably a minimum speed that would bug me, but, the firmware has always been better than this (excluding the short lived 4.6.9660).

[DNSB]

Originally Posted by JSWolf

The ePub 3 being sold is really ePub 2 in ePub 3 clothing. It's backwards compatible with ePub 2 Readers and if not, it's a problem with that particular program. You can read the ePub 3 sold at Kobo with RMDSK (ADE) no problem or you can read as kepub. So the choice is yours as to which renderer you want to use.

I have to say it all depends. Out of the epub3 ebooks, I've purchased from Kobo there have been a few that were real epub3 books and RMSDK/ADE had some odd issues with them (opening in ADE 4.5 running in a VM did a decent job of displaying the content). This does not count the 3 that were FLO epub3 ebooks -- those required the .fxl.kepub.epub extension to look good on my eInk ereaders. ADE in either version I tested and RMSDK were interesting to look at but rather unreadable.

[wingmongyee]

Originally Posted by davidfor

Strangely enough, responsiveness of the device is a very low factor in my reading experience. There is probably a minimum speed that would bug me, but, the firmware has always been better than this (excluding the short lived 4.6.9660).

I guess the reason I'm stuck on responsiveness is that there was such a big difference, i felt, between the Sony reader I was used to, and the Kobo when I switched over two years ago. It really felt like there was a definite pause before I could start reading the next page on the Kobo. And it's not like I'm hyper sensitive or anything. For instance, page refreshes on every pages never bothered me in my first couple eReaders (also Sonys) although having said that, I'm glad page refreshes are much less frequent these days. The Kobo definitely felt sluggish enough to affect my reading experience in a way nothing else did.

But from what you say about the improvements in the Kobo firmware, my concerns about responsiveness are probably no longer justified. I'll have to revisit ePubs again at some point, just out of curiosity though because I'm very happy with KePubs.

[JSWolf]

Originally Posted by davidfor

You might want to look at the example I pointed to. That is definitely an epub3 and uses epub3 only tags. Just opening it an epub2 only app has some formatting problems. For most of the epub3 books I have found, changing the version from 3.0 to 2.0 is enough. But, this needed more work. And I couldn't reproduce some of the style in epub2, so I left as epub3 and a kepub.

Was it a fixed layout ePub 3?

[JSWolf]

The reason I prefer ePub is because of the better overall typesetting. There are some issues when you set kepub for better typesetting.

[davidfor]

Originally Posted by JSWolf

Was it a fixed layout ePub 3?

No. It is just coded to used epub3 features. It is a well constructed book that looks good. And I didn't want to screw with it to much to go back to only epub2 standards. Plus, there is absolutely no reason why I should.