A Deep Dive Into Page Sync

Page Sync is the feature in Earleaf where you photograph a page from your physical book and the app finds that position in the audiobook. It takes about two seconds. Everything runs on your phone. This post is about how it actually works under the hood. The problem You're reading a physical book at home. You get in the car and switch to the audiobook. Where were you? You could scrub around trying to find the right spot. You could try to remember the chapter number and estimate. Or you could take a photo of the page you were on and let the app figure it out. That last option sounds simple until you think about what it actually requires. You need to extract text from a photograph (OCR), extract text from audio (speech recognition), and then figure out where those two texts overlap. Both the OCR and the speech recognition will make mistakes. Different mistakes. Two imperfect signals Here's what makes Page Sync tricky. You're not matching clean text against clean text. You're matching the