Support PDF 2.0

[shuvashish76]

I'm in the process of converting all my .mobi (deprecated by Amazon in late 2023) and .azw3 (Amazon discontinued it in 2022) to open file format standards like PDF and EBUB. So I researched little-bit about them...

Noticed that now we've PDF 2.0, ISO 32000-2 does not include any proprietary technologies and available for free. (reference: https://pdfa.org/sponsored-standards)

I wonder why Calibre still use old PDF v1.4 for conversion? Calibre developers unaware of this or they use it for specific purpose?
I'm not sure what are the benefits of using latest PDF standard (technical aspects) but like any other technology I assume it has some improvements and stability over older editions?

ThankYou

[kovidgoyal]

It doesnt have any relevant improvements PDF 1.4 is completely adequate for converting ebooks.

[shuvashish76]

Thanks for the reply. Which version used for epub? Does epub on Calibre supports latest specifications or it uses older one for similar converting ebooks purposes?

[Quoth]

For conversion from mobi, azw and azw3 the epub2 is fine. You can use epub2 or epub3 (it's a setting). Of course DRM needs to be removed at import time to Calibre.

azw3/KF8 is not discontinued and works on all but 4 earliest Kindles (K1, K2, DX & DXG). The KK3/K3 and later works well with azw3 with last FW update.
azw is old mobi KF7 with different encryption.

No Kindle can read any epub version.

[shuvashish76]

Originally Posted by Quoth

You can use epub2 or epub3 (it's a setting).

Where is that settings?

Also how do I check the current epub version? There is https://github.com/w3c/epubcheck but is it possible to check the version directly from Calibre ?

[Comfy.n]

Preferences -> Output options -> EPUB Output -> EPUB version

You can find the EPUB version by searching the OPF files for version="3.0" with the Quality Check plugin:
https://www.mobileread.com/forums/sh...d.php?t=125428

[shuvashish76]

Originally Posted by Comfy.n

Preferences -> Output options -> EPUB Output -> EPUB version

So it's epub2 by default. I'll keep it that way then.

Originally Posted by Comfy.n

You can find the EPUB version by searching the OPF files for version="3.0" with the Quality Check plugin:
https://www.mobileread.com/forums/sh...d.php?t=125428

Installed the plugin. Sorry again, exactly how to search, from here?

[Karellen]

Originally Posted by shuvashish76

Also how do I check the current epub version?

See the image which is an ebook opened in the Editor...

Image

[shuvashish76]

ThankYou

[thiago.eec]

Originally Posted by shuvashish76

Installed the plugin. Sorry again, exactly how to search, from here?

Quality Check > Search ePubs...

Then use this search expression:

xmlns="http://www\.idpf\.org/2007/opf"(.*?)version="3\.0"

Mark 'Ignore case', 'Show all occurrences'. In the 'Scope' section, choose only 'OPF manifest'.

This will list all your EPUB 3 files. The rest will be EPUB 2.

* There is no easy way to detect minor versions, like EPUB 3.2 or EPUB 3.3, but I don't think you would need that. EPUBCheck can tell you if the e-book conforms to the latest version of EPUB 2 / EPUB 3.

[Comfy.n]

Originally Posted by thiago.eec

Quality Check > Search ePubs...

Then use this search expression:

xmlns="http://www\.idpf\.org/2007/opf"(.*?)version="3\.0"

Mark 'Ignore case', 'Show all occurrences'. In the 'Scope' section, choose only 'OPF manifest'.

This will list all your EPUB 3 files.

That's true for the vast majority of OPF heads. However, in many books the version placement is a bit different:

PHP Code:

<?xml version="1.0" encoding="utf-8"?>
<package version="3.0"

or

PHP Code:

<?xml version="1.0" encoding="UTF-8"?>
<package xmlns:ibooks="http://vocabulary.itunes.apple.com/rdf/ibooks/vocabulary-extensions-1.0/" unique-identifier="BookId" version="3.0"

or

PHP Code:

<?xml version="1.0" encoding="utf-8" ?>
<package prefix="rendition: http://www.idpf.org/vocab/rendition/#" unique-identifier="pub-id" version="3.0" xml:lang="en" xmlns="http://www.idpf.org/2007/opf">

Regarding minor versioning: I've tried to find an epub3 with version value other than 3.0, to no avail. It seems that most publishers and creators still use version="3.0" even if the EPUB file contains newer features, to ensure broader compatibility.

[DNSB]

That is correct. Currently, the only two values allowed are 2.0 and 3.0, minor versions are not supported. If no version is specified, the ePub 2.0.1 specification states the document should be treated as an OEBPS 1.2 document.

From the ePub 3.3 documentation: The version attribute specifies the EPUB specification version to which the given EPUB Package conforms. The attribute MUST have the value "3.0" to indicate compliance with this version of the specification..

While the ePub 2.0.1 specification states: In addition, to be processed as an OPF 2.0 package, a version attribute with a value of 2.0 must be specified on the package element. A package element that omits the version attribute must be processed as an OEBPS 1.2 package.

I find that searching for version="3\.0" works fine for me and allows for those files that add additional bits or rearrange the items in the <package> field.

[Comfy.n]

Originally Posted by DNSB

That is correct. Currently, the only two values allowed are 2.0 and 3.0, minor versions are not supported. If no version is specified, the ePub 2.0.1 specification states the document should be treated as an OEBPS 1.2 document.

From the ePub 3.3 documentation: The version attribute specifies the EPUB specification version to which the given EPUB Package conforms. The attribute MUST have the value "3.0" to indicate compliance with this version of the specification..

While the ePub 2.0.1 specification states: In addition, to be processed as an OPF 2.0 package, a version attribute with a value of 2.0 must be specified on the package element. A package element that omits the version attribute must be processed as an OEBPS 1.2 package.

Thanks so much for this info, I had searched the specs yesterday but couldn't find this specific section about the version attribute.

I find that searching for version="3\.0" works fine for me and allows for those files that add additional bits or rearrange the items in the <package> field.

The Quality Check plugin epub search finds the same results using an unescaped dot

[thiago.eec]

Originally Posted by Comfy.n

That's true for the vast majority of OPF heads. However, in many books the version placement is a bit different:

You are right. I guess I was just lucky. I changed my search to just 'version: 3\.0' and got the same results.

[DNSB]

Originally Posted by Comfy.n

The Quality Check plugin epub search finds the same results using an unescaped dot

Mostly a bad habit on my part of escaping special characters.