Coding method, decoding method, apparatus, program, and recording medium
First Claim
1. A coding method implemented by an encoding apparatus for coding an audio signal comprising:
- performing, by processing circuitry of the encoding apparatus,receiving an audio signal in the time domain and converting the audio signal to the frequency domain;
a normalization value calculation step of receiving the audio signal in the frequency domain as an input and calculating a normalization representative value representative of a predetermined number of input samples;
a normalization value quantization step of quantizing the normalization value to obtain a quantized normalization value and a normalization-value quantization index corresponding to the quantized normalization value;
a quantization-candidate calculation step of subtracting a value corresponding to the quantized normalization value from a value corresponding to the magnitude of each of the samples to obtain a difference value and, when the difference value is positive and the value of each of the samples is positive, setting the difference value as a quantization candidate corresponding to the sample, when the difference value is positive and the value of each of the samples is negative, reversing the sign of the difference value and setting the sign-reversed value as an quantization candidate corresponding to the sample, and when the difference value is not positive, setting 0 as an quantization candidate corresponding to the sample;
a vector quantization step of jointly vector-quantizing a plurality of quantization candidates corresponding to the plurality of samples to obtain a vector quantization index; and
transmitting the normalization-value quantization index to a decoding apparatus.
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Accused Products
Abstract
A normalization value calculator 12 calculates a normalization value that is representative of a predetermined number of input samples. A normalization value quantizer 13 quantizes the normalization value to obtain a quantized normalization value and a normalization-value quantization index corresponding to the quantized normalization value. An quantization-candidate calculator 14 subtracts a value corresponding to the quantized normalization value from a value corresponding to the magnitude of each of the samples to obtain a difference value and, when the difference value is positive and the value of each of the samples is positive, sets the difference value as an quantization candidate corresponding to the sample. When the difference value is positive and the value of each of the samples is negative, the quantization-candidate calculator 14 reverses the sign of the difference value and setting the sign-reversed value as an quantization candidate corresponding to the sample. When the difference value is not positive, the quantization-candidate calculator 14 sets 0 as an quantization candidate corresponding to the sample. A vector quantizer 15 jointly vector-quantizes a plurality of quantization candidates corresponding to a plurality of samples to obtain a vector quantization index.
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Citations
30 Claims
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1. A coding method implemented by an encoding apparatus for coding an audio signal comprising:
performing, by processing circuitry of the encoding apparatus, receiving an audio signal in the time domain and converting the audio signal to the frequency domain; a normalization value calculation step of receiving the audio signal in the frequency domain as an input and calculating a normalization representative value representative of a predetermined number of input samples; a normalization value quantization step of quantizing the normalization value to obtain a quantized normalization value and a normalization-value quantization index corresponding to the quantized normalization value; a quantization-candidate calculation step of subtracting a value corresponding to the quantized normalization value from a value corresponding to the magnitude of each of the samples to obtain a difference value and, when the difference value is positive and the value of each of the samples is positive, setting the difference value as a quantization candidate corresponding to the sample, when the difference value is positive and the value of each of the samples is negative, reversing the sign of the difference value and setting the sign-reversed value as an quantization candidate corresponding to the sample, and when the difference value is not positive, setting 0 as an quantization candidate corresponding to the sample; a vector quantization step of jointly vector-quantizing a plurality of quantization candidates corresponding to the plurality of samples to obtain a vector quantization index; and transmitting the normalization-value quantization index to a decoding apparatus. - View Dependent Claims (2, 3, 4, 19)
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5. A decoding method implemented by a decoding apparatus for decoding a coded audio signal comprising:
performing, by processing circuitry of the decoding apparatus, a normalization value decoding step of obtaining a decoded normalization value corresponding to an input normalization-value quantization index, the normalization-value quantization index being received from a coding apparatus and generated based on an audio signal inputted to the coding apparatus; a vector decoding step of obtaining a plurality of values corresponding to an input vector quantization index as a plurality of decoded values; a normalization value recalculation step of calculating a recalculated normalization value from decoded normalization values and decoded values those are not zero, the recalculated normalization value being specifically calculated to have a value which has a magnitude that is inversely related to a cumulative sum of the absolute values of a predetermined number of the decoded values; a combining step of, when the decoded value is zero, obtaining as a decoded signal a value having an absolute value that is the recalculated normalization value multiplied by a first constant, and when the decoded value is not zero, obtaining as a decoded signal the linear sum of the decoded value or the absolute value of the decoded value and the decoded normalization value, the linear sum reflecting the sign of the decoded value; wherein the decoded signal from the combining step is in the frequency domain, and the method further includes converting the decoded signal from the frequency domain to the time domain to reproduce an audio signal in the time domain that corresponds to the audio signal originally inputted to the coding apparatus. - View Dependent Claims (6, 7, 8, 9)
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10. A coding apparatus for coding an audio signal comprising:
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processing circuitry configured to implement a frequency domain converter that receives an audio signal in the time domain and converts the audio signal to the frequency domain; a normalization value calculator that receives the audio signal in the frequency domain as an input and calculates a normalization representative value representative of a predetermined number of input samples; a normalization value quantizer that quantizes the normalization value to obtain a quantized normalization value and a normalization-value quantization index corresponding to the quantized normalization value; an quantization-candidate calculator that substracts a value corresponding to the quantized normalization value from a value corresponding to the magnitude of each of the samples to obtain a difference value and, when the difference value is positive and the value of each of the samples is positive, sets the difference value as a quantization candidate corresponding to the sample, when the difference value is positive and the value of each of the samples is negative, reverses the sign of the difference value and sets the sign-reversed value as an quantization candidate corresponding to the sample, and when the difference value is not positive, sets 0 as an quantization candidate corresponding to the sample; and a vector quantizer that jointly vector-quantizes a plurality of quantization candidates corresponding to the plurality of samples to obtain a vector quantization index, wherein the processing circuitry is configured to control transmission of the normalization-value quantization index to a decoding apparatus. - View Dependent Claims (11, 12, 13)
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14. A decoding apparatus for decoding a coded audio signal comprising:
processing circuitry configured to implement a normalization value decoder that obtains a decoded normalization value corresponding to an input normalization-value quantization index, the normalization-value quantization index being received from a coding apparatus and generated based on an audio signal inputted to the coding apparatus; a vector decoder that obtains a plurality of values corresponding to an input vector quantization index as a plurality of decoded values; a normalization value recalculator that calculates a recalculated normalization value from decoded normalization values and decoded values those are not zero, the recalculated normalization value being specifically calculated to have a value which has a magnitude that is inversely related to a cumulative sum of the absolute values of a predetermined number of the decoded values; a synthesizer that, when the decoded value is zero, obtains as a decoded signal a value having an absolute value that is the recalculated normalization value multiplied by a first constant, and when the decoded value is not zero, obtains as a decoded signal the linear sum of the decoded value or the absolute value of the decoded value and the decoded normalization value, the linear sum reflecting the sign of the decoded value, wherein the decoded signal obtained by the synthesizer is in the frequency domain; and a time domain converter that converts the decoded signal from the frequency domain to the time domain to reproduce an audio signal in the time domain that corresponds to the audio signal originally inputted to the coding apparatus. - View Dependent Claims (15, 16, 17, 18)
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20. A decoding method for decoding a coded audio signal comprising:
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a normalization value decoding step of obtaining a decoded normalization value corresponding to an input normalization-value quantization index, the normalization-value quantization index being received from a coding apparatus and generated based on an audio signal inputted to the coding apparatus; a decoding-candidate normalization value calculating step of multiplying the decoded normalization value by a second constant to obtain a decoding-candidate normalization value; the vector decoding step of multiplying each of a plurality of values corresponding to an input vector quantization index by the decoding-candidate normalization value to obtain a plurality of decoded values; a normalization value recalculation step of calculating a recalculated normalization value from decoded normalization values and decoded values those are not zero, the recalculated normalization value being specifically calculated to have a value which has a magnitude that is inversely related to a cumulative sum of the absolute values of a predetermined number of the decoded values; a combining step of, when the decoded value is zero, obtaining as a decoded signal a value having an absolute value that is the recalculated normalization value multiplied by a first constant, and when the decoded value is not zero, obtaining as a decoded signal the linear sum of the decoded value or the absolute value of the decoded value and the decoded normalization value, the linear sum reflecting the sign of the decoded value; and wherein the decoded signal from the combining step is in the frequency domain, and the method further includes converting the decoded signal from the frequency domain to the time domain to reproduce an audio signal in the time domain that corresponds to the audio signal originally inputted to the coding apparatus. - View Dependent Claims (22, 23, 24, 25, 30)
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21. A decoding apparatus for decoding a coded audio signal comprising:
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a normalization value decoder that obtains a decoded normalization value corresponding to an input normalization-value quantization index, the normalization-value quantization index being received from a coding apparatus and generated based on an audio signal inputted to the coding apparatus; a decoding-candidate normalization value calculator that multiplies the decoded normalization value by a second constant to obtain a decoding-candidate normalization value; the vector decoder that multiplies each of a plurality of values corresponding to an input vector quantization index by the decoding-candidate normalization value to obtain a plurality of decoded values; a normalization value recalculator that calculates a recalculated normalization value from decoded normalization values and decoded values those are not zero, the recalculated normalization value being specifically calculated to have a value which has a magnitude that is inversely related to a cumulative sum of the absolute values of a predetermined number of the decoded values; and a synthesizer that, when the decoded value is zero, obtains as a decoded signal a value having an absolute value that is the recalculated normalization value multiplied by a first constant, and when the decoded value is not zero, obtains as a decoded signal the linear sum of the decoded value or the absolute value of the decoded value and the decoded normalization value, the linear sum reflecting the sign of the decoded value, wherein the decoded signal obtained by the synthesizer is in the frequency domain; and a time domain converter that converts the decoded signal from the frequency domain to the time domain to reproduce an audio signal in the time domain that corresponds to the audio signal originally inputted to the coding apparatus. - View Dependent Claims (26, 27, 28, 29)
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Specification