METHOD AND DEVICE FOR SPECTRAL BAND REPLICATION, AND METHOD AND SYSTEM FOR AUDIO DECODING
First Claim
1. A method for spectral band replication, comprising:
- A. searching for a position of a certain tone of an audio signal in MDCT frequency domain coefficients;
B. according to the position of the tone, determining a spectral band replication period and a source frequency segment, this spectral band replication period being a bandwidth from a 0 frequency point to a frequency point of the tone position, and this source frequency segment being a frequency segment from a frequency point of the 0 frequency point shifting copyband_offset frequency points backwards to a frequency point of the frequency point of the tone position shifting the copyband_offset frequency points backwards, wherein said offset copyband_offset is greater than or equal to 0;
C. according to the spectral band replication period, carrying out the spectral band replication on zero bit encoding subbands.
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Abstract
The present invention relates to a method and device for spectral band replication, and a method and system for audio decoding, and the method for spectral band replication comprises: A. searching for the position of a certain tone of an audio signal in MDCT frequency domain coefficients; B. according to the tone position, determining a spectral band replication period which is a bandwidth from a 0 frequency point to a frequency point of tone position, and a source frequency segment which is a frequency segment from a frequency point of the 0 frequency point shifting copyband_offset frequency points backwards to a frequency point of the frequency point of the tone position shifting the copyband_offset frequency points backwards, wherein said offset copyband_offset is greater than or equal to 0; and C. according to the spectral band replication period, carrying out spectral band replication on zero bit encoding subbands.
33 Citations
23 Claims
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1. A method for spectral band replication, comprising:
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A. searching for a position of a certain tone of an audio signal in MDCT frequency domain coefficients; B. according to the position of the tone, determining a spectral band replication period and a source frequency segment, this spectral band replication period being a bandwidth from a 0 frequency point to a frequency point of the tone position, and this source frequency segment being a frequency segment from a frequency point of the 0 frequency point shifting copyband_offset frequency points backwards to a frequency point of the frequency point of the tone position shifting the copyband_offset frequency points backwards, wherein said offset copyband_offset is greater than or equal to 0; C. according to the spectral band replication period, carrying out the spectral band replication on zero bit encoding subbands. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A device for spectral band replication, comprising:
- a tone position searching module, a period and source frequency segment calculating module, a source frequency segment replication starting sequence number calculating module and a spectral band replicating module connected in sequence, wherein
the tone position searching module is for searching for a position of a certain tone of an audio signal in MDCT frequency domain coefficients; the period and source frequency segment calculating module is for determining a spectral band replication period and a source frequency segment for the replication according to the position of the tone, this spectral band replication period being a bandwidth from a 0 frequency point to a frequency point of the tone position, and said source frequency segment being a frequency segment from a frequency point of the 0 frequency point shifting copyband_offset frequency points backwards to a frequency point of the frequency point of the tone position shifting the copyband_offset frequency points backwards; the source frequency segment replication starting sequence number calculating module is for calculating a source frequency segment replication starting sequence number of a zero bit encoding subband according to the source frequency segment and a starting sequence number of this zero bit encoding subband which requires the spectral band replication; said spectral band replicating module is for starting from the source frequency segment replication starting sequence number, periodically replicating frequency domain coefficients of the source frequency segment to the zero bit encoding subband, with the spectral band replication period being a period. - View Dependent Claims (11, 12, 13, 14)
- a tone position searching module, a period and source frequency segment calculating module, a source frequency segment replication starting sequence number calculating module and a spectral band replicating module connected in sequence, wherein
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15. A method for audio decoding, comprising:
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A. carrying out decoding and inverse quantization on each amplitude envelop encoded bit in a bit stream to be decoded to obtain an amplitude envelop of each encoding subband; B. carrying out bit allocation on each encoding subband, and carrying out decoding and inverse quantization on non-zero bit encoding subbands to obtain frequency domain coefficients of the non-zero bit encoding subbands; C. searching for a position of a certain tone of an audio signal in MDCT frequency domain coefficients, taking a bandwidth from a 0 frequency point to a frequency point of the tone position as a spectral band replication period, taking a frequency segment from a frequency point of the 0 frequency point shifting copyband_offset frequency points backwards to a frequency point of the frequency point of the tone position shifting the copyband_offset frequency points backwards as a source frequency segment, carrying out spectral band replication on zero bit encoding subbands, and according to an amplitude envelop of a current encoding subband, carrying out energy adjustment on the frequency domain coefficients obtained by the replication, and combining noise filling, obtaining reconstructed frequency domain coefficients of the zero bit encoding subband, wherein said offset copyband_offset is greater than or equal to 0; D. carrying out Inverse Modified Discrete Cosine Transform on frequency domain coefficients of the non-zero bit encoding subbands and reconstructed frequency domain coefficients of the zero bit encoding subbands to obtain a final audio signal. - View Dependent Claims (16, 17, 18)
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19. A system for audio decoding, comprising:
- a bit stream demultiplexer (DeMUX), an amplitude envelop decoding unit, a bit allocating unit, a frequency domain coefficient decoding unit, a spectral band replicating unit, a noise filling unit, and an Inverse Modified Discrete Cosine Transform (IMDCT) unit, wherein
said DeMUX is for separating amplitude envelop encoded bits, frequency domain coefficient encoded bits and noise level encoded bits from a bit stream to be decoded; said amplitude envelop decoding unit, which is connected with the DeMUX, is for carrying out decoding and inverse quantization for the amplitude envelop encoded bits outputted by said bit stream demultiplexer to obtain an amplitude envelop of each encoding subband; said bit allocating unit, which is connected with said amplitude envelop decoding unit, is for carrying out bit allocation to obtain the number of encoded bits allocated to each frequency domain coefficient of each encoding subband; the frequency domain coefficient decoding unit, which is connected with the amplitude envelop decoding unit and the bit allocating unit, is for carrying out decoding, inverse quantization and inverse normalization for encoding subbands to obtain frequency domain coefficients; said spectral band replicating unit, which is connected with said DeMUX, frequency domain coefficient decoding unit, amplitude envelop decoding unit, and bit allocating unit, is for searching for a position of a certain tone of an audio signal in MDCT frequency domain coefficients, taking a bandwidth from a 0 frequency point to a frequency point of the tone position as a spectral band replication period, taking a frequency segment from a frequency point of the 0 frequency point shifting copyband_offset frequency points backwards to a frequency point of the frequency point of the tone position shifting the copyband_offset frequency points backwards as a source frequency segment, carrying out spectral band replication on zero bit encoding subbands, wherein said offset copyband_offset is greater than or equal to 0; and
is also for according to an amplitude envelop of a current encoding subband, carrying out energy adjustment on the frequency domain coefficients obtained by the replication;the noise filling unit, which is connected with the amplitude envelop decoding unit, bit allocating unit, and spectral band replicating unit, is for according to the amplitude envelop of the current zero bit encoding subband, filling noise for this encoding subband to obtain reconstructed frequency domain coefficients of the zero bit encoding subband; the IMDCT unit, which is connected with said noise filling unit, is for carrying out IMDCT on the frequency domain coefficients after the noise filling to obtain an audio signal. - View Dependent Claims (20, 21, 22, 23)
- a bit stream demultiplexer (DeMUX), an amplitude envelop decoding unit, a bit allocating unit, a frequency domain coefficient decoding unit, a spectral band replicating unit, a noise filling unit, and an Inverse Modified Discrete Cosine Transform (IMDCT) unit, wherein
Specification