Audio decoding apparatus and audio decoding method
First Claim
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1. An audio decoding apparatus for decoding an audio signal from a bitstream, the bitstream containing encoded information about a narrowband audio signal and additional information for expanding the narrowband signal to a wideband signal, and the additional information containing high frequency component information denoting a feature of a higher frequency band than the band of the encoded information, and sinusoid-adding information denoting a sinusoidal signal added to a specific frequency band, the audio decoding apparatus comprising:
- a bitstream demultiplexer for demultiplexing the encoded information and the additional information from the bitstream;
a decoding means for decoding a narrowband audio signal from the demultiplexed encoded information;
an analysis subband filter for separating the narrowband audio signal into multiple first subband signals;
a high frequency signal generator for generating multiple second subband signals in a higher frequency band than the band of the encoded information from at least one of the first subband signal and the high frequency component information from the demultiplexed additional information;
a sinusoidal signal addition means for adding a sinusoidal signal to a specific subband of the multiple second subband signals based on the sinusoid-adding information from the demultiplexed additional information;
a compensation signal generator for generating, based on the phase characteristic and amplitude characteristic of the sinusoidal signal, a compensation signal for suppressing aliasing component signals produced in subbands near a specific subband as a result of adding a sinusoidal signal; and
a real-valued calculation synthesis subband filter for combining the multiple first subband signals and the multiple second subband signals to obtain a wideband audio signal.
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Abstract
A wideband, high quality audio signal is decoded with few calculations at a low bitrate. Unwanted spectrum components accompanying sinusoidal signal injection by a synthesis subband filter built with real-value operations are suppressed by inserting a suppression signal to subbands adjacent to the subband to which the sine wave is injected. This makes it possible to inject a desired sinusoid with few calculations.
50 Citations
24 Claims
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1. An audio decoding apparatus for decoding an audio signal from a bitstream,
the bitstream containing encoded information about a narrowband audio signal and additional information for expanding the narrowband signal to a wideband signal, and the additional information containing high frequency component information denoting a feature of a higher frequency band than the band of the encoded information, and sinusoid-adding information denoting a sinusoidal signal added to a specific frequency band, the audio decoding apparatus comprising: -
a bitstream demultiplexer for demultiplexing the encoded information and the additional information from the bitstream;
a decoding means for decoding a narrowband audio signal from the demultiplexed encoded information;
an analysis subband filter for separating the narrowband audio signal into multiple first subband signals;
a high frequency signal generator for generating multiple second subband signals in a higher frequency band than the band of the encoded information from at least one of the first subband signal and the high frequency component information from the demultiplexed additional information;
a sinusoidal signal addition means for adding a sinusoidal signal to a specific subband of the multiple second subband signals based on the sinusoid-adding information from the demultiplexed additional information;
a compensation signal generator for generating, based on the phase characteristic and amplitude characteristic of the sinusoidal signal, a compensation signal for suppressing aliasing component signals produced in subbands near a specific subband as a result of adding a sinusoidal signal; and
a real-valued calculation synthesis subband filter for combining the multiple first subband signals and the multiple second subband signals to obtain a wideband audio signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An audio decoding method for decoding an audio signal from a bitstream,
the bitstream containing encoded information about a narrowband audio signal and additional information for expanding the narrowband signal to a wideband signal, and the additional information containing high frequency component information denoting a feature of a higher frequency band than the band of the encoded information, and sinusoid-adding information denoting a sinusoidal signal added to a specific frequency band, the audio decoding method comprising: -
a step for demultiplexing the encoded information and additional information from the bitstream;
a step for decoding a narrowband audio signal from the demultiplexed encoded information;
a step for separating the narrowband audio signal into multiple first subband signals;
a step for generating multiple second subband signals in a higher frequency band than the band of the encoded information from at least one first subband signal and high frequency component information from the demultiplexed additional information;
a step for adding a sinusoidal signal to a specific subband of the multiple second subband signals based on the sinusoid-adding information of the demultiplexed additional information;
a compensation signal generating step for generating, based on the phase characteristic and amplitude characteristic of the sinusoidal signal, a compensation signal for suppressing aliasing component signals produced in subbands near a specific subband as a result of adding a sinusoidal signal; and
a real-valued calculation synthesis step for combining the first subband signals and second subband signals to obtain a wideband audio signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Current AssigneeNEC Corporation, Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
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Original AssigneeNEC Corporation, Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
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InventorsShimada, Osamu, Chong, Kok Seng, Nomura, Toshiyuki, Norimatsu, Takeshi, Takamizawa, Yuichiro, Tanaka, Naoya, Tsushima, Mineo, Neo, Sua Hong, Serizawa, Masahiro, Kuah, Kim Hann
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Granted Patent
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Time in Patent OfficeDays
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Field of Search
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US Class Current704/229
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CPC Class CodesG10L 19/02 using spectral analysis, e....G10L 21/038 using band spreading techni...
