This freeware based on MAX runs on Mac and allows, after adding a little bit of electronics to the projector, to read a quicktime file based on the actual speed of the projector.

Zachpoff website

It is a possibility to pass an original or a working copy with a digital sound in stereo with a specific but minimal hardware: a slightly modified projector and a computer. The app looks well done (we have not tested). The electronics that are proposed to modify the projector is a bit rustic and should be able to be improved and made more universal (in terms of types of projectors that can be modified) using components like infrared sensors, while remaining very simple to manufacture. Let’s do it.