A write clock signal and a write select signal are outputted from an input video clock generator, a read clock signal and a read select signal are outputted from a display video clock generator, either of first and second field memories is selected as the write memory or the read memory in compliance with the signal level of the respective select signal and writing is carried out in the selected write memory once a predetermined time has elapsed following inversion of the write select signal. When reading has commenced from the first and second buffer memory, a match is detected between the signal levels of the write select signal and the read select signal at each field or at each frame and writing and thus reading address passing is predicted.