PURPOSE: To convert to interlace data in real time by alternately writing non- interlace data in the 1st and 2nd field buffer in the unit of line and alternately reading them out in the unit of field.

CONSTITUTION: Writing action of the data LDa of the odd-number scanning line of the non-interlace data NINT in a field buffer FBa in the unit of line and writing action of even-number scanning line data LDb in a field buffer FBb are performed alternately. The odd-number field data FDa are read out from the field buffer FBa in the unit of field. Then, by reading the even-number field data FBb from the field buffer FBb in the unit of field, the interlace data INT can be obtained. In short, the interlace data NINT can be converted into the interlace data INT.