A 3D video system is disclosed. The 3D video system includes a frame rate converter that stores an input video signal in a rate conversion frame memory included in the frame rate converter, then reads and outputs the input video signal at a doubled clock rate, a signal format converter that converts a pixel sequence of the video signal output from the frame rate converter and outputs the converted video signal, a controller that outputs a timing signal based on the converted video signal, 3D glasses that transmit light alternately to left and right eyes, and switch the transmission of the light to the left and right eyes, based on the converted video signal and the outputted timing signal, and a spatial modulator that spatially modulates light emitted from a light source, based on the converted video signal. The 3D video system enables the modulated light to be viewed stereoscopically.