 The chosen design used a disc nearly 16 inches (about 40 cm) in diameter rotating at 33 1/3 rpm.This could play for 11 minutes, the running time of 1000 ft of film at 90 ft/min (24 frames/s).Because of the larger diameter the minimum groove velocity of 70 ft/min (14 inches or 356 mm/s) was only slightly less than that of a standard 10-inch 78 rpm commercial disc.