IMPROVED HARMONIC TRANSFORMATION BASED ON A BLOCK OF SUB-BANDS Russian patent published in 2023 - IPC G10L19/02 G10L19/22 G10L19/32 G10L21/38 G10L21/04 G10L25/18 

FIELD: audio systems.

SUBSTANCE: invention relates to source audio coding systems that use a harmonic transformation method for high frequency reconstruction (HFR), as well as to digital effects processors, such as exciters, in which the generation of harmonic distortion adds brightness to the processed signal, and to time expanders, in which the duration signal increases while maintaining the spectral composition. A system and method are claimed, which are configured to generate a time-stretched and/or frequency-converted signal from an input signal. The system includes an analysis filter unit (101) configured to create an analysis subband signal from an input signal, where the analysis subband signal includes a number of complex-valued analysis discrete values, each of which has a phase and an amplitude. In addition, the system includes a subband processing module (102) configured to determine a synthesis subband signal from an analysed subband signal using a subband transform factor Q and a subband stretch factor S. The subband processing module (102) performs non-linear processing on a unit basis, where the amplitude of the discrete values of the synthesized subband signal is determined from the amplitude of the corresponding samples of the analysed subband signal and the predetermined discrete value of the analysed subband signal. In addition, the system includes a synthesis filter unit (103) configured to generate a time-stretched and/or frequency-converted signal from a synthesis subband signal.

EFFECT: suppression of combinational components caused by non-linear processing of subband signals, reduction of requirements for the unit of analysing/synthesizing filters in terms of frequency resolution and oversampling degree.

18 cl, 7 dwg