| Remember back in school when they would play 16mm films in class, and you would see numbers counting down like this before the show?
8.. 7.. 6.. 5.. 4.. 3.. 2-BEEP!
Well, that countdown is called the SMPTE leader. This leader is placed on pretty much all release prints, and allows a projectionist to do several things:
- Know exactly where the feature starts; it's supposed to start right after the "2". This allows the projectionist to ready the projector so that the feature can be started with no delay...
- Synchronize audio with film. The beep is supposed to correspond to the "2" frame, so the projector sound sync can be adjusted if necessary.
The specifications for the leader are a countdown, from 8 to 2, with each number lasting 24 frames except for the 2, which lasts only one frame, and then 47 frames of darkness. A "sync pop", basically a beep sound, is placed on the soundtrack to coincide with the "2".
Of course, back in school the teacher just wanted to show you the film, and didn't really care about presentation... So the whole reel would be played, leader and all. And hey, counting down with the leader was fun!
SMPTE stands for Society of Motion Picture and Television Experts. | 
