Signal processing apparatus and method, and program
First Claim
Patent Images
1. A computer-implemented method for processing an audio signal, the method comprising:
- receiving an encoded low-frequency range signal corresponding to the audio signal;
performing filter processing on the decoded signal, the filter processing separating the decoded signal into low-frequency range band signals, wherein filter processing is performed by a QMF (Quadrature Mirror Filter) analysis filter;
performing a smoothing process on the low-frequency range band signals, the smoothing process smoothing the non-zero energy depression of the decoded signal;
performing a frequency shift on the smoothed low-frequency range band signals, the frequency shift generating high-frequency range band signals from the low-frequency range band signals;
combining the low-frequency range band signals and the high-frequency range band signals to generate an output signal, wherein combining is performed by a QMF synthesis filter; and
outputting the output signal,wherein performing the smoothing process on the low-frequency range band signals further comprises;
computing an average energy of a plurality of low-frequency range band signals;
computing a ratio for a selected one of the low-frequency range band signals by computing a ratio of the average energy of the plurality of low-frequency range band signals to an energy for the selected low-frequency range band signal; and
multiplying the selected low-frequency range band signal by the computed ratio.
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Abstract
A method, system, and computer program product for processing an encoded audio signal is described. In one exemplary embodiment, the system receives an encoded low-frequency range signal and encoded energy information used to frequency shift the encoded low-frequency range signal. The low-frequency range signal is decoded and an energy depression of the decoded signal is smoothed. The smoothed low-frequency range signal is frequency shifted to generate a high-frequency range signal. The low-frequency range signal and high-frequency range signal are then combined and outputted.
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Citations
24 Claims
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1. A computer-implemented method for processing an audio signal, the method comprising:
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receiving an encoded low-frequency range signal corresponding to the audio signal; performing filter processing on the decoded signal, the filter processing separating the decoded signal into low-frequency range band signals, wherein filter processing is performed by a QMF (Quadrature Mirror Filter) analysis filter; performing a smoothing process on the low-frequency range band signals, the smoothing process smoothing the non-zero energy depression of the decoded signal; performing a frequency shift on the smoothed low-frequency range band signals, the frequency shift generating high-frequency range band signals from the low-frequency range band signals; combining the low-frequency range band signals and the high-frequency range band signals to generate an output signal, wherein combining is performed by a QMF synthesis filter; and outputting the output signal, wherein performing the smoothing process on the low-frequency range band signals further comprises; computing an average energy of a plurality of low-frequency range band signals; computing a ratio for a selected one of the low-frequency range band signals by computing a ratio of the average energy of the plurality of low-frequency range band signals to an energy for the selected low-frequency range band signal; and multiplying the selected low-frequency range band signal by the computed ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A device for processing an audio signal, the device comprising:
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a low-frequency range decoding circuit configured to receive an encoded low-frequency range signal corresponding to the audio signal and decode the encoded signal to produce a decoded signal having an energy spectrum of a shape including a non-zero energy depression; a filter processor configured to perform filter processing on the decoded signal, the filter processing separating the decoded signal into low-frequency range band signals, wherein filter processor comprises a QMF (Quadrature Mirror Filter) analysis filter; a high-frequency range generating circuit configured to; perform a smoothing process on the low-frequency range band signals, the smoothing process smoothing the energy depression; a combinatorial circuit configured to combine the low-frequency range band signals and the high-frequency range band signals to generate an output signal, and output the output signal, wherein the combinatorial circuit comprises a QMF synthesis filter, wherein the high-frequency range generating circuit is further configured to perform the smoothing process on the low-frequency range band signals by; computing an average energy of a plurality of low-frequency range band signals; computing a ratio for a selected one of the low-frequency range band signals by computing a ratio of the average energy of the plurality of low-frequency range band signals to an energy for the selected low-frequency range band signal; and multiplying the selected low-frequency range band signal by the computed ratio. - View Dependent Claims (16)
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17. A non-transitory computer-readable storage medium including instructions that, when executed by a processor, perform a method for processing an audio signal, the method comprising:
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receiving an encoded low-frequency range signal corresponding to the audio signal; performing filter processing on the decoded signal, the filter processing separating the decoded signal into low-frequency range band signals, wherein filter processing is performed by a QMF (Quadrature Mirror Filter) analysis filter; performing a smoothing process on the low-frequency range band signals, the smoothing process smoothing the energy depression of the decoded signal; performing a frequency shift on the smoothed low-frequency range band signals, the frequency shift generating high-frequency range band signals from the low-frequency range band signals; combining the low-frequency range band signals and the high-frequency range band signals to generate an output signal, wherein combining is performed by a QMF synthesis filter; and outputting the output signal, wherein performing the smoothing process on the low-frequency range band signals further comprises; computing an average energy of a plurality of low-frequency range band signals; computing a ratio for a selected one of the low-frequency range band signals by computing a ratio of the average energy of the plurality of low-frequency range band signals to an energy for the selected low-frequency range band signal; and multiplying the selected low-frequency range band signal by the computed ratio. - View Dependent Claims (18)
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19. A computer-implemented method for processing a signal, the method comprising:
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receiving an input signal; extracting a low-frequency range signal from the input signal; performing filter processing on the low-frequency range signal, the filter processing separating the signal into low-frequency range band signals having at least one non-zero energy depression, wherein filter processing is performed by a QMF (Quadrature Mirror Filter) analysis filter; smoothing the at least one non-zero energy depression of the low-frequency range band signals; calculating energy information for the low-frequency range band signals; encoding the low-frequency range signal and the energy information; and outputting the encoded low-frequency range signal and the encoded energy information, wherein smoothing the at least one non-zero energy depression of the low-frequency range band signals further comprises; computing an average energy of a plurality of low-frequency range band signals; computing a ratio for a selected one of the low-frequency range band signals by computing a ratio of the average energy of the plurality of low-frequency range band signals to an energy for the selected low-frequency range band signal; and performing a smoothing process by multiplying the selected low-frequency range band signal by the computed ratio. - View Dependent Claims (20)
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21. A device for processing a signal, the device comprising:
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a downsampler configured to receive an input signal and extract a low-frequency range signal from the input signal; a high-frequency range coding circuit configured to; perform filter processing on the low-frequency range signal, the filter processing separating the signal into low-frequency range band signals having at least one non-zero energy depression, wherein filter processing is performed by a QMF (Quadrature Mirror Filter) analysis filter; smooth the at least one non-zero energy depression of the low-frequency range band signals; calculate energy information for the low-frequency range band signals; and encode the energy information; a low-frequency range coding circuit configured to encode the low-frequency range signal; and a multiplexing circuit configured to output the encoded low-frequency range signal and the encoded energy information, wherein the high-frequency range coding circuit is further configured to smooth the at least one non-zero energy depression of the low-frequency range band signals by; computing an average energy of a plurality of low-frequency range band signals; computing a ratio for a selected one of the low-frequency range band signals by computing a ratio of the average energy of the plurality of low-frequency range band signals to an energy for the selected low-frequency range band signal; and performing a smoothing process by multiplying the selected low-frequency range band signal by the computed ratio. - View Dependent Claims (22)
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23. A non-transitory computer-readable storage medium including instructions that, when executed by a processor, perform a method for processing an audio signal, the method comprising:
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receiving an input signal; extracting a low-frequency range signal from the input signal; performing filter processing on the low-frequency range signal, the filter processing separating the signal into low-frequency range band signals having at least one non-zero energy depression, wherein filter processing is performed by a QMF (Quadrature Mirror Filter) analysis filter; smoothing the at least one non-zero energy depression of the low-frequency range band signals; calculating energy information for the low-frequency range band signals; encoding the low-frequency range signal and the energy information; and outputting the encoded low-frequency range signal and the encoded energy information, wherein smoothing the at least one non-zero energy depression of the low-frequency range band signals further comprises; computing an average energy of a plurality of low-frequency range band signals; computing a ratio for a selected one of the low-frequency range band signals by computing a ratio of the average energy of the plurality of low-frequency range band signals to an energy for the selected low-frequency range band signal; and performing a smoothing process by multiplying the selected low-frequency range band signal by the computed ratio. - View Dependent Claims (24)
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Specification