missing magazine covers in FSF

[dhdurgee]

I am trying to help FSF track down a problem with the kindle magazine covers on my KT2. Some of their issues appear to be missing what our screen saver pulls from the magazine for the cover, which also impacts the kindle's directory display in cover mode. Our screen saver shows something similar to the magazine masthead instead of the cover for these issues. The cover mode directory display shows the magazine name and date in a white box over a generic screen saver background.

Can someone give me a pointer to what the hack is looking for, which I assume is the same thing the firmware is for its cover mode display? The FSF people tell me they are seeing the cover in color, so I assume they are looking on a fire as opposed to a paper white display.

I should also note that I DO see the cover from within the magazine, so it might be a missing link of some sort in the file as opposed to an outright missing image.

I should also note that I have issues that DO display properly, so if someone can give me a way to test this I can run it against both working and failing issues.

Dave

[pdurrant]

Originally Posted by dhdurgee

I should also note that I have issues that DO display properly, so if someone can give me a way to test this I can run it against both working and failing issues.

You should look at KindleUnpack.

[dhdurgee]

Originally Posted by pdurrant

You should look at KindleUnpack.

Just thought to do that and I am still puzzled. Both the issue that shows and cover and the one that doesn't unpack fine. I can inspect the opf files and the images from both without errors. I guess I will have to inspect the images further for problems of some sort.

Dave

[dhdurgee]

How critical are the image sizes? All images are jpeg formatted, Greyscale single layer. There is a thumbnail and a cover image in each. In the one that works the thumbnail is 158x240 and the cover is 363x550 while in the one that fails the thumbnail is 160x240 and the cover is 366x550 in the example files I tried.

If the size is critical, I will inspect the other issues that fail to see if the pattern continues.

Dave

PS: suspect disproved as sizes that worked vary

[dhdurgee]

I just successfully used kindleunpack on six issues, four without covers displayed and two with covers displayed. In all cases I see cover images in the unpacked issues. I am not sure of this, but what is being grabbed by the screen saver is another image in the issue. The grabbed image is a header as opposed to the proper cover.

Would inspection of the .opf and .ncx files provide anything of interest in determining the problem? Can I post them here for others to inspect?

Dave

[pdurrant]

I wrote a QuickLook cover display for Mobipocket long ago. It still work on Kindle books. But I've long forgotten the exact details of how to find the right image for the cover.

But my guess would be that some of the metatdata is wrong. Don't forget that the opf and ncx produced by KindleUnpack aren't really in the MOBI format kindle file. You might want to experiment with the kindleunpack options to get the exact metadata out of the MOBI file without mangling.

I also have a subscription to F&SF. I can't remember noticing bad covers. Give me some issue numbers for good and bad covers and I'll re-download and take a look.

[dhdurgee]

recent FSF Issues:

March, 2018 - cover missing
January, 2018 - cover missing
November, 2017 - cover shows
September, 2017 - cover shows
July, 2017 - cover missing
May, 2017 - cover missing
March, 2017 - cover shows
January, 2017 - cover shows

Where I note the cover shows, I see a cover in cover mode for the folder on the KT2 and the screen saver pulls a cover from it. Where the cover is missing I see a generic document background with the name and date of the magazine while the screen saver pulls a FSF page header instead of the cover. If I open the issue I can see the cover within the issue, it just is not seen from outside.

I assume the problem is with the mobi file. I have reported this to FSF and they have asked me to work with them as they are not seeing the problem on a kindle fire where they see a color cover. Perhaps the document delivered to the fire is in another format, I don't have one to check on this.

Dave

[dhdurgee]

Originally Posted by pdurrant

I wrote a QuickLook cover display for Mobipocket long ago. It still work on Kindle books. But I've long forgotten the exact details of how to find the right image for the cover.

But my guess would be that some of the metatdata is wrong. Don't forget that the opf and ncx produced by KindleUnpack aren't really in the MOBI format kindle file. You might want to experiment with the kindleunpack options to get the exact metadata out of the MOBI file without mangling.

I also have a subscription to F&SF. I can't remember noticing bad covers. Give me some issue numbers for good and bad covers and I'll re-download and take a look.

I hope you have a chance to look into this further. I posted to FSF on their forum about this when I posted here and they asked for any additional information I could provide on this. It might well be limited to the paper white kindles, as they report seeing color covers. Does the kindle fire use the same format for magazines? If not, that might explain this difference.

I see the cover inside the issue, but not in the cover view listing of issues or when I have the screen saver in cover mode.

Dave

[pdurrant]

Originally Posted by dhdurgee

I hope you have a chance to look into this further. I posted to FSF on their forum about this when I posted here and they asked for any additional information I could provide on this. It might well be limited to the paper white kindles, as they report seeing color covers. Does the kindle fire use the same format for magazines? If not, that might explain this difference.

Amazon tweaks the file sent to different devices. Often the file sent to E-Ink Kindles will include only a greyscale cover image. Files sent to Kindle Fires will certainly have a colour image.

(For example, for Amazon and Analog a massive file gets sent to iOS/Android that includes page images as well as flowable text, while a much smaller file with just the flowable text is sent to E-Ink Kindles.)

I'll try to get a look at the files tomorrow. Remind me again if you don't here from me by this time tomorrow!

[dhdurgee]

Originally Posted by pdurrant

Amazon tweaks the file sent to different devices. Often the file sent to E-Ink Kindles will include only a greyscale cover image. Files sent to Kindle Fires will certainly have a colour image.

(For example, for Amazon and Analog a massive file gets sent to iOS/Android that includes page images as well as flowable text, while a much smaller file with just the flowable text is sent to E-Ink Kindles.)

I'll try to get a look at the files tomorrow. Remind me again if you don't here from me by this time tomorrow!

Did you make any progress?

Dave

[pdurrant]

Originally Posted by dhdurgee

Did you make any progress?

Dave

Looking now! Thanks for the reminder.

[pdurrant]

I can't reproduce the problem with covers on my Voyage - I see the correct covers in grid mode.

Looking at my QuickLook cover software, I may have a clue for you.

It has two algorithms for finding the cover. The first is to select the first picture in the file. I suspect that may be what the Kindle cover hack is doing.

But to find the correct cover, if the book has an EXTH header you need to find record 201 in the EXTH header, which contains the picture index for the cover image.

This might be covered in the MObileread wiki.

[pdurrant]

I've looked closer, and I still can't see any differences in the files. Is the source for the screen saver hack available? It certainly seems most likely to be a bug in that.

[dhdurgee]

Originally Posted by pdurrant

I've looked closer, and I still can't see any differences in the files. Is the source for the screen saver hack available? It certainly seems most likely to be a bug in that.

Yes, the source is available here:

http://mr-public.auth-2ac4bfee353948...-r14393.tar.xz

Looking at this I believe I am running an earlier version, so I guess I should update and see if that fixes the screen saver problem.

But that is only part of what I am seeing. When I put the kindle directories in cover mode I don't see the covers there either, at least for the copies that are there. Those copies were downloaded directly from Amazon and are DRM protected. Perhaps I should try sideloading the DRM free ones and see if they exhibit the same behavior. I obtained those by a download to computer for sideloading, so it is possible they have been modified.

Thanks for you efforts thus far. I hope we can get to the bottom of this.

Dave

[dhdurgee]

Originally Posted by pdurrant

I've looked closer, and I still can't see any differences in the files. Is the source for the screen saver hack available? It certainly seems most likely to be a bug in that.

A follow-up to my previous post, when I checked on the KT2 itself the files with missing covers are a different size than those I downloaded from Amazon to my laptop. I have emailed you the versions from there with DRM removed.

I also tried copying the versions I downloaded from Amazon and removed DRM from to a sub-directory of my KT2 documents directory, being sure to change the prefix to .pobi to match the other issues. When I went to cover view of the issues I now showed new issues with covers, AND THE COVERS APPEARED ON THE ISSUES ALREADY THERE AS WELL. I have not yet tried it, but I suspect the screensaver will work now for those issues.

Given there is a difference in file sizes I suspect you will see something strange in the KT2 version of the 2018 issues. Hopefully this will be something that is definitely wrong with those issues that I can report to FSF so that they can fix them and avoid this in the future.

This also, potentially, gives me a work around by side-loading the issues.

Dave