In digital cinema the projector and the playback server does a handshake and key exchange before you can play encrypted content.The rest of this story might not be entirely correct, I've been out of the business for a few years and this happened maybe 5-6 years ago, but it's a bit fun and kind of relevant.
This usually works without any issues, but on one type of projector they had used a non-shielded network cable internally in the projector and if the projector lamp was lit juuuust at the right moment, the handshake would fail and the film would not play. Normally it wouldn't be a huge deal as the handshake happens just before the film and the lamp is usually lit on the beginning of the show long before the film starts. HOWEVER, there was this one cinema chain that had standardized their playlists in such a way that they for some stupid reason turned of the projector lamp in between the trailers and the film (I think to "introduce" the film) and then turned it on again just before the film with the result that the handshake failed 3 out of 10 times or so.
Long term solution was to replace the shoddy cable. Short term solution was to change all their playlist templates to blind the lamp instead of turning it off. Like they should have done to begin with.
This usually works without any issues, but on one type of projector they had used a non-shielded network cable internally in the projector and if the projector lamp was lit juuuust at the right moment, the handshake would fail and the film would not play. Normally it wouldn't be a huge deal as the handshake happens just before the film and the lamp is usually lit on the beginning of the show long before the film starts. HOWEVER, there was this one cinema chain that had standardized their playlists in such a way that they for some stupid reason turned of the projector lamp in between the trailers and the film (I think to "introduce" the film) and then turned it on again just before the film with the result that the handshake failed 3 out of 10 times or so.
Long term solution was to replace the shoddy cable. Short term solution was to change all their playlist templates to blind the lamp instead of turning it off. Like they should have done to begin with.