Make an EPUB2 into an EPUB3

[theducks]

Originally Posted by Winnito

I store all/most of my ebooks in epub and then convert them into mobi or docx or whatever else I need. I almost never read in epub format except when opening in calibre. I guess was just wondering if epub3 can still convert flawlessly into other formats that need to use the TOC in some other way.

Reason for conversion? COVID19 extra free time, upgrading to better standard, having nicer file internals...dunno.

Why worry about a spec of LINT sized file? 8K in a 300K+ book

This might have made sense back in the early 2000's when PDA RAM was tiny.
My ancient K4 has 1C of books and almost half the storage (4G) unused

[Winnito]

Just looking for ways to improve my library, nothing else. The same reason I try and replace my 128kbs MP3 music with something better. Wondering if there's any cost/benefit to such a task, tho.

[DNSB]

Originally Posted by Winnito

Just looking for ways to improve my library, nothing else. The same reason I try and replace my 128kbs MP3 music with something better. Wondering if there's any cost/benefit to such a task, tho.

For me, I see no real benefit to converting an epub2 to an epub3. Creating an epub3 does offer advanced features including the accessibility ones. In theory, any epub3 features should be treated as no-ops by an epub2 renderer.

In terms of your music, it would be like converting your 128kbs MP3 music to FLAC and expecting the quality to improve.

[Tex2002ans]

Originally Posted by DNSB

For me, I see no real benefit to converting an epub2 to an epub3. Creating an epub3 does offer advanced features including the accessibility ones. In theory, any epub3 features should be treated as no-ops by an epub2 renderer.

For some arguments, see JSWolf's 2017 topic:

"Why ePub 3?"

DiapDealer and KevinH explain a lot of the EPUB3 advantages, and has been explaining it for years and years.

And JSWolf has been stubbornly insisting EPUB2 is the be all end all final and only way, his way or the highway.

Personally, I still stick with EPUB2, but I see no harms if you code your EPUB3 with EPUB2 fallbacks. (Or EPUB2 with some slight EPUB3-compatible CSS/semantics/enhancements.)