Mobi files which allow custom fonts?

[NoRightNoWrong]

Hi! This is my first post at this community. I was wondering if someone could please help me.

Here's the thing: I've got a Kindle 7 and, unless I convert .mobi files into .azw3 format, I'm unable to switch to my custom fonts. *But* the other day I found not one but two books in .mobi format which allow me to choose those custom fonts, without converting to .azw3 or any other format.

How can this be possible? If there's a way to change fonts while reading a .mobi ebook, which is it? (Is there any app to analyze those files' setup, configuration, metadata, etc.? I'm clueless about what makes those .mobi files different from the other ones I've been handling so far).

Thanks in advance for your advice.

[hobnail]

As I understand it there are 2 mobi things, the mobi file/container and the mobi format. The mobi file/container is that where the file suffix is .mobi while the mobi format is the old PocketBook mobi format, inside the mobi file/container, which is quite limited in what it can do. A .mobi file/container has the ability to contain the book in both the old mobi format as well as the newer KF8 format. With a .mobi file/container older kindles don't see the newer KF8 formatted book while newer kindles use the KF8 formatted book and ignore the old mobi formatted book.

I may have made a hash of that but the wiki here has a more complete explanation:

https://wiki.mobileread.com/wiki/MOBI

[NoRightNoWrong]

Originally Posted by hobnail

As I understand it there are 2 mobi things, the mobi file/container and the mobi format. The mobi file/container is that where the file suffix is .mobi while the mobi format is the old PocketBook mobi format, inside the mobi file/container, which is quite limited in what it can do. A .mobi file/container has the ability to contain the book in both the old mobi format as well as the newer KF8 format. With a .mobi file/container older kindles don't see the newer KF8 formatted book while newer kindles use the KF8 formatted book and ignore the old mobi formatted book.

I may have made a hash of that but the wiki here has a more complete explanation:

https://wiki.mobileread.com/wiki/MOBI

Hi and thank you for your reply.

I've now just tried converting a regular .mobi file into a .mobi container. That being done, my Kindle allows me to choose from the custom fonts I loaded in first place, but photo cover goes blank right after I save the .mobi container to my device. Is there any way to keep it? (I mean, the photo cover's thumbnail).

[pdurrant]

Originally Posted by NoRightNoWrong

Hi and thank you for your reply.

I've now just tried converting a regular .mobi file into a .mobi container. That being done, my Kindle allows me to choose from the custom fonts I loaded in first place, but photo cover goes blank right after I save the .mobi container to my device. Is there any way to keep it? (I mean, the photo cover's thumbnail).

I beleive that if you transfer it to your Kindle using calibre, calibre will created the necessary cover thumnbail file on your Kindle.

For old-style .mobi files, the Kindle will do this itself, but oddly not for combined .mobi or .azw3 files.

[NoRightNoWrong]

Originally Posted by pdurrant

I beleive that if you transfer it to your Kindle using calibre, calibre will created the necessary cover thumnbail file on your Kindle.

For old-style .mobi files, the Kindle will do this itself, but oddly not for combined .mobi or .azw3 files.

Hi!

I've tried transfering files through Calibre, but the result is the same: cover photos go blank within seconds.

One thing I've just noticed about those files I downloaded as .mobi and show both covers *and* custom fonts, it's that they somehow generated two .azw3r and .azw3f (sic) files inside their own folder.

Let me see if I can show you...

[JSWolf]

Mobi aka Mobipocket does not allow embedded fonts.

[pdurrant]

Originally Posted by NoRightNoWrong

Hi!

I've tried transfering files through Calibre, but the result is the same: cover photos go blank within seconds.

Then other possibility is that your ebooks have an ASIN in the metadata, and so the kindle is trying to pull the cover image from Amazon's servers. If the ASIN isn't valid, that might exaplain the blank cover.

(The fonts thing is simple - original MOBI format and they won't work, AZW3 (also known as KF8) or the dual format and they will work.)

[jhowell]

There is a fix for the disappearing Kindle cover thumbnail images in the latest version of calibre. See the FAQ:

Covers for books I send to my e-ink Kindle show up momentarily and then are replaced by a generic cover?

[JSWolf]

Originally Posted by pdurrant

Then other possibility is that your ebooks have an ASIN in the metadata, and so the kindle is trying to pull the cover image from Amazon's servers. If the ASIN isn't valid, that might exaplain the blank cover.

(The fonts thing is simple - original MOBI format and they won't work, AZW3 (also known as KF8) or the dual format and they will work.)

But they won't work for the Mobi part of a dual Mobi eBook.

[JSWolf]

Originally Posted by jhowell

There is a fix for the disappearing Kindle cover thumbnail images in the latest version of calibre. See the FAQ:

Covers for books I send to my e-ink Kindle show up momentarily and then are replaced by a generic cover?

And keep WiFi off after disconnecting from Calibre. Don't turn on WiFi unless you really need to. Don't turn on WiFi when you are not going to be near your Calibre library for too long (e.g., on vacation).

[pdurrant]

Originally Posted by jhowell

There is a fix for the disappearing Kindle cover thumbnail images in the latest version of calibre. See the FAQ:

Covers for books I send to my e-ink Kindle show up momentarily and then are replaced by a generic cover?

Fascinating. Thanks! I've learned something new.

[JSWolf]

Originally Posted by pdurrant

Fascinating. Thanks! I've learned something new.

But it's only a temporary fix. As soon as you sync, you blow away the cover images until the next time you connect to Calibre.

[jhowell]

Originally Posted by JSWolf

But it's only a temporary fix. As soon as you sync, you blow away the cover images until the next time you connect to Calibre.

Not true. Amazon only overwrites the cover once for each book. Once a book cover is fixed it should stay fixed.

[NoRightNoWrong]

Originally Posted by jhowell

There is a fix for the disappearing Kindle cover thumbnail images in the latest version of calibre. See the FAQ:

Covers for books I send to my e-ink Kindle show up momentarily and then are replaced by a generic cover?

Solved!

Thank you so much. And thanks to everyone who replied, as well!

[rcentros]

Originally Posted by jhowell

There is a fix for the disappearing Kindle cover thumbnail images in the latest version of calibre. See the FAQ:

Covers for books I send to my e-ink Kindle show up momentarily and then are replaced by a generic cover?

It worked. Thanks! I converted a book from ePub, thought it had a cover image at first, which then disappeared(?). But I wasn't sure if I remembered right. It was one of those things I was going to look into, but hadn't gotten to it. Now I know I wasn't crazy (and it also gave me a good reason to upgrade to 4.17).