| 摘要 |
The invention regards a method of hierarchically filtering an input signal to achieve a nearly arbitrary time/frequency decomposition. The method comprises the steps of: (a) buffering samples of the input signal into frames of N samples ( 2900 ); (b) multiplying the N samples in each frame by an N-sample window function ( 2900 ); (c) applying an N-point transform to produce N/2 transform coefficients ( 2902 ); (d) dividing the N/2 residual transform coefficients into P groups of M i coefficients ( 2906 ), such that the sum of the M i coefficients is N/2 f ˆˆ 1 �¢ l 2 (e) for each of P groups, applying a (2* M i )-point inverse transform to the transform coefficients to produce (2* M i ) sub-band samples from each group ( 2906 ); (f) in each sub-band i, multiplying the (2* M i ) sub-band samples by a (2* M i )-point window function ( 2908 ); (g) in each sub-band i, overlapping with M i previous samples and adding corresponding values to produce M i new samples for each sub-band ( 2910 ); and (h) repeating steps (a)-(g) on one or more of the sub-bands of M i new samples using successively smaller transform sizes N ( 2912 ) until the desired time/transform resolution is achieved ( 2914 ). The invention further comprises a method of hierarchically reconstructing time samples of an input signal, in which each input frame contains M i time samples in each of P sub-bands. |
