RP 136:2004 - SMPTE Recommended Practice - Time and Control Codes for 24, 25 or 30 Frame-Per-Second Motion-Picture Systems

This practice specifies digital code formats and modulation methods for motion-picture film to be used for timing, control, editing, and synchronization purposes. This practice also specifies the relationship of the code to the motion-picture frame. The codes described in this practice are similar to the continuous code described in SMPTE 12M. — There are two types of codes described in this practice. The first type, type C, is a continuous code which is very similar to the continuous code specified in SMPTE 12M. This type of code can be used in situations where the film is moving continuously at the time of both recording and reproduction. — The second type of code, type B, is a noncontinuous, block-type code, composed of blocks of data, each complete in itself, with gaps between the blocks. It is designed so that the code may be recorded and played back on equipment with intermittent film motion but still be decoded with the same type of electronic equipment used to read the type C or continuous time code. — The codes described in this practice can be used at various frame rates, the ones currently of interest being 24, 25, and 30 frames per second.