Convert to same format vs. Send/Save w/t metadata update

[Starson17]

When you change metadata in Calibre, it does not automatically update the internal metadata in all of the saved formats.

1. When you later Send or Save a format, Calibre does update the internal metadata (assuming you have that option selected.)
   
2. One way to get metadata updated in the Calibre copy of a format updated is to convert that format to the same format.

Is there any difference between the result of option 1 vs. 2? I know option 2 can introduce additional changes - such as adding a cover page or removing a cover, controlling page breaks, removing header/footers, etc. Do these changes happen with option 1?

[kovidgoyal]

1. updates only metadata, it does not affect internal structure.

[chaley]

Originally Posted by Starson17

When you change metadata in Calibre, it does not automatically update the internal metadata in all of the saved formats.

1. When you later Send or Save a format, Calibre does update the internal metadata (assuming you have that option selected.)
   
2. One way to get metadata updated in the Calibre copy of a format updated is to convert that format to the same format.

Is there any difference between the result of option 1 vs. 2? I know option 2 can introduce additional changes - such as adding a cover page or removing a cover, controlling page breaks, removing header/footers, etc. Do these changes happen with option 1?

I have wondered about a relative of this question. Hope that I am not too OT.

I run into the situation where I want my epub to have the correct metadata (contain the correct OPF). Sending the book to a folder does this update. I send, delete the format, then add the 'sent' version back into the book. This works well enough for me, although clunky.

However, sometimes I want to add/update a jacket. I would be very happy to have an operation that updates the OPF and adds the jacket page to the spine. Unfortunately, I don't have that, so I am left with convert epub->epub. The conversion makes me nervous because I am not certain that formatting will not change. I don't want any margin changes, TOC changes, font changes, or any other changes to the book content. I just want the new jacket and the OPF. Being paranoid, I usually end up doing nothing.

If someone knows the epub->epub conversion option settings that ensure an absolute minimum of formatting changes, I would love to hear them.

[Starson17]

Originally Posted by kovidgoyal

1. updates only metadata, it does not affect internal structure.

That's what I thought. I have occasionally told people who want to update the metadata in formats stored in their library to do 2. However, I have worried that could affect internal structure when all they want is a metadata update per 1.

I probably should recommend a Save to Disk, followed by replacing the library copy format with the updated Saved format copy.

For me it makes little difference, but some people do access the formats directly. They may have an external editor set up to handle that format instead of Calibre's viewer. Calibre passes the internally stored format directly from the Library to the OS associated program instead of updating metadata first.

[kovidgoyal]

disable font size rescaling to ensure minimal changes. That's the only really invasive change calibre does

It should be trivial to implement an action to update metadata in library copies of selected books on user request. Both of you are capable of implementing that, so I leave it to you.