Patent ID: 6253303
Filing Date: 2001-06-26
Classification: H04B

Abstract:
An audio signal processing method for obtaining output audio samples from input subband samples that have been previously divided for each frequency band and quantized, providing a DCT memory for storing DCT samples requantized from said input subband samples, a DCT circuit for generating band synthesis samples by applying a discrete-cosine-transform to DCT samples stored in said DCT memory, and a band synthesis memory for storing the band synthesis samples generated by said DCT circuit, the method comprising steps of:generating band synthesis samples from input subband samples by requantizing and applying a discrete-cosine-transform;generating a first address series and a second address series that comprise mutually different mapping methods for storing said band synthesis samples in said band synthesis memory;storing band synthesis samples into the band synthesis memory, by alternating between said first and second address series at every sample generation; andgenerating the output audio samples from the band synthesis samples stored in said band synthesis memory,wherein said band synthesis memory has only M-1 blocks, where M is a positive integer representing a number of band synthesis samples necessary for generating an audio output sample, each block stores a number of N band synthesis samples, wherein N is an integer product of 4, wherein said band synthesis samples are generated from every N input subband samples by requantizing and applying a discrete-cosine-transform, wherein every N band synthesis samples are stored into each block of the band synthesis memory, according to address series alternated between the first and second address series, and wherein each output audio sample is generated from M band synthesis samples picked out in the blocks of the band synthesis memory for each sampling period.