calibre 7.11: support for adding thumbnails for Kindle Scribe

[tomsem]

Seems to be working, and I have not seen any 'disappearing thumbnails' after sync, restart, etc. So I don't think there's any need to restore them by re-connecting to calibre etc. even if WiFi is on (as it always is for me).

But duh, we didn't have thumbnails in the first place (at least not since the MTP update).

I still have never been able to reproduce the issue on other Kindles.

[Dr. Drib]

Tried it and it works great!

Thank you to all those responsible.

[OuyangZhu]

I'm windows 11 and kindle scribe, I tried to use calibre 7.11 to send the file to my kindle scribe, however it did not work, the book cover did not not exsit in my library list as the calibre version before.

[JSWolf]

Originally Posted by OuyangZhu

I'm windows 11 and kindle scribe, I tried to use calibre 7.11 to send the file to my kindle scribe, however it did not work, the book cover did not not exsit in my library list as the calibre version before.

It says in the first post that you have to reconnect to calibre.

[DNSB]

Originally Posted by tomsem

Seems to be working, and I have not seen any 'disappearing thumbnails' after sync, restart, etc. So I don't think there's any need to restore them by re-connecting to calibre etc. even if WiFi is on (as it always is for me).

Originally Posted by JSWolf

It says in the first post that you have to reconnect to calibre.

'Nuff said.

[tomsem]

Originally Posted by JSWolf

It says in the first post that you have to reconnect to calibre.

That has been the workaround for other kindles, where apparently a sync can remove the thumbnails that calibre put there.

I've never been able to reproduce this, but my Kindles are all running latest update, which lets you sync Kindle time to actual internet/local time, so files copied over have timestamps that match the Kindle's local time.

Kindles that aren't updated to latest firmware run GMT as local time, not local time of the computer copying the files, which means that side loaded files appear to be 'old' by whatever the time zone offset is with respect to the system copying files to the Kindle.

I think this resulted in sync removing 'old' thumbnails, and failing to download 'new' ones because ASIN was made up by calibre (to associate with the thumbnail folder) and so there's nothing that matches on Amazon server to download.

Calibre adds a /amazon-cover-bug folder with copies of the thumbnails, and when calibre re-connects to the Kindle, calibre moves the thumbnail back, and then it 'sticks', because the last-modified timestamp is set to current local Kindle time and is no longer 'old', and a candidate for removal. (and it might have sufficed had calibre set modified date of thumbnail to GMT to begin with)

At least that is my theory. Since I don't have a Kindle of proper vintage, I cannot test it. (*)

Note this behavior is consistent with use case of side loading a file downloaded from Content and Devices: there will be no thumbnail (or X-ray or existing annotations) until and unless Kindle can connect to Amazon servers and add these things. It wants to 'update' all of these things if they exist on the device.

Kindle will let you side load supported file types, but /system/thumbnails is 'hidden', and is a sign that side-loaded thumbnails aren't really supported.

But at least with the latest updates, sync will not remove thumbnails because they are 'old'.

Sync will replace thumbnails if ASIN matches up to something on Amazon, but leaves them alone otherwise.

I side loaded one file that had a real ASIN and another with a phony ASIN generated by calibre (necessary in order to associate a book with its thumbnail). Then I noticed that the thumbnail for the latter was fuzzy, whereas the one for the former was not.

Turns out that calibre 7.11 is sending low resolution thumbnails: the default height for MTP devices is only 160px. For other Kindles height is 500px. Sync replaced the thumbnail for the one with real ASIN, it is something like 454px high and in greyscale, while the other one retained its 160px color thumbnail.

I filed a bug, hopefully it'll be fixed in next release.

(*) I do have a Kindle Touch. I might be able to test my theory on it.

[OuyangZhu]

Originally Posted by JSWolf

It says in the first post that you have to reconnect to calibre.

Sorry, I tried to reconnect the kindle scribe to calibre 7.11 again, but it did not work, neither. The thumbnail of book did not exist in my kindle library list.

By the side, my book's ASIN was made by the calibre, and the book is sideloaded into the calibre.