TL/DR: I need some kind of frame sync output, LED would be nicest.
I am building a film scanner, for 35mm (and maybe later 16mm) film.
The idea is to take a picture across the width of the film, through a thin slit.
Then advance the film a tiny increment with a stepper motor, repeat.
Each captured image would represent only one line of the scanned film. For a "2K" width scan, you'd want maybe 3000 lines per (still image) or 1500 lines for a 2 perf cine image.
Just to be clear, each taken image would in my post processing throw away almost all of the image data. For instance a 1920x1080 picture would be converted to a "1920x1" image and then 3000 of those would be assembled into one "1920x3000".
I could do this with still images but it would take a million years and 3000 still images.
Something MUCH nicer would be to use video, but then the question comes about syncing camera frames with advancement of film. (With the stepper motor.)
The nicest, cleanest way would be if the camera outputs a pulse on the LED each video frame it captures. Then I can strobe a lightsource behind the film each time.
There are other ways to try to compensate in post, for instance by advancing the film more slowly and oversample (or something), but it would be slowing down an already slow process and add a lot of complexity.
I can program in C, I have done embedded programming etc, but it feels very daunting to cold start where to find my way in the codebase - help deeply appreciated.
I also think this feature would be very welcome for other purposes, like trick filming and motion control rigs.