Complex exponential modulated filter bank for high frequency reconstruction
First Claim
1. A signal processing device for filtering and performing high frequency reconstruction of an audio signal, the signal processing device comprising:
- an analysis filter bank that receives real valued time domain input audio samples and generates complex valued subband samples;
a high frequency reconstructor that generates modified complex valued subband samples through a high frequency reconstruction process; and
a synthesis filter bank that receives the modified complex valued subband samples and generates time domain output audio samples,wherein the analysis filter bank comprises analysis filters (hk(n)) that are complex exponential modulated versions of a prototype filter (p0(n)) according to;
0≦
n<
N,0≦
k<
M where A is an arbitrary phase shift constant, the analysis filter bank has M channels, the prototype filter (p0(n)) has a length N, and the analysis filter bank and synthesis filter bank have a system delay of D samples,wherein one or more of the analysis filter bank, the high frequency reconstructor, and the synthesis filter bank is implemented, at least in part, by one or more hardware elements of the signal processing device.
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Abstract
An apparatus and method are disclosed for filtering and performing high frequency reconstruction of an audio signal. The apparatus includes an analysis filter bank, a high frequency reconstructor, and a synthesis filter bank. The analysis filterbank receives real-valued time domain input audio samples and generates complex valued subband samples. The high frequency reconstructor modifies at least some of the complex valued subband samples. The synthesis filter bank receives the modified complex valued subband samples and generates time domain output audio samples. The analysis filter bank comprises analysis filters that are complex exponential modulated versions of a prototype filter with an arbitrary phase shift.
8 Citations
9 Claims
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1. A signal processing device for filtering and performing high frequency reconstruction of an audio signal, the signal processing device comprising:
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an analysis filter bank that receives real valued time domain input audio samples and generates complex valued subband samples; a high frequency reconstructor that generates modified complex valued subband samples through a high frequency reconstruction process; and a synthesis filter bank that receives the modified complex valued subband samples and generates time domain output audio samples, wherein the analysis filter bank comprises analysis filters (hk(n)) that are complex exponential modulated versions of a prototype filter (p0(n)) according to;
0≦
n<
N,0≦
k<
Mwhere A is an arbitrary phase shift constant, the analysis filter bank has M channels, the prototype filter (p0(n)) has a length N, and the analysis filter bank and synthesis filter bank have a system delay of D samples, wherein one or more of the analysis filter bank, the high frequency reconstructor, and the synthesis filter bank is implemented, at least in part, by one or more hardware elements of the signal processing device. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method performed by an signal processing device for filtering and performing high frequency reconstruction of an audio signal, the method comprising:
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receiving real-valued time domain input audio samples; filtering the real-valued time domain input audio samples with an analysis filter bank to generate complex valued subband samples; generating modified complex valued subband samples through a high frequency reconstruction process; receiving the modified complex valued subband samples; filtering the modified complex valued subband samples with a synthesis filter bank to generate time domain output audio samples, wherein the analysis filter bank comprises analysis filters (hk(n)) that are complex exponential modulated versions of a prototype filter (p0(n)) according to;
0≦
n<
N,0≦
k<
Mwhere A is an arbitrary phase shift constant, the analysis filter bank has M channels, the prototype filter (p0(n)) has a length N, and the analysis filter bank and synthesis filter bank have a system delay of D samples, wherein the signal processing device comprises one or more hardware elements. - View Dependent Claims (9)
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Specification