FIELD: information technology.
SUBSTANCE: more efficient encoder/decoder is provided in which an N-point MDCT transform is mapped into smaller sized N/2-point DCT-IV, DST-IV and/or DCT-II transforms. The MDCT may be systematically decimated by factor of 2 by utilising a uniformly scaled 5-point DCT-II core function as opposed to the DCT-IV or FFT core functions used in many existing MDCT designs in audio codecs. Various transform factorisations of the 5-point transforms may be implemented to more efficiently implement a transform.
EFFECT: efficient implementation of smaller transforms, desirably for implementing a bigger transform, using a smaller basic transform.
52 cl, 32 dwg
