2-3 pulldown

This chapter discusses the conversion of film to video at frame rates different from the native 24 Hz of film. A piece of equipment that performs film-to-video conversion in realtime is called a telecine. Film has historically been transferred to 480i29.97 video using a technique called 2-3 pulldown, whereby successive film frames are scanned first twice then three times to produce five video fields. Motion picture film originates at 24 frames per second. Many television programs, including the majority of prime-time programs, originate on film at this rate. The term film scanner implies nonrealtime operation. In a sequence containing 2-3 pulldown, cadence refers to the temporal regularity of the A-frames. Careful editing preserves cadence; careless editing disrupts it. A simple method to convert from the 24 Hz film frame rate to any other rate could write successive film lines into a dual port frame buffer at film scan rate, then read successive lines out of the buffer at video scan rate.