Abstract: A stereoscopic video signal converting apparatus having A/D converters, field memories, and a D/A converter shared by both the parallel processing system and the time-division multiplex processing system. The shared portions are selectively used for either one of the two systems in accordance with an instruction such as a parallel/time-division multiplex selection signal which selects either one of two types of the read and write pulses for the field memories. A suitable processing system of the two types is selected depending on whether a picture quality or one channel transmission is required without increasing a cost of the apparatus. The apparatus provides compatibility between the two systems so that an operability of the system is enhanced.