Simultaneous time-domain and frequency-domain noise shaping for TDAC transforms
First Claim
1. A frequency-domain noise shaping method for interpolating a spectral shape and a time-domain envelope of a quantization noise in a windowed and transform-coded audio signal, comprising:
- splitting transform coefficients of the windowed and transform-coded audio signal into a plurality of spectral bands; and
for each spectral band;
calculating a first gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a first transition between a first time window and a second time window;
calculating a second gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a second transition between the second time window and a third time window; and
an operation of filtering the transform coefficients of the second time window, the filtering operation receiving as first input the transform coefficients of the second time window and as second input the first and second gains to filter said transform coefficients of the second time window using the second input, first and second gains to interpolate between the first and second transitions the spectral shape and the time-domain envelope of the quantization noise.
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Abstract
A frequency-domain noise shaping method and device interpolates a spectral shape and a time-domain envelope of a quantization noise in a windowed and transform-coded audio signal. In the method and device, transform coefficients of the windowed and transform-coded audio signal are split into a plurality of spectral bands. For each spectral band, a first gain representing a spectral shape of the quantization noise at a first transition between a first time window and a second time window is calculated, a second gain representing a spectral shape of the quantization noise at a second transition between the second time window and a third time window is calculated, and the transform coefficients of the second time window are filtered based on the first and second gains, to interpolate between the first and second transitions the spectral shape and the time-domain envelope of the quantization noise.
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Citations
38 Claims
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1. A frequency-domain noise shaping method for interpolating a spectral shape and a time-domain envelope of a quantization noise in a windowed and transform-coded audio signal, comprising:
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splitting transform coefficients of the windowed and transform-coded audio signal into a plurality of spectral bands; and for each spectral band; calculating a first gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a first transition between a first time window and a second time window; calculating a second gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a second transition between the second time window and a third time window; and an operation of filtering the transform coefficients of the second time window, the filtering operation receiving as first input the transform coefficients of the second time window and as second input the first and second gains to filter said transform coefficients of the second time window using the second input, first and second gains to interpolate between the first and second transitions the spectral shape and the time-domain envelope of the quantization noise. - View Dependent Claims (3, 5, 6, 7, 9, 10)
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2. A frequency-domain noise shaping method for interpolating a spectral shape and a time-domain envelope of a quantization noise in a windowed and transform-coded audio signal, comprising:
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splitting transform coefficients of the windowed and transform-coded audio signal into a plurality of spectral bands; and for each spectral band; calculating a first gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a first transition between a first time window and a second time window; calculating a second gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a second transition between the second time window and a third time window; and an operation of filtering the transform coefficients of the second time window, the filtering operation receiving as first input the transform coefficients of the second time window and as second input the first and second gains to filter said transform coefficients of the second time window using the second input, first and second gains to interpolate between the first and second transitions the spectral shape and the time-domain envelope of the quantization noise; wherein the windowed and transform-coded audio signal is windowed using successive overlapping windows, wherein the first gain is a noise gain calculated at a middle point of an overlap between the first and second time windows, and wherein the second gain is a noise gain calculated at a middle point of an overlap between the second and third time windows.
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4. A frequency-domain noise shaping method for interpolating a spectral shape and a time-domain envelope of a quantization noise in a windowed and transform-coded audio signal, comprising:
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splitting transform coefficients of the windowed and transform-coded audio signal into a plurality of spectral bands; and for each spectral band; calculating a first gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a first transition between a first time window and a second time window; calculating a second gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a second transition between the second time window and a third time window; and an operation of filtering the transform coefficients of the second time window, the filtering operation receiving as first input the transform coefficients of the second time window and as second input the first and second gains to filter said transform coefficients of the second time window using the second input, first and second gains to interpolate between the first and second transitions the spectral shape and the time-domain envelope of the quantization noise; wherein filtering the transform coefficients comprises achieving a desired spectral shape of the quantization noise at the first and second transitions and a smooth transition of an envelope of this spectral shape from the first transition to the second transition.
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8. A frequency-domain noise shaping method for interpolating a spectral shape and a time-domain envelope of a quantization noise in a windowed and transform-coded audio signal, comprising:
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splitting transform coefficients of the windowed and transform-coded audio signal into a plurality of spectral bands; and for each spectral band; calculating a first gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a first transition between a first time window and a second time window; calculating a second gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a second transition between the second time window and a third time window; and an operation of filtering the transform coefficients of the second time window, the filtering operation receiving as first input the transform coefficients of the second time window and as second input the first and second gains to filter said transform coefficients of the second time window using the second input, first and second gains to interpolate between the first and second transitions the spectral shape and the time-domain envelope of the quantization noise; wherein filtering the transform coefficients comprises calculating filter parameters on the basis of the first and second calculated gains.
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11. A frequency-domain noise shaping device for interpolating a spectral shape and a time-domain envelope of a quantization noise in a windowed and transform-coded audio signal having transform coefficients, comprising:
a processor comprising; a splitter module configured to split the transform coefficients of the windowed and transform-coded audio signal into a plurality of spectral bands; a calculator module configured to calculate, for each spectral band, a first gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a first transition between a first time window and a second time window, and a second gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a second transition between the second time window and a third time window; and a filter module configured to filter the transform coefficients of the second time window, the filter module receiving as first input the transform coefficients of the second time window and as second input the first and second gains to filter said transform coefficients of the second time window using the second input, first and second gains to interpolate between the first and second transitions the spectral shape and the time-domain envelope of the quantization noise. - View Dependent Claims (13, 15, 16, 17, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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12. A frequency-domain noise shaping device for interpolating a spectral shape and a time-domain envelope of a quantization noise in a windowed and transform-coded audio signal having transform coefficients, comprising:
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a processor comprising; a splitter module configured to split the transform coefficients of the windowed and transform-coded audio signal into a plurality of spectral bands; a calculator module configured to calculate, for each spectral band, a first gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a first transition between a first time window and a second time window, and a second gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a second transition between the second time window and a third time window; and a filter module configured to filter the transform coefficients of the second time window, the filter module receiving as first input the transform coefficients of the second time window and as second input the first and second gains to filter said transform coefficients of the second time window using the second input, first and second gains to interpolate between the first and second transitions the spectral shape and the time-domain envelope of the quantization noise; wherein the windowed and transform-coded audio signal is windowed using successive overlapping windows, and wherein the calculator module calculates the first gain at a middle point of an overlap between the first and second time windows, and the second gain at a middle point of an overlap between the second and third time window. - View Dependent Claims (33, 34)
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14. A frequency-domain noise shaping device for interpolating a spectral shape and a time-domain envelope of a quantization noise in a windowed and transform-coded audio signal having transform coefficients, comprising:
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a processor comprising; a splitter module configured to split the transform coefficients of the windowed and transform-coded audio signal into a plurality of spectral bands; a calculator module configured to calculate, for each spectral band, a first gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a first transition between a first time window and a second time window, and a second gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a second transition between the second time window and a third time window; and a filter module configured to filter the transform coefficients of the second time window, the filter module receiving as first input the transform coefficients of the second time window and as second input the first and second gains to filter said transform coefficients of the second time window using the second input, first and second gains to interpolate between the first and second transitions the spectral shape and the time-domain envelope of the quantization noise, wherein the transform coefficient filter module achieves a desired spectral shape of the quantization noise at the first and second transitions and a smooth transition of an envelope of this spectral shape from the first transition to the second transition. - View Dependent Claims (35, 36)
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18. A frequency-domain noise shaping device for interpolating a spectral shape and a time-domain envelope of a quantization noise in a windowed and transform-coded audio signal having transform coefficients, comprising:
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a processor comprising; a splitter module configured to split the transform coefficients of the windowed and transform-coded audio signal into a plurality of spectral bands; a calculator module configured to calculate, for each spectral band, a first gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a first transition between a first time window and a second time window, and a second gain representing, together with corresponding gains calculated for the other spectral bands, a spectral shape of the quantization noise at a second transition between the second time window and a third time window; and a filter module configured to filter the transform coefficients of the second time window, the filter module receiving as first input the transform coefficients of the second time window and as second input the first and second gains to filter said transform coefficients of the second time window using the second input, first and second gains to interpolate between the first and second transitions the spectral shape and the time-domain envelope of the quantization noise, wherein the transform coefficient filter module calculates filter parameters on the basis of the first and second calculated gains. - View Dependent Claims (37, 38)
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Specification