Encoding apparatus, decoding apparatus, and methods
First Claim
1. A coding apparatus, comprising:
- a processor; and
a memory that stores instructions which, when executed by the processor, cause the processor to perform operations comprising;
encoding a first band of an input audio signal;
normalizing a first spectrum included in each sub-band of the first band using a spectrum power envelope;
performing a clipping process on the normalized first spectrum, the clipping process being a process for comparing between a predetermined threshold and the absolute value of an amplitude of the spectrum and replacing the amplitude value of the spectrum with the threshold if the absolute value of the amplitude of the spectrum exceeds the threshold;
calculating a correlation between a spectrum in each divided band of a second band and a spectrum in a plurality of candidate bands containing the clipped normalized first spectrum, the second spectrum being higher than a predetermined frequency;
identifying the best bands of the plurality of candidate bands; and
encoding the second spectrum using lag information identifying the best band for transmitting the lag information to a decoder side.
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Abstract
A coding apparatus encodes a first band of an input audio signal, normalizes a first spectrum included in each sub-band of the first band using a spectrum power envelope, performs a clipping process on the normalized first spectrum, the clipping process comparing between a predetermined threshold and the absolute value of an amplitude of the spectrum and replaces the amplitude value of the spectrum with the threshold if the absolute value of the amplitude of the spectrum exceeds the threshold, calculates a correlation between a spectrum in each divided band of a second band and a spectrum in a plurality of candidate bands containing the clipped normalized first spectrum, the second spectrum being higher than a predetermined frequency, identifies the best bands of the plurality of candidate bands, and encodes the second spectrum using lag information identifying the best band for transmitting the lag information to a decoder.
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Citations
18 Claims
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1. A coding apparatus, comprising:
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a processor; and a memory that stores instructions which, when executed by the processor, cause the processor to perform operations comprising; encoding a first band of an input audio signal; normalizing a first spectrum included in each sub-band of the first band using a spectrum power envelope; performing a clipping process on the normalized first spectrum, the clipping process being a process for comparing between a predetermined threshold and the absolute value of an amplitude of the spectrum and replacing the amplitude value of the spectrum with the threshold if the absolute value of the amplitude of the spectrum exceeds the threshold; calculating a correlation between a spectrum in each divided band of a second band and a spectrum in a plurality of candidate bands containing the clipped normalized first spectrum, the second spectrum being higher than a predetermined frequency; identifying the best bands of the plurality of candidate bands; and encoding the second spectrum using lag information identifying the best band for transmitting the lag information to a decoder side. - View Dependent Claims (2, 3, 4, 5)
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6. A decoding apparatus, comprising:
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a processor; and a memory that stores instructions which, when executed by the processor, cause the processor to perform operations comprising; decoding first encoded data, generated by encoding a first band of an input audio to obtain a first spectrum; normalizing the first spectrum included in each sub-band of the first band using a spectrum power envelope, performing a clipping process on the normalized first spectrum, the clipping process being a process for comparing between a predetermined threshold and the absolute value of an amplitude of the spectrum and replacing the amplitude value of the spectrum with the threshold if the absolute value of the amplitude of the spectrum exceeds the threshold; obtaining lag information identifying the best band; and generating a second spectrum by using the best band; wherein the lag information indicating the particular band having a best correlation between each divided band of an encoding-side second spectrum and an encoding-side first spectrum, that results from normalizing a spectrum generated by decoding the first encoded data, the best bands being selected from a plurality of candidate bands, the second spectrum is higher than the predetermined frequency in a coding apparatus. - View Dependent Claims (7, 8, 9)
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10. A coding method, comprising:
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encoding a first band of an input audio signal; normalizing a first spectrum included in each sub-band of the first band using a spectrum power envelope; performing a clipping process on the normalized first spectrum, the clipping process being a process for comparing between a predetermined threshold and the absolute value of an amplitude of the spectrum and replacing the amplitude value of the spectrum with the threshold if the absolute value of the amplitude of the spectrum exceeds the threshold; calculating a correlation between a spectrum in each divided band of a second band and a spectrum in a plurality of candidate bands containing the clipped normalized first spectrum, the second spectrum being higher than a predetermined frequency; identifying the best bands of the plurality of candidate bands; and encoding the second spectrum using lag information identifying the best band for transmitting the lag information to a decoder side. - View Dependent Claims (11, 12, 13, 14)
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15. A decoding method, comprising:
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decoding first encoded data, generated by encoding a first band of an input audio to obtain a first spectrum; normalizing the first spectrum included in each sub-band of the first band, using a spectrum power envelope, performing a clipping process on the normalized first spectrum, the clipping process being a process for comparing between a predetermined threshold and the absolute value of an amplitude of the spectrum and replacing the amplitude value of the spectrum with the threshold if the absolute value of the amplitude of the spectrum exceeds the threshold; obtaining lag information identifying the best band; and generating a second spectrum by using the best band; wherein the lag information indicating the particular band having a best correlation between each divided band of an encoding-side second spectrum and an encoding-side first spectrum, that results from normalizing a spectrum generated by decoding the first encoded data, the best bands being selected from a plurality of candidate bands, the second spectrum is higher than the predetermined frequency in a coding apparatus. - View Dependent Claims (16, 17, 18)
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Specification