[Enhancement]: Ability to estimate equivalent timestamp/page numbers between ebooks and audiobooks

[mr-ransel]

Describe the feature/enhancement

Please note, this is specifically not a duplicate of #189. This is a much lower barrier to entry request.

While the ideal endgame is definitely #189, an interim solution to provide 80% of the value for this solution would be a very basic tool on audiobooks and ebooks that allows the user to select an ebook and an audiobook "pair" of books to synchronize, and it provides a estimate of an equivalent timestamp/page number in the other document.

This can be done by:

• If the audiobook and ebook both have chapter demarcationa, calculate the percentage complete the chapter is based on the page number or timestamp is within that chapter, and spit out the corresponding timestamp/page number would be as an estimate.
• If there aren't chapter markers in one of them, then allow the user to provide an override chapter start+end marker optionally if they have it
• Finally if there are no chapter markers at all, provide the raw full book percentage mapping, but the drift on this will be pretty large.

Then the user can manually scrub a bit forward and back, or a few pages to find the precise page.

This would be a huge step towards whispersync for fairly minimal implementation cost and be a big user experience improvement.

An addition that would greatly improve these estimates in the "no chapter marker" scenario would be to allow the user to put in the actual mapping between the mediums and track a few of them through the book and do a. Basic linear regression on them which will calibrate the entire books page<->timestamp mapping very effectively. (I do this myself manually with hardcover books and ebooks and even without chapter markers, with 3-4 data points throughout a book you can get down to within 2-3 pages of the target every time.)