Signal generation system and signal generation method

Abstract

This invention provides an improved and efficient method of mutual product high-frequency reconstruction (HFR) in which a new frequency component QΩ+rΩ0 is generated based on the existing components Ω and Ω+Ω0. [Solution] The present invention performs block harmonic transposition, where time blocks of complex subband samples are processed together with a common phase correction component. The superposition of the corrected samples has the advantageous effect of limiting unwanted intermodulation products, thereby enabling the use of coarse frequency resolution and / or a low degree of oversampling. In one embodiment, the present invention uses a window function suitable for use with the improved block intermodulation HFR. The hardware configuration of the present invention comprises an analysis filter bank (101), a subband processing unit (102) set by control data (104), and a synthesis filter bank (103).

Claims

1. A system configured to generate a time-stretched and / or frequency-transposed signal from an input signal, comprising: a control data receiving unit configured to receive control data; an analysis filter bank; a subband processing unit; and a synthesis filter bank. The analysis filter bank is configured to derive Y (Y=2) analysis subband signals from the input signal, and each analysis subband signal has a plurality of complex analysis samples, each having phase and amplitude; The subband processing unit is configured to generate a composite subband signal from the Y analyzed subband signals using a subband transposition factor Q and a subband stretching factor S, wherein at least one of Q and S is greater than 1, and the subband processing unit is configured to determine the composite subband signal taking the control data into consideration, and the subband processing unit comprises a block extraction unit, a nonlinear frame processing unit, and an overlap addition unit; The block extraction unit is configured to form Y frames of L input samples, each frame being extracted from the plurality of complex analysis samples of the analysis subband signal, where L is a frame length greater than 1, and the block extraction unit is configured to apply a block hop size of h samples to the plurality of complex analysis samples before forming subsequent frames of the L input samples, thereby generating a sequence of frames of the input samples; The nonlinear frame processing unit is configured to generate a frame of a processing sample based on Y corresponding frames of the input sample formed by the block extraction unit, by determining the phase and amplitude of each processing sample of the frame, with respect to at least one processing sample: i) The phase of the processed sample is based on the phase of each corresponding input sample in each of the Y frames of the input sample; and ii) The amplitude of the processed sample is based on the average value of the amplitude of the corresponding input sample in the first frame of the input sample and the amplitude of the corresponding input sample in the second frame of the input sample; The overlap summing unit is configured to determine the composite subband signal by overlapping and adding samples from a sequence of frames of the processed sample; The composite filter bank is configured to generate the time-stretched and / or frequency-transposed signal from the composite subband signal; The system is configured such that the block extraction unit derives at least one frame of the input sample by downsampling the complex analysis sample of the analysis subband signal.

2. The aforementioned analysis filter bank has an analysis time progression width Δt Ａ Apply the above input signal, The analysis filter bank has an analysis frequency interval Δf Ａ Use n = 0 , . . , N-1 is the analysis subband index, and when N > 1, the analysis filter bank has N analysis subbands, One of the N analysis subbands is associated with the frequency band of the input signal. The aforementioned composite filter bank is composed of a composite time progression width Δt Ｓ Apply the above-mentioned composite subband signal, The composite filter bank has a composite frequency interval Δf Ｓ Use m = 0 , . . , When M-1 is the composite subband index and M > 1, the composite filter bank has M composite subbands, The system according to claim 1, wherein one of the M composite subbands is associated with the frequency band of the time-stretched and / or frequency-transposed signal.

3. The subband processing unit further comprises a cross-processing control unit, the cross-processing control unit processes the subband index n related to the analyzed subband signal and the analyzed subband index m. １ ,n ２ It is configured to generate cross-processing control data that defines the subband index, and the subband index is associated with an approximate integer solution to the following equation, [Math 1] Ω ０ Ω is the fundamental frequency belonging to the dominant pitch component of the input signal, and Ω is the frequency of the input signal for the analysis filter bank. σ = 0 or 1 / 2, Q = (Δt Ｓ / Δt Ａ )Q φ where Q φ It is a transposition factor, r is 1 ≤ r ≤ Q φ The system according to claim 2, wherein the integer is -1.

4. The value of r that maximizes the minimum amplitude of the subbands in the two frames formed by extracting the analysis sample from the analysis subband signal is the subband index n. １ ,n ２ The system according to claim 3, wherein the cross-processing control unit is configured to generate processing control data, based on the above.

5. The system according to claim 4, wherein the amplitude of the subband in each frame of L input samples is the amplitude of the central or near-central sample.

6. The system further comprises a plurality of subband processing units and a merge unit provided downstream of the plurality of subband processing units and upstream of the composite filter bank. Each of the plurality of subband processing units is configured to determine an intermediate composite subband signal using different values ​​of the subband transposition factor Q and / or the subband stretching factor S. The system according to any one of claims 1 to 5, wherein the merging unit is configured to merge corresponding intermediate composite subband signals in order to determine the composite subband signal.

7. The analysis filter bank is configured to form Y × Z analysis subband signals from the input signal. The subband processing unit generates Z composite subband signals from the Y × Z analyzed subband signals, and applies pairs of S and Q values ​​to each group of Y analyzed subband signals that form the basis of a given composite subband signal. The system according to any one of claims 1 to 6, wherein the composite filter bank is configured to generate Z time-stretched and / or frequency-transposed signals from the Z composite subband signals.

8. A method for generating a time-stretched and / or frequency-transposed signal from an input signal, Step of receiving control data; A step of deriving Y (Y=2) analysis subband signals from the input signal, wherein each analysis subband signal has a plurality of complex analysis samples, each having a phase and amplitude; A step of forming Y frames of L input samples, wherein each frame is extracted from the plurality of complex analysis samples of the analysis subband signal, and L is a frame length greater than 1; Before deriving subsequent frames of L input samples, the step of applying a block hop size of h samples to the plurality of complex analysis samples to generate a sequence of frames of the input samples; A step of generating a frame of a processing sample based on Y corresponding frames of an input sample and taking into account the control data, by determining the phase and amplitude of each processing sample of the frame, wherein with respect to at least one processing sample: i) The phase of the processed sample is based on the phase of each corresponding input sample in each of the Y frames of the input sample; and ii) The amplitude of the processed sample is based on the average value of the amplitude of the corresponding input sample in the first frame of the input sample and the amplitude of the corresponding input sample in the second frame of the input sample; A step of determining a composite subband signal by overlapping and adding samples from a sequence of frames of the processed sample; and A step of generating the time-stretched and / or frequency-transposed signal from the composite subband signal, wherein forming the frame of the input sample includes downsampling the complex analysis sample of the analysis subband signal; A method that includes this.

9. A data carrier for storing computer-readable instructions for performing the method described in claim 8.

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