WO2010073977A1 - Procédé de codage, procédé de décodage, appareil, programme et support d'enregistrement associé - Google Patents

Procédé de codage, procédé de décodage, appareil, programme et support d'enregistrement associé Download PDF

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WO2010073977A1
WO2010073977A1 PCT/JP2009/071100 JP2009071100W WO2010073977A1 WO 2010073977 A1 WO2010073977 A1 WO 2010073977A1 JP 2009071100 W JP2009071100 W JP 2009071100W WO 2010073977 A1 WO2010073977 A1 WO 2010073977A1
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parcor coefficient
value
order
coefficient
code
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PCT/JP2009/071100
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English (en)
Japanese (ja)
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優 鎌本
登 原田
守谷　健弘
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日本電信電話株式会社
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Priority to JP2010544032A priority Critical patent/JP5253518B2/ja
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS OR SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/04—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using predictive techniques
    • G10L19/06—Determination or coding of the spectral characteristics, e.g. of the short-term prediction coefficients

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  • the present invention relates to a technique for encoding a time-series signal by linear prediction analysis, and particularly to a method for encoding and decoding a PARCOR coefficient obtained by linear prediction analysis, a device thereof, a program, and a recording medium.
  • Non-Patent Document 1 When transmitting time-series signals such as audio signals and video information through a communication channel or recording them on an information recording medium, the method of transmitting and recording after converting the time-series signals into compressed codes is the transmission efficiency and recording efficiency. This is effective.
  • lossless compression coding methods that require complete reproduction of the original signal are more important than lossy compression coding methods that prioritize high compression rates.
  • a technology for reversibly compressing and encoding an acoustic signal using elemental technology such as linear prediction analysis has been approved as an international standard “MPEG-4 ⁇ ALS” of MPEG (Moving Picture Expert Group) (for example, Non-patent document 2).
  • FIG. 1 is a block diagram for explaining a functional configuration of an encoding device 1010 of a conventional lossless compression encoding method.
  • FIG. 2 is a block diagram for explaining a functional configuration of a decoding apparatus 1020 that decodes a code generated by the encoding apparatus 1010 of FIG.
  • FIG. 3 is a diagram for explaining how the first-order PARCOR coefficient and the second-order PARCOR are encoded in the encoding apparatus 1010 of FIG.
  • a sampled and quantized PCM (pulse code modulation) time series signal x (n) (n is an index indicating discrete time) is input to the frame buffer 1011 of the encoding apparatus 1010.
  • the linear prediction analysis unit 1012 performs linear to M-th order by linear prediction analysis.
  • M is a positive integer indicating the predicted order.
  • the m-th order PARCOR coefficient means a PARCOR coefficient of a linear prediction model of the prediction order m.
  • a linear prediction model based on this assumption is as follows.
  • a PARCOR coefficient k (m) (m 1, 2,..., M) or the like that can be converted thereto.
  • ⁇ ⁇ ⁇ represents a product ⁇ ⁇ ⁇ of ⁇ and ⁇ .
  • e (n) x (n) + ⁇ (1) ⁇ x (n-1) + ⁇ (2) ⁇ x (n-2) + ... + ⁇ (M) ⁇ x (nM)
  • a time series signal y (n) at a certain time point n is converted into M time points n-1, n-2,..., NM time series signals x (n-1)
  • a linear FIR (Finite Impulse Response) filter of the following equation that is estimated using x (n ⁇ 2),..., x (nM) is called a “linear prediction filter”.
  • y (n) - ⁇ (1) ⁇ x (n-1) + ⁇ (2) ⁇ x (n-2) + ... + ⁇ (M) ⁇ x (nM) ⁇
  • the “quantized PARCOR coefficient” may be the quantized value of the PARCOR coefficient itself or an index attached to the quantized value of the PARCOR coefficient.
  • the subtraction unit 1017 calculates a prediction residual (also referred to as “prediction error”) e (n) obtained by subtracting the linear prediction value y (n) from the time-series signal x (n) (prediction filter processing).
  • Prediction error also referred to as “prediction error”
  • Calculated prediction residuals e (n) is sent to residual coding unit 1018, where entropy-coded by residual code C e is generated.
  • a coefficient code C k generated by the coefficient coding section 1014, residual code C e generated by the residual encoding unit 1018 is sent to the synthesis unit 1019. Coefficient code C k and the residual code C e is combined by the combining unit 1019, the code C g is generated.
  • Code C g input to the decoding device 1020 is separated into a coefficient code C k and the residual code C e by the demultiplexer 1021.
  • a linear prediction value y (n) is generated by the prediction.
  • the adder 1026 adds the linear prediction value y (n) and the prediction residual e (n) to generate a time series signal x (n) (inverse prediction filter processing).
  • An object of the present invention is to provide a technique for improving the coding compression rate of a PARCOR coefficient obtained by linear prediction analysis of a time series signal.
  • a code corresponding to the PARCOR coefficient is generated using the correlation between the primary PARCOR coefficient and the secondary PARCOR coefficient.
  • the PARCOR coefficient is decoded using the correlation between the primary PARCOR coefficient and the secondary PARCOR coefficient.
  • At the time of encoding at least a first-order PARCOR coefficient and a second-order PARCOR coefficient are calculated by performing linear prediction analysis on an input time-series signal, and the calculated first-order PARCOR coefficient is calculated.
  • the parameter determined according to the relational expression established between the value determined according to the PARCOR coefficient and the value determined according to the second order PARCOR coefficient is calculated, and the parameter and the first order PARCOR coefficient or the second order PARCOR coefficient are calculated.
  • chord corresponding to the information containing any one is produced
  • a code corresponding to information including the parameter and either the primary PARCOR coefficient or the secondary PARCOR coefficient is decoded, and at least the parameter and the primary PARCOR are decoded.
  • a decoded value corresponding to the coefficient or a decoded value corresponding to the second-order PARCOR coefficient is generated, and a restoration value of the second-order PARCOR coefficient is calculated using the parameter and the decoded value corresponding to the first-order PARCOR coefficient.
  • the restoration value of the first order PARCOR coefficient is calculated.
  • At the time of encoding at least a first-order PARCOR coefficient and a second-order PARCOR coefficient are respectively calculated by performing linear prediction analysis on the input time-series signal.
  • the first variable length encoding method is selected as an encoding method for generating a code corresponding to the secondary PARCOR coefficient
  • the primary PARCOR When the absolute value of the coefficient is less than the threshold, a second variable length encoding method different from the first variable length encoding method is selected as an encoding method for generating a code corresponding to the secondary PARCOR coefficient, Using the selected encoding method, the second-order quantized PARCOR coefficient obtained by quantizing the second-order PARCOR coefficient is encoded to generate a code corresponding to the second-order PARCOR.
  • the absolute value of the decoded value of the code corresponding to the primary PARCOR coefficient is compared with a predetermined threshold value, and the secondary value is determined by the decoding method corresponding to the predetermined first variable length encoding method. Whether the code corresponding to the PARCOR coefficient is decoded, or the code corresponding to the secondary PARCOR coefficient is decoded by a decoding method corresponding to a predetermined second variable length encoding method different from the first variable length encoding method Determine.
  • the total code amount of codes corresponding to the primary PARCOR coefficient and the secondary PARCOR coefficient is reduced as compared with the case where the primary PARCOR coefficient and the secondary PARCOR coefficient are encoded independently of each other. Can do.
  • the PARCOR coefficient is encoded using the correlation between the first-order PARCOR coefficient and the second-order PARCOR coefficient, the PARCOR obtained by the linear prediction analysis of the time-series signal is performed.
  • the coding compression rate of the coefficient can be improved.
  • the block diagram for demonstrating the function structure of the encoding apparatus of the conventional lossless compression encoding system The block diagram for demonstrating the function structure of the decoding apparatus which decodes the code
  • FIG. 5A shows the ratio k (2) / k (1) between the first-order PARCOR coefficient k (1) and the second-order PARCOR coefficient k (2) obtained by linear prediction analysis of the acoustic signal. It is a graph which illustrates frequency.
  • FIG. 5B is a graph for explaining that the appearance probability distribution of the secondary PARCOR coefficient k (2) changes according to the magnitude of the primary PARCOR coefficient k (1).
  • FIG. 8A is a block diagram for explaining the details of the nonlinear quantization unit and the parameter calculation unit shown in FIG. 7, and FIG. 8B is the details of the coefficient encoding unit shown in FIG. It is a block diagram for demonstrating.
  • FIG. 10A is a block diagram for explaining details of the coefficient decoding unit shown in FIG. 9, and
  • FIG. 10B is a diagram for explaining details of the PARCOR coefficient calculation unit shown in FIG. It is a block diagram.
  • the flowchart for demonstrating the encoding method of 1st Embodiment The flowchart for demonstrating the decoding method of 1st Embodiment.
  • FIG. 15A is a block diagram for explaining details of the nonlinear quantization unit and the parameter calculation unit of the second embodiment
  • FIG. 15B shows details of the PARCOR coefficient calculation unit of the second embodiment. It is a block diagram for demonstrating.
  • the flowchart for demonstrating the decoding method of 2nd Embodiment. The block diagram for demonstrating the function structure of the encoding apparatus of 3rd Embodiment.
  • FIG. 20A is a block diagram for explaining details of the nonlinear quantization unit and the parameter calculation unit shown in FIG. 18, and FIG. 20B shows details of the PARCOR coefficient calculation unit shown in FIG. It is a block diagram for demonstrating.
  • the block diagram for demonstrating the detail of the PARCOR coefficient calculation part shown in FIG. The flowchart for demonstrating the encoding method of 4th Embodiment.
  • the flowchart for demonstrating the decoding method of 4th Embodiment The block diagram for demonstrating the detail of the nonlinear quantization part of the encoding apparatus in the modification 1 of 4th Embodiment, a selection part, and a parameter calculation part.
  • the flowchart for demonstrating the decoding method of the modification 1 of 4th Embodiment The block diagram for demonstrating the function structure of the encoding apparatus of 5th Embodiment.
  • the block diagram for demonstrating the detail of the coefficient encoding part shown in FIG. The block diagram for demonstrating the function structure of the decoding apparatus of 5th Embodiment.
  • the block diagram for demonstrating the detail of the coefficient decoding part shown in FIG. The flowchart for demonstrating the encoding method of 5th Embodiment.
  • the primary PARCOR coefficient is often near 1, and in this case, the secondary PARCOR coefficient is often near -1.
  • the second-order PARCOR coefficient is often close to 0.
  • FIG. 4 is a graph plotting the relationship between the first-order PARCOR coefficient k (1) and the second-order PARCOR coefficient k (2) obtained by linear prediction analysis of the acoustic signal.
  • the horizontal axis represents the primary PARCOR coefficient k (1)
  • the vertical axis represents the secondary PARCOR coefficient k (2).
  • the first-order PARCOR coefficient k (1) is near 1
  • the second-order PARCOR coefficient k (2) is often near -1.
  • the primary PARCOR coefficient k (1) and the secondary PARCOR coefficient k (2) There is a strong correlation between
  • FIG. 5A shows the ratio k (2) / k (1) between the first-order PARCOR coefficient k (1) and the second-order PARCOR coefficient k (2) obtained by linear prediction analysis of the acoustic signal. ).
  • the horizontal axis indicates the ratio k (2) / k (1)
  • the vertical axis indicates the frequency.
  • the sign of the first-order PARCOR coefficient k (1) and the second-order PARCOR coefficient k (2) is likely to be reversed, and the first-order PARCOR coefficient k (1) and the second-order PARCOR coefficient k (1) It can be seen that there is a correlation with the PARCOR coefficient k (2).
  • This graph also shows that the absolute value of the second-order PARCOR coefficient k (2) tends to be smaller than the absolute value of the first-order PARCOR coefficient k (1).
  • FIG. 5B is a graph for explaining that the appearance probability distribution of the second-order PARCOR coefficient k (2) changes according to the magnitude of the first-order PARCOR coefficient k (1).
  • the horizontal axis indicates the secondary index
  • the vertical axis indicates the appearance probability.
  • the secondary index means an index attached to the quantized value of the secondary PARCOR coefficient k (2).
  • the graph shown in black shows the probability distribution of the secondary index when the primary index is 0, 1, 2, and the graph shown in white shows the primary index.
  • the appearance probability distribution of the secondary index in the case of 10, 11, 12 is shown.
  • the primary index means an index attached to the quantized value of the primary PARCOR coefficient k (1).
  • the index in this example is a value that decreases monotonously in a broad sense with respect to an increase in the absolute value of the PARCOR coefficient.
  • the secondary index corresponds to a secondary PARCOR coefficient k (2) that is negative.
  • the primary indexes 0, 1, 2 are indexes assigned to the quantized values of the primary PARCOR coefficient k (1) near 0.99.
  • the primary indexes 10, 11, and 12 are indexes assigned to the quantized values of the primary PARCOR coefficient k (1) near 0.9.
  • the secondary indexes 10, 11, 12, and 13 are indexes attached to the quantized values of the secondary PARCOR coefficient k (2) in the vicinity of -0.5 to -0.4.
  • the secondary indexes 1, 2, 3, and 4 are indexes assigned to the quantized values of the secondary PARCOR coefficient k (2) in the vicinity of ⁇ 0.9 to ⁇ 0.8.
  • the secondary PARCOR coefficient k (2) when the primary PARCOR coefficient k (1) is large (for example, around 0.99), the secondary PARCOR coefficient k (2) (for example, having a large absolute value) The probability of obtaining ⁇ 0.9 to ⁇ 0.8) is increased.
  • the primary PARCOR coefficient k (1) when the primary PARCOR coefficient k (1) is small (for example, around 0.9), the secondary PARCOR coefficient k (2) (for example, ⁇ 0.5 to ⁇ 0.4) having a small absolute value. ) Is likely to be obtained. That is, the frequency distribution of the secondary PARCOR coefficient k (2) varies depending on the magnitude of the primary PARCOR coefficient k (1). As the primary PARCOR coefficient k (1) is large and close to 1, the secondary PARCOR coefficient k (2) is small and close to ⁇ 1 (the absolute value is large and close to 1).
  • the encoding device calculates (II) at least a first-order PARCOR coefficient and a second-order PARCOR coefficient by performing linear prediction analysis on the input time-series signal.
  • a parameter determined according to a relational expression established between a value determined according to the first-order PARCOR coefficient and a value determined according to the second-order PARCOR coefficient, and (III) the parameter and the first-order PARCOR coefficient Alternatively, a code corresponding to information including any one of the secondary PARCOR coefficients is generated.
  • the decoding apparatus in this case includes (IV) a parameter determined according to a relational expression established between a value determined according to the first-order PARCOR coefficient and a value determined according to the second-order PARCOR coefficient, and the first-order PARCOR A code corresponding to information including either a coefficient or the second-order PARCOR coefficient, and at least the decoded value corresponding to the first-order PARCOR coefficient or the second-order PARCOR coefficient A corresponding decoded value is generated, and a restored value of the second-order PARCOR coefficient is calculated using the parameter and the decoded value corresponding to the first-order PARCOR coefficient, or the parameter and the second-order PARCOR coefficient are calculated.
  • the restoration value of the first-order PARCOR coefficient is calculated using the decoded value corresponding to.
  • the total code amount of codes corresponding to the primary PARCOR coefficient and the secondary PARCOR coefficient can be reduced.
  • the absolute value of the parameter approaches a specific value
  • the variance of the parameter is the variance of the first-order PARCOR coefficient or 2
  • this variable length encoding method preferably satisfies the following conditions.
  • 1st frequency The frequency with which the code
  • Second frequency The frequency at which a code having a longer code length than the second encoding target code is assigned to the first encoding target. That is, the frequency with which the code length of the code assigned to the first encoding target is longer than the code length of the code assigned to the second encoding target.
  • relational expression established between the value determined according to the first-order PARCOR coefficient and the value determined according to the second-order PARCOR coefficient is, for example, the following relational expression (A) or (B).
  • the above-mentioned parameters are, for example, the following parameters (A) or (B).
  • a value determined according to the first-order PARCOR coefficient is a value that monotonously increases (monotonically non-decreases) at least with respect to an increase in the positive first-order PARCOR coefficient.
  • the value determined according to the second-order PARCOR coefficient is a value that monotonically increases in a broad sense with respect to an increase in at least the negative second-order PARCOR coefficient.
  • the absolute value of the parameter increases monotonously in a broad sense with respect to the first variable value that satisfies the above-described relational expression (A).
  • a value determined according to the first-order PARCOR coefficient is a value that monotonously decreases (monotonically non-increases) at least with respect to an increase in the positive first-order PARCOR coefficient.
  • the value determined according to the second-order PARCOR coefficient is a value that monotonously decreases in a broad sense with respect to an increase in at least a negative second-order PARCOR coefficient.
  • the absolute value of the parameter increases monotonously in a broad sense with respect to an increase in the second variable value that satisfies the above-described relational expression (B).
  • the first-order PARCOR coefficient and the second-order PARCOR coefficient The larger the correlation with the PARCOR coefficient is, the closer the absolute value of the parameter is to 0, and the variance of the parameter is smaller than the variance of the primary PARCOR coefficient or the variance of the secondary PARCOR coefficient.
  • 1st frequency The frequency with which the code
  • Second frequency The frequency at which a code having a longer code length than the second encoding target code is assigned to the first encoding target.
  • variable-length coding methods include Rice code (Rice (code) (sometimes referred to as “Golomb-Rice code”), Golomb code, unary code (Unary code) (sometimes referred to as “alpha code”), Huffman code, and the like.
  • Rice code
  • Golomb-Rice code Golomb code
  • Unary code unary code
  • Huffman code Huffman code
  • the PARCOR coefficient takes a value between ⁇ 1 and +1. Further, the correlation between the first-order PARCOR coefficient and the second-order PARCOR coefficient is larger as the absolute values of the first-order PARCOR coefficient and the second-order PARCOR coefficient are closer to 1, and smaller as they are closer to 0. Therefore, when the absolute value of the first-order PARCOR coefficient is equal to or greater than a predetermined threshold (threshold is a value between 0 and +1), the correlation between the first-order PARCOR coefficient and the second-order PARCOR coefficient is used.
  • the first-order PARCOR coefficient and the second-order PARCOR coefficient may be independently encoded when the PARCOR coefficient is less than a predetermined threshold value.
  • the method of conversion may be determined. That is, when the absolute value of the second-order PARCOR coefficient is equal to or greater than a predetermined threshold value (threshold value is 0 or more and +1 or less), the correlation between the first-order PARCOR coefficient and the second-order PARCOR coefficient is used.
  • the first-order PARCOR coefficient and the second-order PARCOR coefficient may be independently encoded when the PARCOR coefficient is less than a predetermined threshold value.
  • the threshold determination may be performed in a region before quantization or may be performed in a region after quantization.
  • the region after quantization means a region of quantized values or an index region attached to the quantized values.
  • the magnitude relationship in threshold determination is reversed between the pre-quantization region and the post-quantization region.
  • the process of performing “Process 1” when A ⁇ T and performing “Process 2” when A ⁇ T is performed when A ′ ⁇ T ′.
  • “Process 1” is performed on the screen
  • “Process 2” is performed when A ′> T ′.
  • a and T are values of the region before quantization
  • a 'and T' are values of the region after quantization with respect to it. The same applies to threshold determination at the time of decoding (the same applies hereinafter).
  • the encoding apparatus when the encoding apparatus performs the above steps (II) and (III) when the absolute value of the primary PARCOR coefficient is greater than or equal to a predetermined first threshold, the absolute value of the primary PARCOR coefficient May be less than the first threshold, a code corresponding to information including the primary PARCOR coefficient and the secondary PARCOR coefficient may be generated.
  • the encoding apparatus executes the above steps (II) and (III), and the absolute value of the second-order PARCOR coefficient May be less than the first threshold, a code corresponding to information including the primary PARCOR coefficient and the secondary PARCOR coefficient may be generated.
  • the decoding apparatus may specify the decoding method using the magnitude of the absolute value of the primary or secondary PARCOR coefficient as an index. That is, the step (V) executed by the decoding device may include the following steps (V-a) or (V-b).
  • Step (V-a) The absolute value of the decoded value corresponding to the primary PARCOR coefficient is compared with a predetermined second threshold value. From the comparison result, it is determined whether or not the restoration value of the second-order PARCOR coefficient is calculated using the parameter and the decoded value corresponding to the first-order PARCOR coefficient.
  • Step (V-b) The absolute value of the decoded value corresponding to the second-order PARCOR coefficient is compared with a predetermined second threshold value or more. From the comparison result, it is determined whether or not the restoration value of the primary PARCOR coefficient is calculated using the parameter and the decoded value corresponding to the secondary PARCOR coefficient.
  • the code length of the code can be shortened.
  • the encoding device calculates (VI) at least a first-order PARCOR coefficient and a second-order PARCOR coefficient by performing linear prediction analysis on the input time-series signal, and (VII) a first-order PARCOR coefficient, respectively.
  • the first variable length encoding method is selected as the encoding method for generating a code corresponding to the second-order PARCOR coefficient
  • a second variable length encoding method different from the first variable length encoding method is selected as an encoding method for generating a code corresponding to the second order PARCOR coefficient.
  • step (VIII) Using the encoding method selected in step (VII), the second-order quantized PARCOR coefficient obtained by quantizing the second-order PARCOR coefficient is encoded, and a code corresponding to the second-order PARCOR is obtained. It is formed.
  • the predetermined threshold value in step (VII) is a value between ⁇ 1 and 1 inclusive, but the threshold determination may be performed in the region before quantization or in the region after quantization. May be.
  • the frequency distribution of the secondary PARCOR coefficient varies depending on the magnitude of the primary PARCOR coefficient. Therefore, by selecting a variable-length coding method for encoding the second-order quantized PARCOR coefficient according to the magnitude of the first-order PARCOR coefficient (step (VII)), it corresponds to the second-order PARCOR coefficient.
  • the code amount of the code can be reduced.
  • the secondary index is encoded using the following first variable length encoding method (A). To do.
  • the primary index is 10, 11, 12, the secondary index is encoded using the following second variable length encoding method (B).
  • First variable length encoding method (A) A variable length encoding method in which the third frequency is higher than the fourth frequency when the first encoding target is closer to 5 or 6 than the second encoding target. That is, when the distance between the first encoding target value and 5 or 6 is shorter than the distance between the second encoding target value and 5 or 6, the third frequency is a variable length higher than the fourth frequency. Encoding method.
  • 3rd frequency Frequency at which a code having a shorter code length than that of the second encoding target code is assigned to the first encoding target.
  • Fourth frequency The frequency with which a code having a longer code length than the second encoding target code is assigned to the first encoding target.
  • First variable length encoding method (B) A variable length encoding method in which the third frequency is higher than the fourth frequency when the first encoding target is closer to 7 or 8 than the second encoding target. That is, when the distance between the first encoding target value and 7 or 8 is shorter than the distance between the second encoding target value and 7 or 8, the third frequency is a variable length higher than the fourth frequency. Encoding method.
  • variable length encoding method is the Rice encoding method or the Huffman encoding method. Thereby, the amount of codes can be reduced as compared with the case where the secondary index is always encoded using the following variable length encoding method (C).
  • Variable-length encoding method (C) A variable-length encoding method in which the third frequency is higher than the fourth frequency when the first encoding target is closer to 6 or 7 than the second encoding target. That is, when the distance between the first encoding target value and 6 or 7 is shorter than the distance between the second encoding target value and 6 or 7, the third frequency is a variable length higher than the fourth frequency. Encoding method.
  • the first variable length encoding method selected in step (VII) is such that the absolute value of the first encoding target is set to a first value that is predetermined in advance than the absolute value of the second encoding target.
  • the third frequency is an encoding method higher than the fourth frequency. That is, the first variable length encoding method uses the third frequency when the distance between the first encoding target value and the first value is shorter than the distance between the second encoding target value and the first value. Is an encoding method higher than the fourth frequency.
  • the third frequency is greater than the fourth frequency when the absolute value of the first encoding target is closer to the predetermined second value than the absolute value of the second encoding target.
  • the second variable length encoding method uses the third frequency when the distance between the first encoding target value and the second value is shorter than the distance between the second encoding target value and the second value. Is an encoding method higher than the fourth frequency.
  • the first value is larger than the second value.
  • the second-order quantized PARCOR coefficient corresponding to the second-order PARCOR coefficient is smaller as the absolute value of the second-order PARCOR coefficient is closer to 1, the first value is smaller than the second value.
  • the quantization step size (which may be referred to as “interval ⁇ size”) when quantizing the second-order PARCOR coefficient is changed according to the absolute value of the first-order PARCOR coefficient.
  • a predetermined first quantization method is selected between the steps (VI) and (VII) when the absolute value of the first-order PARCOR coefficient is greater than or equal to a predetermined second threshold.
  • a predetermined second quantization method having a quantization step size larger than that of the first quantization method is selected, and the selected quantization is selected.
  • the method performs a step of quantizing the second-order PARCOR coefficient and generating a quantized value of the second-order PARCOR coefficient.
  • Relational expression A value determined according to the second-order PARCOR coefficient by the sum of the first multiplication value obtained by multiplying a predetermined weighting coefficient by a value determined according to the first-order PARCOR coefficient and the first variable value.
  • ⁇ Value determined according to the first order PARCOR coefficient First order PARCOR coefficient. This is a “value that increases monotonously in a broad sense with respect to an increase in the first-order PARCOR coefficient”.
  • second-order PARCOR coefficient This is “a value that increases monotonically in a broad sense with respect to an increase in the second-order PARCOR coefficient”.
  • the first quantized variable value obtained by quantizing the first variable value that satisfies the above relational expression. This is a “value determined according to the first variable value”, and the absolute value of the parameter increases monotonously in a broad sense with respect to the increase in the first variable value.
  • the “first quantized variable value” may be the quantized value itself of the first variable value, or may be an index attached to the quantized value of the first variable value (the same applies hereinafter). ).
  • FIG. 7 is a block diagram for explaining a functional configuration of the encoding device 10 according to the first embodiment.
  • 8A is a block diagram for explaining details of the nonlinear quantization unit 11 and the parameter calculation unit 12 shown in FIG. 7, and
  • FIG. 8B is a coefficient encoding unit shown in FIG. 13 is a block diagram for explaining the details of FIG.
  • FIG. 9 is a block diagram for explaining a functional configuration of the decoding device 20 according to the first embodiment.
  • FIG. 10A is a block diagram for explaining details of the coefficient decoding unit 21 shown in FIG. 9, and FIG. 10B shows details of the PARCOR coefficient calculating unit 22 shown in FIG. It is a block diagram for.
  • the same reference numerals as those in FIGS. 1 and 2 are used for the same components as those in FIGS.
  • the encoding apparatus 10 includes a frame buffer 1011, a linear prediction analysis unit 1012, a nonlinear quantization unit 11, a parameter calculation unit 12, a coefficient encoding unit 13, a linear prediction coefficient conversion unit 1015, A linear prediction unit 1016, a subtraction unit 1017, a residual encoding unit 1018, and a synthesis unit 1019 are included.
  • the parameter calculation unit 12 of this embodiment includes an inverse quantization unit 12a, a weight coefficient multiplication unit 12b, a subtraction unit 12c, and a parameter quantization unit 12d. As shown in FIG.
  • the coefficient encoding unit 13 of this embodiment includes a PARCOR coefficient encoding unit 13a and a parameter encoding unit 13b.
  • the decoding device 20 includes a separation unit 1021, a coefficient decoding unit 21, a PARCOR coefficient calculation unit 22, a linear prediction coefficient conversion unit 23, a residual decoding unit 1023, a linear prediction unit 1025, And an adder 1026.
  • the coefficient decoding unit 21 of this embodiment includes a PARCOR coefficient decoding unit 21a and a parameter decoding unit 21b.
  • the PARCOR coefficient calculation unit 22 of this embodiment includes inverse quantization units 22a and 22c, a weight coefficient multiplication unit 22b, and an addition unit 22d.
  • the encoding apparatus 10 and the decoding apparatus 20 of this embodiment are, for example, a known computer or a dedicated computer including a CPU (central processing unit), a RAM (random-access memory), a ROM (read-only memory), This is a special device configured by reading a predetermined program and executing it by the CPU.
  • the frame buffer 1011 of the encoding device 10 is a memory such as a RAM, a cache memory, and a register, for example, and includes a linear prediction analysis unit 1012, a nonlinear quantization unit 11, a parameter calculation unit 12, a coefficient encoding unit 13, a linear encoding unit, and the like.
  • the prediction coefficient conversion unit 1015, the linear prediction unit 1016, the subtraction unit 1017, the residual encoding unit 1018, and the synthesis unit 1019 are, for example, processing units that are constructed when the CPU executes a predetermined program. Further, the separation unit 1021, the coefficient decoding unit 21, the PARCOR coefficient calculation unit 22, the linear prediction coefficient conversion unit 23, the residual decoding unit 1023, the linear prediction unit 1025, and the addition unit 1026 of the decoding device 20 are, for example, predetermined by the CPU. It is a processing part constructed by executing this program. Further, at least a part of these processing units may be configured by an electronic circuit such as an integrated circuit.
  • the encoding device 10 or the decoding device 20 may be provided with a temporary memory that stores data output by the processing of each processing unit and reads the data during another processing of each processing unit.
  • the method for realizing each processing unit is the same in the following embodiments and modifications thereof.
  • FIG. 11 is a flowchart for explaining the encoding method of the first embodiment.
  • the encoding method of this embodiment will be described with reference to FIG. In the following, only the processing for one frame will be described, but actually the same processing is executed for each frame.
  • the sampled and quantized PCM format time series signal x (n) is input to the frame buffer 1011 of the encoding apparatus 10 (FIG. 7).
  • These time series signals x (n) may be linearly quantized (sometimes referred to as “uniform quantization”), or companded (for example, ITU-T Recommendation G. 711, “Pulse Code Modulation (PCM)” of “Voice“ Frequencies ”)) may be used for nonlinear quantization (sometimes referred to as“ non-uniform quantization ”).
  • the time series signal x (n) may not be a signal in the PCM format but a signal that is not quantized.
  • the configuration may be such that linear prediction analysis is performed after the sequence signal x (n) is mapped to linear quantization or other nonlinear quantization.
  • the PARCOR coefficient may be calculated by a sequential method such as the Levinson-Durbin method or the Burg method, or for each prediction order M such as an autocorrelation method or a covariance method. Alternatively, simultaneous equations (simultaneous equations having a linear prediction coefficient that minimizes the prediction residual) as a solution may be performed.
  • the PARCOR coefficient k (m) takes a value between ⁇ 1 and 1 inclusive. However, since an infinite digit operation cannot be performed by an arithmetic unit using a computer or the like, it is actually expressed by an integer from ⁇ 32768 to +32767, for example. Processing may be performed using a PARCOR coefficient k (m) mapped to a possible range.
  • the “quantized PARCOR coefficient” may be the quantized value of the PARCOR coefficient itself or an index attached to the quantized value of the PARCOR coefficient. Further, the “quantized PARCOR coefficient” may be monotonically increasing in a broad sense with respect to an increase in the value of the PARCOR coefficient, or may be monotonically decreasing in a broad sense with respect to an increase in the value of the PARCOR coefficient. .
  • the “quantized PARCOR coefficient” may be monotonically increasing with an increase in the absolute value of the PARCOR coefficient, or monotonically decreasing with an increase in the absolute value of the PARCOR coefficient. Also good. Also, the closer the absolute value of the PARCOR coefficient is to 1, the greater the influence that the quantization error of the PARCOR coefficient has on the linear prediction result. For this reason, it is desirable to perform nonlinear quantization in which the quantization step size is smaller as the absolute value of the PARCOR coefficient is closer to 1.
  • FIG. 13 is a graph for illustrating and explaining a nonlinear quantization method for a first-order PARCOR coefficient
  • FIG. 14 is a graph for illustrating and explaining a nonlinear quantization method for a second-order PARCOR coefficient. is there.
  • the horizontal axis of these graphs indicates the PARCOR coefficient generated by the linear prediction analysis unit 1012
  • the vertical axis indicates the index assigned to the quantized value of the PARCOR coefficient.
  • the quantization step size is increased as the first-order PARCOR coefficient k (1) is closer to 1, as illustrated in FIG. Perform nonlinear quantization to make it smaller.
  • FIG. 13 is a graph for illustrating and explaining a nonlinear quantization method for a first-order PARCOR coefficient
  • FIG. 14 is a graph for illustrating and explaining a nonlinear quantization method for a second-order PARCOR coefficient. is there.
  • the horizontal axis of these graphs indicates the PARCOR coefficient generated by the linear prediction analysis unit 1012
  • the possible range ( ⁇ 1 to 1) of the PARCOR coefficient k (1) has three regions (regions from ⁇ 1 to p 2 , regions from p 2 to p 6 , and regions from p 6 to 1).
  • the quantization step size is different for each region.
  • the quantization step increases as the second-order PARCOR coefficient k (2) approaches ⁇ 1.
  • the graph illustrating the non-linear quantization illustrated in FIG. 14 is obtained by inverting the sign of the horizontal axis of the graph illustrating the non-linear quantization illustrated in FIG.
  • first-order and second-order PARCOR coefficients are nonlinearly quantized
  • the quantization of the third or higher order PARCOR coefficient may be linear quantization or non-linear quantization.
  • the quantization value of the PARCOR coefficient may increase monotonously in a broad sense or increase monotonously in a broad sense with respect to the increase of the PARCOR coefficient.
  • step S30 first, the inverse quantization unit 12a of the parameter calculation unit 12 (FIG. 8A) inversely quantizes the first-order quantized PARCOR coefficient i (1) output from the nonlinear quantization unit 11, A primary PARCOR coefficient k ′ (1) (corresponding to “a value determined according to the primary PARCOR coefficient”) is generated (step S31). Note that the process of dequantizing the quantized PARCOR coefficient i (m) is performed by any one of predetermined values k ′ (within the range of the PARCOR coefficient k (m) corresponding to the quantized PARCOR coefficient i (m). This is a process for obtaining m).
  • the PARCOR coefficient k ′ obtained by dequantizing the quantized PARCOR coefficient i (m) is the average value of ⁇ 1 and ⁇ 2.
  • a second-order PARCOR coefficient k (2) (corresponding to “a value determined according to the second-order PARCOR coefficient”) output from the linear prediction analysis unit 1012 by the weight coefficient multiplication unit 12b and the subtraction unit 12c.
  • the weighted difference value k (2) ⁇ a ⁇ k ′ (1) is calculated using the predetermined weighting coefficient a and the first-order PARCOR coefficient k ′ (1) obtained by inverse quantization.
  • the weighting coefficient multiplication unit 12b calculates a first multiplication value a ⁇ k ′ (1) obtained by multiplying a predetermined weighting coefficient a by a primary PARCOR coefficient k ′ (1), and the subtraction unit 12c.
  • the weighting factor a may be positive or negative. However, when there is a correlation between the primary PARCOR coefficient and the secondary PARCOR coefficient, the positive and negative tend to be reversed. (See FIG. 5A.)
  • the weighting factor a is preferably a negative value.
  • the weighted difference value k (2) ⁇ a ⁇ k ′ (1) approaches 0 as the first-order PARCOR coefficient and the second-order PARCOR coefficient are correlated.
  • the weight coefficient a -0.8 can be exemplified.
  • the parameter quantization unit 12d quantizes the weighted difference value k (2) ⁇ a ⁇ k ′ (1) calculated in step S32 to generate a parameter b, and outputs the parameter b (step b). S33).
  • the quantization performed by the parameter quantization unit 12d may be linear quantization or non-linear quantization.
  • the parameter b in this example may be the quantized value itself of the weighted difference value k (2) ⁇ a ⁇ k ′ (1), or may be an index attached to the quantized value. Good.
  • the absolute value of the parameter b increases monotonously in a broad sense with respect to an increase in the corresponding weighted difference value k (2) ⁇ a ⁇ k ′ (1).
  • This parameter b may be monotonically increasing in a broad sense with respect to the corresponding weighted difference value k (2) ⁇ a ⁇ k ′ (1), or monotonously decreasing in a broad sense
  • the increase in absolute value of the corresponding weighted difference value k (2) ⁇ a ⁇ k ′ (1) may be monotonically increasing in a broad sense or may be monotonously decreasing in a broad sense ([[ End of description of details of step S30].
  • the coefficient encoding unit 13 (FIG. 8B) performs the parameter code C b corresponding to the parameter b and the quantized PARCOR coefficients i (m ′) from the first order to the Mth order (excluding the second order).
  • the parameter encoding unit 13 b generates a parameter code C b corresponding to the parameter b output from the parameter calculation unit 12, and the PARCOR coefficient encoding unit 13 a is output from the nonlinear quantization unit 11.
  • the encoding of the parameter b is performed by, for example, Rice encoding or entropy encoding.
  • N 1, ..., N
  • the prediction filter process may be performed.
  • Coefficient encoding unit 13 parameter codes C b generated by the coefficient code C k, the residual coding unit 1018 residual code C e generated by and sent to the synthesis unit 1019, where it is synthesized code C g is generated (step S80). Then, the encoding device 10 outputs the generated code Cg .
  • FIG. 12 is a flowchart for explaining the decoding method according to the first embodiment.
  • the decoding method of this embodiment will be described with reference to FIG. In the following, only the processing for one frame will be described, but actually the same processing is executed for each frame.
  • the separation unit 1021 of the decoding device 20 (FIG. 9) separates the code C g input to the decoding device 20, and the parameter code C b corresponding to the parameter b from the first to the Mth order (excluding the second order).
  • parameter decoding section 21b of the coefficient decoding portion 21 (FIG. 10 (A)) performs decoding of parameter codes C b
  • PARCOR coefficient decoding portion 21a decodes the coefficient code C k.
  • the first-order quantized PARCOR coefficient i (1) obtained by decoding by the PARCOR coefficient decoding unit 21a corresponds to “decoded value corresponding to the first-order PARCOR coefficient”.
  • the PARCOR coefficient calculation unit 22 uses the parameter b output from the coefficient decoding unit 21 and the first-order quantized PARCOR coefficient i (1), and uses the second-order PARCOR coefficient k ′ (2) (“second order”. (Corresponding to “restored value of PARCOR coefficient of”) (step S140).
  • the inverse quantization unit 22c inversely quantizes the parameter b output from the coefficient decoding unit 21, and generates an inverse quantization value b ′ of the parameter b (step S142).
  • the weight coefficient multiplication unit 22b and the addition unit 22d perform the first-order PARCOR coefficient k ′ (1) obtained by inverse quantization, the predetermined weight coefficient a, and the inverse quantization value b of the parameter b.
  • Is used to generate a second-order PARCOR coefficient k ′ (2) a ⁇ k ′ (1) + b ′ (step S143).
  • the weight coefficient multiplication unit 22b multiplies the first multiplication value a ⁇ k ′ (1) obtained by multiplying the predetermined weight coefficient a by the first-order PARCOR coefficient k ′ (1) obtained by inverse quantization.
  • the addition unit 22d adds the first multiplication value a ⁇ k ′ (1) and the inverse quantized value b ′ of the parameter b to generate the second-order PARCOR coefficient k ′ (2).
  • the second-order PARCOR coefficient k ′ (2) may be obtained by other methods (end of description of [Details of Step S140]).
  • Relational expression A value determined according to the second-order PARCOR coefficient by the sum of the first multiplication value obtained by multiplying a predetermined weighting coefficient by a value determined according to the first-order PARCOR coefficient and the first variable value.
  • ⁇ Value determined according to the second-order PARCOR coefficient A second-order quantized PARCOR coefficient obtained by quantizing the second-order PARCOR coefficient.
  • ⁇ Parameter The first variable value that satisfies the above relational expression. This is a “value determined according to the first variable value”, and the absolute value of the parameter increases monotonously in a broad sense with respect to the increase in the first variable value.
  • a difference in configuration between the second embodiment and the first embodiment is a parameter calculation unit of the encoding device 10 and a PARCOR coefficient calculation unit of the decoding device 20.
  • FIG. 15A is a block diagram for explaining the details of the nonlinear quantization unit 11 and the parameter calculation unit 112 of the second embodiment
  • FIG. 15B is a PARCOR coefficient calculation unit of the second embodiment
  • 12 is a block diagram for explaining details of 122; FIG. Since the configuration other than the parameter calculation unit 112 and the PARCOR coefficient calculation unit 122 is the same as that of the first embodiment, the description thereof is omitted.
  • the parameter calculation unit 112 includes a weight coefficient addition unit 112b and a subtraction unit 112c.
  • the PARCOR coefficient calculation unit 122 includes an inverse quantization unit 122a, a weight coefficient multiplication unit 122b, and an addition unit 122c.
  • FIG. 16 is a flowchart for explaining the encoding method according to the second embodiment.
  • the encoding method of the second embodiment will be described with reference to FIG.
  • step S230 is executed instead of step S30 (FIG. 11). Below, only the process of step S230 is demonstrated.
  • the first-order quantized PARCOR coefficient i (1) is a value that increases monotonically in a broad sense with respect to an increase in at least a positive first-order PARCOR coefficient k (1)
  • the second-order quantized PARCOR coefficient is a value that increases monotonically in a broad sense with respect to an increase in at least a negative second-order PARCOR coefficient k (2).
  • the first-order quantized PARCOR coefficient i (1) is a value that decreases monotonically in a broad sense with respect to an increase in at least a positive first-order PARCOR coefficient k (1)
  • the second-order quantized PARCOR coefficient i (2 ) Is a value that decreases monotonically in a broad sense with respect to an increase in at least a negative second-order PARCOR coefficient k (2).
  • a weighting coefficient a is set so that the difference can be corrected by scaling.
  • the primary quantization PARCOR coefficient The scale of i (1) 1 ⁇ 2 is equal to the scale of the second-order quantized PARCOR coefficient i (2). In this case, it is desirable that a value obtained by multiplying 1/2 by the original weight is used as the weight coefficient a.
  • the weight coefficient multiplication unit 212b calculates a first multiplication value a ⁇ i (1) obtained by multiplying a predetermined weight coefficient a by a first-order quantized PARCOR coefficient i (1), and performs subtraction.
  • the parameter b may be obtained by other methods such as calculating the parameter b by repeating the process of subtracting i (1) with i (2) as an initial value a times.
  • FIG. 17 is a flowchart for explaining the decoding method according to the second embodiment.
  • the decoding method according to the second embodiment will be described with reference to FIG.
  • step S340 is executed instead of step S140 (FIG. 12). Below, only the process of step S340 is demonstrated.
  • step S340 the PARCOR coefficient calculation unit 122 (FIG. 15B) uses the parameter b output from the coefficient decoding unit 21 and the first-order quantized PARCOR coefficient i (1) to generate a second-order PARCOR coefficient k. '(2) (corresponding to “restored value of second-order PARCOR coefficient”) is calculated (step S340).
  • the weighting factor multiplication unit 122b generates a first multiplication value a ⁇ i (1) obtained by multiplying a predetermined weighting factor a by a first-order quantized PARCOR coefficient i (1), and an addition unit 122d adds the first multiplied value a ⁇ i (1) and the parameter b to generate a second-order quantized PARCOR coefficient i (2).
  • the second-order quantized PARCOR coefficient i (2) is calculated by other methods, such as calculating the second-order quantized PARCOR coefficient i (2) by repeating the process of adding i (1) a time with the parameter b as an initial value. You may ask for 2).
  • Quantized PARCOR coefficients i (m) (m 1, 2,..., M) from the first order to the Mth order, which are composed of the quantized PARCOR coefficients i (2), are dequantized, and the first order to the Mth order.
  • Relational expression a value determined according to the primary PARCOR coefficient by the sum of a second multiplication value obtained by multiplying a predetermined weighting coefficient by a value determined according to the secondary PARCOR coefficient and a second variable value.
  • ⁇ Value determined according to the first order PARCOR coefficient First order PARCOR coefficient. This is a “value that increases monotonously in a broad sense with respect to an increase in the first-order PARCOR coefficient”.
  • second-order PARCOR coefficient This is “a value that increases monotonically in a broad sense with respect to an increase in the second-order PARCOR coefficient”.
  • Step (III) code a code corresponding to information including parameters and secondary PARCOR coefficients.
  • FIG. 18 is a block diagram for explaining a functional configuration of the encoding apparatus 210 according to the third embodiment.
  • FIG. 19 is a block diagram for explaining a functional configuration of the decoding device 320 according to the third embodiment.
  • 20A is a block diagram for explaining the details of the nonlinear quantization unit 11 and the parameter calculation unit 212 shown in FIG. 18, and
  • FIG. 20B shows the PARCOR coefficient shown in FIG. 4 is a block diagram for explaining details of a calculation unit 222.
  • the difference in configuration between the third embodiment and the first embodiment is a parameter calculation unit 212 of the encoding device 210 and a PARCOR coefficient calculation unit 222 of the decoding device 220. Since the configuration other than these is the same as that of the first embodiment, the description thereof is omitted.
  • the parameter calculation unit 212 includes an inverse quantization unit 212a, a weight coefficient multiplication unit 212b, a subtraction unit 212c, and a parameter quantization unit 212d.
  • the PARCOR coefficient calculation unit 222 includes inverse quantization units 222a and 222c, a weight coefficient multiplication unit 222b, and an addition unit 122c.
  • FIG. 21 is a flowchart for explaining an encoding method according to the third embodiment.
  • the encoding method of the third embodiment will be described with reference to FIG.
  • step S430 is executed instead of step S30 (FIG. 11), and step S440 instead of step S40. This is the point where the process is executed. Below, only the process of step S430 and S440 is demonstrated.
  • step S430 the parameter calculation unit 212 determines the relationship between the value determined according to the primary PARCOR coefficient k (1) and the value determined according to the secondary PARCOR coefficient k (2). A fixed parameter is calculated (step S430).
  • step S430 first, the inverse quantization unit 212a of the parameter calculation unit 212 inversely quantizes the second-order quantized PARCOR coefficient i (2) output from the nonlinear quantization unit 11, and the second-order PARCOR coefficient k ′. (2) (corresponding to “a value determined according to the second-order PARCOR coefficient”) is generated (step S431).
  • the first-order PARCOR coefficient k (1) (corresponding to “a value determined according to the first-order PARCOR coefficient”) output from the linear prediction analysis unit 1012 by the weight coefficient multiplication unit 212b and the subtraction unit 212c.
  • the weighted difference value k (1) ⁇ a ⁇ k ′ (2) is calculated using a predetermined weighting coefficient a and the second-order PARCOR coefficient k ′ (2) obtained by inverse quantization.
  • the weight coefficient multiplication unit 312b calculates a second multiplication value a ⁇ k ′ (2) obtained by multiplying a predetermined weight coefficient a by a secondary PARCOR coefficient k ′ (2), and the subtraction unit 212c.
  • the parameter quantization unit 212d quantizes the weighted difference value k (1) ⁇ a ⁇ k ′ (2) calculated in step S432 to generate and output the parameter b (step S433).
  • the quantization performed by the parameter quantization unit 12d may be linear quantization or non-linear quantization.
  • the parameter b in this example may be the quantized value itself of the weighted difference value k (1) ⁇ a ⁇ k ′ (2), or may be an index attached to the quantized value. Good.
  • the absolute value of the parameter b increases monotonously in a broad sense with respect to an increase in the corresponding weighted difference value k (1) ⁇ a ⁇ k ′ (2).
  • the parameter b may be monotonically increasing in a broad sense with respect to the corresponding weighted difference value k (1) ⁇ a ⁇ k ′ (2), may be monotonically decreasing in a broad sense,
  • the weighted difference value k (1) ⁇ a ⁇ k ′ (2) may increase monotonously in a broad sense or decrease monotonically in a broad sense ([Step End of description of details of S430].
  • FIG. 22 is a flowchart for explaining a decoding method according to the third embodiment.
  • the decoding method according to the third embodiment will be described with reference to FIG.
  • step S510 is executed instead of step S110 (FIG. 12), and step S540 instead of step S140. This is the point where the process is executed.
  • steps S510 and S540 will be described.
  • step S510 the separation unit 1021 of the decoding device 220 separates the code C g input to the decoding device 220, and the parameter code C b corresponding to the parameter b and the quantized PARCOR coefficients i from the second order to the M order.
  • step S540 the PARCOR coefficient calculation unit 222 uses the parameter b output from the coefficient decoding unit 21 and the second-order quantized PARCOR coefficient i (2), and the first-order PARCOR coefficient k ′ (1) (“1 (Corresponding to “restored value of the next PARCOR coefficient”) (step S540).
  • the inverse quantization unit 222c inversely quantizes the parameter b output from the coefficient decoding unit 21, and generates an inverse quantized value b ′ of the parameter b (step S542).
  • the weight coefficient multiplication unit 222b and the addition unit 222d perform a second-order PARCOR coefficient k ′ (2) obtained by inverse quantization, a predetermined weight coefficient a, and an inverse quantization value b of the parameter b.
  • a first-order PARCOR coefficient k ′ (1) a ⁇ k ′ (2) + b ′ (step S543).
  • the weight coefficient multiplication unit 222b uses a second multiplication value a ⁇ k ′ (2) obtained by multiplying a predetermined weight coefficient a by a second-order PARCOR coefficient k ′ (2) obtained by inverse quantization.
  • the addition unit 222d generates the first-order PARCOR coefficient k ′ (1) by adding the second multiplication value a ⁇ k ′ (2) and the inverse quantized value b ′ of the parameter b.
  • the first-order PARCOR coefficient k ′ (1) a ⁇ k ′ (2) + b ′ is calculated by repeating the process of adding k ′ (2) with the inverse quantized value b ′ as an initial value a times.
  • the first-order PARCOR coefficient k ′ (1) may be obtained by other methods (end of description of [Details of Step S540]).
  • the third embodiment reverses the handling of the first-order PARCOR coefficient and the second-order PARCOR coefficient in the first embodiment, and encodes the PARCOR coefficient by a code corresponding to information including the second-order PARCOR coefficient and the parameter.
  • the first-order PARCOR coefficient can be restored from this code.
  • the handling of the primary PARCOR coefficient and the secondary PARCOR coefficient in the second embodiment is reversed, and the PARCOR coefficient is encoded by a code corresponding to the information including the secondary PARCOR coefficient and the parameter.
  • restore a primary PARCOR coefficient may be sufficient.
  • Relational expression a value determined according to the primary PARCOR coefficient by the sum of a second multiplication value obtained by multiplying a predetermined weighting coefficient by a value determined according to the secondary PARCOR coefficient and a second variable value.
  • ⁇ Value determined according to the second-order PARCOR coefficient A second-order quantized PARCOR coefficient obtained by quantizing the second-order PARCOR coefficient.
  • FIG. 23 is a block diagram for describing a functional configuration of an encoding apparatus 310 according to Modification 2 of the third embodiment.
  • the parameter calculation unit 12 generates a parameter (denoted as b 1 ) as described in the first embodiment, and the parameter calculation unit 212 uses the parameter (b 2 as described in the third embodiment). Is written).
  • the coefficient coding unit 313 outputs the total code amount of the code of the parameter b 1 and the code of the first-order quantized PARCOR coefficient i (1) output from the parameter calculation unit 12 and the parameter calculation unit 212.
  • the code amount of the parameter b 2 and the code of the second-order quantized PARCOR coefficient i (2), the code of the first-order quantized PARCOR coefficient i (1) and the second-order quantized PARCOR coefficient i ( The total code amount with the code of 2) is compared, and an encoding method that minimizes the total code amount is selected.
  • a configuration in which the encoding amount when the PARCOR coefficient is encoded by the method of any form or modification or the conventional method is compared, and the encoding method having the smallest encoding amount is selected for each frame It may be.
  • Steps (II) and (III) are steps that are executed when the absolute value of the first-order PARCOR coefficient is equal to or greater than a predetermined first threshold value. If the absolute value of the primary PARCOR coefficient is less than the first threshold, a step of generating a code corresponding to information including the primary PARCOR coefficient and the secondary PARCOR coefficient is executed.
  • Step (V) uses a parameter and a decoded value corresponding to the first order PARCOR coefficient when the absolute value of the decoded value corresponding to the first order PARCOR coefficient is equal to or larger than a predetermined second threshold value. This is a step of calculating a restoration value of the secondary PARCOR coefficient.
  • Relational expression A value determined according to the second-order PARCOR coefficient by the sum of the first multiplication value obtained by multiplying a predetermined weighting coefficient by a value determined according to the first-order PARCOR coefficient and the first variable value.
  • ⁇ Value determined according to the first order PARCOR coefficient First order PARCOR coefficient. This is a “value that increases monotonously in a broad sense with respect to an increase in the first-order PARCOR coefficient”.
  • second-order PARCOR coefficient This is “a value that increases monotonically in a broad sense with respect to an increase in the second-order PARCOR coefficient”.
  • Parameter The first quantized variable value obtained by quantizing the first variable value that satisfies the above relational expression. This is a “value determined according to the first variable value”, and the absolute value of the parameter increases monotonously in a broad sense with respect to the increase in the first variable value.
  • FIG. 24 is a block diagram for explaining a functional configuration of the encoding device 410 according to the fourth embodiment.
  • FIG. 25 is a block diagram for explaining the details of the nonlinear quantization unit 11, the parameter calculation unit 12, and the selection unit 411 shown in FIG.
  • FIG. 26 is a block diagram for explaining a functional configuration of the decoding apparatus 420 according to the fourth embodiment.
  • FIG. 27 is a block diagram for explaining the details of the PARCOR coefficient calculation unit 422 shown in FIG.
  • the same reference numerals as those in the first embodiment are used for the portions already described in the first embodiment, and the description thereof is simplified.
  • the difference in configuration between the fourth embodiment and the first embodiment is that, in the fourth embodiment, the selection unit 411 of the encoding device 410 and the PARCOR coefficient calculation unit of the decoding device 420 are the same. 422. Since the configuration other than these is the same as that of the first embodiment, the description thereof is omitted.
  • the encoding device 410 includes a selection unit 411 in addition to the functional configurations included in the encoding device 10 of the first embodiment.
  • the selection unit 411 includes a determination unit 411a and a switching unit 411b.
  • the PARCOR coefficient calculation unit 422 includes inverse quantization units 22a and 22c, a weight coefficient multiplication unit 22b, an addition unit 22d, a determination unit 422a, and a switching unit 422b.
  • FIG. 28 is a flowchart for explaining an encoding method according to the fourth embodiment.
  • the encoding method of the fourth embodiment will be described using FIG. 28 with a focus on differences from the first embodiment.
  • the encoding device 410 executes the process of step S10 described in the first embodiment.
  • the determination unit 411a of the selection unit 411 determines whether or not the absolute value of the primary PARCOR coefficient k (1) is greater than or equal to a predetermined threshold value (corresponding to a “first threshold value”) (step S630). This threshold value (corresponding to the “first threshold value”) is determined in a range (0 or more and 1 or less) that the absolute value of the PARCOR coefficient can take.
  • this threshold determination may be performed in an area before quantization or in an area after quantization. However, as described later, when the same threshold value determination is performed at the time of decoding and information on the encoding method is shared between the encoding device 410 and the decoding device 420, the threshold value is determined between the encoding time and the decoding time due to the quantization error. It is desirable that the threshold determination in step S630 be performed in the region after quantization or the region inversely quantized therefrom so that the determination results do not differ. For example, when the threshold determination in step S630 is performed in the quantized region, the determination unit 411a converts the input first-order PARCOR coefficient k (1) into the first-order quantized PARCOR coefficient i (1).
  • the threshold value of the first-order quantized PARCOR coefficient i (1) is determined.
  • the threshold used for threshold determination is the threshold converted into the quantized area.
  • the threshold determination performed in the quantized region or the like corresponds to “determining whether or not the absolute value of the primary PARCOR coefficient k (1) is equal to or greater than a predetermined threshold”.
  • the determination target is smaller than the threshold value in order to determine whether the determination target is equal to or greater than a predetermined threshold value. It is also possible to perform processing for determining whether or not the discrete value adjacent to the threshold value is exceeded.
  • step S630 If it is determined in step S630 that the absolute value of the primary PARCOR coefficient k (1) is greater than or equal to a predetermined threshold (corresponding to the “first threshold”), the process branching by the switching unit 411b According to the control, the processing of steps S20 to S80 (FIG. 11) described in the first embodiment is executed.
  • a predetermined threshold corresponding to the “first threshold”.
  • the first embodiment is performed according to the processing branch control by the switching unit 411b.
  • step S640 the processes of steps S50 to S70 described in the first embodiment are executed, and then the synthesis unit 1019 synthesizes the coefficient code C k and the residual code C e to obtain a quantized PARCOR coefficient.
  • FIG. 29 is a flowchart for explaining a decoding method according to the fourth embodiment.
  • the encoding method of the fourth embodiment will be described using FIG. 29 with a focus on differences from the first embodiment.
  • a predetermined threshold second threshold
  • step S740 If it is determined in step S740 that the first-order quantized PARCOR coefficient i (1) is greater than or equal to a predetermined threshold (second threshold), the coefficient decoding unit 21 follows the processing branch control by the switching unit 422b. After decoding the parameter code C b output from the separation unit 1021 and generating the parameter b (step S760), step S140 described in the first embodiment (“decoding corresponding to parameters and first-order PARCOR coefficients” (Corresponding to the step of calculating the restoration value of the second-order PARCOR coefficient using the value) (FIG. 17) is executed, and the processing of steps S150 and S160 (FIG. 12) is further executed.
  • a predetermined threshold second threshold
  • step S740 if it is determined in step S740 that the first-order quantized PARCOR coefficient i (1) is less than a predetermined threshold (second threshold), the PARCOR coefficient is determined according to the processing branch control by the switching unit 422b.
  • step S750 the processes of steps S150 and S160 described in the first embodiment are executed.
  • the first modification of the fourth embodiment also uses the correlation between the primary PARCOR coefficient and the secondary PARCOR coefficient of the present invention when the primary PARCOR coefficient is equal to or greater than a predetermined threshold. Is executed, and when the primary PARCOR coefficient is less than a predetermined threshold, the primary PARCOR coefficient and the secondary PARCOR coefficient are encoded independently of each other.
  • the “encoding method using the correlation between the first-order PARCOR coefficient and the second-order PARCOR coefficient” is realized by the method described in the first embodiment. In the first modification of the embodiment, this is realized by the method described in the second embodiment. That is, the first modification of the fourth embodiment relates to the following configuration in the framework described in [First aspect] of [Principle] described above. However, this does not limit the present invention.
  • Steps (II) and (III) are steps that are executed when the absolute value of the first-order PARCOR coefficient is equal to or greater than a predetermined first threshold value. If the absolute value of the primary PARCOR coefficient is less than the first threshold, a step of generating a code corresponding to information including the primary PARCOR coefficient and the secondary PARCOR coefficient is executed.
  • Step (V) uses a parameter and a decoded value corresponding to the first order PARCOR coefficient when the absolute value of the decoded value corresponding to the first order PARCOR coefficient is equal to or larger than a predetermined second threshold value. This is a step of calculating a restoration value of the secondary PARCOR coefficient.
  • Relational expression A value determined according to the second-order PARCOR coefficient by the sum of the first multiplication value obtained by multiplying a predetermined weighting coefficient by a value determined according to the first-order PARCOR coefficient and the first variable value.
  • ⁇ Value determined according to the second-order PARCOR coefficient A second-order quantized PARCOR coefficient obtained by quantizing the second-order PARCOR coefficient.
  • ⁇ Parameter The first variable value that satisfies the above relational expression. This is a “value determined according to the first variable value”, and the absolute value of the parameter increases monotonously in a broad sense with respect to the increase in the first variable value.
  • FIG. 30 is a block diagram for explaining details of the nonlinear quantization unit 11, the selection unit 511, and the parameter calculation unit 122 of the encoding device 410 according to Modification 1 of the fourth embodiment.
  • FIG. 31 is a block diagram for explaining details of the PARCOR coefficient calculation unit 522 of the decoding device 420 according to Modification 1 of the fourth embodiment. Since the configuration other than these is the same as that of the fourth embodiment, description thereof is omitted.
  • the selection unit 511 includes a determination unit 511a and a switching unit 511b
  • the parameter calculation unit 122 includes a weight coefficient addition unit 112b and a subtraction unit 112c.
  • the PARCOR coefficient calculation unit 522 includes a determination unit 522a, a switching unit 522b, an inverse quantization unit 122a, a weight coefficient multiplication unit 122b, and an addition unit 122c.
  • FIG. 32 is a flowchart for explaining an encoding method according to the first modification of the fourth embodiment.
  • the encoding method of the modification 1 of 4th Embodiment is demonstrated using FIG.
  • the processes of steps S10 and S20 described in the first embodiment are executed.
  • the determination unit 511a of the selection unit 511 determines whether or not the absolute value of the first-order quantized PARCOR coefficient i (1) is greater than or equal to a predetermined threshold (step S830). This is equivalent to determining whether or not the absolute value of the primary PARCOR coefficient k (1) is greater than or equal to a predetermined threshold (corresponding to a “first threshold”) in the quantized region.
  • the threshold value used for threshold determination of the first-order quantized PARCOR coefficient i (1) is obtained by converting the first threshold value into a region after quantization.
  • step S830 the absolute value of the first-order quantized PARCOR coefficient i (1) is equal to or greater than a predetermined threshold (the absolute value of the first-order PARCOR coefficient k (1) is a predetermined threshold (“ Is equal to or greater than “first threshold value”), the processes of steps S230 and S40 to S80 described in the second embodiment (FIG. 16) are executed according to the process branching control by the switching unit 511b.
  • a predetermined threshold the absolute value of the first-order PARCOR coefficient k (1) is a predetermined threshold (“ Is equal to or greater than “first threshold value”.
  • step S830 the absolute value of the first-order quantized PARCOR coefficient i (1) is less than a predetermined threshold value (the absolute value of the first-order PARCOR coefficient k (1) is a predetermined threshold value). (Corresponding to “first threshold value”), it is determined that the processing in steps S640, S50 to S70, and step S650 described in the fourth embodiment is performed according to the processing branch control by the switching unit 511b. Executed.
  • FIG. 33 is a flowchart for explaining a decoding method according to the first modification of the fourth embodiment.
  • the encoding method according to the first modification of the fourth embodiment will be described with reference to FIG. 33 with a focus on differences from the fourth embodiment.
  • the determination unit 522a of the PARCOR coefficient calculation unit 522 determines that the first-order quantized PARCOR coefficient i (1) (corresponding to “decoded value corresponding to the first-order PARCOR coefficient”) output from the coefficient decoding unit 21 in advance. It is determined whether or not it is equal to or greater than a predetermined threshold (second threshold) (step S740).
  • This threshold value (second threshold value) is obtained by converting the first threshold value into a region after quantization.
  • step S740 If it is determined in step S740 that the first-order quantized PARCOR coefficient i (1) is greater than or equal to a predetermined threshold value (second threshold value), according to the process branch control by the switching unit 522b, the fourth embodiment Step S760 described in step S760 (FIG. 29) is executed, and then step S340 described in the second embodiment (“reconstruction of the second-order PARCOR coefficient using the parameter and the decoded value corresponding to the first-order PARCOR coefficient is performed. (Corresponding to “step for calculating value”) (FIG. 17) is executed, and further, the processes of steps S150 and S160 (FIG. 12) are executed.
  • a predetermined threshold value second threshold value
  • step S740 if it is determined in step S740 that the first-order quantized PARCOR coefficient i (1) is less than a predetermined threshold (second threshold), the PARCOR coefficient is determined according to the processing branch control by the switching unit 522b.
  • step S750 the processes of steps S150 and S160 described in the first embodiment are executed.
  • Steps (II) and (III) are steps that are executed when the absolute value of the secondary PARCOR coefficient is equal to or greater than a predetermined first threshold value.
  • a step of generating a code corresponding to information including the primary PARCOR coefficient and the secondary PARCOR coefficient is executed.
  • Step (V) uses a parameter and a decoded value corresponding to the second order PARCOR coefficient when the absolute value of the decoded value corresponding to the second order PARCOR coefficient is equal to or greater than a predetermined second threshold value. This is a step of calculating a restoration value of the primary PARCOR coefficient.
  • Relational expression a value determined according to the primary PARCOR coefficient by the sum of a second multiplication value obtained by multiplying a predetermined weighting coefficient by a value determined according to the secondary PARCOR coefficient and a second variable value.
  • the second quantized variable value obtained by quantizing the second variable value that satisfies the above relational expression. This is a “value determined according to the second variable value” and a “value that increases monotonously in a broad sense with respect to an increase in the second variable value”.
  • the value determined according to the first-order PARCOR coefficient is the first-order PARCOR coefficient
  • the value determined according to the second-order PARCOR coefficient is the second-order PARCOR coefficient
  • the parameters satisfy the above relational expression.
  • a value determined according to the first-order PARCOR coefficient a first-order quantized PARCOR coefficient obtained by quantizing the first-order PARCOR coefficient.
  • ⁇ Value determined according to the second-order PARCOR coefficient A second-order quantized PARCOR coefficient obtained by quantizing the second-order PARCOR coefficient.
  • Parameter A second variable value that satisfies the above relational expression. It may be configured as follows.
  • FIG. 34 is a block diagram for explaining a functional configuration of an encoding apparatus 610 according to the fifth embodiment.
  • FIG. 35 is a block diagram for explaining details of the quantization method selection unit 611, the quantization unit 612, and the encoding method selection unit 613 shown in FIG. 34
  • FIG. 36 is the same as FIG. 5 is a block diagram for explaining details of a coefficient encoding unit 614.
  • FIG. 37 is a block diagram for explaining a functional configuration of the decoding device 620 according to the fifth embodiment.
  • FIG. 38 is a block diagram for explaining details of the coefficient decoding unit 621 shown in FIG.
  • the structural differences from the encoding device 10 in the first embodiment of the encoding device 610 are the non-linear quantization unit 11, the parameter calculation unit 12, and the coefficient encoding unit of the encoding device 10. 13 is a point replaced with a quantization method selection unit 611, a quantization unit 612, an encoding method selection unit 613, and a coefficient encoding unit 614.
  • the quantization method selection unit 611 of this embodiment includes a determination unit 611a and a switching unit 611b.
  • the quantization unit 612 includes a quantization unit 612a, a low-precision quantization unit 612b, and a high-precision quantum.
  • a conversion unit 612c As shown in FIG. 36, the coefficient encoding unit 614 of this embodiment includes a determination unit 614a, a switching unit 614b, and variable length encoding units 614c to 614e.
  • the structural difference from the decoding device 20 in the first embodiment of the decoding device 620 is that the coefficient decoding unit 21 and the PARCOR coefficient calculation unit 22 of the decoding device 20 are different from each other in the coefficient decoding unit 621.
  • the PARCOR coefficient calculation unit 622 As shown in FIG. 38, the coefficient decoding unit 621 of this embodiment includes variable length decoding units 621a, 621d, and 621e, determination units 621b and 621f, switching units 621c and 621g, and inverse quantization units 621h to 621j.
  • FIG. 39 is a flowchart for explaining an encoding method according to the fifth embodiment.
  • the encoding method of this embodiment will be described with reference to FIG. In the following, only the processing for one frame will be described, but actually the same processing is executed for each frame.
  • the output primary PARCOR coefficient k (1) is input to the encoding method selection unit 613 (FIG. 35), and the encoding method selection unit 613 determines the absolute value of the primary PARCOR coefficient k (1) in advance.
  • the first variable length encoding method is selected as an encoding method for generating a code corresponding to the second order PARCOR coefficient k (2), and the first order PARCOR coefficient k ( When the absolute value of 1) is less than the threshold value T1, a second variable length code different from the first variable length coding method as a coding method for generating a code corresponding to the second-order PARCOR coefficient k (2)
  • the conversion method is selected (step S910).
  • step S910 first, the encoding method selection unit 613 determines whether or not the absolute value of the primary PARCOR coefficient k (1) is greater than or equal to a predetermined threshold T1 (step S911).
  • This threshold value T1 is determined in advance in a range (0 or more and 1 or less) that the absolute value of the PARCOR coefficient can take. Further, this threshold determination may be performed in a region before quantization or may be performed in a region after quantization. However, as described later, since it is necessary to perform the same threshold determination at the time of decoding and to share information on the encoding method between the encoding device 610 and the decoding device 620, at the time of encoding and decoding due to quantization errors.
  • the threshold determination in step S911 is performed in a region after quantization or a region inversely quantized from the region so that the threshold determination result does not differ between.
  • the encoding method selection unit 613 converts the input first-order PARCOR coefficient k (1) to the first-order quantized PARCOR coefficient i (1). After the conversion, the threshold value of the first-order quantized PARCOR coefficient i (1) is determined. In this case, the threshold used for threshold determination is the threshold converted into the quantized area.
  • the threshold determination performed in the quantized region or the like corresponds to “determining whether or not the absolute value of the primary PARCOR coefficient k (1) is equal to or greater than a predetermined threshold”.
  • the determination target is smaller than the threshold value in order to determine whether the determination target is equal to or greater than a predetermined threshold value. It is also possible to perform processing for determining whether or not the discrete value adjacent to the threshold value is exceeded.
  • the encoding method selection unit 613 determines that the absolute value of the primary PARCOR coefficient k (1) is equal to or greater than a predetermined threshold T1
  • the encoding method selection unit 613 selects the first variable length encoding method (step S912). If not, the second variable length coding method is selected, and the parameter b indicating the selected content is output (step S913).
  • variable length coding method and the second variable length coding method are as described in [Second Aspect] of [Principle] described above, and a specific example of such a coding method is a Rice code. And the Huffman encoding method (end of description of [Details of Step S910]).
  • the primary and secondary PARCOR coefficients k (1), k (2) output from the linear prediction analysis unit 1012 are also input to the quantization method selection unit 611 (FIG. 35), and the quantization method selection unit 611 Selects a predetermined first quantization method when the absolute value of the primary PARCOR coefficient k (1) is equal to or greater than a predetermined second threshold T2, and selects the primary PARCOR coefficient k (1) When the absolute value of is less than a predetermined second threshold T2, a predetermined second quantization method having a quantization step size larger than that of the first quantization method is selected, and 2 is selected depending on the selected quantization method.
  • the next PARCOR coefficient k (2) is quantized to generate a second-order quantized PARCOR coefficient (step S920).
  • step S920 first, the determination unit 611a of the quantization method selection unit 611 determines whether or not the input first-order PARCOR coefficient k (1) is greater than or equal to a predetermined second threshold T2 (step S920). S921).
  • This threshold value T2 is determined in advance in a range (0 or more and 1 or less) that the absolute value of the PARCOR coefficient can take.
  • the other details of the threshold determination in step S921 are the same as the threshold determination described in step S911, and thus the description thereof is omitted.
  • the high-precision quantization unit 612c When it is determined that the absolute value of the primary PARCOR coefficient k (1) is equal to or greater than a predetermined threshold value T2, the high-precision quantization unit 612c performs the first quantization according to the processing branch control by the switching unit 611b.
  • the second-order PARCOR coefficient k (2) input by the method is quantized to generate and output a second-order quantized PARCOR coefficient i (2) (step S922).
  • the low-precision quantization unit 612b performs the second quantization according to the processing branch control by the switching unit 611b.
  • the second-order PARCOR coefficient k (2) input by the method is quantized to generate and output a second-order quantized PARCOR coefficient i (2) (step S923).
  • the first quantization method and the second quantization method may be a method for linearly quantizing an input signal or a method for nonlinear quantization.
  • the quantization step size of the first quantization method for a certain amplitude range of the input signal is smaller than the quantization step size of the second quantization method for the same amplitude range.
  • the number of quantization steps of the first quantization method for a certain amplitude range of the input signal is larger than the number of quantization steps of the second quantization method for the same amplitude range. That is, the first quantization method is a method of performing quantization of the input signal with finer granularity than the second quantization method (end of description of [Details of Step S920]).
  • the first-order, third-order to M-th order PARCOR coefficients k (1), k (3),..., K (M) are input to the quantization unit 612a.
  • the quantization unit 612a quantizes these using a predetermined fixed quantization method, and performs first-order, third-order to M-order quantized PARCOR coefficients i (1), i (3),. M) is generated and output (step S930).
  • the quantization performed by the quantization unit 612a may be linear quantization or non-linear quantization.
  • the second-order quantized PARCOR coefficient i (2) and the parameter b are input to the coefficient encoding unit 614 (FIG. 36), and the coefficient encoding unit 614 is selected in step S910 indicated by the parameter b.
  • the second-order quantized PARCOR coefficient i (2) is encoded to generate a coefficient code C k (2) corresponding to the second-order PARCOR (step S940).
  • the variable-length encoding unit 614d converts the input second-order quantized PARCOR coefficient i (2) to the first variable length according to the processing branch control by the switching unit 614b.
  • the coefficient code C k (2) is generated by encoding using the encoding method and is output (step S932).
  • variable-length encoding unit 614e converts the input second-order quantized PARCOR coefficient i (2) into the second variable-length code according to the processing branch control by the switching unit 614b.
  • the coefficient code C k (2) is generated and output by the encoding method (end of description of step S933 / [detail of step S940]).
  • variable length coding unit 614c fixes the input first-order, third-order to M-order quantized PARCOR coefficients i (1), i (3),..., I (M) in a predetermined fixed manner.
  • the coefficient codes C k (1), C k (3),..., C k (M) are generated and output by the variable length encoding method (step S950).
  • An example of variable length encoding performed by the variable length encoding unit 614c is Rice encoding.
  • the coefficient code C k (C k (1),..., C k (M)) generated by the coefficient encoding unit 614. If, residual code C e generated by the residual encoding unit 1018 is sent to the synthesis unit 1019 (FIG. 34), where combined with code C g is generated (step S980). Then, the encoding device 610 outputs the generated code Cg .
  • FIG. 40 is a flowchart for explaining an encoding method according to the fifth embodiment.
  • the decoding method of this embodiment will be described with reference to FIG. In the following, only the processing for one frame will be described, but actually the same processing is executed for each frame.
  • step S120 of the first embodiment is executed, and the variable length decoding unit 621a of the coefficient decoding unit 621 (FIG. 38) further receives the input coefficient codes C k (1), C k (3). ,..., C k (M) and generate first-order, third-order to M-order quantized PARCOR coefficients i (1), i (3),. S1030).
  • the determination unit 621b compares the absolute value of the decoded value i (1) of the coefficient code C k (1) corresponding to the primary PARCOR coefficient with a predetermined threshold T3, and determines a predetermined first value.
  • the coefficient code C k (2) corresponding to the second-order PARCOR coefficient is decoded by a decoding method corresponding to the variable length coding method, or a second variable length coding determined in advance different from the first variable length coding method. It is determined whether the coefficient code C k (2) corresponding to the second-order PARCOR coefficient is decoded by the decoding method corresponding to the method, and the variable length decoding units 621d and 621e decode the coefficient code C k (2) (step S1040).
  • the first-order quantized PARCOR coefficient i (1) that is the decoded value of the coefficient code C k (1) output from the variable length decoding unit 621a is input to the determination unit 621b.
  • the determination unit 621b determines whether or not the absolute value of the first-order quantized PARCOR coefficient i (1) is equal to or greater than a predetermined threshold T3.
  • the threshold value T3 is a value obtained by quantizing the threshold value T1 in step S910 with the quantization method in step S930.
  • variable-length decoding unit 621d inputs the input according to the processing branch control by the switching unit 621c.
  • the obtained coefficient code C k (2) is decoded by a decoding method corresponding to the first variable length coding method, and a second-order quantized PARCOR coefficient i (2) is generated and output (step S1042).
  • the variable length decoding unit 621e is input in accordance with the processing branch control by the switching unit 621c.
  • the coefficient code C k (2) is decoded by a decoding method corresponding to the second variable length coding method, and a second-order quantized PARCOR coefficient i (2) is generated and output (step S1043).
  • step S1040 when the magnitude relationship between the values in the pre-quantization region and the post-quantization region is reversed, the magnitude relationship in the threshold determination in step S1040 is reversed (end of description of [details of step S1040]).
  • the determination unit 621f compares the absolute value of the decoded value of the coefficient code C k (1) corresponding to the primary PARCOR coefficient with a predetermined second threshold value T4, and determines a predetermined first inverse A quantization method is used to inverse-quantize a decoded value obtained by decoding a code corresponding to a second-order PARCOR coefficient, or a predetermined first quantization step size larger than that of the first inverse quantization method is used. 2. Determine whether to decode the decoded value obtained by decoding the code corresponding to the second-order PARCOR coefficient using the 2 inverse quantization method, and the inverse quantization units 621i and 621j inversely quantize the decoded value. (Step S1050).
  • the first-order quantized PARCOR coefficient i (1) that is the decoded value of the coefficient code C k (1) output from the variable length decoding unit 621a is input to the determination unit 621f.
  • the determination unit 621f determines whether or not the absolute value of the first-order quantized PARCOR coefficient i (1) is greater than or equal to a predetermined threshold T4.
  • the threshold value T4 is a value obtained by quantizing the threshold value T2 in step S920 with the quantization method in step S930.
  • the inverse quantization unit 621i is set to 2 according to the processing branch control by the switching unit 621g.
  • the next quantized PARCOR coefficient i (2) is inversely quantized with high accuracy to generate a second-order PARCOR coefficient k ′ (2) (step S1052).
  • This high-precision inverse quantization is the inverse quantization of the high-precision quantization in step S922 and corresponds to the first inverse quantization.
  • the inverse quantization unit 621j performs the secondary quantization according to the processing branch control by the switching unit 621g.
  • the quantized PARCOR coefficient i (2) is subjected to low-precision inverse quantization to generate a second-order PARCOR coefficient k ′ (2) (step S1053).
  • This low-precision inverse quantization is the inverse quantization of the low-precision quantization in step S923 and corresponds to the second inverse quantization.
  • step S1050 when the magnitude relationship between the values in the pre-quantization region and the post-quantization region is reversed, the magnitude relationship in the threshold determination in step S1050 is reversed (end of description of [Details of step S1050]).
  • the first-order, third-order to M-order quantized PARCOR coefficients i (1), i (3),..., I (M) output from the variable length decoding unit 621a are input to the inverse quantization unit 621h.
  • the inverse quantization unit 621h performs inverse quantization to generate first-order, third-order to M-order PARCOR coefficients k ′ (1), k ′ (3),..., K ′ (M).
  • This inverse quantization is the inverse quantization of the quantization in step S930.
  • steps S150 and S160 of the first embodiment are executed.
  • [Modification 1 of Fifth Embodiment] The threshold determination process of steps S911 and S921 of the fifth embodiment may be integrated, and the threshold determination process of steps S1041 and S1051 may be integrated.
  • step S911 in step S911 (FIG. 39), it is determined whether or not the absolute value of the primary PARCOR coefficient k (1) is greater than or equal to a predetermined threshold T1, and the secondary quantized PARCOR.
  • a variable length encoding method for the coefficient i (2) is determined, and in step S920 (FIG. 39), it is determined whether or not the absolute value of the primary PARCOR coefficient k (1) is greater than or equal to a predetermined threshold T2.
  • the quantization method of the PARCOR coefficient k (2) is determined. However, it is determined whether or not the absolute value of the primary PARCOR coefficient k (1) is greater than or equal to a predetermined threshold T1, and the quantization method of the secondary PARCOR coefficient k (2) is determined according to the determination result.
  • variable length coding method of the second-order quantized PARCOR coefficient i (2) may be determined. For example, when the absolute value of the primary PARCOR coefficient k (1) is greater than or equal to a predetermined threshold T1, the first variable length encoding method and the first quantization method are selected, and the primary PARCOR coefficient k When the absolute value of (1) is less than a predetermined threshold T1, the second variable length encoding method and the second quantization method may be selected. In the fifth embodiment, it is determined in step S1041 (FIG. 40) whether or not the absolute value of the first-order quantized PARCOR coefficient i (1) is greater than or equal to a predetermined threshold T3.
  • the decoding method of the coefficient code C k (2) corresponding to the quantized PARCOR is determined, and whether or not the absolute value of the first-order quantized PARCOR coefficient i (1) is equal to or greater than a predetermined threshold T4 in step S1051. It was determined and the inverse quantization method of the second-order quantized PARCOR coefficient i (2) was determined. However, it is determined whether or not the absolute value of the primary quantized PARCOR coefficient i (1) is greater than or equal to a predetermined threshold T3, and the coefficient code corresponding to the secondary quantized PARCOR is determined according to the determination result. Both the decoding method of C k (2) and the inverse quantization method of the second-order quantized PARCOR coefficient i (2) may be determined.
  • the decoding method corresponding to the first variable length coding method and the first dequantization method are selected.
  • the absolute value of the first-order quantized PARCOR coefficient i (1) is less than a predetermined threshold T3
  • the decoding method corresponding to the second variable length coding method and the second dequantization method are selected. May be.
  • the coefficient encoding unit of the encoding device separately generates the coefficient code C k corresponding to the PARCOR coefficient and the parameter code C b corresponding to the parameter, A code composed of the coefficient code C k and the parameter code C b is a code corresponding to the PARCOR coefficient and the parameter.
  • the coefficient encoding unit of the encoding device may generate a code corresponding to the PARCOR coefficient and the parameter, for example, by encoding a bit combination value of the quantized PARCOR coefficient and the parameter.
  • a code corresponding to the secondary PARCOR coefficient k (2) is generated.
  • the first variable length coding method is selected as the coding method for the first time, and the absolute value of the first order PARCOR coefficient k (1) is less than the threshold value T1, the second order PARCOR coefficient k (2) is supported.
  • a second variable length coding method different from the first variable length coding method is selected as a coding method for generating a code (step S910), and a first order PARCOR coefficient k (1) and a second order PARCOR coefficient k. (2) was encoded separately (steps S940 and S950).
  • the bit combination value of the primary PARCOR coefficient k (1) and the secondary PARCOR coefficient k (2) may be one encoding target. That is, when the absolute value of the primary PARCOR coefficient k (1) is equal to or greater than a predetermined threshold T1, the first variable length coding is used as an encoding method for generating a code corresponding to the bit combination value.
  • a first variable length encoding method as an encoding method for generating a code corresponding to the bit combination value when the method is selected and the absolute value of the primary PARCOR coefficient k (1) is less than the threshold T1
  • a second variable length encoding method different from the above may be selected, and the primary PARCOR coefficient k (1) and the secondary PARCOR coefficient k (2) may be encoded together.
  • a relational expression other than that described in the first to fourth embodiments is used.
  • the PARCOR coefficient may be encoded using a parameter determined according to the relational expression. For example, an equation that can express a value determined according to the second-order PARCOR coefficient by a sum of a value determined according to the first-order PARCOR coefficient and the first variable value without using a weighting coefficient in the relational expression. And a value determined according to the first variable value that satisfies the condition may be used as a parameter.
  • Such a relational expression is also “depending on the secondary PARCOR coefficient by the sum of the first multiplication value obtained by multiplying a predetermined weighting coefficient by a value determined according to the primary PARCOR coefficient and the first variable value. It is included in the concept of “equations that can express values determined by Further, for example, an equation that can represent a value determined according to the first-order PARCOR coefficient by the sum of the value determined according to the second-order PARCOR coefficient and the second variable value is set as the above relational expression, and A value determined according to the variable value may be used as a parameter.
  • Such a relational expression is also “depending on the primary PARCOR coefficient by the sum of the second multiplication value obtained by multiplying a predetermined weighting coefficient by a value determined according to the secondary PARCOR coefficient and the second variable value. It is included in the concept of “equations that can express values determined by Further, for example, as this relational expression, an equation indicating a ratio between a value determined according to the first-order PARCOR coefficient and a value determined according to the second-order PARCOR coefficient is used, and the value determined according to the ratio is used as a parameter. It may be used. In this case, the absolute value of the parameter approaches 1 as the correlation between the primary PARCOR coefficient and the secondary PARCOR coefficient increases.
  • the program describing the processing contents can be recorded on a computer-readable recording medium.
  • a computer-readable recording medium for example, any recording medium such as a magnetic recording device, an optical disk, a magneto-optical recording medium, and a semiconductor memory may be used.
  • this program is distributed by selling, transferring, or lending a portable recording medium such as a DVD or CD-ROM in which the program is recorded. Furthermore, the program may be distributed by storing the program in a storage device of the server computer and transferring the program from the server computer to another computer via a network.
  • a computer that executes such a program first stores a program recorded on a portable recording medium or a program transferred from a server computer in its own storage device.
  • the computer reads a program stored in its own recording medium and executes a process according to the read program.
  • the computer may directly read the program from the portable recording medium and execute processing according to the program, and the program is transferred from the server computer to the computer.
  • the processing according to the received program may be executed sequentially.
  • the program is not transferred from the server computer to the computer, and the above-described processing is executed by a so-called ASP (Application Service Provider) type service that realizes a processing function only by an execution instruction and result acquisition. It is good.
  • the program in this embodiment includes information that is used for processing by an electronic computer and that conforms to the program (data that is not a direct command to the computer but has a property that defines the processing of the computer).
  • a lossless compression encoding / decoding technique of an acoustic signal can be exemplified.
  • the present invention can also be applied to lossless compression encoding / decoding techniques such as video signals, biological signals, seismic wave signals, and sensor array signals in addition to audio signals.

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Abstract

Selon l'invention, au moins un coefficient PARCOR de premier ordre et un coefficient PARCOR de deuxième ordre sont respectivement calculés par l'analyse par prédiction linéaire d'un signal en série temporelle d'entrée ; un paramètre est déterminé conformément à la relation qui est établie entre une valeur qui est déterminée selon le coefficient PARCOR de premier ordre calculé et une valeur qui est déterminée selon le coefficient PARCOR de deuxième ordre calculé ; et un code correspondant à des informations comprenant le paramètre et le coefficient PARCOR de premier ordre ou le coefficient PARCOR de deuxième ordre est généré. Lors du décodage, la corrélation entre le coefficient PARCOR de premier ordre et le coefficient PARCOR de deuxième ordre est utilisée pour décoder les coefficients PARCOR.
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WO2015111568A1 (fr) * 2014-01-24 2015-07-30 日本電信電話株式会社 Dispositif, procédé et programme d'analyse par prédiction linéaire et support d'enregistrement

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CN110299146A (zh) * 2014-01-24 2019-10-01 日本电信电话株式会社 线性预测分析装置、方法、程序以及记录介质
CN110349590A (zh) * 2014-01-24 2019-10-18 日本电信电话株式会社 线性预测分析装置、方法、程序以及记录介质
CN106415718B (zh) * 2014-01-24 2019-10-25 日本电信电话株式会社 线性预测分析装置、方法以及记录介质
CN110415715A (zh) * 2014-01-24 2019-11-05 日本电信电话株式会社 线性预测分析装置、方法、程序以及记录介质
CN110415714A (zh) * 2014-01-24 2019-11-05 日本电信电话株式会社 线性预测分析装置、方法、程序以及记录介质
CN110415715B (zh) * 2014-01-24 2022-11-25 日本电信电话株式会社 线性预测分析装置、线性预测分析方法以及记录介质
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