ADAPTIVE HYBRID TRANSFORMATION FOR ANALYSIS AND SYNTHESIS OF SIGNS.

摘要

A method of generating an output signal, comprising: receiving samples of a source signal that has spectral content; apply a primary transform to overlapping segments of the samples to generate a plurality of sets of spectral coefficients, in which the primary transform is a modified discrete cosinusoidal transform and each set of spectral coefficients has distortion effects by aliases in the time domain and represents the spectral content of a respective segment of the source signal for a set of frequencies; obtain a plurality of spectral coefficients that represent the same frequency in the set of frequencies from the plurality of sets of spectral coefficients and assemble the plurality of spectral coefficients into one or more spectral coefficient blocks, in which the number of spectral coefficients which are assembled in each of the one or more blocks is adapted in response to a block length control signal; apply a secondary transform to the one or more spectral coefficient blocks to generate one or more sets of hybrid transform coefficients, in which the secondary transform is a discrete cosinusoidal transform that is applied to blocks of spectral coefficients that do not overlap each other and the length of the secondary transform that is applied to each of the one or more spectral coefficient blocks is adapted in response to the block length control signal; and assembling information representing the one or more sets of hybrid transform coefficients and the block length control signal in the output signal.