Approaches to improving the picture quality in high speed play while keeping sufficient picture quality in normal play are described. According to the approaches considered, variable length coding is controlled to be completed within a synchronized block. Each compression block is constructed of DCT (discrete cosine transform) blocks, which separate each other on the screen. The DCT blocks which are in the adjacent synchronized block on the tape are in the adjacent position on the screen. Lower-frequency components are located in the first half of the synchronized block. Computer simulation concerning an evaluation of reproduced picture quality in high-speed play showed that the best method of coding for high-speed play is to form a compression block with DCT blocks adjacent on the screen.
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