Issue with ePub file (Min-Max Volume 5) using 3rd party reader (FBReader iOS)

redmasq

Hello,
I've already reached out to the 3rd party developer (FBReader) and done some personal triage. The developer is still investigating the issue, but I figured I would cross-post here on the off chance that it is useful.

The file in question is Min-Maxing My TRPG Build in Another World_ Volume 5.epub. Using both command-line Info-Zip and 7-zip, I have verified that the ePub file checks integrity. The specific symptom is the application shutting down suddenly (iOS 16.3; attaching the console in Xcode makes it look like an out-of-memory error) Downloading the file again does not make a difference and it does open correctly in Calibre and the Windows version of the application. What does make a difference is extracting the contents and then using Info-Zip to rebuild the file

# Assume in the same directory as the already unzipped ePub
# For any curious browsers, the listing of the mimetype file followed
# by the  directories is to ensure order since mimetype not being the
# first causes various applications to whine
zip -9ru -Z deflate  "Min-Maxing My TRPG Build in Another World_ Volume 5.epub" mimetype META-INF OEBPS

At which point the file can be opened with no failure or seen on console memory inflation.

Again, I've filed a bug report with the developer already, but I thought it would be useful to cross-post here in case someone having a similar issue and need a quick fix, or if j-novel club wants to look into it.

Thank you

admin

@redmasq In case it helps, we build our epubs with Sigil, which handles the zipping part... Very strange that simply recompressing would fix things, since that shouldn't in theory change the contents of the files within the zip at all...

redmasq

@admin,
If you like I can email you, or send by other means, copies of the file I have vs the file I rezipped. The CRC of the contents are the same (if it still reproduced, I was going to try down scaling the images to see if it was a resolution problem) and the file opens file under both Windows and Linux (probably could guess since since I rezipped it and opened it in Calibre), so I don't think it's fundamentally broken, but perhaps some compatibility issue with it. Maybe a difference in something in the ZipDirectory structure, or perhaps one of the files that got compressed instead of stored or vice-versa is setting it off.

I don't know what library is being used in their code. Since, last time I checked, neither Objective C nor Swift offered one natively, I don't have any obvious candidate to so an isolated test-- not that I'm exactly an iOS programmer... so, slightly outside of my forte.

None the less, I need to write a manual for something at work, maybe I'll install Sigil again (easy enough to export to PDF later) and see if I can break the app with that (yes, programmers do sometime document... sometimes). But something that will have to wait until the weekend (I still need to play around more with chocolatekey's api: I want to setup auto-download into my Calibre library when purchased books release... Too much going on at work, can't play around enough).

But, I can send the set of files if requested. If not, I at least have a work around for the moment. Hopefully, any bug or implementation incompatibility will be fixed in the reader soon. As long as Dahlia opens, somehow, the wifey will be happy, and I won't get told to post in the forum to ask when the next chapter comes out (I will have to actually ask, even knowing the answer is that you don't speak of releases until they actually come out).

Thank you

chocolatkey

@redmasq Can you please send a copy of your premium epub to chocolatkey@j-novel.club ? Maybe there's something special about it and I'll find a fix. Thanks

Travis Butler

FWIW, Min-Max 5 does open and read for me in Apple Books... but it shares a problem all the JNC releases have had for some time, the Table of Contents doesn't work at the app level. Tap the app ToC button, and it shows the in-app rendering of the ToC, but tapping any of the entries takes you to the cover page. Scrolling to the ToC at the end of the book, tapping on any of the links works there.

Trying to open Min-Max 5 from Dropbox (using the Export feature) in the Marvin ePub reader crashed Marvin. After re-opening Marvin from the home screen, it worked and the book read properly. The in-app ToC worked.

Opening it from Dropbox in Bluefire worked fine, and the in-app ToC worked; the default font size was badly off and had to be shrunk three sizes.

jpwong

Can confirm that the ToC works fine in Google Play Books (I actually had to go find my second most recent purchase because apparently Fushi no Kami just has an image for the ToC instead of an actual page with clickable links)

myskaros

@Travis-Butler said in Issue with ePub file (Min-Max Volume 5) using 3rd party reader (FBReader iOS):

FWIW, Min-Max 5 does open and read for me in Apple Books... but it shares a problem all the JNC releases have had for some time, the Table of Contents doesn't work at the app level.

I've never had any problem with the TOC in Apple Books. I just downloaded a book from my library to try and it works fine. Feels like you might need to update your OS or app version, or clear saved settings or something.

redmasq

@chocolatkey,
It's been sent. Please let me know if you have any questions.

Thank you

mDuo13

I seem to be having the same issue with FBreader Premium on Android, specifically with the premium ePub volumes 18 and 19 of Grimgar. Somehow I was able to get 18 to open past the opening images and it worked more or less normally from there, except images were replaced with the text "Encrypted Content". I haven't managed to do it again, but this makes me think something to do with how the images are built/compressed/etc is tripping up FBreader specifically. Viewing my bookshelf in a format that shows the covers also sometimes causes FBReader to crash.

I would be inclined to say this is a problem with FBreader, but Grimgar 1-17 work fine for me as do all the books I've read of several other series (e.g. Kokoro Connect, Sexiled, Infinite Dendrogram). Some of those earlier volumes I downloaded quite a while ago and I haven't re-downloaded the "updated" versions, so if there was a change to the process of building the files, I can't say for sure that the versions currently available on the site all work. But I confirmed by redownloading 18 and 19 that those volumes specifically don't.

Going out on a limb, maybe the images are encoded/compressed/whatever using a new format, or maybe something about these volumes' images is different (larger resolution, maybe?) in a way that is "invalid" or at least unexpected by FBreader, causing it to bug out? I'll be keeping an eye out for updates.

jpwong

@mDuo13 If you're interested in checking if the images appear different, you can open an epub with most zip tools and just pull the images out to check them.

redmasq

@mDuo13 I had since attached a listener to the iOS version debug output and have been getting out-of-memory errors. I currently don't have an Android device that would run the Premium version (lack of Google). I suspect the issue might be in whatever library the developer is using for the Zip File handling since rezipping manually (or, less technical, but imperfect, open in Sigil and Save As) allows the files to open (and don't crash the scrolling either) and doesn't inflate memory usage. If they are using a common 3rd party library or rolling their own (possible if the UI for iOS is in Objective C and Java wit JNI or uses the NDK for Android, both with the same C/C++ support libraries). The Windows version is different than the mobile versions given how it is an UWP app and likely uses those APIs for zip instead.

At any rate, I got some debug data over to the FBReader telegram account (listed on official website); might be worth filing an Android version report so they can add something to Bugzilla or whatever they use internally since it would narrow down to any common code.

mDuo13

@redmasq That's good to know. I don't have Telegram and don't particularly want to sign up just for this thing, but it doesn't look like there's any other way to report an issue to the dev(s). I was able to get into the 4.x beta program and found that the 4.x beta versions have the same problem as the 3.x versions. =/