Kobalt: an alternative reader app for Kobo devices

[JSWolf]

Originally Posted by MrSilverstrike

No plans for this right now. It'd require too many changes to how page numbering works and you'd need books that support the `page-map` extension. It's not something I'm personally interested in supporting right now, at least not before v1.0 is out.

I think we can do without page-map. This is just for the page numbers displayed in the header/footer.

[MrSilverstrike]

Originally Posted by JSWolf

I think we don't need the page-map extension. I don't read books with alternate page numbers. And if the book has them, I remove them.

You misunderstand: I need to support Adobe's page-map extension for epub files in order to support what you're asking for.

[JSWolf]

Originally Posted by MrSilverstrike

You misunderstand: I need to support Adobe's page-map extension for epub files in order to support what you're asking for.

Why would that be? Count Pages supports ADE page numbers without the page-map.

[MrSilverstrike]

Originally Posted by JSWolf

Why would that be? Count Pages supports ADE page numbers without the page-map.

Specifically, ADE page numbers are... technically inaccurate. Wildly so.

Without page numbers baked into the file they're literally made up based on the size of the compressed archive. That can vary based on how the epub was made. This way, 20 dense screens of text which may count as 10 pages in a printed book might translate to only 2 pages with this counting system (if there's an abundance of repeated text).

I'd say that's not ideal. It's not a massive problem, but it's definitely a technical flaw.

But look, it's a standard (to some degree). If I can find a nice way to make this work and present it as such, I'll add it as an opt-in feature. But I'm not sure yet whether it makes sense, and I doubt it'll make it into the app before v1.0 is ready.

[Dal Bhat]

technically inaccurate. Wildly so.

I don't know where the numbers come from as counted/displayed in Kobalt, but, yeah, way off. Example from one of my current books: 234 pages according to Calibre; 538 on the device in Kobalt.

The former is much more reasonable based on what the book is.

[MrSilverstrike]

Originally Posted by Dal Bhat

I don't know where the numbers come from as counted/displayed in Kobalt, but, yeah, way off.

Kobalt just counts the screens, so it depends on your text settings and how big your device is!

[DNSB]

For what it may be worth, there are two types of Adobe page numbers. The page map numbers which like the ePub3 page list matches the page numbers in a specific physical books and the Abobe Synthetic Page Number algorithm which is the one that uses the compressed data as part of the calculation.

1. Calculate the byte length of every resource referenced in the spine subtracting encryption overhead.
2. Divide the byte length by 1024 and round up.
3. Take the calculated number of pages in the resource, count the number of Unicode characters in the uncompressed resource; distribute synthetic page breaks by dividing the number of characters by the number of pages. If the output of the division is not evenly distributed, round the number of characters per page up and let the last page contain less characters than the rest of the pages.

The main advantage to the Adobe SPN algorithm is that the number of pages is the same regardless of text size, formatting, etc. The disadvantage is a page number can and will fall in the middle of a page. Another disadvantage which I've seen a couple of times in the wild is where the ebook creator for some reason used base64 images which caused wildly inflated page counts.

I checked one of my grand-niblings university etextbooks (all 15 of them) back in September and 12 of them were ePub3 with an ePub3 page list in the navigation document. Only 1 of the 12 that had a page list did not also have an ePub2 NCX navigation document which also carried the page list. Of the remaining 3, two were ePub2 and did not have a page list/page map and the other was ePub2 with an embedded Adobe page map.

I suspect that adding the ability to use a page list would be the most useful to most people.

[Dal Bhat]

Originally Posted by MrSilverstrike

Kobalt just counts the screens, so it depends on your text settings and how big your device is!

Now I know. So x of y tells me which screen of y total screens remaining in the chapter I'm reading.

That's OK, too!

[Glennza]

Just installed beta 5 on my Clara HD (BW). Looks great so far.

Only issue I have is that the settings menu says Page Turn Animations are "not supported on this device". This is a bit weird as I have NickelDissolve installed and it works great on the built-in reader. Any ideas?