Some time ago, I tore a piece of cinema film from local cinema theatre. The movie was some dark work, about vampires or something. Recently, in wikipedia I found article about Dolby digital encoding on the film tape.
I found my film strip and checked it for digital data. Under microscope I found dolby digital data encoded in matrix bar-code between perforation. Also, I found three additional low rate digital data tracks. There is no data what is encoded here. In wikipedia example there must be analog channels…
I made the photo using small microscope with 25x magnification. Width between two graduations with numbers are one millimeter. You can see Dolby Digital logo in the center of dot matrix . Last image is borrowed from wikipedia:
