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US 9,318,127 B2Granted
Device and method for improved magnitude response and temporal alignment in a phase vocoder based bandwidth extension method for audio signals
AssigneesFraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Dolby International AB
InventorsSascha Disch, Frederik Nagel, Stephan Wilde, Lars Villemoes, Per Ekstrand
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Abstract
An apparatus for generating a bandwidth extended audio signal from an input signal, includes a patch generator for generating one or more patch signals from the input signal, wherein the patch generator is configured for performing a time stretching of subband signals from an analysis filterbank, and wherein the patch generator further includes a phase adjuster for adjusting phases of the subband signals using a filterbank-channel dependent phase correction.
Claims25
An apparatus for generating a bandwidth extended audio signal from an input signal, comprising:
- a patch generator for generating one or more patch signals from the input signal, wherein a patch signal comprises a patch center frequency being different from a patch center frequency of a different patch or from a center frequency of the input audio signal,
- wherein the patch generator is configured for performing a time stretching of subband signals from an analysis filterbank, and
- wherein the patch generator comprises a phase adjuster for adjusting phases of the subband signals using a filterbank-channel dependent phase correction, the filterbank-channel dependent phase correction comprising:
- πC(k+½)
- wherein k indicates a filterbank channel and C is a real number between 2 and 4.
2 more elements
A method of generating a bandwidth extended audio signal from an input signal, comprising:
- generating one or more patch signals from the input signal, wherein a patch signal comprises a patch center frequency being different from a patch center frequency of a different patch or from a center frequency of the input audio signal,
- wherein a time stretching of subband signals from an analysis filterbank is performed, and
- wherein phases of the subband signals are adjusted using a filterbank-channel dependent phase correction, the filterbank-channel dependent phase correction comprising:
- πC(k+½)
- wherein k indicates a filterbank channel and C is a real number between 2 and 4.
2 more elements
A non-transitory storage medium having stored thereon a computer program comprising a program code for performing, when running in a computer, the method of generating a bandwidth extended audio signal from an input signal, the method comprising:
- generating one or more patch signals from the input signal, wherein a patch signal comprises a patch center frequency being different from a patch center frequency of a different patch or from a center frequency of the input audio signal,
- wherein a time stretching of subband signals from an analysis filterbank is performed, and
- wherein phases of the subband signals are adjusted using a filterbank-channel dependent phase correction, the filterbank-channel dependent phase correction comprising:
- πC(k+½)
- wherein k indicates a filterbank channel and C is a real number between 2 and 4.
2 more elements
An apparatus for generating a bandwidth extended audio signal from an input signal, comprising:
- a patch generator for generating one or more patch signals from the input signal, wherein a patch signal comprises a patch center frequency being different from a patch center frequency of a different patch or from a center frequency of the input audio signal,
- wherein the patch generator is configured for performing a time stretching of subband signals from an analysis filterbank, and
- wherein the patch generator comprises a phase adjuster for adjusting phases of the subband signals using a filterbank-channel dependent phase correction,
- wherein the apparatus is configured for performing a bandwidth extension using at least two transposition factors, wherein the patch generator is configured:
- for the first transposition factor,
- to extract using a block advance value and to use no or a first decimation using a first decimation factor;
- to phase adjust the samples of the block of subband samples;
- to zero pad the phase adjusted block to a certain length to acquire a first transpose signal;
- for the second transposition factor,
- to extract a block of subband samples using a block advance value and to use a decimation using a second decimation factor being greater than the first decimation factor;
- to phase adjust the samples of the block of subband samples;
- and
- to zero pad the phase adjusted block to a certain length to acquire a second transposed signal;
- to add the first and the second transposed signal in a sample-by-sample to acquire a transpose block;
- and
- to overlap-add sequential transpose blocks using an advance value being greater than the block advance value to acquire a transposed subband signal.
13 more elements
A method of generating a bandwidth extended audio signal from an input signal, comprising:
- generating one or more patch signals from the input signal, wherein a patch signal comprises a patch center frequency being different from a patch center frequency of a different patch or from a center frequency of the input audio signal,
- wherein a time stretching of subband signals from an analysis filterbank is performed, and
- wherein phases of the subband signals are adjusted using a filterbank-channel dependent phase correction,
- wherein the method comprises performing a bandwidth extension using at least two transposition factors, wherein the generating one or more patch signals comprises:
- for the first transposition factor,
- extracting using a block advance value and using no or a first decimation using a first decimation factor;
- phase adjusting the samples of the block of subband samples;
- zero padding the phase adjusted block to a certain length to acquire a first transpose signal;
- for the second transposition factor,
- extracting a block of subband samples using a block advance value and using a decimation using a second decimation factor being greater than the first decimation factor;
- phase adjusting the samples of the block of subband samples;
- and
- zero padding the phase adjusted block to a certain length to acquire a second transposed signal;
- adding the first and the second transposed signal in a sample-by-sample to acquire a transpose block;
- and
- overlap-adding sequential transpose blocks using an advance value being greater than the block advance value to acquire a transposed subband signal.
13 more elements
A non-transitory storage medium having stored thereon a computer program comprising a program code for performing, when running in a computer, the method of generating a bandwidth extended audio signal from an input signal, the method comprising:
- generating one or more patch signals from the input signal, wherein a patch signal comprises a patch center frequency being different from a patch center frequency of a different patch or from a center frequency of the input audio signal,
- wherein a time stretching of subband signals from an analysis filterbank is performed, and
- wherein phases of the subband signals are adjusted using a filterbank-channel dependent phase correction,
- wherein the method comprises performing a bandwidth extension using at least two transposition factors, wherein the generating one or more patch signals comprises:
- for the first transposition factor,
- extracting using a block advance value and using no or a first decimation using a first decimation factor;
- phase adjusting the samples of the block of subband samples;
- zero padding the phase adjusted block to a certain length to acquire a first transpose signal;
- for the second transposition factor,
- extracting a block of subband samples using a block advance value and using a decimation using a second decimation factor being greater than the first decimation factor;
- phase adjusting the samples of the block of subband samples;
- and
- zero padding the phase adjusted block to a certain length to acquire a second transposed signal;
- adding the first and the second transposed signal in a sample-by-sample to acquire a transpose block;
- and
- overlap-adding sequential transpose blocks using an advance value being greater than the block advance value to acquire a transposed subband signal.
13 more elements
An apparatus for generating a bandwidth extended audio signal from an input signal, comprising:
- a patch generator for generating one or more patch signals from the input signal, wherein a patch signal comprises a patch center frequency being different from a patch center frequency of a different patch or from a center frequency of the input audio signal,
- wherein the patch generator is configured for performing a time stretching of subband signals from an analysis filterbank,
- wherein the patch generator comprises a phase adjuster for adjusting phases of the subband signals using a filterbank-channel dependent phase correction, and
- wherein the phase adjuster is configured for applying a phase adjustment to sampling values of a block of sampling values, the phase adjustment being a combination of a phase value depending on a time stretching amount and on an actual phase of the block, and a signal-independent phase value depending on the channel number as the phase correction.
1 more element
A method of generating a bandwidth extended audio signal from an input signal, comprising:
- generating one or more patch signals from the input signal, wherein a patch signal comprises a patch center frequency being different from a patch center frequency of a different patch or from a center frequency of the input audio signal,
- wherein a time stretching of subband signals from an analysis filterbank is performed,
- wherein phases of the subband signals are adjusted using a filterbank-channel dependent phase correction, and
- wherein a phase adjustment is applied to sampling values of a block of sampling values, the phase adjustment being a combination of a phase value depending on a time stretching amount and on an actual phase of the block, and a signal-independent phase value depending on the channel number as the phase correction.
1 more element
A non-transitory storage medium having stored thereon a computer program comprising a program code for performing, when running in a computer, the method of generating a bandwidth extended audio signal from an input signal, the method comprising:
- generating one or more patch signals from the input signal, wherein a patch signal comprises a patch center frequency being different from a patch center frequency of a different patch or from a center frequency of the input audio signal,
- wherein a time stretching of subband signals from an analysis filterbank is performed,
- wherein phases of the subband signals are adjusted using a filterbank-channel dependent phase correction, and
- wherein a phase adjustment is applied to sampling values of a block of sampling values, the phase adjustment being a combination of a phase value depending on a time stretching amount and on an actual phase of the block, and a signal-independent phase value depending on the channel number as the phase correction.
1 more element
Dependencies are inferred from the claim text.