| 摘要 |
A device for decoding audio signals subjected to a noise-reduction encoding such as a Dolby-B encoding comprises a plurality of processing blocks ( 612, 616, 620, 624, 628, 632, 636, 640 ) for generating, starting from an input signal ( 610 ) containing the audio signal subjected to encoding superimposed on a noise component, an output signal ( 626 ) consisting of a replication of the audio signal with the noise component reduced. The aforesaid processing blocks are implemented in a digital form and comprise a sliding-band filtering structure ( 612 ) fed with the input signal ( 610 ) and designed to generate a filtered signal ( 614 ). The filtered signal ( 614 ) is fed, according to a general feedforward scheme, to an overshoot-suppression stage ( 616 ) in view of the generation, in an adder node ( 620 ), of a difference signal ( 622 ) starting from which the output signal is obtained via filtering ( 624 ). The same filtered signal ( 614 ) is also used to drive a control chain ( 632, 636, 640 ) preceded by a further linear filter ( 628 ). The control chain generates respective control signals for the sliding-band filtering structure ( 612 ) and for the filters ( 624, 628 ) that reproduce the output signal ( 626 ) and the input signal ( 630 ) for the control chain. The aforesaid two filters ( 624, 628 ) are preferably all-pole filters, the function of which is to minimize the error introduced by the sliding-band filtering structure ( 612 ).
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