AndyD said:
I have had good success, except when there are pictures. By default Calibre removes pictures I think so it can mess up formatting. So on a few I actually had to set the pictures to be kept which fixed the formatting. This is mainly in books that have image headers in chapters and short chapters, and illuminated books as well.
I think if we find a mobi that gives issues, we can all work on it and see if we come up with a fix. There are so many settings in the conversion options for Calibre, I am just starting to scratch the surface.
I think this may be happening because you're leaving the automatic chapter detection on, so sometimes it will start the chapter on whatever is after the image (like a header), leaving the image at the end of the previous chapter.
Some general tips... First of all I always open the EPUB in Sigil to make sure the chapters are already broken up. If not, I will manually hit the "Chapter" button to create one wherever appropriate. Calibre can add the chapter/page breaks by itself, but I prefer not to let it do it since sometimes it may break up things I didn't intend for it to.
While in Sigil I look at the format that the chapter headers have. If it's just something like <h2 class="chapter"> (or whatever is in place of "chapter," so long as it's unique) I leave it. Sometimes the header may be the same for the main header and subheaders, though, which will create bad pagebreaks. So for that I change the name to
<h2 class="cchapter"> and just copy the .chapter stuff in the stylesheet and rename it .cchapter (to make sure no formatting is lost). You can use whatever denominator you want, of course.
After that, just go into Calibre to convert. Under Structure Detection I will run the wizard under "Detect Chapters" and in each of the three fields I will put "h2, class, cchapter." On Insert Page Breaks, so it doesn't mess with the formatting that was in Sigil, I put a single slash, which nulls it.
Then go to Table of Contents and select "Force use of auto-generated table of contents." Then go to MOBI Output. If the book already has a TOC, check "Do not add table of contents to book." If it doesn't, just leave it, so that one gets added.
The reason for using the "Force TOC" option is so that Calibre creates the NCX file, which is what the Kindle uses to create those little chapter stops at the bottom, the ones you can navigate with the 5-way button. I personally hate reading on the Kindle without these.
Other things...
If you have only an image as a chapter header, you can in Sigil add a "class=cchapter" (or again, whatever else you're using for the chapters) to its code. And you also need to make sure it has an alt property with proper capitalization, like "alt="Chapter 2"", so that it shows up with a name under the TOC (if you're generating one). So it would look like
<img src="xxx.jpg" alt="Chapter 2" class="cchapter">.Then in Calibre, use the Detect Chapter wizard and enter "*, class, cchapter".
Also an easier way to just do this, when you don't want to mess with images and stuff (or if headers are formatted the same as paragraphs, which is a pain in the ass), is to just add
<div class="chapter"> at the end of every <body> tag in every chapter on Sigil. Then in Calibre just put "div, class, chapter". The only problem with this is that the NCX list will not have any labels on it. It doesn't matter since you never see it but I don't know if it may cause any problems anywhere in the future or anything. Maybe you can use an
alt tag to label it, but I've never bothered to check...
The most important piece of advice I can give: GET SIGIL!!! Otherwise you're fumbling in the dark.
Hope that helps someone. At first Calibre is very counter-intuitive, but once you get the basics down, it's a piece of cake. It took me like three days of trial-and-error to figure it all out. And yeah, the books end up looking the exact same. The HTML on the formatting is always preserved on EPUB > MOBI... the tricky part is getting all the chapter detection stuff right.
Edit: Another thing. To check the end results, instead of plugging the Kindle in each time, just download Amazon's Kindle Previewer app:
http://www.amazon.com/gp/feature.html?ie=UTF8&docId=1000234621
