Originally Posted by Manichean
So I'd suggest trying to go <input format> -> ODT -> fix ODT in OO.org -> reimport and reconvert.
I probably misunderstood something somewhere, but I was under the impression that the only format choices in the conversion output menu, useful to use to go out of calibre to fix were:
epub for Sigil fix.
rtf for Word or OOo fix.
pdf for Acrobat fix which I like to avoid.
htmlz which I should probably use after I learn more html.
txt or txtz but I try to avoid those (for what I thought were good reasons but may not be.)
mobi for Mobipocket Creator (for Microsoft OS users, but not anyone else I think.)
I need to pick something (eg RTF) to go out of calibre into the cleaning app with. So if I understand you correctly, you're suggesting: OriginalFormat --> rtf --> odt --> PreferredFormat.
The file size reduction is significantly larger with docx preceding odt in that sequence: OriginalFormat --> rtf --> docx --> odt --> PreferredFormat. I think. Filesize results, I tested several months ago. Next time I have some books to test on I'll check that.
Edit: After I had tested the filesize results either way back then, I didn't test quality results with eliminating docx from the sequence.