Method and apparatus for improved video decompression by selection of IDCT method based on image characteristics

摘要

A video decoding system examines a block of DCT coefficients prior to computation of an inverse discrete cosine transform (IDCT) to determine the number of nonzero coefficients. A plurality of IDCT engines are available in the video system including an IDCT engine utilizing fewer computations for a sparse picture and an IDCT engine utilizing fewer computations for a nonsparse picture. The video decoding system selects an IDCT engine to minimize the number of computations performed and to thereby reduce the computational burden of IDCT transformation.