JP2002374171A - Encoding device and method, decoding device and method, recording medium and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable coding, without enlarging the scale of a code sequence table. SOLUTION: A control section 31 rearranges, as required, the lines of quantized spectra 401, which are put together into one group by M pieces to integrate them into ascending order or descending order, and encodes them by controlling a encoding section 32. Also the section 31 controls an encoding section 33 to encode rearrangement information representing the original arrangement of the spectra 401. The section 32 encodes the M pieces of quantized spectra, which are put together into one a single group by using a prescribed code sequence table. The section 33 encodes the rearrangement information by using a prescribed code sequence table.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoding apparatus and method, a decoding apparatus and method, a recording medium, and a program, and performs encoding, transmission, recording, and reproduction of input digital data by so-called high-efficiency encoding. The present invention relates to an encoding device and method, a decoding device and method, a recording medium, and a program suitable for use in obtaining a reproduced signal by decoding.

[0002]

2. Description of the Related Art There are various methods for high-efficiency encoding of signals such as audio or voice. For example, an audio signal or the like on a time axis is divided into a plurality of frequency bands and encoded without being blocked. Sub-band coding (sub-band coding: SBC (Subband Coding)), which is a non-blocking frequency band division method, or converting a signal on the time axis to a signal on the frequency axis (spectral conversion), A block frequency band division method of dividing the signal into frequency bands and encoding the respective bands, that is, a so-called transform coding method can be used.

[0003] Also, a high-efficiency coding method combining the above-mentioned band division coding and transform coding has been considered.
In this case, for example, after band division is performed by band division coding, the spectrum of the signal in each band is converted into a signal on the frequency axis, and the spectrum-converted band is encoded. Here, as a filter for band division described above, for example, a QMF filter (Quadrature Mirror Filter)
For this, for example, 1976 RECrochiere
Digital coding of speech in subbands, Bell Syst.
Tech. J. Vol. 55, No. 8 1976.

Also, ICASSP 83, BOSTON Polyphase Quadr
ature filters-A new subband coding technique, Jose
ph H. Rothweiler describes an equal bandwidth filter partitioning technique. Here, as the above-mentioned spectral transform, for example, an input audio signal is divided into blocks in a predetermined unit time (frame), and a discrete Fourier transform (DFT), a discrete cosine transform (Discrete Cosine Transform) is performed for each block. (DCT), Modified Discrete Cosine Transfo
rm) (MDCT) or the like, there is a spectrum conversion that converts the time axis to the frequency axis. For MDCT, for example, ICASSP 1987 Subband / Transform Coding Using Filt
er Bank Designs Based on Time Domain Aliasing Canc
ellation, JPPrincen ABBradley Univ. of Surr
ey Royal Melbourne Inst. of Tech.

[0005] By quantizing the signal divided for each band by the filter or the spectrum conversion as described above,
A band in which quantization noise is generated can be controlled, and a more efficient coding can be perceptually performed by utilizing properties such as a masking effect. Further, if the normalization is performed for each band, for example, with the maximum value of the absolute value of the signal component in the band before the quantization is performed, more efficient encoding can be performed.

[0006] As a frequency division width for quantizing each frequency component divided into frequency bands, for example, band division is performed in consideration of human auditory characteristics. That is, an audio signal may be divided into a plurality of bands (for example, 32 bands) in a band generally called a critical band (critical band) such that the higher the band, the wider the bandwidth. When encoding data in each band at this time, predetermined bits are allocated to each band, or encoding is performed by adaptive bit allocation (bit allocation) for each band.

For example, when encoding the coefficient data obtained by the MDCT processing by the bit allocation, adaptively assigning to the MDCT coefficient data of each band obtained by the MDCT processing of each block is performed. The encoding is performed with the number of bits. The following two methods are known as bit allocation methods.

The first method is Adaptive Transform Codin
g of Speech Signals, R. Zelinskiand P. Noll, IEEE Tr
ansactions of Accoustics, Speech, and Signal Process
ing, vol. ASSP-25, No. 4, August 1977. Here, bit allocation is performed based on the magnitude of the signal in each band. In this method, the quantization noise spectrum is flattened and the noise energy is minimized, but the actual noise sensation is not optimal because the masking effect is not used for the sense of hearing.

The second method is ICASSP 1980 The crit
ical band coder-digital encodingof the perceptual
requirements of the auditory system, MAKransner
Disclosed to MIT. Here, a method is described in which a necessary signal-to-noise ratio is obtained for each band by using auditory masking and fixed bit allocation is performed. However, in this method, even when the characteristic is measured with a sine wave input, the characteristic value is not so good because the bit allocation is fixed.

[0010] In order to solve these problems, all bits that can be used for bit allocation include a fixed bit allocation pattern predetermined for each small block and a bit allocation depending on the signal size of each block. A high-efficiency coding apparatus has been proposed in which a division ratio is used depending on the amount to be performed, and the division ratio depends on a signal related to an input signal, and the smoother the spectrum of the signal, the larger the division ratio into the fixed bit allocation pattern. ing.

According to this apparatus, when energy is concentrated on a specific spectrum such as a sine wave input, a large number of bits are allocated to a block including the spectrum, thereby significantly improving the entire signal-to-noise characteristic. Can be improved. In general, human hearing is extremely sensitive to signals having steep spectral components. Therefore, using such a method to improve the signal-to-noise characteristics merely improves the numerical values measured. In addition, it is effective in improving sound quality in terms of hearing.

[0012] Many other methods of bit allocation have been proposed. In addition, if an auditory model is refined and the capacity of the encoding device is increased, a code that is more efficient in terms of auditory sense will be provided. Becomes possible.

The present inventors have also disclosed in Japanese Patent Application No. 5-15286.
No. 5 has previously proposed a method of separating a tone component, which is particularly important in terms of audibility, from a spectral signal and coding the component separately from other spectral components. As a result, it is possible to efficiently encode an audio signal or the like at a high compression rate with almost no audible deterioration.

When the above-described DFT or DCT is used as a method of converting a waveform signal into a spectrum, M independent real number data can be obtained by performing conversion using a time block including M samples. In order to reduce the connection distortion between time blocks, each block usually overlaps the neighboring blocks with M1 samples each, so on average, DF
In T or DCT, M real number data is quantized and encoded for (M-M1) samples.

On the other hand, when the above-mentioned MDCT is used as a method of converting into a spectrum, independent 2N samples are overlapped with N times each of the adjacent times.
Since M pieces of real number data are obtained, on average, the MDCT quantizes and codes M pieces of real number data for M samples. In the decoding device, it is possible to reconstruct the waveform signal from the code obtained by using the MDCT in this way by adding the waveform elements obtained by performing the inverse transform in each block while interfering with each other. it can.

In general, by extending the time block for the transformation, the frequency resolution of the spectrum is increased,
Energy concentrates on specific spectral components. Therefore, the DFT is performed by using a MDCT in which the conversion is performed with a long block length by overlapping the neighboring blocks by half each and the number of obtained spectral signals does not increase with respect to the number of original time samples. It is possible to perform more efficient coding than when DCT or DCT is used.
In addition, by providing a sufficiently long overlap between adjacent blocks, distortion between blocks of a waveform signal can be reduced.

In constructing an actual code sequence, first, quantization accuracy information and normalization coefficient information are encoded with a predetermined number of bits for each band in which normalization and quantization are performed. What is necessary is just to encode the quantized spectrum signal.

For encoding a spectrum signal, a method using a variable length code such as a Huffman code is known. For Huffman codes, for example,
DavidA. Huffman, "A Method for the Construction of
Minimum-Redundancy Codes ", Proceedings of the I.
RE, pp 1098-1101, Sep., 1952.

Further, a plurality of spectral signals are collected into one
A method using a multidimensional variable length code expressed by two codes is known. Generally, in an encoding method using a multidimensional variable length code, as the order of the code is larger, more efficient encoding can be performed in terms of compression efficiency. However, as the order increases, the size of the code string table dramatically increases, which causes a problem in practical use. In practice, an optimal order according to the purpose is selected in consideration of the compression efficiency and the size of the code string table.

In general, in an acoustic waveform signal, energy is often concentrated on a fundamental frequency component and a frequency component that is an integral multiple of the fundamental frequency, that is, a so-called harmonic component, and the level of a spectrum signal around the frequency is higher than that of a so-called harmonic component. Since it is very small, the probability of being quantized to zero increases. In order to efficiently encode such a signal, it is sufficient to encode a spectrum signal quantized to 0 having a large occurrence probability with a minimum amount of information.
When a one-dimensional variable length code is used, even if each spectrum signal is encoded with the shortest code length of 1 bit, N
The spectrum of the book requires N bits of information. Order N
In the case of using the multi-dimensional variable-length code, since N spectra can be encoded with the shortest code length of 1 bit, efficient encoding can be performed on a signal having frequency components as described above. Can be performed.

However, in the encoding method using a multidimensional variable length code, increasing the order of the code has a considerable advantage in terms of compression efficiency, but in consideration of practical use, the code of the code is not limited. It is impossible to increase the order.

Normally, a code string table is prepared for each piece of quantization accuracy information set for each band. If the quantization precision is low, the value of the spectral signal that can be represented is small, so increasing the order does not increase the size of the code string table so much, but if the quantization precision is high, the value of the spectral signal that can be represented Therefore, even if the order is increased by one, the size of the code string table is significantly increased.

The above will be further described with reference to specific examples. Now, it is assumed that an input signal is subjected to MDCT conversion and a spectrum as shown in FIG. 1 is obtained. FIG. 1 shows the absolute value of the spectrum of the MDCT with the level converted to dB. The input signal is converted into 64 spectral signals for each predetermined time block, and these are combined into eight coding units [1] to [8], and normalization and quantization are performed.

By changing the quantization accuracy for each coding unit depending on the distribution of the frequency components, it is possible to minimize the deterioration of the sound quality and perform audio-efficient coding. The quantization accuracy information required in each coding unit can be obtained, for example, by calculating a minimum audible level and a masking level in a band corresponding to each coding unit based on an auditory model. The normalized and quantized spectrum signal is converted into a variable length code, and is encoded in each encoding unit together with quantization accuracy information and normalization information.

FIG. 2 is a diagram for explaining a method of expressing quantization accuracy information. When the quantization accuracy information code is expressed by 3 bits, up to eight types of quantization accuracy information can be set. In this example, 1, 3, 5, 7, 15, 31, 63, or 1
The quantization is performed by any of the eight steps of 27 steps. Here, being quantized in one step means that the spectral signals in the coding unit are all quantized to a value of zero.

FIG. 3 is a diagram for explaining a conventional variable-length coding method. The spectrum signal is quantized based on quantization accuracy information determined for each coding unit, and a quantized spectrum is obtained. When encoding the quantized spectrum, it is converted into a corresponding code string by referring to a code string table as shown in FIG.
As is clear from FIG. 4, a code string table is prepared for each piece of quantization accuracy information.

In FIG. 3, in the coding unit [1], a code “011” is selected as quantization accuracy information. Therefore, as shown in FIG. 4, quantization is performed in seven steps, and the values of the quantized spectrum signals (quantized spectrum) are in order from the lowest frequency.
3, -1, 2, and 2. When these are converted into code strings using the code string table in which the quantization accuracy information code of FIG. 4 is “011”, they are 1110, 101, 1100, and 110, respectively.
0, and the code lengths are 4, 3, 4, and 4, respectively.

In the coding unit [2], a code "010" is selected as quantization accuracy information. In this case, as shown in FIG. 4, quantization is performed in five steps. In this example, the quantization spectrum is -2, 1, 0, 1 in order from the lowest frequency. These are converted into code strings using the code string table with the quantization accuracy information code of “010” in FIG.
0, 0, 100, and the code lengths are 3, 3, 1,
It becomes 3.

Similarly, in the coding unit [3], the code “001” is selected as the quantization accuracy information.
The quantization is performed by the number of steps in the step, the quantized spectrum is 0, -1, 0, 0, the code sequence is 0, 11, 0, 0, and the code length is 1, 2, 1, 1.

FIG. 5 is a diagram for explaining a two-dimensional variable length coding method. FIG. 5 shows the same encoding unit as in FIG.

Assuming that a two-dimensional code string table as shown in FIG. 6 is used as the code string table when the quantization accuracy information code is “001”, the coding unit [3] in FIG.
Are grouped into one group by two and converted into one code string. Therefore, the quantized spectra of the four spectral signals 0, -1, 0,
0s are grouped into two groups of (0, -1) and (0, 0) and are converted into two code strings of 101 and 0.

When the spectrum signal of the coding unit [3] is coded with a one-dimensional variable length code as shown in FIG. 3, the required information amount is 1 + 2 + 1 + 1 = 5 bits. On the other hand, as shown in FIG. 5, when encoding is performed using a two-dimensional variable length code, the information amount is 3 + 1 = 4 bits. That is, it can be seen that when the degree is increased, encoding can be performed with a smaller amount of information.

[0033]

As described above,
Quantized spectra of a plurality of (N) spectral signals are grouped into one group to form N-dimensional data,
By encoding this into a variable length code according to the code string table, the code length can be reduced as compared with the case where a one-dimensional variable length code is used. However, when the order (the value of N) increases, the size of the code string table significantly increases, and there is a problem that practical use becomes difficult.

For example, when a two-dimensional variable length code is used, the quantization accuracy information code is "001", "01".
As shown in FIGS. 6 to 8, the code sequence table in the case of 0 ″ and “110” has a larger code sequence table than the code sequence table in the case of using a one-dimensional variable length code (FIG. 4). I have.

The present invention has been made in view of such a situation, and performs encoding with a short code length without increasing the size of a code string table as in the case of using multidimensional variable length encoding. Is what you can do.

[0036]

An encoding apparatus according to the present invention comprises:
Unifying means for unifying the arrangement of the M numbers in ascending or descending order, first encoding means for encoding the unified numbers in the ascending or descending order by the unifying means, and A second encoding unit that encodes the permutation information used for the restoration, and an output of the first encoding unit and a second encoding unit.
And a code string generating means for generating a code string including the output of the coding means.

The code string generating means can generate the code string so as to include the output of the first coding means and the output of the second coding means alternately.

The second encoding means can not encode the reordering information when the M numerical values are the same.

The first encoding means can encode the numerical value into a variable-length code string.

The variable-length code string can be a Huffman code.

The numerical sequence can be a quantized acoustic waveform signal.

According to the encoding method of the present invention, a unifying step of unifying the arrangement of M numbers in ascending or descending order and a first step of encoding the unified numbers in ascending or descending order in the unifying step are performed. , A second encoding step of encoding permutation information used to restore the arrangement of the M numbers, and an output in the processing of the first encoding step and a second encoding step. A code string generating step of generating a code string including an output in the processing of the coding step.

The program of the first recording medium of the present invention comprises:
A unifying step of unifying the arrangement of the M numbers in ascending or descending order, a first encoding step of encoding the unified numbers in the ascending or descending order in the processing of the unifying step, and A second encoding step of encoding the permutation information used to restore the arrangement, and a code including an output in the processing of the first encoding step and an output in the processing of the second encoding step And a code sequence generating step of generating a sequence.

A first program according to the present invention comprises a unifying step for unifying the arrangement of M numbers in ascending or descending order, and a unifying step for encoding the unified numbers in ascending or descending order in the unifying step. 1 encoding step, a second encoding step of encoding permutation information used to restore the arrangement of the M numerical values, an output in the processing of the first encoding step, and a second encoding step. And a code string generating step of generating a code string including an output in the processing of the encoding step.

In the encoding apparatus and method of the present invention, the program of the first recording medium, and the first program, the arrangement of M numbers is unified in ascending or descending order, and the arrangement is unified in ascending or descending order. Is encoded as M
The permutation information used to restore the arrangement of the numerical values is encoded, and a code string including a code string of the numerical values and a code string of the permutation information is generated.

The decoding apparatus of the present invention uses a first code string in which M numbers, whose order is unified in ascending or descending order, are grouped into one group and encoded, and an arrangement of M numbers. Input means for inputting a code string including the second code string of the permutation information for returning to the first order, first decoding means for decoding the first code string, and second means for decoding the second code string. And a reordering means for restoring the arrangement of M numerical values decoded by the first decoding means to the original sequence based on the reordering information decoded by the second decoding means. And

The input means can input a code string in which the first code string and the second code string are alternately included.

The decoding method of the present invention is based on a first code string in which M numbers, whose order is unified in ascending or descending order, are grouped into one group and coded, and an arrangement of M numbers. An input step of inputting a code string including a second code string of the permutation information for returning to the first order, a first decoding step of decoding the first code string, and a second decoding step of decoding the second code string.
And a rearranging step of restoring the arrangement of the M numerical values decoded in the processing of the first decoding step based on the rearrangement information decoded in the processing of the second decoding step. It is characterized by including.

The program of the second recording medium of the present invention comprises:
A first code string in which M numbers whose values are unified in ascending or descending order are grouped into one group and encoded;
Second sort information for reordering the M numbers
An input step of inputting a code string including the following code string, a first decoding step of decoding a first code string, a second decoding step of decoding a second code string, and a first decoding step And a rearranging step of restoring the arrangement of the M numerical values decoded in the processing of the second decoding step based on the rearrangement information decoded in the processing of the second decoding step.

The second program according to the present invention comprises: a first code string in which M numbers, whose arrangement is unified in ascending or descending order, are grouped into one group and encoded; Inputting a code string including a second code string of the permutation information for restoring the first code string, a first decoding step of decoding the first code string, and decoding the second code string A second decoding step, and a rearrangement step of restoring the arrangement of the M numerical values decoded in the processing of the first decoding step based on the rearrangement information decoded in the processing of the second decoding step And causing the computer to execute a process including:

In the decoding apparatus and method of the present invention, the program of the second recording medium, and the second program, M numbers, whose arrangement is unified in ascending or descending order, are grouped into one group and encoded. A code string including the obtained first code string and a second code string of the permutation information for restoring the arrangement of the M numeric values is input, the first code string is decoded, and the second code string is decoded. Is decoded, and the arrangement of the decoded M numbers is based on the decoded permutation information,
It will be restored.

[0052]

FIG. 9 shows an example of the configuration of an encoding apparatus to which the present invention is applied.

The signal waveform 10 input to this encoding device
1 is converted into a signal frequency component 102 by a conversion circuit 1, each component is encoded by a signal component encoding circuit 2, and a code sequence is generated by a code sequence generation circuit 3. This code string is transmitted to a predetermined transmission path or recorded on the information recording medium 4.

FIG. 10 shows a configuration example of the conversion circuit 1.

The signal components 211 and 212 divided into two bands by the band dividing filter 11 are converted into spectral signal components 221 and 222 by the forward spectrum transform circuits 12 and 13 such as MDCT in each band. It has been done. The bandwidth of the signals 211 and 212 is １ ／ of the bandwidth of the signal 201 (signal 2
01 has been decimated to 1/2).

Note that 201 in FIG. 10 is replaced with 101 in FIG.
221 and 222 in FIG. 10 respectively correspond to 102 in FIG.

A large number of conversion circuits other than this embodiment are conceivable. For example, the input signal may be directly converted to a spectrum signal by MDCT, or DF instead of MDCT.
It may be converted by T or DCT.

Although it is possible to process a signal without converting it into a spectrum simply by dividing a signal into band components by a band division filter, the method of the present invention is particularly effective when energy is concentrated at a specific frequency. Therefore, it is convenient to adopt a method of converting a large number of frequency components into frequency components by spectral conversion that can be obtained with a relatively small amount of calculation.

FIG. 11 shows a configuration example of the signal component encoding circuit 2.

Each signal component 301 is normalized by the normalizing circuit 21 for each predetermined band, and then input to the quantizing circuit 22 as a signal 302, where the quantization precision determining circuit 2
3 is quantized on the basis of the quantization precision signal 303 calculated in Step 3 and is output as a signal 304. 11 corresponds to 102 in FIG. 9, and 304 in FIG. 11 corresponds to 103 in FIG. 9, respectively.
Here, 304 (103) includes normalization coefficient information and quantization accuracy information in addition to the quantized signal components.

FIG. 12 shows a configuration example of the code string generation circuit 3.

The control unit 31 controls the quantization spectrum 401 of the spectrum signals grouped into M groups by one.
Are rearranged as necessary, and unified in ascending or descending order, and then the encoding is controlled by the encoding unit 32.

For example, in FIG. 5, the quantized spectrum of the coding unit [3] is grouped into two groups of (0, -1) and (0, 0). , -1) are 0> -1, so their order is descending. That is, when the arrangement is unified in ascending order, (0, -1) is rearranged into (-1, 0) and encoded.

The control unit 31 controls the encoding unit 33 to encode permutation information indicating the original arrangement of the quantized spectrum 401.

The encoding section 32 encodes the M quantized spectra which are grouped into one group by using a predetermined code string table. The encoding unit 33 encodes the rearrangement information using a predetermined code string table.

The code sequence (code sequence of the quantized spectrum) 402 generated by the coding unit 32 and the coding unit 33
(Code sequence of rearrangement information) 40 generated by
3 is output to a predetermined transmission path or an information recording medium 4.

Note that reference numeral 401 in FIG.
In addition, 402 and 403 in FIG. 12 correspond to 104 in FIG. 9, respectively.

Next, the operation of the encoding device (FIG. 9) will be described. The acoustic waveform signal 101 (201) is input to the band division filter 11 (FIG. 10) of the conversion circuit 1, and a lower frequency signal component 211 and a higher frequency signal component 2
12 are divided. Lower frequency signal component 211
Is input to the forward spectrum conversion circuit 12 and converted into a spectrum signal component 221. Similarly, the higher frequency signal component 212 is input to the forward spectrum conversion circuit 13, converted into a spectrum signal component 222, and output.

That is, with reference to FIG. 1, the forward spectrum transform circuit 12 unitizes a lower frequency spectrum signal to generate coding units [1] to [6]. Further, the forward spectrum conversion circuit 13
Unitizes the higher frequency spectral signal components to generate coding units [7], [8].

The spectrum signal components 221 and 222 (102) output from the forward spectrum conversion circuits 12 and 13
Is the normalization circuit 21 of the signal component encoding circuit 2 (FIG. 11)
Is input to the quantization accuracy determination circuit 23. Normalization circuit 2
1 divides the value of each signal by its maximum value among a plurality of spectral signal components in the encoding unit,
Normalization is performed, and the obtained normalization coefficient 302 is supplied to the quantization circuit 22.

The quantization precision determination circuit 23 determines the quantization precision of the input spectral signal component by coding unit by calculating the minimum audible level and masking level in the band corresponding to each coding unit. I do. The quantization circuit 22 quantizes the normalization coefficient 302 supplied from the normalization circuit 21 with the quantization precision 303 supplied from the quantization precision determination circuit 23, and obtains the obtained quantization spectrum 3
04 (103) is supplied to the code string generation circuit 3.

The code string generation circuit 3 calculates the quantization spectrum 3
04 is converted into a code string.
This will be described with reference to the flowchart of FIG.

In step S1, the code string generation circuit 3
Control unit 31 examines the quantized spectrums of the M spectral signals combined into one group, determines whether or not all have the same value, and determines that all are not the same value, Proceed to S2.

In step S2, the control unit 31 rearranges the M quantized spectra so as to be in ascending order or descending order. That is, by this processing, the arrangement of the M quantized spectra is unified in ascending or descending order.

Next, in step S3, the control unit 31
Controls the encoding unit 32 to encode M quantized spectra whose order is unified in ascending or descending order using an M-dimensional variable length code.

For example, when two-dimensional variable length codes are unified in ascending order (M = 2), the encoding unit 32
Converts the two quantized spectra into a corresponding code sequence by referring to a code sequence table as shown in FIG.

FIG. 14 shows that the quantization accuracy information code is “0”.
A code string table for “01”, a code string table for “010”, and a code string table for “011” are shown. In these code string tables, a code string of 6 words and a code of 15 words are shown. A sequence and a code sequence of 28 words are prepared.

In the case of this example, the two quantized spectra arranged in one group are rearranged in ascending order (step S2), so that the quantized spectra arranged in descending order are not encoded. Therefore, the code string table of FIG. 14 does not include a code string corresponding to the pattern of the quantized spectrum arranged in descending order. As described above, by unifying the arrangement of the quantized spectra grouped into one group, for example, in ascending order, it is not necessary to prepare a code string corresponding to a pattern in descending order. Can be reduced by minutes.

On the other hand, in the conventional variable length code, a code string corresponding to both ascending and descending patterns must be prepared, so that the size of the code string table becomes large. For example, in the code string table when the quantization accuracy information code in the two-dimensional variable length code is “001”, FIG.
9 is prepared, the code string table for “010” is prepared for the 25-word code string shown in FIG. 7, and the code string table for “011” is shown in FIG. 4 shown in 8
It is necessary to prepare a code string of 9 words.

Although not shown, in the case of four dimensions, the quantization accuracy information codes are "001" and "01".
When 0 ", the size of the code string table of the present invention is 15 words and 70 words, but in the conventional case, it is 81 words and 625 words.

Returning to FIG. 13, in step S4, the control unit 31 controls the encoding unit 33 to, for example,
Are encoded according to a code string table as shown in FIG.

FIG. 15 shows a code string table used when two-dimensional variable length codes are unified in ascending order (M = 2).

In FIG. 15, A represents a quantized spectrum smaller than one of the two quantized spectra in one group, and B represents a quantized spectrum larger than A. That is, when the data can be expressed as (A, B) before the rearrangement and can be expressed as (A, B) after the rearrangement, the rearrangement information is set to “0”, and the encoded data is encoded with one bit. Is done.

When the data can be expressed as (B, A) before the rearrangement and can be expressed as (A, B) after the rearrangement, the rearrangement information is set to “1”.
It is encoded with one bit.

In the present invention, unifying in ascending order, 2
When a variable length code of dimension is used, after all, in addition to the code string table shown in FIG. 14, the code string table of FIG. 15 is required. However, since the size of the code string table of FIG. Even if the code string tables are combined, encoding can be performed with a smaller code string table than before.

If it is determined in step S1 that all M quantized spectra have the same value (there is no magnitude relation), the process proceeds to step S5, where the control unit 3 controls the encoding unit 32 Then, the M quantized spectra having the same value are encoded by an M-dimensional variable length code.

For example, when two-dimensional variable-length codes are unified in ascending order, the encoding unit 32 refers to the code string table shown in FIG. The quantized spectrum is converted into a corresponding code string.

When the permutation information is encoded in step S4, or when M quantized spectra having the same value are encoded in step S5, the process ends, and the M quantum quantizers of the next group are processed. Step S1 for the normalized spectrum
Steps S5 to S5 are similarly executed.

Next, an encoding unit shown in FIG. 16 and having a quantization precision information code of “010” and having 16 spectral signals (in the example of FIG. 1, encoding of [7] or [8]) The operation of the above-described code sequence generation circuit 3 will be described again by taking a unit as an example. In the case of this example, it is assumed that the spectral signals of the encoding units are grouped into two (= M) groups, and the arrangement is unified in ascending order.

When encoding the quantized spectra (2, -1) of the two spectral signals from the lower frequency, they are not the same value (step S
1), sorted in ascending order (step S2), (-1,
2) is encoded as one unit based on the code string table of FIG. 14 into 7-bit “1111101” (step S3). Subsequently, the rearrangement information is encoded based on the code string table in FIG. In this case, (B (= 2), A (= − 1)) can be expressed before the rearrangement, and (A (= − 1), B
(= 2)), the sorting information is “
1 "and is encoded with one bit.

The next group of quantized spectra (0,
0) are the same value (= 0) (step S1), so that the rearrangement (step S2) and the encoding of the rearrangement information (4) are not performed. It is encoded to “0” (step S
5).

By being encoded in this way,
In the present invention, the encoding unit shown in FIG. 16 includes 7-bit “1111101” (code sequence of (−1, 2)) and 1-bit “1” (code sequence of rearrangement information) and 1-bit “ 0 ”(code sequence of (0,0)), 3-bit“ 1 ”
00 ”(code sequence of (0, 1)) and 1 bit“ 1 ”
(Code sequence of rearrangement information), 7-bit "111110"
0 "((-2, -1) code string) and 1-bit"
0 (code sequence of rearrangement information), 1-bit “0”
((0,0) code string) 5-bit "11100"
(Code sequence of (0, 2)) and 1-bit “0” (code sequence of rearrangement information), 5-bit “11011” ((−
1, -1) and a 5-bit "1110"
0 ”(code sequence of (0, 2)) and 1-bit“ 0 ”
(Code sequence of the permutation information), the code length is 39 (= 8 + 1 + 4 + 8 + 1 + 6 + 5 + 6). The conventional two-dimensional variable length code has 39 bits as shown in FIG.

FIG. 18 shows an example of the configuration of a decoding device for decoding and outputting an audio signal from a code sequence generated by the coding device of FIG.

The information has been transmitted or the information recording medium 4
The code of each signal component is extracted by the code sequence decomposition circuit 41 from the code sequence 501 reproduced from
2 by the signal component decoding circuit 42
3 is decoded, and an acoustic waveform signal 504 is generated and output by the inverse conversion circuit 43.

FIG. 19 shows an example of the configuration of the code string decomposition circuit 41.

The control unit 51 controls the decoding unit 52 to read the code sequence of the quantized spectrum read from the code sequence 601 of the coding unit input to the code sequence decomposition circuit 41 (more precisely, the sequence is A code string of M quantized spectra (unified in ascending or descending order) is decoded. Note that M
Indicates the number of quantized spectra grouped into one group at the time of encoding.

The control unit 51 also controls the decoding unit 53 to decode the code sequence of the permutation information read from the code sequence 601 of the coding unit, and, based on the permutation information, arranges the quantized spectrum. Is restored and output to the signal component decoding circuit 42.

601 in FIG. 19 is replaced with 501 in FIG.
Reference numeral 602 in FIG. 9 corresponds to reference numeral 502 in FIG.

FIG. 20 shows a configuration example of the inverse conversion circuit 43. This corresponds to the conversion circuit 1 shown in FIG.
The signals 711 and 712 of each band obtained from the band 02 are synthesized by the band synthesizing filter 63 and output as a signal 721. 701 and 70 in FIG.
2 corresponds to 503 in FIG. 18, and 721 in FIG.
4 respectively.

Next, the operation of the decoding device will be described.
The code string decomposition circuit 41 performs a code string decomposition process as shown in the flowchart of FIG.

That is, in step S21, the control section 51 controls the decoding section 52 to read M from the code string of the coding unit and combine them into one group.
(Code sequence of M quantized spectra whose order is unified in ascending or descending order) is decoded.

Next, at step S22, the control unit 5
1 means that the code obtained by the decoding in step S21 is
It is determined whether or not they are all the same, and if it is determined that they are not the same, the process proceeds to step S23.

In step S23, the control unit 51
The decoding unit 53 is controlled to decode the code sequence of the permutation information that is input after the code sequence of the M quantized spectra, and in step S24, based on the permutation information, obtained in step S21. Rearrange the order of the signs.

Since the control unit 51 has a table corresponding to FIG. 15, for example, when the sorting information of “1” is obtained, (A, B) is sorted into (B, A). , "0" is not rearranged.

If it is determined in step S22 that the codes obtained in step S21 are all the same, or if rearrangement based on the rearrangement information has been performed in step S24, the process ends. The processing of step S21 and subsequent steps is similarly performed on the code string of the input quantized spectrum.

The code 502 (FIG. 18) extracted by the code string decomposing circuit 41 is input to the signal component decoding circuit 42 and decoded. This signal component decoding circuit 42 performs a process reverse to that of the signal component encoding circuit 2 shown in FIG.

The signal 503 output from the signal component decoding circuit 42 has the lower frequency spectrum signal component 701 input to the inverse spectrum conversion circuit 61, and the higher frequency spectrum signal component 702 has the inverse frequency spectrum signal component 702. The signal is input to the spectrum conversion circuit 62. The inverse spectrum conversion circuits 61 and 62 convert the input spectrum signal components 701 and 702 into acoustic signals 711 and 711 on the time axis, respectively.
712, and outputs the result to the band synthesis filter 63. The band synthesis filter 63 outputs the lower frequency sound signal 71.
1 and an audio signal 712 of a higher frequency are synthesized and output as a synthesized audio signal 721 (504).

As described above, a signal obtained by subjecting a signal once subjected to a band division filter to spectrum conversion by MDCT is used as a band division circuit, and an inverse MDCT (IMD
Although the embodiment using the inverse spectrum transformed by (CT) and applied to the band synthesizing filter has been described, it is needless to say that the MDCT transform and the IMDCT transform are performed directly without using the band dividing filter and the band synthesizing filter. You may do it. Also, the type of spectrum conversion is not limited to MDCT, and DFT, DCT, etc. may be used.

Further, the band division and the band synthesis may be performed only by the band division filter and the band synthesis filter without using the spectrum conversion. In this case, a band divided by the filter or a band obtained by combining a plurality of these bands is defined as an encoding unit. However, the method of the present invention can be applied efficiently by performing spectral conversion such as MDCT and converting into a large number of spectral signals, and then configuring the coding unit as described using the embodiment. .

In the above description, the case of processing an acoustic waveform signal has been described. However, the method of the present invention can be applied to other types of signals, for example, to image signals. It is possible.

Furthermore, the method according to the present invention can be used in combination with a conventional method using a variable length code. For example, when the quantization precision is low, that is, when the number of quantization steps is small, encoding is performed using a two-dimensional or four-dimensional code sequence table by a conventional method, and the quantization precision is high, that is, the number of quantization steps is large. In the case where is large, it is more effective if the encoding is performed using the method according to the present invention in consideration of the scale of the code string table.

The above-described series of processing can be realized by hardware, but can also be realized by software. When a series of processing is realized by software, a program constituting the software is installed in a computer, and the program is executed by the computer, so that the above-described encoding device and decoding device are functionally realized. Is done.

FIG. 22 is a block diagram showing the configuration of an embodiment of the computer 101 functioning as the above-described encoding device or decoding device. CPU (Central Pro
), an input / output interface 116 is connected to the CPU 111 via a bus 115.
When a user inputs a command through the input / output interface 116 from an input unit 118 including a keyboard, a mouse, and the like, for example, the ROM (Read Only Memory) 11
2. A program stored in a recording medium such as a magnetic disk 131, an optical disk 132, a magneto-optical disk 133, or a semiconductor memory 134 mounted on the hard disk 114 or the drive 120 is stored in a RAM (Random).
Access Memory) 113 for execution. Thus, the various processes described above (for example, the processes shown by the flowcharts in FIGS. 13 and 21) are performed. Further, the CPU 111 transmits the processing result to an LCD (Liquid Crystal Diode) via the input / output interface 116, for example.
splay) or the like is output as necessary. The program is stored on the hard disk 114 or RO
M112 is stored in advance and provided to the user integrally with the computer 101, the magnetic disk 131, the optical disk 132, the magneto-optical disk 133, the semiconductor memory 1
34, packaged media such as satellite,
It can be provided to the hard disk 114 via a communication unit 119 from a network or the like.

In this specification, the steps of describing a program provided by a recording medium may be performed not only in chronological order according to the described order but also in chronological order. This also includes processing executed in parallel or individually.

[0115]

According to the encoding apparatus and method of the present invention, the program of the first recording medium, and the first program, the arrangement of M numbers is unified in ascending or descending order, and the arrangement is ascending or descending. To encode the permutation information used to restore the arrangement of the M numbers to the original, and to generate a code string including the code string of the numerical values and the code string of the permutation information. Therefore, for example, encoding with high compression efficiency can be performed without increasing the scale of the code string table very much.

According to the decoding apparatus and method of the present invention, the program of the second recording medium, and the second program,
A first code string in which M numerical values whose order is unified in ascending or descending order are grouped into one group and encoded;
Second sort information for reordering the M numbers
, A first code string is decoded, a second code string is decoded, and a sequence of the decoded M numbers is determined based on the decoded permutation information. , The encoding can be performed with high compression efficiency without increasing the size of the code string table.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a spectrum of an encoding unit.

FIG. 2 is a diagram illustrating a method of expressing quantization accuracy information.

FIG. 3 is a diagram illustrating an encoding method using a variable length code according to the related art.

FIG. 4 is a diagram illustrating an example of a code string table.

FIG. 5 is a diagram illustrating an encoding method using a multidimensional variable length code according to the related art.

FIG. 6 is a diagram showing an example of a multidimensional code string table according to the related art.

FIG. 7 is a diagram showing an example of another multi-dimensional code string table according to the related art.

FIG. 8 is a diagram showing an example of another multidimensional code string table according to the related art.

FIG. 9 is a block diagram illustrating a configuration example of an encoding device to which the present invention has been applied.

FIG. 10 is a block diagram illustrating a configuration example of a conversion circuit in FIG. 9;

11 is a block diagram illustrating a configuration example of a signal component encoding circuit in FIG. 9;

12 is a block diagram illustrating a configuration example of a code string generation circuit in FIG. 9;

FIG. 13 is a flowchart illustrating an operation of the code sequence generation circuit.

FIG. 14 is a diagram illustrating an example of a code string table used in the present invention.

FIG. 15 is a diagram illustrating an example of another code string table used in the present invention.

FIG. 16 is a diagram illustrating an encoding method according to the present invention.

FIG. 17 is another diagram illustrating an encoding method according to the related art.

FIG. 18 is a block diagram illustrating a configuration example of a decoding device to which the present invention has been applied.

19 is a block diagram illustrating a configuration example of a code string decomposition circuit in FIG. 18;

20 is a block diagram illustrating a configuration example of the inverse conversion circuit in FIG. 18;

FIG. 21 is a flowchart illustrating an operation of the code string decomposition circuit.

FIG. 22 is a block diagram illustrating a configuration example of a computer 101.

[Explanation of symbols]

Reference Signs List 1 conversion circuit, 2 signal component coding circuit, 3 code string generation circuit, 4 information recording medium, 11 band division filter, 12 forward spectrum conversion circuit, 13 forward spectrum conversion circuit, 21 normalization circuit, 22 quantization circuit, 23 Quantization accuracy determination circuit, 31 control unit,
32 encoding unit, 33 encoding unit, 41 code string decomposition circuit, 42 signal component decoding circuit, 43 inverse conversion circuit, 51 control unit, 52 decoding unit, 53 decoding unit, 61, 62 inverse spectrum conversion circuit, 63
Band synthesis filter

Continuation of the front page (72) Inventor Minoru Tsuji 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo F-term in Sony Corporation (reference) 5D045 DA20 5J064 AA04 BA16 BB07 BC01 BC02 BC11 BC17 BC18 BD02 BD04

Claims (14)

[Claims] 1. An encoding device that encodes numerical values forming a numerical sequence into a group of M numbers in one group, comprising: unifying means for unifying the arrangement of the M numerical values in ascending or descending order; First encoding means for encoding the numerical values whose order is unified in ascending or descending order; and second encoding means for encoding permutation information used to restore the arrangement of the M numerical values. An encoding apparatus comprising: an encoding unit; and a code sequence generating unit configured to generate a code sequence including an output of the first encoding unit and an output of the second encoding unit. 2. The apparatus according to claim 1, wherein said code string generation means generates a code string so as to include an output of said first encoding means and an output of said second encoding means alternately. An encoding device according to claim 1. 3. The encoding apparatus according to claim 1, wherein the second encoding unit does not encode the rearrangement information when the M numerical values have the same value. 4. The first encoding means converts the numerical value into
2. The encoding method according to claim 1, wherein the encoding is performed into a variable-length code string.
An encoding device according to claim 1. 5. The encoding apparatus according to claim 4, wherein the variable-length code string is formed of a Huffman code. 6. The encoding apparatus according to claim 1, wherein the numerical sequence is a quantized acoustic waveform signal. 7. An encoding method for an encoding apparatus, which encodes numerical values forming a numerical sequence into a group of M numbers at a time, and unifies the arrangement of the M numerical values in ascending or descending order. A first encoding step of encoding the numerical values whose order has been unified in ascending or descending order in the processing of the unifying step; and reordering information used to restore the order of the M numerical values. A second encoding step of encoding; and a code string generating step of generating a code string including an output in the processing of the first encoding step and an output in the processing of the second encoding step. An encoding method, characterized in that: 8. A program for an encoding apparatus for encoding numerical values constituting a numerical value sequence into a group of M numbers each, wherein the unifying step unifies the arrangement of the M numerical values in ascending or descending order. A first encoding step of encoding the numerical values whose order is unified in ascending or descending order in the processing of the unifying step; and sorting information used to restore the order of the M numerical values. And a code string generating step of generating a code string including an output in the processing of the first coding step and an output in the processing of the second coding step. A recording medium on which a computer-readable program is recorded. 9. A program for an encoding device for encoding numerical values forming a numerical sequence into a group of M numbers each, wherein the unifying step unifies the arrangement of the M numerical values in ascending or descending order. A first encoding step of encoding the numerical values whose order is unified in ascending or descending order in the processing of the unifying step; and sorting information used to restore the order of the M numerical values. And a code string generating step of generating a code string including an output in the processing of the first coding step and an output in the processing of the second coding step. A program for causing a computer to execute a process including the above. 10. An unified M in ascending or descending order.
A code string including a first code string in which the numerical values are grouped into one group and encoded, and a second code string of permutation information for restoring the arrangement of the M numerical values are Input means for inputting; first decoding means for decoding the first code string; second decoding means for decoding the second code string; and M decoding means decoded by the first decoding means. And a rearranging means for restoring the arrangement of the numerical values of the above based on the rearrangement information decoded by the second decoding means. 11. The decoding apparatus according to claim 10, wherein said input means inputs a code string including said first code string and said second code string alternately. 12. The M which is arranged in ascending or descending order
A code string including a first code string in which the numerical values are grouped into one group and encoded, and a second code string of permutation information for restoring the arrangement of the M numerical values are An inputting step of inputting, a first decoding step of decoding the first code string, a second decoding step of decoding the second code string, and decoding in the processing of the first decoding step A reordering step of restoring the arrangement of the M numbers based on the reordering information decoded in the processing of the second decoding step. 13. An unified M in an ascending or descending order.
A code string including a first code string in which the numerical values are grouped into one group and encoded, and a second code string of permutation information for restoring the arrangement of the M numerical values are An inputting step of inputting, a first decoding step of decoding the first code string, a second decoding step of decoding the second code string, and decoding in the processing of the first decoding step A computer-readable program, comprising a rearrangement step of restoring an arrangement of M numerical values based on the rearrangement information decoded in the processing of the second decoding step. Recording media. 14. An M array in which the order is unified in ascending or descending order
A code string including a first code string in which the numerical values are grouped into one group and encoded, and a second code string of permutation information for restoring the arrangement of the M numerical values are An inputting step of inputting, a first decoding step of decoding the first code string, a second decoding step of decoding the second code string, and decoding in the processing of the first decoding step A non-transitory computer-readable storage medium storing a program for causing a computer to execute a process including a rearrangement step of restoring an arrangement of M numerical values based on the rearrangement information decoded in the processing of the second decoding step.