SMPTE comes in several flavors; 30 fps, 29.97 fps, 25 fps, and 24 fps (fps= frames per second). In the visual world these refer to how many video or film frames are shown each second. Audio on analog tape does not occur in discrete chunks. The audio can be recorded at any speed from 1 7/8 inches per second up to 30 inches per second, and anywhere in between with the use of variable speed tape machines. If you only want to synchronize [sync] analog audio machines, you can use any rate of SMPTE that you desire.