It seems that Adobe Digital Editions (http://www.adobe.com/products/digitaleditions/) Version 1.7.2 and older cannot properly display epubs exported with ID CS6. Somewhere in the font embedding engine something goes terribly wrong.
Here we see an epub exported from ID CS6 (trial)
And here we see the same book. Exported from ID CS5.5 (licensed, all updates).
What is strange: Adobe Digital Edition Preview (1.8.4 http://labs.adobe.com/technologies/digitaleditions1-8/) displays the ID CS 6 generated epub ok.
For those who ask, the language is Romanian. The typeface (font used) is LiberationSerif.ttf. I have tried embedding other fonts (Warnock pro otf, Times new roman and the problem remains). We use glyphs from the Latin 2 Extended map like ăîșțâ ĂÎȘȚÂ or legacy Ş/ş andŢ/ţ (instead of coma below/cedilla for S/s and T/t for proper displaying in old e-ink devices and so on). I am sure other languages have the same problem. Especially eastern European languages.
So I asked my self what happens? Both ID CS 5.5 and CS 6 strip the font character map deleting unused glyphs when embedding. Meaning that the character map is reduced to hold only the glyphs used in the document and so the typeface would be smaller in KB.
When I look into the epub I see these. Font embedded in ID CS 5.5 export LiberationSerif.ttf 98 KB.
Also I am able to open the font and have a look at it in Font Lab, (here below the ID CS 5.5 embedded font LiberationSerif.ttf 98 KB).
I am not able to open the font embedded from ID CS 6 exported epub in Font Lab, (here below the ID CS 6 embedded font LiberationSerif.ttf which is smaller in kb than the one in the ID CS 5.5 export – only 23 KB).
I am not able to see/view the font that ID CS 6 uses in the exported epub also (with any other font viewer).
What is strange? The adobe digital editions preview seems to display the epub ok. So does Calibre. But not the standard ADE (which is still used at a large scale not only on desktops but on several devices).
So why does ID CS 6 export to epub makes the font unusable and ID CS 5.5 keeps it ok?
Furthermore if I expand the book and copy only the font from the ID CS 5.5 exported epub to the ID CS 6 exported epub then all comes just fine. Meaning the epub will display ok on ADE.
I need the new features in ID CS 6 but why buy a software that cannot properly generate epub files for my language?