| 摘要 |
PURPOSE: An inverse discrete cosine transform device is provided to reduce an error due to truncation by shifting constants to the left as many as n-m bits when integers are obtained by multiplying constants by 2. CONSTITUTION: An inverse discrete cosine transform device is made up of a first dimensional IDCT(Inverse Discrete Cosine Transform), a second first dimensional IDCT, and a transpose buffer. Compressed data is inputted through an input(31). A multiplier and adder(32) multiplies constants by 2 to convert the constants into integers. A shifter(34), a final end of a first dimensional IDCT operation, shifts constants to the left as many as n-m bits. Another shifter, a final end of a second first dimensional IDCT operation, shifts constants to the right as many as n+m bits. |
