I've been using Calibre for a little while now, but there's something I don't understand. When I started using it, I had all my ebooks in a directory (My documents/My ebooks). I used "Add Books" to add them to Calibre, and when I added a book, Calibre created a new folder (with subfolders) for the book in my chosen directory (My Documents/Calibre ebooks), and copied the book file into the new location (it remains in the old location, but Calibre doesn't care about that).

Okay - that's fine. So then, what exactly is the purpose of the "Save to disk" function? Hasn't Calibre already effectively saved the book to disk, when I "added" it to Calibre and Calibre copied it to my "Calibre ebooks" directory? Why would I ever need to use the Save to Disk function? Is it simply to allow easy backup? I've seen a few things suggesting that saving to disk has something to do with changing book file metadata, but I can't quite figure this out, and I can't find anything in the documentation to help me.

Maybe this question is related to something that's confusing me in the thread about the new beta version - people keep talking about loading their libraries into the new version of Calibre, and how long it takes. But when I install a new version, all my books just appear right there. There's no loading time. I don't even think I understand what a Calibre library is - isn't it just the list of book folders and subfolders in my designated Calibre directory? Does this have something to do with Saving to Disk?

I feel like I'm failing to understand some important aspect of Calibre, and again, I've not been able to find anything in the documentation that lays any of this out. I'm not even sure I'm formulating my questions correctly, and it may be that the answers are somewhere in the forums if only I knew where to look, but I've failed to find them, so I'd be incredibly grateful if someone who gets it (maybe really what I'm asking is how Calibre works???) could explain to me.

Thank you! :-)

Your calibre library is the 'My Documents/Calibre ebooks' directory. When importing calibre will store the books there. The entire library consists of the book files, covers, and the metadata.db file. Leave the library alone and do not touch anything in it outside of calibre.

'Save to disk' is exactly what it says it saves the file to disk. calibre stores the ebook files in the library but the metadata is stored separately in the metadata.db file. When you use 'Save to disk' it will save the file in your requested location and update the metadata on that file.

'Save to disk' is necessary for instances when calibre doesn't support a particular reader because it still allows you to save books onto it. Also, it allows you to back up your collection without backing up the actual library (just the ebooks with the correct metadata). It is also handy if you want to put a book on say a thumb drive to share with a friend.

'Save to disk' is exactly what it says it saves the file to disk. calibre stores the ebook files in the library but the metadata is stored separately in the metadata.db file. When you use 'Save to disk' it will save the file in your requested location and update the metadata on that file.

So does this mean that if I import a file into my Calibre library, then use Calibre to change the metadata for that book, the metadata stored in the ebook file itself remains what it was when it was imported - the changes are stored only in the metadata.db file but the book file itself isn't updated? Is there a reason for this - a reason that the file metadata isn't updated when I change it in Calibre? And could this explain why sometimes when I send an ebook to my Kindle, some of the metadata changes I've made in Calibre aren't reflected when the ebook gets to my Kindle? (Sometimes I've had to make changes to the metadata of the Calibre library file using something like mobi2mobi in order to make the metadata correct on the Kindle.)

It sounds like in order to make the changes to the file metadata, I'd have to do a "save to disk" and then re-import the ebook, which seems strange to me.

As for the Calibre library...I understand what it is now. Is there a way to move my entire library? What if I no longer want it in "My Documents/Calibre ebooks" but instead want it somewhere else - can I do that easily? (And I still don't understand about the time for loading a library into a new version of Calibre - although maybe it has to do with this, with moving the library location?)

Thank you for your help!

So does this mean that if I import a file into my Calibre library, then use Calibre to change the metadata for that book, the metadata stored in the ebook file itself remains what it was when it was imported - the changes are stored only in the metadata.db file but the book file itself isn't updated? Is there a reason for this - a reason that the file metadata isn't updated when I change it in Calibre?

It's not updated for two major reasons. Each book can have multiple formats, say you edit 1000 books using the bulk metadata dialog which have 5 books each. That's 5000 files that need to be updated. Some ebook types require the entire book to be decompiled and re-compiled to change something as simple as the author. Over 5000 files this would be an intensive operation. Also, not all formats support changing the metadata. So it's only updated as needed, E.g. with 'Save to disk' and 'Send to device".

And could this explain why sometimes when I send an ebook to my Kindle, some of the metadata changes I've made in Calibre aren't reflected when the ebook gets to my Kindle? (Sometimes I've had to make changes to the metadata of the Calibre library file using something like mobi2mobi in order to make the metadata correct on the Kindle.)

The mobi file you've imported doesn't support changing the metadata. When you convert it you're taking the content and putting it into a mobi container that supports changing the metadata.

It sounds like in order to make the changes to the file metadata, I'd have to do a "save to disk" and then re-import the ebook, which seems strange to me.

Basically but you shouldn't need to have the metadata changed on every file. Just when you need that file outside of calibre. The metadata is also changed when using 'Send to device'.

As for the Calibre library...I understand what it is now. Is there a way to move my entire library? What if I no longer want it in "My Documents/Calibre ebooks" but instead want it somewhere else - can I do that easily? (And I still don't understand about the time for loading a library into a new version of Calibre - although maybe it has to do with this, with moving the library location?)

It sounds like you are still using 0.5.x. It's been awhile since I've done anything that version. 0.6 was just released and it makes moving the library very easy (it might be the same in 0.5.x). Simply move your library, open calibre, click preferences, the first item in the dialog is Location of ebooks, point it to the location of your library.

The mobi file you've imported doesn't support changing the metadata. When you convert it you're taking the content and putting it into a mobi container that supports changing the metadata.

Just to be sure I understand: so there are some mobi/prc files that don't permit changing metadata, even though they have the .mobi or .prc extension? I didn't know this - it would explain a lot; namely, why the metadata for these files isn't being changed when I Send to Device to reflect the changes I've made inside Calibre! If I were to do a Save to Disk with Calibre, would that have the same effect as using mobi2mobi - taking the content and putting it into a new container that supports changing metadata? Is there any easy way to tell from within Calibre which files will permit metadata changes and which ones I have to do further manipulation on before sending to the Kindle (which is my device)?

It sounds like you are still using 0.5.x. It's been awhile since I've done anything that version. 0.6 was just released and it makes moving the library very easy...

No, I am using v 0.6 (or the beta, rather - haven't made the final switch yet) - have been since the beta was released. I've just never tried to move the library, and now that I've decided I want to, I didn't know how to do it.

I think Calibre is absolutely fantastic - only wish the documentation were more thorough. That's not a criticism - I totally get that the developer is busy with other very important things, and I'd even offer to help with documentation myself; I just don't think I have a thorough enough understanding to be the one to do it. But I feel like there are lots of features or aspects of the program that the developer has put time and effort into but that I either don't fully understand or don't even know about, and wish I did so I could take advantage of them (another is the "Series" feature of the Calibre metadata - I read something recently that suggested something happens if you transfer all items in a series to the device at the same time? Maybe I should open a new thread to ask about this...)

Anyway, thanks very much for this - I really appreciate your help!

Just to be sure I understand: so there are some mobi/prc files that don't permit changing metadata, even though they have the .mobi or .prc extension?

Yes and no. Mobi files (like eReader files) can have the metadata set a number of different ways (3 actually). Calibre supports reading all 3 for mobi but only supports setting one. If that section is not already present in the file it will not change the metadata because changing it would require rebuilding the entire file. It would basically have to run mobi2mobi (or in the case of 0.6.x, ebook-convert in.mobi .mobi)

If I were to do a Save to Disk with Calibre, would that have the same effect as using mobi2mobi - taking the content and putting it into a new container that supports changing metadata?

No. you will have to run ebook-convert in.mobi .mobi yourself.

Is there any easy way to tell from within Calibre which files will permit metadata changes and which ones I have to do further manipulation on before sending to the Kindle (which is my device)?

Not that I'm a where of. I don't do much with mobi though so maybe.

I think Calibre is absolutely fantastic - only wish the documentation were more thorough. That's not a criticism - I totally get that the developer is busy with other very important things, and I'd even offer to help with documentation myself; I just don't think I have a thorough enough understanding to be the one to do it. But I feel like there are lots of features or aspects of the program that the developer has put time and effort into but that I either don't fully understand or don't even know about, and wish I did so I could take advantage of them...

It's a valid criticism. I'm very guilty of not documenting anything I've worked on (the / path tag and field:false in the search are two major things that people don't know exist but keep asking for). The only part that gets documented even close to what it should is the command line interface.

(another is the "Series" feature of the Calibre metadata - I read something recently that suggested something happens if you transfer all items in a series to the device at the same time? Maybe I should open a new thread to ask about this...)

If you transfer all items in a series to a PRS-505 or 700 it should create a collection with the books in the series order. If you do them individually it may or may not. Or is it when you transfer all of them it transfers in the order you select the books... I can't remember, it's been a bit since I touched the the 505 and 700 drivers and that was mainly just moving them to use the USBMS driver framework.

Okay, that's very helpful.

No. you will have to run ebook-convert in.mobi .mobi yourself.

Let me make sure I understand the syntax here. What is the "in" in "in.mobi"? - is that the filename? So if I'm converting book.mobi, I just run 'ebook-convert book.mobi .mobi' - from within the Calibre library directory? And this has the effect of rebuilding the file with the metadata that I've already set in Calibre - replacing the old mobi file with the new? And Calibre will continue to see the new, converted mobi file in its library? Can you do the same thing using the GUI - a mobi to mobi conversion?

The fact that you can't tell whether the Send to Device operation will change the metadata on a particular mobi file is kind of a pain - no way to know if you need to do this mobi-to-mobi conversion before sending until you've tried sending and seen that the file on the device has the wrong metadata. But maybe there's no way around that. Or do most people just routinely do a mobi-to-mobi conversion on all their books?

It's a valid criticism. I'm very guilty of not documenting anything I've worked on (the / path tag and field:false in the search are two major things that people don't know exist but keep asking for). The only part that gets documented even close to what it should is the command line interface.

This is unfortunate, because it means that a lot of the features you work so hard on probably never get used, or only by a very few users; all that work deserves more. And it probably means the software has fewer users than it otherwise would, because it's not as accessible. I know I'm pretty techy, and comfortable with figuring out how software works, and yet I still get pretty frustrated with the lack of documentation and a central source of information about Calibre. I resisted using it for a while because I didn't understand a lot of the things people were talking about on the forum and couldn't find any explanations - even now that I use it, I still do a lot of things manually that Calibre could probably do for me, and Calibre's behavior sometimes baffles me (like with the mobi metadata).

It's a difficult problem, though, because only the developers know enough to be able to document all the features, and they're the ones who don't have time - or probably interest - in doing it.