Apparatus and a Method for Generating Bandwidth Extension Output Data
First Claim
1. An encoder for encoding an audio signal, the audio signal comprising components in a first frequency band and components in a second frequency band, the encoder comprising:
- a core coder for encoding the components in the first frequency band to acquire an encoded audio signal;
an envelope data calculator for calculating bandwidth extension (BWE) data based on the components in the second frequency band, the envelope data calculator comprising an apparatus for generating bandwidth extension output data for the audio signal, the bandwidth extension output data being adapted to control a synthesis of the components in the second frequency band, the apparatus comprising;
a noise floor measurer for measuring noise floor data of the second frequency band for a time portion of the audio signal;
a signal energy characterizer for deriving energy distribution data, the energy distribution data characterizing an energy distribution in a spectrum of the time portion of the audio signal; and
a processor for combining the noise floor data and the energy distribution data to acquire the bandwidth extension output data,wherein the bandwidth extension data comprise the bandwidth extension data and envelope data; and
a bitstream payload formatter adapted for outputting a coded audio stream by combining the bandwidth extension data with the encoded audio signal, wherein the processor is part of the bitstream payload formatter.
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Abstract
An apparatus for generating bandwidth extension output data for an audio signal has a noise floor measurer, a signal energy characterizer and a processor. The audio signal has components in a first frequency band and components in a second frequency band, the bandwidth extension output data are adapted to control a synthesis of the components in the second frequency band. The noise floor measurer measures noise floor data of the second frequency band for a time portion of the audio signal. The signal energy characterizer derives energy distribution data, the energy distribution data characterizing an energy distribution in a spectrum of the time portion of the audio signal. The processor combines the noise floor data and the energy distribution data to obtain the bandwidth extension output data.
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Citations
16 Claims
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1. An encoder for encoding an audio signal, the audio signal comprising components in a first frequency band and components in a second frequency band, the encoder comprising:
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a core coder for encoding the components in the first frequency band to acquire an encoded audio signal; an envelope data calculator for calculating bandwidth extension (BWE) data based on the components in the second frequency band, the envelope data calculator comprising an apparatus for generating bandwidth extension output data for the audio signal, the bandwidth extension output data being adapted to control a synthesis of the components in the second frequency band, the apparatus comprising; a noise floor measurer for measuring noise floor data of the second frequency band for a time portion of the audio signal; a signal energy characterizer for deriving energy distribution data, the energy distribution data characterizing an energy distribution in a spectrum of the time portion of the audio signal; and a processor for combining the noise floor data and the energy distribution data to acquire the bandwidth extension output data, wherein the bandwidth extension data comprise the bandwidth extension data and envelope data; and a bitstream payload formatter adapted for outputting a coded audio stream by combining the bandwidth extension data with the encoded audio signal, wherein the processor is part of the bitstream payload formatter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of encoding an audio signal, the audio signal comprising components in a first frequency band and components in a second frequency band, the method comprising:
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encoding the components in the first frequency band to acquire an encoded audio signal; calculating bandwidth extension data by an envelope data calculator based on the components in the second frequency band, calculating comprising generating bandwidth extension output data for the audio signal, the bandwidth extension output data being adapted to control a synthesis of the components in the second frequency band, generating bandwidth extension output data comprising; measuring noise floor data of the second frequency band for a time portion of the audio signal; deriving energy distribution data, the energy distribution data characterizing an energy distribution in a spectrum of the time portion of the audio signal; and combining the noise floor data and the energy distribution data to acquire the bandwidth extension output data; and wherein the bandwidth extension data comprise the bandwidth extension output data and envelope data, and bitstream payload formatting and outputting a coded audio stream by combining the bandwidth extension data with the encoded audio signal, wherein combining is part of bitstream payload formatting.
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10. A bandwidth extension tool for generating components in a second frequency band of an audio signal based on bandwidth extension output data and based on a raw signal spectral representation for the components in the second frequency band, wherein the bandwidth extension output data comprise energy distribution data, the energy distribution data characterizing an energy distribution in a spectrum of a time portion of the audio signal, the bandwidth extension tool comprising:
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a noise floor modifier tool, which is configured to modify a transmitted noise floor in accordance to the energy distribution data; and a combiner for combining the raw signal spectral representation with the modified noise floor to generate the components in the second frequency band with the modified noise floor. - View Dependent Claims (11)
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12. A decoder for decoding a coded audio stream to acquire an audio signal comprising:
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a bitstream deformatter separating an encoded signal and the BWE output data; a bandwidth extension tool for generating components in a second frequency band of an audio signal based on bandwidth extension output data and based on a raw signal spectral representation for the components in the second frequency band, wherein the bandwidth extension output data comprise energy distribution data, the energy distribution data characterizing an energy distribution in a spectrum of a time portion of the audio signal, the bandwidth extension tool comprising;
a noise floor modifier tool, which is configured to modify a transmitted noise floor in accordance to the energy distribution data; and
a combiner for combining the raw signal spectral representation with the modified noise floor to generate the components in the second frequency band with the modified noise floor;a core decoder for decoding components in a first frequency band from the encoded audio signal; and a synthesis unit for synthesizing the audio signal by combining the components of the first and second frequency band.
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13. A method for decoding a coded audio stream to acquire an audio signal, the audio signal comprising components in a first frequency band and bandwidth extension output data, wherein the bandwidth extension output data comprise energy distribution data and noise floor data, the energy distribution data characterizing an energy distribution in a spectrum of a time portion of the audio signal, the method comprising:
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separating from the coded audio stream an encoded audio signal and the BWE output data; decoding components in a first frequency band from the encoded audio signal; generating a raw signal spectral representation for components in a second frequency band from the components in the first frequency band; modifying a noise floor in accordance to the energy distribution data and in accordance to the transmitted noise floor data; combining the raw signal spectral representation with the modified noise floor to generate the components in the second frequency band with the calculated noise floor; and synthesizing the audio signal by combining the components of the first and second frequency band.
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14. Computer program for performing, when running on a computer, a method of encoding an audio signal, the audio signal comprising components in a first frequency band and components in a second frequency band, the method comprising:
- encoding the components in the first frequency band to acquire an encoded audio signal;
calculating bandwidth extension data by an envelope data calculator based on the components in the second frequency band, calculating comprising generating bandwidth extension output data for the audio signal, the bandwidth extension output data being adapted to control a synthesis of the components in the second frequency band, generating bandwidth extension output data comprising;
measuring noise floor data of the second frequency band for a time portion of the audio signal;
deriving energy distribution data, the energy distribution data characterizing an energy distribution in a spectrum of the time portion of the audio signal; and
combining the noise floor data and the energy distribution data to acquire the bandwidth extension output data; and
wherein the bandwidth extension data comprise the bandwidth extension output data and envelope data, and bitstream payload formatting and outputting a coded audio stream by combining the bandwidth extension data with the encoded audio signal, wherein combining is part of bitstream payload formatting.
- encoding the components in the first frequency band to acquire an encoded audio signal;
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15. Computer program for performing, when running on a computer, a method for decoding a coded audio stream to acquire an audio signal, the audio signal comprising components in a first frequency band and bandwidth extension output data, wherein the bandwidth extension output data comprise energy distribution data and noise floor data, the energy distribution data characterizing an energy distribution in a spectrum of a time portion of the audio signal, the method comprising:
- separating from the coded audio stream an encoded audio signal and the BWE output data;
decoding components in a first frequency band from the encoded audio signal;
generating a raw signal spectral representation for components in a second frequency band from the components in the first frequency band;
modifying a noise floor in accordance to the energy distribution data and in accordance to the transmitted noise floor data;
combining the raw signal spectral representation with the modified noise floor to generate the components in the second frequency band with the calculated noise floor; andsynthesizing the audio signal by combining the components of the first and second frequency band.
- separating from the coded audio stream an encoded audio signal and the BWE output data;
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16. An encoded audio stream, comprising:
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an encoded audio signal for components in a first frequency band of an audio signal; noise floor data adapted to control a synthesis of a noise floor for components in a second frequency band of the audio signal; energy distribution data adapted to control a modification of the noise floor; and envelope data for the components in the second frequency band.
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Specification