DISCRETE CONSINE TRANSFORMING CIRCUIT, INVERSE DISCRETE CONSINE TRANSFORMING CIRCUIT, MPEG VIDEO CODER, AND MPEG VIDEO DECODER

摘要

PURPOSE: To provide the IDCT(inverse discrete cosine transforming) circuit which can operate at high speed and is small in hardware scale. CONSTITUTION: The IDCT circuit 1 generates output data f(y1) and f(y2) as IDCT arithmetic results of input data F(x1)-F(x8). Respective constant multipliers 11-18 multiply the respective input data F(xi)-F(x8) by constants C0-C7 respectively. The signs of the outputs of the respective constant multipliers 12, 13, and 15-18 are based upon combinations of the input data F(x1)-F(x8) as shown in (a) and selected as shown in (b). Then combinations of f(y1) and f(y2) shown in (c) are obtained from the combinations of f(x1)-F(x8) shown in (a).