Calibre on iOS

[DJDarren]

Yesterday I finally picked up a lightning to USB adapter so I could run a decent microphone into my phone for podcasting. As an added bonus, I noticed that it could also connect to my Kindle, which led me to wondering if any work has been done towards porting a version of Calibre for iOS that can convert formats and edit metadata. Or is the current userbase for that setup just too small for it to be worth it?

Thing is, with iPadOS picking up more and more ‘Mac’ features every year, it’s only a matter of time before people are only using an iPad as their primary computer.

Essentially, I’m looking for ways to move my entire computing workflow away from a dedicated computer, so I can do it all on iPhone/iPad. Kindle management and torrenting are the two major holdouts at this point. Well, mastering audio on GarageBand as well, but my new microphone should make that less necessary...

[kovidgoyal]

Use the calibre content server it can do both. Run it in the cloud somewhere.

[DJDarren]

Hi Kovid!

First up, thanks for your work on Calibre, it’s a wonderful tool.

I don’t understand what you mean. Could I, for example, put my Calibre library in iCloud then access it on my phone? How would that help me with converting ePub to KFX without needing a Mac?

[JSWolf]

Originally Posted by DJDarren

Hi Kovid!

First up, thanks for your work on Calibre, it’s a wonderful tool.

I don’t understand what you mean. Could I, for example, put my Calibre library in iCloud then access it on my phone? How would that help me with converting ePub to KFX without needing a Mac?

You cannot use iOS to convert ePub to KFX.

[kovidgoyal]

No, the calibre content server https://manual.calibre-ebook.com/server.html

[DJDarren]

Originally Posted by JSWolf

You cannot use iOS to convert ePub to KFX.

That’s what I’m trying to get to. Is there a technical reason why this couldn’t be done? Is there a restriction in iOS that stops it from being able to convert formats? Because as far as I can tell new devices are certainly powerful enough for the task. My XR can mix down lengthy podcasts without batting an eyelid.

[BetterRed]

IOS is a device oriented OS - i.e. phones and tablets, as is Android. calibre requires a desktop/laptop oriented OS i.e. Windows, MacOS or Linux.

BR

[DJDarren]

Yes, I understand the difference between a desktop OS and iOS, but given that I have apps that are able to convert audio files from AAC to MP3 or WAV, or AIFF, then doesn’t it follow that the system is also capable of converting an ePub to AZW3 or KFX? Theoretically, the system is able to do this, right? Assuming an app is written for this process?

If this isn’t the case, then what restrictions exist to stop it from happening? And why? I mean, at this stage iPad Pro is essentially a full blown PC in terms of its power. Indeed, it’s likely more powerful than the MacBook I’ve had for nine years, but my Mac will convert books with ease.

I’m happy to be set straight on this, as I don’t actually know anything at all about app development, which likely shows...

[pazos]

Originally Posted by DJDarren

If this isn’t the case, then what restrictions exist to stop it from happening? And why? I mean, at this stage iPad Pro is essentially a full blown PC in terms of its power. Indeed, it’s likely more powerful than the MacBook I’ve had for nine years, but my Mac will convert books with ease.

In terms of processor an iPad is a capable system. In terms of os is just a toy OS (a good one). with a lot of limitations:


- Apps are sandboxed (no access to filesystem outside its own directory)
- System calls are not available. You need to adapt the software you want to port or use a drop-in replacement (like https://github.com/holzschu/ios_system)
- running interpreted code is forbidden. Code must be compiled in (that would mean no plugins!!!)
- qtwidgets is not optimized for a touch device. Need to rewrite the whole UI using UIkit or QtQuick.
...

[kovidgoyal]

I'm sure its possible, its just not going to happen, its not worth the amount of effort, at least to me. As I said use the calibre content server, it can edit metadata and convert books. The only downside is you have to rent a server to run it on for a few dollars a month.

[DJDarren]

So essentially, it is theoretically possible, but would be a huge effort that would amount to very little use outside those very few people who have a really quite pricey lightning/USB dongle?

I suppose my thought process is that, with iPads having USB-C now, and more and more people looking to use them instead of a PC, a tool like this could become really quite useful. For my own situation, it’s literally this and the ability to torrent that is holding me back from going fully iOS. Making podcasts on my phone has become a joy, and iOS is finally beginning to shape up into what it looked like it could be.

[ilovejedd]

Just keep a desktop or get a NAS or something.

Incidentally, I do believe Calibre runs on the Raspberry Pi 4. It’s ARM-based and significantly less powerful than even a 2-3 generations old iPad. However, barring packages incompatible with ARM, it does offer the full Linux experience so you can install Calibre on it. Meanwhile, iOS is restricted by design.

By the way, the iOS Files app couldn’t handle my Paperwhite 3 which has around 2000+ books. It even managed to make my Kindle crash somehow.

The Files app uses an abstraction layer or something and doesn’t actually provide direct file system access. I’ve had it crash on me a few times during normal use, no external storage connected. I wouldn’t trust it not to corrupt my data.

Also note, I do believe the KFX output plugin requires Kindle Previewer. Even if someone does write an ebook conversion app for the iPad, converting to KFX likely won’t be an option.

[JSWolf]

IN order to get Calibre to run on iOS, you would need QTWebKit, Python 2.x, and Kindle Previewer all ported to iOS. There could be other things needing porting Because there is no way all the various components will be ported, it's a no go for iOS.

[DNSB]

Originally Posted by JSWolf

IN order to get Calibre to run on iOS, you would need QTWebKit, Python 2.x, and Kindle Previewer all ported to iOS. There could be other things needing porting Because there is no way all the various components will be ported, it's a no go for iOS.

Why not Python3? As for Kindle Previewer? I have it on my computer but never use it with calibre.

Plus as mentioned anything that currently runs from source would need to be compiled and approved. I.e. all those calibre plugins we love.

[JSWolf]

Originally Posted by DNSB

Why not Python3? As for Kindle Previewer? I have it on my computer but never use it with calibre.

Plus as mentioned anything that currently runs from source would need to be compiled and approved. I.e. all those calibre plugins we love.

Because the current non-beta Calibre uses Python 2.