an apparatus converts a subsampled video frame signal into an interpolated original video signal with a improved computational speed by using : a zero stuffing circuit for generating the / 2 video line signals alternately decimated ; a first interpolation circuit for generating an interpolated even video line signal ; a second interpolation circuit for generating an interpolated odd video line signal ; and delay lines for simultaneously coupling the / 2 video line signals to the first and the second interpolation circuits to thereby allow the simultaneous generation of the interpolated even and odd video line signals .