VIDEO COMPRESSION EXPANSION CIRCUIT

摘要

PURPOSE:To obtain a video image in matching with an aspect ratio of a screen of a display device by reducing/magnifying an entire video image into an optional size. CONSTITUTION:A video signal is written sequentially in a field memory 103 by a write clock from an input terminal 118. A clock generating circuit 119 gives a read clock whose frequency is nearly a multiple of 4/3 of a write clock frequency to a field memory 103. A vertical magnification control circuit 110 reads a video signal from the field memory 103 by a line period in response to the magnification factor. The write of a 1-line memory 105 is stopped by a similar period to obtain a line delay output of an output signal from the field memory 103. A vertical interpolation circuit 106 generates a scanning line signal through interpolation arithmetic operation according to a control signal from the vertical magnification control circuit 110.