Method and apparatus for low bit rate encoding and decoding
First Claim
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1. A method of low bit rate encoding comprising:
- transforming input audio signals in a time domain into spectral signals in a frequency domain;
extracting spectrum components from the spectral signals in the frequency domain, and quantizing the spectrum components based on a psychoacoustic analysis of the spectral signals;
extracting residual-spectrum components other than the spectrum components from the spectral signals in the frequency domain, and calculating and quantizing a noise level corresponding to noise components of the residual-spectrum components based on the psychoacoustic analysis of the spectral signals; and
encoding the quantized spectrum components and the quantized noise level losslessly, without the noise components, and outputting encoded bitstreams.
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Abstract
An apparatus and method of low bit rate encoding and reproducing. The method includes transforming input audio signals in a time domain into spectral signals in a frequency domain, extracting important-spectrum components from the spectral signals in the frequency domain, and quantizing the important-spectrum components, extracting residual-spectrum components other than the important-spectrum components from the spectral signals in the frequency domain, and calculating and quantizing a noise level of the residual-spectrum components, and encoding the quantized important-spectrum components and the quantized noise level losslessly, and outputting encoded bitstreams.
19 Citations
15 Claims
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1. A method of low bit rate encoding comprising:
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transforming input audio signals in a time domain into spectral signals in a frequency domain; extracting spectrum components from the spectral signals in the frequency domain, and quantizing the spectrum components based on a psychoacoustic analysis of the spectral signals; extracting residual-spectrum components other than the spectrum components from the spectral signals in the frequency domain, and calculating and quantizing a noise level corresponding to noise components of the residual-spectrum components based on the psychoacoustic analysis of the spectral signals; and encoding the quantized spectrum components and the quantized noise level losslessly, without the noise components, and outputting encoded bitstreams. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for low bit rate encoding, comprising:
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a spectrum component processing unit that extracts spectrum components from a spectral signal in a frequency domain and quantizes the spectrum components; a psychoacoustic modeling unit performing a psychoacoustic analysis of the spectral signals; a noise component processing unit that extracts residual-spectrum components other than the spectrum components from the spectral signal in the frequency domain, and calculates and quantizes noise levels corresponding to noise components of the residual-spectrum components based on the psychoacoustic analysis performed by the psychoacoustic modeling unit; and a lossless encoding unit that losslessly encodes the spectrum components and the noise level, without the noise components and outputs encoded bitstreams. - View Dependent Claims (8, 9)
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10. A computer-readable storage medium encoded with processing instructions for causing a processor to execute a method of low bit rate encoding, the method comprising:
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transforming an input audio signal from the time domain to the frequency domain; extracting spectrum components from a spectral signal in a frequency domain, and quantizing the spectrum components based on a psychoacoustic analysis of the spectral signals; extracting residual-spectrum components other than the spectrum components from the spectral signal in the frequency domain, and calculating and quantizing a noise level corresponding to noise components of the residual-spectrum components based on the psychoacoustic analysis of the spectral signals; and encoding the quantized spectrum components and the quantized noise level losslessly, without the noise components, and outputting encoded bitstreams.
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11. A method of low bit rate decoding, comprising:
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decoding input bitstreams into spectral signals losslesslylossless-decoding, performed by at least one processor, a bitstream to obtain quantized spectrum components; dequantizing the quantized spectrum components, of decoded spectral signals, surrounded by spectrum components during an encoding of the input bitstream that were quantized to zero within the encoding; dequantizing a noise level of additional information of the decoded spectral signals and a subband from the bitstream in order to obtain a dequantized noise level; generating a respective noise components component, using the dequantized noise level, for residue each spectrum components component set to zero other than the each spectrum components component set to non-zero; and generating spectral signals in a frequency domain using the dequantizedreplacing each of spectrum components and thecomponents set to zero with its respective noise componentscomponent; and generating a digital audio signal, based on the replacing and the spectrum component set to non-zero of the subband for audio reproduction, wherein in the replacing, a frequency range of spectrum components set to zero around the spectrum component set to non-zero for which their noise components are to be replaced is determined based on a frame length. - View Dependent Claims (12)
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13. An apparatus for low bit rate decoding, comprising:
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a lossless decoding unit implemented by a processor that decodes input bitstreams into spectral signals losslessly lossless-decodes a bitstream to obtain quantized spectrum components; a spectrum component dequantizing unit implemented by the processor that dequantizes the quantized spectrum components, of the decoded spectral signals, surrounded by spectrum components during an encoding of the input bitstream that were quantized to zero within the encoding; a noise component processing unit implemented by the processor that dequantizes a noise level of additional information of the decoded spectral signals a subband from the bitstream in order to obtain a dequantized noise level and generates a respective noise components component using the dequantized noise level, for residue each spectrum components component set to zero other than the each spectrum components component set to non-zero; a spectrum combining unit implemented by the processor that combines replaces each of the dequantized spectrum components and the components set to zero with its respective noise components component to be output as a spectral signals signal in a frequency domain; and a signal generating unit implemented by the processor that generates spectral signals in a time domain from the spectral signals in the frequency domain a digital audio signal, based on the replacing and the spectrum component set to non-zero of the subband for audio reproduction, wherein in the replacing, a frequency range of spectrum components set to zero around the spectrum component set to non-zero for which their noise components are to be replaced is determined based on a frame length. - View Dependent Claims (14)
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15. A non-transitory computer-readable storage medium encoded with processing instructions for causing a processor to execute a method of low bit rate decoding, comprising:
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decoding input bitstreams into spectral signals losslesslylossless-decoding, performed by at least one processor, a bitstream to obtain quantized spectrum components; dequantizing the quantized spectrum components, of decoded spectral signals, surrounded by spectrum components during an encoding of the input bitstream that were quantized to zero within the encoding; dequantizing a noise level of additional information of the decoded spectral signals and a subband from the bitstream in order to obtain a dequantized noise level;
generating a respective noise components component, using the dequantized noise level, for each spectrum components component set to zero other than the each spectrum components quantized component set to non-zero;
andgenerating spectral signals in a frequency domain using the dequantizedreplacing each of spectrum components and theset to zero with its respective noise componentscomponent; and generating a digital audio signal, based on the replacing and the spectrum component set to non-zero of the subband for audio reproduction, wherein in the replacing, a frequency range of spectrum components set to zero around the spectrum component set to non-zero for which their noise components are to be replaced is determined based on a frame length.
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Specification