Spotify is testing a feature that syncs audiobooks with paper editions

Using Page Match will require users to unlock or purchase the audiobook on Spotify and own either the paper or ebook version of the same book. The feature works by scanning the page you’re currently reading with your device camera, using optical character recognition (OCR) to identify passages that are then matched to specific timestamps in the audiobook.

Big if true. Hopefully they pilot the feature. I wish you could do something similar with apps like Libby. It would be a fun experiment to try building something for public domain books using LibriVox and Project Gutenberg 🤔