In a quite complicated theater-like scene I need to project a movie on a monitor. The movie must be played when a sensor is engaged (no, I can't use an IR remote control). I was thinking about using some cheap board with an HDMI output, like the Raspberry or the BeagleBone Black, which also have some discrete I/O. On the software side I feel pretty confident it's achievable. My main concern is: these boards use Linux, which needs a proper procedure to shutdown and avoid corruption of the data on the mass storage (be it mmc or sdcard or whatever). My customer wants to be able to shutdown the system instantly, just unplugging the power.
My question is: is it enough if, once I "feature freeze" the software for my board, I set the mass storage to read only? Do you have any recommendation? (or maybe an alternative solution for a player which can be interfaced with some I/O?)