Method and apparatus for efficient implementation of single-sideband filter banks providing accurate measures of spectral magnitude and phase
First Claim
1. A device for processing an input signal comprising input signal samples representing audio information, said device comprisingbuffer means for receiving a plurality of said input signal samples and forming a sequence of signal sample blocks,spectral means for generating first spectral representations by applying a first single-sideband filter bank to said sequence of signal sample blocks, and generating second spectral representations by applying a second single-sideband filter bank to said sequence of signal sample blocks,phasor means for deriving measures of magnitude and/or phase of spectral components in said audio information in response to said first and second spectral representations, andprocessor means for processing said first spectral representations to generate an output signal suitable for transmission or storage, wherein said processing is adapted in response to said measures of magnitude and/or phase of spectral components.
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Abstract
Accurate measures of estimated spectral power and phase are derived from two spectral representations of each of one or more input signals generated by single-sideband filter banks including critically-sampled perfect-reconstruction filter banks implemented by generalized forms of Time Domain Aliasing Cancellation transforms. The derived measures of spectral magnitude and phase may be used in various applications including adaptive bit allocation in perceptual coding systems. An efficient implementation of one particular single-sideband critically-sampled filter bank comprises folding and shuffling blocks of real-valued input signal samples into blocks of complex-valued samples, rotating the complex-valued samples in the complex plane, transforming the rotated samples into transform coefficients, and rotating and shuffling the transform coefficients to form the spectral representation.
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Citations
20 Claims
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1. A device for processing an input signal comprising input signal samples representing audio information, said device comprising
buffer means for receiving a plurality of said input signal samples and forming a sequence of signal sample blocks, spectral means for generating first spectral representations by applying a first single-sideband filter bank to said sequence of signal sample blocks, and generating second spectral representations by applying a second single-sideband filter bank to said sequence of signal sample blocks, phasor means for deriving measures of magnitude and/or phase of spectral components in said audio information in response to said first and second spectral representations, and processor means for processing said first spectral representations to generate an output signal suitable for transmission or storage, wherein said processing is adapted in response to said measures of magnitude and/or phase of spectral components.
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7. A device for processing two or more input signals comprising input signal samples representing audio information, wherein said device comprises for each respective input signal
buffer means for receiving a plurality of said input signal samples representing said respective input signal and forming a sequence of signal sample blocks, spectral means for generating first spectral representations by applying a first single-sideband filter bank to said sequence of signal sample blocks, and generating second spectral representations by applying a second single-sideband filter bank to said sequence of signal sample blocks, and phasor means for deriving measures of magnitude and/or phase of spectral components in said respective input signal in response to said first and second spectral representations, and further comprises processor means for processing first spectral representations for each respective input signal to generate an output signal suitable for transmission or storage, wherein said processing is adapted in response to said measures of magnitude and/or phase of spectral components corresponding to each of said input signals.
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15. A method for processing an input signal comprising input signal samples representing audio information, said device comprising
receiving a plurality of said input signal samples and forming a sequence of signal sample blocks, generating first spectral representations by applying a first single-sideband filter bank to said sequence of signal sample blocks, and generating second spectral representations by applying a second single-sideband filter bank to said sequence of signal sample blocks, deriving measures of magnitude and/or phase of spectral components in said audio information in response to said first and second spectral representations, and processing said first spectral representations to generate an output signal suitable for transmission or storage, wherein said processing is adapted in response to said measures of magnitude and/or phase of spectral components.
Specification