Interesting Discovery

[romad]

I've been downloading Kindle books and importing them into Calibre for years. I'd then convert them to ePub format. Since Amazon switched from Mobi to ePub, I figured I'd try using the Kindle Unpack plugin and it does work fine. However, I found a major difference between doing a CONVERSION vs UNPACKING to get an ePub I can use. ePubs from both methods can be read just fine but there is a type size problem. In Converted books on my eReader application (MapleRead SE), I can resize the type without a problem but Unpacked books, while the application shows the type size can be changed, it actually never changes. I don't know why the type size can't be changed because of something in Calibre and Kindle Unpack not working properly or if there is something in the Unpacked ePub that blocks the resizing in the application. So it looks like I have to go back to the long way of converting.

[DNSB]

That would be something in the CSS stylesheet setting a fixed font size. Personally, I tend to edit almost all ebooks before they get out of my Intake library so fixed font sizes get bit bucketed at that point.

[theducks]

I would guess the CSS is calling an absolute size: in, cm, px ...

em is a relative size, so it scales

[tomsem]

I've not had many issues with converting AZW3 to ePub with calibre. Exception is for fixed layout (images + text) books, then KindleUnpack does better (calibre does not support fixed layout ePub).

For image only books (comics, manga), the ePub KindleUnpack (at least for some books) generates leaves a couple of issues that calibre Edit book complains about (no ToC, item in spine without a target, some CSS issue), but even after fixing these issues, there are issues rendering pages properly (in particular 2 page spreads are not handled correctly).

If I get a KFX with Kindle for PC, import that and convert to fixed layout ePub with From KFX, then the spreads are rendered properly. Edit book shows no errors, and they render properly in Thorium and Apple Books.

Ideally KindleUnpack would work as well, as getting decoded KFX may not remain possible. I will see if I can figure out what the issues are and report them to @DiapDealer.

Unfortunately I have a number of these in my library and only in last few months realized calibre's conversion to ePub wasn't good. So I have to hunt them all down and fix them.

It might be nice if one could configure calibre to avoid attempting to convert fixed layout AZW3.

[romad]

Well, I first tried Kindle Unpack because of a single author. For some reason when I bought his books on Amazon, after converting from AZW3 to ePub starting on the second page of every chapter, the text block would shift one character left on each page, which made the book unreadable. However, when he sent me a copy of the ePub he provided Amazon, it did not have that character shift. He and I could never figure out what was causing the shift. Kindle Upacked ePubs also didn't have the problem.

So I'll continue to use Kindle Unpack just for his books but convert all others from AZW3 to ePub in Calibre. It is way less labor intensive than editing the CSS.

Thank you for your suggestions, though.