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US 9,805,735 B2Granted
Apparatus, method and computer program for generating a wideband signal using guided bandwidth extension and blind bandwidth extension
AssigneeFraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V.
InventorsFrederik Nagel, Max Neuendorf, Markus Schnell, Markus Multrus
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Abstract
An apparatus, method and computer program for generating a wideband signal using a lowband input signal includes a processor for performing a guided bandwidth extension operation using transmitted parameters and a blind bandwidth extension operation only using derived parameters rather than transmitted parameters. To this end, the processor includes a parameter generator for generating the parameters for the blind bandwidth extension operation.
Claims13
Apparatus for generating a wideband audio signal using a lowband audio input signal and a first parameter set describing the frequency content above a maximum frequency of the lowband audio input signal and up to a first frequency being higher than the maximum frequency of the lowband audio input signal, wherein parameters describing a frequency content above the first frequency are not comprised in the first parameter set, comprising:
- a processor
- that performs a guided bandwidth extension operation using the lowband audio input signal and the first parameter set and generates a first frequency content comprising frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency, and
- that performs a blind bandwidth extension operation using the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency and a second parameter set different from the first parameter set and generates a second frequency content comprising frequencies extending up to a second frequency being higher than the first frequency,
- wherein the processor, in performing of the guided bandwidth extension operation
- extracts the first parameter set and the lowband audio input signal from a bitstream;
- performs the guided bandwidth extension operation using a patching of the lowband audio input signal and using the first parameter set, the performing of the guided bandwidth extension operation comprising shaping a signal, based on the lowband audio input signal, to be shaped using the first parameter set to acquire a first shaped signal, wherein the guided bandwidth extension operation generates a first bandwidth extended audio signal comprising the first frequency content, the first bandwidth extended audio signal having a shaped spectral envelope, the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency;
- wherein the processor comprises a parameter generator that generates the second parameter set from the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency,
- wherein the parameter generator
- performs an extrapolation of energy information of the shaped spectral envelope of the first bandwidth extended audio signal having the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency, to obtain extrapolated energy information for the second frequency content comprising frequencies extending up to the second frequency being higher than the first frequency, and
- derives, from a result of the extrapolation, spectral envelope parameters for the second parameter set for the second frequency content comprising the frequencies extending up to the second frequency being higher than the first frequency,
- wherein the processor, in performing the blind bandwidth extension operation,
- uses a patching of the first bandwidth extended audio signal having the shaped spectral envelope and uses the spectral envelope parameters of the second parameter set, wherein the patching of the first bandwidth extended audio signal generates a second bandwidth extended audio signal having the second frequency content having a spectral envelope defined by the spectral envelope parameters of the second parameter set, wherein the processor comprises a combiner that combines the first bandwidth extended audio signal and the second bandwidth extended audio signal, and the lowband audio signal to obtain and output the wideband audio signal, and wherein at least one of the processor and the parameter generator comprises a hardware implementation.
9 more elements
Method of generating a wideband audio signal using a lowband audio input signal and a first parameter set describing the frequency content above a maximum frequency of the lowband audio input signal and up to a first frequency being higher than the maximum frequency of the lowband audio input signal, wherein parameters describing a frequency content above the first frequency are not comprised in the first parameter set, comprising:
- performing, by a processor, a guided bandwidth extension operation using the lowband audio input signal and the first parameter set and generating a first frequency content comprising frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency, the performing of the guided bandwidth extension operation comprising:
- extracting the first parameter set and the lowband audio input signal from a bitstream;
- patching of the lowband audio input signal and using the first parameter set, the performing of the guided bandwidth extension operation comprising shaping a signal, based on the lowband audio input signal, to be shaped using the first parameter set to acquire a first shaped signal, wherein the guided bandwidth extension operation generates a first bandwidth extended audio signal comprising the first frequency content, the first bandwidth extended audio signal having a shaped spectral envelope, the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency, and
- performing, by the processor, a blind bandwidth extension operation using the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency and a second parameter set different from the first parameter set and generating a second frequency content comprising frequencies extending up to a second frequency being higher than the first frequency
- wherein the performing the blind bandwidth extension operation comprises generating, by a parameter generator, the second parameter set from the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency
- wherein the generating, by the parameter generator, comprises:
- performing an extrapolation of energy information of the shaped spectral envelope of the first bandwidth extended audio signal having the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency to obtain extrapolated energy information for the second frequency content comprising frequencies extending up to the second frequency being higher than the first frequency, and
- deriving, from a result of the extrapolation, spectral envelope parameters for the second parameter set for the second frequency content comprising the frequencies extending up to the second frequency being higher than the first frequency,
- wherein the performing the blind bandwidth extension operation further comprises:
- patching of the first bandwidth extended audio signal having the shaped spectral envelope and using the spectral envelope parameters of the second parameter set, wherein the patching of the first bandwidth extended audio signal generates a second bandwidth extended audio signal having the second frequency content having a spectral envelope defined by the spectral envelope parameters of the second parameter set, wherein the processor comprises a combiner that combines the first bandwidth extended audio signal and the second bandwidth extended audio signal, and the lowband audio signal to obtain and output the wideband audio signal,
- wherein at least one of the processor and the parameter generator comprises a hardware implementation.
8 more elements
Non-transitory storage medium having stored thereon a computer program comprising a program code for performing, when running on a computer, the method of generating a wideband audio signal using a lowband audio input signal and a first parameter set describing the frequency content above a maximum frequency of the lowband audio input signal and up to a first frequency being higher than the maximum frequency of the lowband audio input signal, wherein parameters describing a frequency content above the first frequency are not comprised in the first parameter set, the method comprising:
- performing a guided bandwidth extension operation using the lowband audio input signal and the first parameter set and generating a first frequency content comprising frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency, the performing of the guided bandwidth extension operation comprising:
- extracting the first parameter set and the lowband audio input signal from a bitstream;
- patching of the lowband audio input signal and using the first parameter set, the performing of the guided bandwidth extension operation comprising shaping a signal to be shaped using the first parameter set to acquire a first shaped signal, based on the lowband audio input signal, wherein the guided bandwidth extension operation generates a first bandwidth extended audio signal comprising the first frequency content, the first bandwidth extended audio signal having a shaped spectral envelope, the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency, and
- performing a blind bandwidth extension operation using the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency and a second parameter set different from the first parameter set and generating a second frequency content comprising frequencies extending up to a second frequency being higher than the first frequency
- wherein the performing the blind bandwidth extension operation comprises generating the second parameter set from the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency, wherein the generating comprises:
- performing an extrapolation of energy information of the shaped spectral envelope of the first bandwidth extended audio signal having the first frequency content comprising the frequencies being higher than the maximum frequency of the lowband audio input signal and extending up to the first frequency to obtain extrapolated energy information for the second frequency content comprising frequencies extending up to the second frequency being higher than the first frequency, and
- deriving, from a result of the extrapolation, spectral envelope parameters for the second parameter set for the second frequency content comprising the frequencies extending up to the second frequency being higher than the first frequency, and
- patching of the first bandwidth extended audio signal having the shaped spectral envelope and using the spectral envelope parameters of the second parameter set, wherein the patching of the first bandwidth extended audio signal generates a second bandwidth extended audio signal having the second frequency content having a spectral envelope defined by the spectral envelope parameters of the second parameter set, further comprising combining the first bandwidth extended audio signal and the second bandwidth extended audio signal, and the lowband audio signal to obtain and output the wideband audio signal.
5 more elements
Dependencies are inferred from the claim text.