FIELD: audio source encoding systems.
SUBSTANCE: invention relates to audio source encoding systems that employ harmonic transform techniques for high frequency reconstruction (HFR) in digital effects processors such as exciters that generate harmonic distortion to add brightness to the signal being processed, and in time stretchers that increase duration signal while maintaining the spectral composition. The claimed system provides for the efficient implementation of high-frequency reconstruction (HFR), enhanced by cross products, where the new component with frequency QΩ+rΩ0 is generated based on existing components with frequencies Ω and Ω+Ω0. The invention provides for a sub-band block-based harmonic transformation, where a time block of complex-valued sub-band samples is processed by a well-known phase modification. The superposition of several modified samples has the net effect of limiting unwanted combinational components, whereby coarser frequency resolution and/or less oversampling is made possible. In one embodiment of the invention, the invention further comprises a windowing function suitable for use with an HFR based subband block enhanced with cross products. The hardware embodiment of the invention may include an analysis filter unit (101), a subband processing module (102) configurable by control data (104), and a synthesis filter unit (103).
EFFECT: creation of a method that ensures reproduction of an audio signal with high accuracy while reducing computational costs.
3 cl, 9 dwg
