JP3242353B2 - Audio signal quantization apparatus, audio signal inverse quantization apparatus, audio signal quantization method, and audio signal inverse quantization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio signal such as an audio signal or a music signal ,
Data (audio feature vector) as sub data (sub vector
Audio signal quantizer for encoding in units of
And audio signal quantization method and audio signal amount
Input the code index output from the child device,
Audio signal inverse quantization for decoding the audio signal
The present invention relates to an apparatus and an audio signal inverse quantization method .

[0002]

2. Description of the Related Art Various techniques have been proposed for efficiently encoding audio signals. A signal having a band of about 20 kHz, such as a music signal, has recently been coded using an MPEG audio system in recent years. MPEG
The method represented by the method converts the digital audio signal on the time axis to the frequency axis using orthogonal transform, and considers information on the frequency axis in consideration of human auditory sensitivity characteristics,
This is a method in which the amount of information is given priority from the auditoryly important information. To express a signal with a considerably smaller amount of information than the information amount of the original digital signal, TCWV
Q (Transform Coding for Weighted Vector Quantizat
ion), there is an encoding method using a vector quantization technique. MPEG audio and TCWVQ are based on ISO / IEC standards IS-11172-3 and T.Moriya, H.Suga: "A
n 8 Kbits transform coder for noisy channels, "Pro
c. Described in ICASSP'89, pp196-199.

Hereinafter, a conventional audio signal quantization apparatus will be described with reference to the drawings. In FIG.
101 is a code book, and 102 is an audio code selection unit. The audio code selection unit 102 receives the audio feature vector as input, and
Audible distances between each code of 01 and the audio feature vector are sequentially calculated, a code having the minimum distance is selected, and a code index corresponding to the selected code is output. Then, on the receiving side, the transmitted code index is decoded by a code decoder, and is converted into an audio feature vector using a receiver-side codebook having the same contents as the codebook 101.

[0004]

The conventional audio signal quantizing apparatus is configured as described above, and is adapted to a code which minimizes the auditory distance between each code of the codebook and the audio feature vector. Quantization is performed by outputting a code index.However, when there are many codes in a codebook, the amount of calculation becomes extremely large when searching for an optimum code, and the amount of data in the codebook is small. In the case of a large number, there is a problem that a large amount of memory is required when configuring with hardware, which is uneconomical. Further, the receiving side also has a problem that a search corresponding to the code index and a memory amount are required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has been made in consideration of the above-described problems. It is an object of the present invention to provide a device and an audio signal inverse quantization device capable of inverse quantization.

[0006]

An audio signal quantization apparatus according to a first aspect of the present invention receives an audio signal.
Frequency-converted data (audio feature vector)
Audio to be encoded in units of sub data (sub vector)
A video signal quantizer, wherein the frequency-converted
Element data belonging to the specified frequency band of the
A phase information extracting unit for extracting phase information of
A plurality of audio codes representing data by a representative value,
A value corresponding to the element data belonging to the predetermined frequency band
Is the absolute value of the audio code excluding the phase component.
Has a codebook to store, corresponding to the sub data
Search for the audio code in the codebook
Information to identify the searched audio code.
Data and the element data from which the phase component has been
Output a code index containing the phase information corresponding to the
And an audio code selection unit for inputting the audio code.

[0007] The audio signal quantization apparatus according to claim 2 of the present invention, in the audio signal quantization apparatus of 請 Motomeko 1, wherein said phase information extraction unit, wherein the frequency
Data of multiple element data included in the converted sub data
Extract the phase information of the element data belonging to the low frequency band
Is what you do.

[0008] The audio signal quantization apparatus according to claim 3 of the present invention, in the audio signal quantization apparatus of 請 Motomeko 1, further groups to the human psychoacoustic model
Sensitivity table showing the sensitivity at each frequency
Wherein the phase information extraction unit comprises:
Is included in the frequency-converted sub-data based on
Of the multiple element data, select a frequency with high hearing sensitivity
This is to extract the phase information of the element data to which it belongs .

[0009] The audio signal quantization apparatus according to claim 4 of the present invention, any one of 請 Motomeko 1 of claim 3
In the audio signal quantization device according to the above, further,
A plurality of sub-data included in the frequency-converted data
The range for each frequency,
And a smoothing unit for smoothing the sub data.
The code selector selects the input of the smoothed sub data.
Before searching for the corresponding audio code
Sub data smoothed based on information from the smoothing unit
After adjusting the scaling of the
Search code .

[0010] The audio signal quantization apparatus according to a fifth aspect of the invention, in the audio signal quantization apparatus of 請 Motomeko 4, further, the audio code selection
Sorting to sort a plurality of the sub data input to the section
Unit, wherein the sorting unit is configured to store information from the smoothing unit
Based on the hearing sensitivity table and the reference result, the audio
Taking into account both the physical characteristics of the data and the human auditory characteristics
Sort multiple sub-data in descending order of importance
It is those that.

Further, the audio signal quantization apparatus according to claim 6 of the present invention, in the audio signal quantization apparatus according to claim 5 請 Motomeko 1, wherein the frequency
The number-converted data converts the input audio signal to M
DCT (Modified Discrete Cosine Transform) Coefficient
Is what you do.

[0012] The audio signal dequantization apparatus according to the seventh aspect of the invention, the frequency inputs an audio signal
Convert the converted data (audio feature vector)
Audio signal to be encoded in data (sub-vector) units
Input the code index output from the quantizer
And an audio signal inverse amount for decoding the audio signal.
A code generator, wherein the code index is
Information that identifies the audio code that
Information including the audio information and the phase information.
Mode corresponds to the element data belonging to the predetermined frequency band.
The value is an absolute value excluding the phase component, and the phase information is
Element data from which the phase component of the corresponding audio code has been removed
The audio signal inverse quantization device
Extracts the phase information included in the code index
Phase information extracting unit, and the sub-data is represented by a representative value.
A plurality of audio codes, wherein the predetermined frequency is
The value corresponding to the element data belonging to the band excludes the phase component
Code book that stores audio codes that are absolute values
Audio that is included in the code index
Code index based on the information identifying the
The audio code corresponding to the audio
And search the code index.
Phase information included in the searched audio code.
Added as phase component of element data with phase component removed
Audio code selection to output this as an output signal
And a selector .

Also, in the audio signal quantizing method according to claim 8 of the present invention , an audio signal is inputted and frequency conversion is performed.
Converted data (audio feature vector) to sub data
Audio signal amount to be encoded in (sub-vector) units
A method of quantizing an audio signal of a decoding device, comprising:
The audio signal quantizer converts the sub data into a representative value.
A plurality of audio codes representing a predetermined frequency
The value corresponding to the element data belonging to the band excludes the phase component
Code book that stores audio codes that are absolute values
Wherein the audio signal quantization method comprises:
Belonging to a predetermined frequency band of the converted sub data
Extracting phase information of the element data to be performed;
The audio code corresponding to the sub data is
Steps to search in the book
Information identifying the radio code and the phase in the sub-data.
Including phase information corresponding to the element data from which the component has been removed
Outputting the code index .

According to a ninth aspect of the present invention, in the audio signal dequantizing method , an audio signal is input and
Convert the converted data (audio feature vector)
Audio signal to be encoded in data (sub-vector) units
Input the code index output from the quantizer
And an audio signal inverse amount for decoding the audio signal.
An audio signal inverse quantization method for a child device,
The code index represents the sub data by a representative value
Information including audio code identification information and phase information
The audio code is in a predetermined frequency band.
The value corresponding to the element data belonging to
The phase information is a corresponding audio code.
Is the phase component of the element data with the phase component of
The audio signal dequantizer substitutes the sub data for
A plurality of audio codes represented by table values,
The value corresponding to the element data belonging to a certain frequency band is the phase
Store audio code that is absolute value excluding components
An audio signal inverse quantization method comprising a codebook
Extracts the phase information included in the code index
And the steps included in the code index.
Audio code based on the information identifying the audio code.
The audio code corresponding to the index
Searching in the book,
The phase information included in the dex is
The phase component of the element data from which the phase component has been
And outputting this as an output signal.
Is included .

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, an audio signal quantization device according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an audio signal quantization device according to the present invention, and FIG. 2 is a diagram illustrating a detailed configuration of an encoding unit included in the audio signal quantization device according to the first embodiment. In the figure, 1 is an encoding unit, 2 is a decoding unit, 3 is a transmission-side codebook having a plurality of audio codes, which are representative values of characteristic amounts of audio signals, and 1
02 is an audio code selection unit, and 107 is a phase information extraction unit. Reference numeral 5 denotes a code decoding unit, and reference numeral 6 denotes a reception-side codebook.

The operation will be described below. When quantizing a digital audio signal on the time axis, data on the time axis is converted into data on the frequency axis by using orthogonal transform called time-frequency conversion. DFF as orthogonal transformation
T (Discrete Fourier Transform), MDCT (Modified Discrete Cosine Transform) and the like.

As shown in FIG. 3, when the data on the frequency axis is regarded as one sound source vector, sub-vectors are obtained by extracting some elements from the sound source vector. In this case, the audio code selection unit 102 calculates the distance between each code in the transmission-side codebook 3 and the input vector, selects the code having the minimum distance, and selects the code of the selected code. The code index in the transmission side codebook 3 is input to the decoding unit 2. The decoding unit 2 serving as a receiving unit receives the output code index as an input to the code decoding unit 5, outputs a code corresponding to the code index in the reception side codebook 6 to the code decoding unit 5, and outputs the code to the code decoding unit 5. 5 is output as an output vector.

In the above operation, the process of inputting an input vector to the encoding unit 1 and outputting the code index by the encoding unit 1 is encoding. Until an output vector is output using the code index as an input. Is the decryption process. In many cases, the transmission-side codebook 3 and the reception-side codebook 6 often have the same contents. However, in the first embodiment, the reception-side codebook 6 stores the transmitted code index as in the related art. The description will be made assuming that the code has the same number of codes. The detailed operation of the encoding unit 1 will be described below with reference to FIGS. Here, it is assumed that coding is performed in 10 bits in order to target 20 KHz. Further, the phase information extraction unit 107 extracts the phase to be extracted from the lowest frequency element to the second element, that is, 2 bits. The input of the audio code selection unit 102 is an audio feature vector. For example, an audio signal is subjected to MDCT (Modified Discrete Cosine Transform).
m), when the coefficient obtained as a single vector is obtained, the vector is divided, and several elements, for example, about 20 elements, are converted into one subvector. At this time, the vectors are X _{0 to} X _19, and the sub-vector element having a smaller subscript of X has a lower MDC having a lower frequency component.
Let it correspond to the T coefficient. Here, the low frequency component is information that is perceptually important to humans, and therefore, by giving priority to coding of these elements, it is difficult for humans to feel deterioration in sound quality during reproduction.

The audio code selection unit 102 calculates the distance between the audio feature vector and each code in the transmission side code book 3. For example, when the code index is i, the distance Di in the code of the code index i can be calculated by Expression 1.

[0020]

(Equation 1)

In the above equation (1), N is the number of all codes in the transmission side code book 3, and Cij is the value of the j-th element in the code index I. M is 19 or less, for example, 1 in the first embodiment. P is the norm in the distance calculation, for example,
2 and so on. Abs () means an absolute value operation.

In the phase information extracting section 107, the minimum distance Di
Index i and M pieces of phase information Ph (j)
Outputs j = 0 to M. The phase information Ph (j) is given by

[0023]

(Equation 2)

The audio feature vector converts the audio signal to the MD.
In the case where the vector is a sub-vector of a CT-transformed vector, the smaller the subscript j of Xj is, the higher the auditory importance of the coefficient is. Therefore, according to this configuration, the phase corresponding to the element of the low frequency component of each sub-vector Regarding (positive / negative), such information is not considered at the time of code search, and is added separately after the search. That is, FIG.
As shown in (a), the sub-vectorized audio feature vector is compared with the code of the transmission side code book 3 ignoring the sign of the two-bit element on the low frequency side. For example, here, the elements of 2 bits on the low frequency side are both stored as positive.
56 codes are stored, and the audio code selection unit 102 searches the input subvector and the 256 codes of the transmission side codebook 3. Then, for the obtained code, the phase information extraction unit 1
07, one of the combinations shown in FIG. 4 (b) is added as a plus / minus sign of 2 bits on the lower frequency side of the subvector, for a total of 10 bi.
Output as a code index of t.

By doing so, the code index sent from the encoding unit 1 to the decoding unit 2 becomes 1 as in the prior art.
The code stored in the transmission side codebook 3 can be set to 8 bits (256) while keeping 0 bits (1024), and the sum of the amount of information with the phase information is calculated as When the amount of information is the same, a substantially equivalent subjective evaluation result can be obtained by comparing the synthesized speech decoded by the following Expression 3 with the synthesized speech of the present configuration.

[0026]

(Equation 3)

Table 1 shows the relationship between the amount of calculation and the amount of memory when this configuration and Equation 3 are used.

[0028]

[Table 1]

In the configuration of the present embodiment, the codebook is one quarter and the amount of calculation has conventionally required 1024 types of search processing. All you have to do is add the two codes.
It can be seen that the amount of calculation and memory can be significantly reduced.

As described above, according to the first embodiment, when encoding is performed by the encoding unit 1, the sub-vector created by dividing the audio feature vector and each audio In selecting the audio code that has the minimum distance from the audible distance to the code,
For the portion corresponding to the sub-vector element having high auditory importance, the audio code selection unit 102 treats the portion ignoring the sign indicating the phase information, and compares it with the audio code in the transmission side code book 3. Do
Separately, the phase information corresponding to the element portion of the sub-vector extracted by the phase information extraction unit 107 is added to the obtained result and output as a code index, so that the perceived sound quality does not deteriorate. The amount of calculation in the audio code selection unit 102 can be reduced, and the number of codes required for the code books 3 and 101 can also be reduced.

Embodiment 2 Hereinafter, an audio signal quantization apparatus according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 5A is a diagram illustrating a configuration of an audio signal quantization device according to Embodiment 2.
In FIG. 3, reference numeral 103 denotes an psychoacoustic weight vector table for storing a table of relative psychological quantities at each frequency in consideration of psychoacoustic characteristics of a human.

The operation will be described below. The difference from the first embodiment is that the psychoacoustic weight vector table 10
3 is a newly added configuration. The psychoacoustic weight vector is based on a human psychoacoustic model, and from an auditory sensitivity table defined as an auditory sensitivity characteristic with respect to frequency, the same frequency band for each element of the audio feature vector that is the input of the present embodiment. It is a collection of elements into a vector. This is illustrated in FIG.
As shown in (b), it has a peak at a frequency of about 2.5 KHz, and it can be seen that the one at the lowest frequency is not necessarily important to human hearing.

That is, in the present embodiment, the audio feature vector is input to the audio code selection unit 102, and the psychoacoustic weight vector table 103 is used as the weight at the time of code selection. The auditory distance from the feature vector is calculated, and the code index for the code that gives the minimum distance is output. When the code index is i, the distance scale Di at the time of code selection in the audio code selection unit 102 is, for example,

[0034]

(Equation 4)

## EQU1 ## Here, N is the number of all codes in the transmission side codebook 3, and Cij is the value of the j-th element in the code index i. M is a number of 19 or less, for example, 1 in the present embodiment. P is a norm in the distance calculation, for example, 2 or the like. Wj
Is the j-th element of the psychoacoustic weight vector table 103. Abs () means an absolute value operation.

The phase information extraction unit 107 determines from the psychoacoustic weight vector table 103 which phase information of an element corresponding to an audio feature vector of which frequency is to be extracted, and a code index I that gives the minimum Di in the range. And M pieces of phase information Ph (j) j = 0 to M are output. The phase information Ph (j) is similarly defined by Expression 2.

As described above, according to the second embodiment, when encoding is performed by the encoding unit 1, the sub-vectors created by dividing the audio feature vector and each audio In selecting the audio code that has the minimum distance from the audible distance to the code,
For the portion corresponding to the sub-vector element having high auditory importance, the audio code selection unit 102 treats the portion ignoring the sign indicating the phase information, and compares it with the audio code in the transmission side code book 3. Do
Separately, the phase information corresponding to the element portion of the sub-vector extracted by the phase information extraction unit 107 is added to the obtained result and output as a code index, so that the perceived sound quality does not deteriorate. The amount of calculation in the audio code selection unit 102 can be reduced, and the number of codes required for the code books 3 and 101 can also be reduced.

The audio code selecting section 102
The audio feature vector handled by ignoring the sign indicating the phase information is weighted using the psychoacoustic weight vector table 103 that stores a table of the relative psychological quantity at each frequency in consideration of the psychoacoustic characteristics of a human. By doing so, it is possible to perform quantization with excellent sound quality more sensuously than in the case of simply selecting a predetermined number of audio feature vectors from the low band as in the first embodiment.

Embodiment 3 Hereinafter, an audio signal quantization device according to Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 6A is a diagram illustrating a configuration of an audio signal quantization device according to the third embodiment.
In the figure, reference numeral 104 denotes a smooth vector table, which actually stores data such as a division curve. 105
Represents the audio feature vector as a smooth vector table 10.
4 is a smoothing unit that performs smoothing by dividing vector elements using the smoothed vector stored in No. 4.

The operation will be described below. What is input to the smoothing unit 105 is an audio feature vector, similarly to the audio signal quantizing devices in the first and second embodiments.
In step 5, a smoothing operation is performed on the input audio feature vector using a division curve that is a smooth vector stored in the smooth vector table 104. This smoothing operation is performed, for example, when the input audio feature vector is X, the smoothed vector 104 is F, the output of the smoothing unit 105 is Y, and the I-th element of each vector is Xi, Fi, Yi. Then, the processing represented by Expression 5 is performed.

[0041]

(Equation 5)

In general, when the audio feature vector is an MDCT coefficient, the smoothed vector table 104 has a value that reduces the variance of the MDCT coefficient.
FIG. 6 (b) schematically shows the smoothing process, in which two of the sub-vectorized elements are counted from the low frequency side.
By performing the division process on one element, the difference (range) of the information amount for each frequency can be reduced.

The output of the smoothing unit 105 is input to the audio code selection unit 102, and the code selection unit 1
02, the phase information of the smoothed audio feature vector is extracted by the phase information extraction unit 107 for the elements from the lowest frequency to the second element, as in the first embodiment. On the other hand, in the audio code selection unit 102, the 256
Search with this code. At this time, a code index (8 bits) corresponding to the search result obtained as it is
Is output, the correct search result cannot be obtained. Therefore, the information at the time of the smoothing process is received from the smoothing vector table 104, the scaling is adjusted, and the code index (8 bits) corresponding to the search result is selected. The result obtained in this way is added with 2-bit phase information, and a 10-bit code index I is output.

At this time, the distance Di between the audio vector and the code stored in the codebook 31 is represented by, for example, Equation 6 where each i-th element of the smoothed vector table 104 is Fi.

[0045]

(Equation 6)

Here, N is the number of all codes in the transmission side code book 31, and Cij is the value of the j-th element in the code index i. In the present embodiment, M is a number of 19 or less, for example, 1 or the like. P is a norm in the distance calculation, for example, 2 or the like. Wj
Is the j-th element of the psychoacoustic weight vector table 103. Abs () means an absolute value operation. The phase information extraction unit 107 outputs a code index i that gives the minimum Di and M pieces of phase information Ph (j) j = 0 to M. The phase information Ph (j) is similarly defined by Expression 2.

As described above, according to the third embodiment, when encoding is performed by the encoding unit 1, the sub-vectors created by dividing the audio feature vector and each audio In selecting the audio code having the minimum distance from the audible distance to the code, a portion corresponding to the element of the sub-vector having high audibility is positive or negative indicating the phase information by the audio code selection unit 102. The code is treated ignoring the code, a comparison search with the audio code of the transmission side code book 31 is performed, and phase information corresponding to the element part of the sub-vector extracted by the phase information extraction unit 107 is separately added to the obtained result. Since the audio code is output as a code index, the audio code selection unit 10 does not cause a perceptible deterioration in sound quality. In reduces the amount of calculation, also can be reduced even code number necessary codebook 3,101.

Further, since the input audio feature vector is smoothed using the smoothing table 104 and the smoothing unit 105, the audio code selecting unit 102
Sender codebook 31 referred to when searching by
The amount of information for each frequency of the codebook stored in the codebook can be reduced as a whole.

Embodiment 4 Hereinafter, an audio signal quantization device according to Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 7 is a diagram showing a configuration of an audio signal quantization device according to Embodiment 4 of the present invention.
In the figure, the difference from the third embodiment shown in FIG. 4 is that when the audio code selecting unit 102 selects a code,
The point is that the psychoacoustic weight vector table 103 used in the second embodiment is used in addition to the smooth vector table 104.

The operation will be described below. Smoothing unit 1
Input to the audio code vector 05 is an audio feature vector, as in the above embodiments. The output of the smoothing unit 105 is input to the audio code selection unit 102, and the audio code selection unit 102 The distance between each code in the book 31 and the output of the smoothing unit 105 is determined based on the information at the time of the smoothing process output from the smoothing vector table 104 while taking into account the scaling at the time of the smoothing process. The calculation is made in consideration of the weighting by the psychoacoustic weight vector 103. Using the same notation as in Embodiments 2 and 3, distance Di is:
For example, it is shown as in equation (7).

[0051]

(Equation 7)

Here, N is the number of all codes in the transmission side code book 31, and Cij is the value of the j-th element in the code index i. M is in the case of this embodiment,
The number is 19 or less, for example, 1 or the like. P is a norm in the distance calculation, for example, 2 or the like. Wj is the j-th element of the psychoacoustic weight vector table 103. Abs () means an absolute value operation. The phase information extraction unit 107 outputs a code index I that gives the minimum Di and M pieces of phase information Ph (j) j = 0 to M. The phase information Ph (j) is similarly defined by the above equation (2).

As described above, according to the fourth embodiment, when encoding is performed by the encoding unit 1, the sub-vectors created by dividing the audio feature vector and each audio In selecting the audio code having the minimum distance from the audible distance to the code, a portion corresponding to the element of the sub-vector having high audibility is positive or negative indicating the phase information by the audio code selection unit 102. The code is treated ignoring the code, a comparison search with the audio code of the transmission side code book 31 is performed, and phase information corresponding to the element part of the sub-vector extracted by the phase information extraction unit 107 is separately added to the obtained result. Since the audio code is output as a code index, the audio code selection unit 10 does not cause a perceptible deterioration in sound quality. It reduces the calculation amount in, and can also reduce the number of codes required for transmitting side code book 31.

The audio code selection unit 102
The audio feature vector handled by ignoring the sign indicating the phase information is weighted using the psychoacoustic weight vector table 103 that stores a table of the relative psychological quantity at each frequency in consideration of the psychoacoustic characteristics of a human. By doing so, it is possible to perform quantization with excellent sound quality more sensuously than in the case of simply selecting a predetermined number of audio feature vectors from the low band as in the first embodiment.

Further, the input audio feature vector is smoothed using the smoothing table 104 and the smoothing unit 105.
Sender-side codebook 3 that is referenced when performing a search in 2
1, the amount of information for each frequency of the codebook stored in the storage unit 1 can be reduced as a whole.

Embodiment 5 Hereinafter, an audio signal quantization device according to Embodiment 5 of the present invention will be described with reference to the drawings. FIG. 8 is a diagram showing a configuration of an audio signal quantization device according to Embodiment 5 of the present invention.
In the figure, reference numeral 106 denotes a sort unit, which outputs the psychoacoustic weight vector table 103 and the smoothed vector table 1.
04, the plurality of the largest elements among the calculated vectors are selected and output.

The operation will be described below. The configuration difference between the fifth embodiment and the fourth embodiment is that the sorting unit 106 is added and the method of selecting and outputting the code index of the audio code selection unit 102 is different. That is, the sorting unit 106 receives the psychoacoustic weight vector table 103 and the output of the smooth vector table 104 as inputs, and
If the ith element is defined as WFj, it is expressed by the following equation (8).

[0058]

(Equation 8)

The sorting unit 106 calculates the largest R elements from the respective elements WFj of the vector WF, and uses the R element numbers as the output of the sorting unit 106. The audio code selection unit 102 calculates the distance Di as in the above embodiments. The distance Di is, for example,
It is shown by the following equation (9).

[0060]

(Equation 9)

Here, Rj is determined by the sorting unit 106.
If the element number is an output element number, Rj is 1, and if it is not an output element number, Rj is 0. N is the number of all codes in the transmission side codebook 31, and Cij is the value of the j-th element in the code index i. M is a number of 19 or less, for example, 1 in the present embodiment.
P is a norm in the distance calculation, for example, 2 or the like. Wj is j in the psychoacoustic weight vector table 103
Element. Abs () means an absolute value operation. The phase information extraction unit 107 outputs a code index I that gives the minimum Di and M pieces of phase information Ph (j) j = 0toR. The phase information Ph (j) is defined by Expression 10.

[0062]

(Equation 10)

However, Ph (j) is calculated only for those corresponding to the element numbers output by the sorting unit 106. In this example, the number is (R + 1). In the case where the configuration of the fifth embodiment is used, it is necessary that the decoding unit 2 having the configuration of FIG.

As described above, according to the fifth embodiment, in the fourth embodiment, the output of the smoothed vector table 104 and the output of the psychoacoustic weight vector table 103 are received. Is selected, ie, a plurality of elements having a large absolute weight value are selected and output to the audio code selection unit 102. Therefore, elements that are significant for human auditory characteristics and elements that are physically important The code index can be calculated in consideration of both factors, and higher quality audio signal compression can be performed. In the fifth embodiment, the number of elements to be selected from those having the largest absolute value of the weight in consideration of both the smooth vector 104 and the psychoacoustic weight vector 103 is R.
The same numerical value as M used in the first to fourth embodiments may be used.

Embodiment 6 FIG. Hereinafter, an audio signal dequantization device according to Embodiment 6 of the present invention will be described with reference to the drawings. FIG. 9 is a diagram showing a configuration of an audio signal inverse quantization apparatus according to Embodiment 6 of the present invention. In FIG. 9, reference numeral 21 denotes the decoding unit of FIG. The code decoding unit 51 includes an audio code selection unit 102 and a phase information extraction unit 107.

The operation will be described below. In the sixth embodiment, when the code index is received and decoded, the quantization scheme shown in the first to fifth embodiments is applied. A comparison search is performed on the remaining 8 bits of the 10-bit code index excluding the 2-bit elements from the low-frequency side of the human auditory significance, with the code stored in the reception-side codebook 61. By extracting the phase information of the 2 bits of the excluded elements using the phase information extracting unit 107 and adding the extracted information to the search result,
The audio feature vector is reproduced, that is, inverse quantization is performed.

In this way, the reception-side codebook only needs to store 256 codes corresponding to 8-bit elements, and the amount of data stored in the reception-side codebook 61 is small. In addition, the calculation in the audio code selection unit 102 is a process of 256 times of code search and a process of adding two codes to the search result, and the amount of calculation can be greatly reduced.

In the sixth embodiment, the first embodiment is used.
Is applied to the configuration on the receiving side, but the configuration shown in Embodiments 2 to 5 can also be applied, and instead of using the receiving side alone, When used in combination with any of the first to fifth embodiments, an audio data transmission / reception system that can smoothly compress and expand an audio signal can be constructed.

[0069]

As described above, according to the audio signal quantization apparatus according to the first aspect of the present invention, the audio signal is
Input and frequency converted data (audio feature vector
) In sub-data (sub-vector) units
An audio signal quantizer, comprising:
Of the sub-data that belongs to the specified frequency band
A phase information extracting unit for extracting phase information of data;
Audio data representing the audio data with a representative value.
Corresponding to the element data belonging to the predetermined frequency band.
Audio code whose absolute value excludes the phase component
A code book for storing the sub-data,
Whether the corresponding audio code is in the codebook
Search and identify the searched audio code
And phase information in the sub-data
Code index including phase information corresponding to raw data
And an audio code selection unit that outputs
There is an effect that the amount of calculation in the audio code selection unit can be reduced and the number of codes to be stored in the code book can be reduced without causing a perceptible deterioration in sound quality.

[0070] Further, according to the audio signal quantization apparatus according to claim 3 of the present invention, in the audio signal quantization apparatus of 請 Motomeko 1, further comprising a human psychoacoustic model
Auditory sensitivity table representing the auditory sensitivity at each frequency based on
And the phase information extracting unit includes the audio information table.
Included in the frequency-converted sub-data based on the
Frequency of high sensitivity
Since the phase information of the element data belonging to the number is extracted , there is an effect that quantization with excellent sound quality can be performed more intuitively.

[0071] Further, according to the audio signal quantization apparatus according to claim 4 of the present invention, according to claim 3 noise from 請 Motomeko 1
In the audio signal quantization apparatus according Rekani, further
A plurality of subs contained in the frequency-converted data.
For data, reduce the range for each frequency,
A smoothing unit for smoothing the sub data of
The audio code selector inputs the smoothed sub data.
When searching for the corresponding audio code
Then, based on the information from the smoothing unit,
After adjusting the data scaling, the corresponding
Since the search for the audio code is performed, the amount of information for each frequency of the codebook stored in the codebook, which is referred to when searching in the audio code selection unit, can be reduced as a whole. effective.

[0072] Further, according to the audio signal quantization apparatus according to claim 5 of the present invention, in the audio signal quantization apparatus of 請 Motomeko 4, further, the audio code
A source for rearranging a plurality of the sub-data input to the selection unit.
A sorting unit, wherein the sorting unit is configured to output information from the smoothing unit.
Based on the hearing sensitivity table and the reference result.
Both the physical characteristics of the audio data and the human auditory characteristics
Multiple sub-data items are arranged in descending order of importance
The code index can be calculated by taking into account both the factors that are significant for the human auditory characteristics and those that are physically important, thus achieving higher quality audio signal compression. There is an effect that can be done.

Further, according to the audio signal dequantizing apparatus according to claim 7 of the present invention, an audio signal is input and
Wave number converted data (audio feature vector)
Audio to be encoded in units of data (subvector)
Enter the code index output from the signal quantizer.
Audio signal to decode and decode the audio signal
The quantization device, wherein the code index is:
Identify audio code that represents sub data with representative value
Information including information and phase information, wherein the audio
The code corresponds to the element data belonging to the predetermined frequency band.
Is the absolute value excluding the phase component, and the phase information is
Element data from which the phase component of the corresponding audio code has been removed
Phase component of the audio signal,
Extract the phase information included in the code index.
A phase information extraction unit to output the sub-data and a representative value.
A plurality of audio codes, wherein the predetermined frequency is
The values corresponding to the element data belonging to several bands exclude the phase component.
Code to store the absolute audio code
Audio code included in the code index
The code index based on the information identifying the
The audio code corresponding to the
And search the code index
Phase information contained in the audio code
Is added as the phase component of the element data with the phase component removed.
In addition, since an audio code selector is provided for outputting this as an output signal, the amount of data stored in the codebook used on the receiving side can be reduced, and the amount of calculation on the receiving side can be greatly increased. There is an effect that can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conceptual configuration of an audio signal quantization device according to the present invention.

FIG. 2 is a diagram illustrating a detailed configuration of an encoding unit of the audio signal quantization device according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of an audio feature vector of the audio signal quantization device according to the first embodiment.

FIG. 4 is a diagram for describing an encoding process of the audio signal quantization device according to the first embodiment.

FIG. 5 is a diagram illustrating a detailed configuration of an encoding unit of the audio signal quantization device according to Embodiment 2 of the present invention, and is a diagram illustrating an example of an psychoacoustic weight vector table.

FIG. 6 is a diagram illustrating a detailed configuration of an encoding unit of an audio signal quantization device according to Embodiment 3 of the present invention, and a diagram for describing processing in a smoothing unit.

FIG. 7 is a diagram illustrating a detailed configuration of an encoding unit of an audio signal quantization device according to Embodiment 4 of the present invention.

FIG. 8 is a diagram illustrating a detailed configuration of an encoding unit of an audio signal quantization device according to a fifth embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of an audio signal inverse quantization device according to Embodiment 6 of the present invention.

FIG. 10 is a diagram showing a configuration of a conventional audio signal quantization device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Encoding part 2, 21 Decoding part 3, 31 Transmission codebook 4 Audio code selection part 5 Code decoding part 6, 61 Reception side codebook 102 Audio code selection part 103 Perceptual psychological weight vector table 104 Smooth vector table 105 Smoothing Conversion unit 106 sorting unit 107 phase information extraction unit

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomokazu Ishikawa 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-9-130260 (JP, A) JP-A-59- 94797 (JP, A) JP-A-7-248799 (JP, A) JP-A-9-8667 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G10L 19/00-19 / 14 H03M 7/30 H04B 14/04

Claims (9)

(57) [Claims] An audio signal is input and frequency-converted.
Data (audio feature vector)
Vector) audio signal quantization unit
A predetermined frequency of the frequency-converted sub-data.
Phase information for extracting phase information of element data belonging to band
An extraction unit, and a plurality of audio codes representing the sub-data as representative values;
Element data belonging to the predetermined frequency band.
Is the absolute value excluding the phase component.
And a code book for storing the audio code.
Search in the codebook and search for
Information identifying the audio code and the position in the sub data
Phase information corresponding to the element data with the phase component removed.
And an audio code selection unit for outputting a code index . 2. The method according to claim 1, wherein the phase information extracting unit is configured to perform the frequency conversion.
Of the multiple element data included in the sub data
Extract phase information of element data belonging to low frequency band
The audio signal quantization device according to claim 1, wherein: 3. The audio signal quantizing device further comprises:
Then, based on the human psychoacoustic model,
A hearing sensitivity table representing perceptual sensitivity, wherein the phase information extraction unit is configured to perform
A plurality of frequency-converted sub-data
Of the element data, belongs to the frequency with high auditory sensitivity
Claims: extracting phase information of element data.
Item 3. The audio signal quantization device according to Item 1 . 4. The audio signal quantizing device further comprises:
A plurality of subs contained in the frequency-converted data.
For data, reduce the range for each frequency,
Said comprising a smoothing unit for smoothing the sub data, the audio code selection unit was smoothed Sabude
Data input and search for the corresponding audio code
On the basis of the information from the smoothing unit,
After adjusting the sub data scaling,
Claim, characterized in that to search for audio code 1
An audio signal quantization device according to any one of claims 1 to 3 . 5. The audio signal quantizing device further comprises:
A plurality of the above-mentioned input to the audio code selection unit.
A sorter for rearranging the sub-data, wherein the sorter includes information from the smoother and the auditory sensitivity
Based on the table and the reference result, the audio data
Importance considering both physical characteristics and human auditory characteristics
Sorting the plurality of sub-data in descending order of
5. The audio signal quantization device according to claim 4, wherein: 6. The frequency-converted data is inputted.
Transform the transformed audio signal (modified discrete cosine)
2. The method according to claim 1, wherein the converted coefficient is used as an element.
An audio signal quantization device according to any one of claims 1 to 5 . 7. An audio signal is input and frequency-converted.
Data (audio feature vector)
Vector) audio signal quantization unit
Enter the code index output from the
Audio signal dequantizer that decodes audio signals
The code index indicates the sub data as a representative value.
Information identifying the audio code to be represented and phase information.
The audio code is at a predetermined frequency.
The value corresponding to the element data belonging to the band excludes the phase component
And the phase information is the corresponding audio code.
Is the phase component of the element data from which the phase component of the
The audio signal dequantizer extracts phase information included in the code index.
A phase information extracting unit, and a plurality of audio codes representing the sub-data as representative values;
Element data belonging to the predetermined frequency band.
Is the absolute value excluding the phase component.
An audio code included in the code index.
Corresponds to the code index based on the identifying information
The audio code from the codebook
Search and included in the code index
Phase information is searched for the phase component in the searched audio code.
Is added as the phase component of the element data from which
Audio code selector for outputting as an output signal
An audio signal inverse quantization device , characterized in that: 8. An audio signal is input and frequency-converted.
Data (audio feature vector)
Vector) audio signal quantization unit
An audio signal quantizing method, wherein the audio signal quantizing device substitutes the sub data.
A plurality of audio codes represented by table values,
The value corresponding to the element data belonging to the frequency band is the phase component
Code that stores the audio code that is the absolute value excluding
Comprising a codebook, said audio signal quantization method, the predetermined frequency of the frequency-converted sub data has been
Step of extracting phase information of element data belonging to a band
And the audio code corresponding to the sub-data is
Searching the code book; information identifying the searched audio code;
Position corresponding to the element data from which the phase component has been
Outputting a code index including phase information
Audio signal quantization direction, characterized in that including bets
Law . 9. An audio signal is input and frequency-converted.
Data (audio feature vector)
Vector) audio signal quantization unit
Enter the code index output from the
Audio signal dequantizer that decodes audio signals
An audio signal inverse quantization method, wherein the code index represents the sub-data as a representative value.
Information identifying the audio code to be represented and phase information.
The audio code is at a predetermined frequency.
The value corresponding to the element data belonging to the band excludes the phase component
And the phase information is the corresponding audio code.
Is the phase component of the element data from which the phase component of the
The audio signal dequantizer includes a plurality of audio codes representing the sub-data as representative values.
Element data belonging to the predetermined frequency band.
Is the absolute value excluding the phase component.
An audio codec, wherein the audio signal dequantization method extracts phase information included in the code index.
And an audio code included in the code index.
Corresponds to the code index based on the identifying information
The audio code from the codebook
Searching , and searching for phase information included in the code index.
Of the audio code with the phase component removed
Output as an output signal.
Audio signal inverse quantization wherein the comprising the steps of.