JP2001044847A - Reversible coding method, reversible decoding method, system adopting the methods and each program recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compress a digital input signal at a high compression rate and to completely reproduce the signal. SOLUTION: This reversible coding method includes a process, where a digital input signal is converted into a bit stream in a code absolute value expression for each frame, a process where the bit stream is separated into each bit (110), a process where the bits are connected by each bit position in time sequence (160), and a process where reversible coding is applied to each bit stream obtained by the connection (150). The reversible decoding method includes a process, where reversible decoding is applied to each frame of reversible coding series (210), a process where each bit obtained by the reversible decoding is separated into respective bits, a process where each bit is connected by each same time in the order of bit location (220), and a process where frames obtained by the connection are connected sequentially (250).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coding method for eliminating the number of bits representing various digital signals (for example, audio signals such as voice and music and image signals), a decoding method for reproducing the codes, The present invention relates to these devices and program recording media.

[0002]

2. Description of the Related Art As a method for compressing information such as voice and image, there are irreversible compression coding allowing distortion and reversible compression coding allowing no distortion. As irreversible compression, ITU
Various systems are known as standards of -T and ISO / IEC MPEG. By using these methods, it is possible to compress the original digital signal to 1/10 or less while suppressing the distortion. However, the distortion depends on the encoding conditions and the input signal, and the degradation of the reproduced signal may be a problem depending on the application. On the other hand, as a reversible compression method capable of completely reproducing an original signal, universal compression encoding which is widely used for compression of computer files and texts is known. In this method, compression encoding is performed while referring to the statistics of the input sequence. Any signal can be compressed, and text can be compressed to about 1/2, but it can be directly applied to audio and image data. Even if applied, the compression effect is only about 20%.

[0003]

As described above, lossy coding and lossless coding have conventionally been used depending on the type and use of information to be compressed. In this case, 1
Since it is necessary to prepare two types of compressed files for one piece of information, the compression efficiency is not improved as a whole, and handling is inconvenient. An object of the present invention is to provide an encoding method for compressing a digital signal with high compression efficiency and no distortion, and a decoding method for restoring a signal compressed by the method to an original signal.

[0004]

SUMMARY OF THE INVENTION In the present invention, a digital input signal is quantized with a small number of bits by using encoding that allows distortion. Then, an error signal (a signal having a reduced amplitude) between the quantized signal and the original digital input signal.
Is compressed using undistorted coding. As a result, it is possible to increase the compression ratio without finally generating distortion, which is a feature not found in the conventional coding using lossless coding and irreversible coding independently.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following embodiments do not limit the claimed invention. In addition, not all combinations of the features described in the embodiments are necessarily required to achieve the purpose. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

§1. First Embodiment FIG. 1 is a block diagram showing a configuration example of an encoding device and a decoding device according to a first embodiment of the present invention. In the encoding device shown in FIG. 1, a time series of a digital input signal (hereinafter, referred to as a “digital input signal series”) is input from an input terminal 100. Then, the frame dividing unit 1
10 converts the digital input signal sequence into, for example, 102
It is sequentially divided into frame units each composed of four digital input signals (that is, 1024 samples).

Next, in order to increase the efficiency of lossless compression encoding by the lossless encoding unit 150, the reordering unit 160
Each digital input signal (ie, bit sequence) in the frame
The bits of Details of the processing by the reordering unit 160 will be described below.

FIG. 2 is an explanatory diagram showing an example of the processing of the reordering unit 160 in the first embodiment. A in FIG.
Indicates an input to the reordering unit 160 (that is, a digital input signal for one frame). In each digital input signal, the amplitude (here, a positive or negative integer) of the digital input signal is represented by a two's complement expression.

First, the reordering unit 160 converts each digital input signal in a frame from a bit string represented by a two's complement representation to a bit string represented by a sign absolute value (see FIG. 2B). In the converted digital input signal, MS
B (Most Significant Bit: most significant bit)-2nd LS
B indicates the absolute value of the amplitude, and LSB (Least Significant)
Bit: least significant bit) indicates the sign of the amplitude.

Next, the reordering unit 160 decomposes the converted digital input signal into individual bits. Finally,
The reordering unit 160 converts each bit generated by the decomposition into a bit position of each bit (ie, MSB, second MS).
B,..., LSB), that is, in the horizontal direction in FIG. 2 (see C in FIG. 2). In addition, the reordering unit 160
Some of the bits generated by the decomposition may be combined instead of all of the bits generated by the decomposition. The reordering unit 160 may combine the bits generated by the disassembly for each of a plurality of bit positions instead of for each bit position.

FIG. 3 is an explanatory diagram showing an example of an output (hereinafter, referred to as a "converted digital input signal") of the reordering unit 160 in the first embodiment. In FIG. 3, each bit string in the horizontal direction (that is, a bit string composed of 1024 bits at the same bit position) is referred to as a “horizontal bit string”.

Next, the lossless encoding unit 150 performs lossless compression encoding on the output of the reordering unit 160. Lossless encoding unit 1
The details of the processing by 50 will be described below.

First, the lossless encoding unit 150 encodes the horizontal bit strings from the MSB to the j-th MSB (for example, the fourth MSB) by the following methods. If the 1024 bits forming the horizontal bit string are all “0”, the horizontal bit string is encoded to “0”. If one of the 1024 bits forming the horizontal bit string is “1”, the horizontal bit string is expressed as:
The bit string indicating the position of the bit “1” (10 bits as an example) is encoded into a bit string concatenated after “10”. If two of the 1024 bits forming the horizontal bit string are “1”, the horizontal bit string is expressed as:
The bit string indicating the position of the bit being “1” (for example, 10 bits × 2) is encoded into a bit string concatenated after “110”. If three or more of the 1024 bits forming the horizontal bit string are “1”, the horizontal bit string is connected after “111”.

Further, the lossless encoding unit 150 generates the (j +
1) Encode horizontal bit strings from the MSB to the LSB. In this case, the lossless encoding unit 150 may encode the horizontal bit string by the above-described methods,
Alternatively, after recombining each digital input signal (that is, in the vertical direction in FIG. 3), encoding may be performed for each digital input signal using a generally well-known encoding method.

The lossless encoding section 150 may perform lossless compression encoding using a case where there is a continuous sequence or a case where there is a frequently appearing sequence, in addition to the above-described encoding method. Entropy coding such as Huffman coding or arithmetic coding is an example. The compression efficiency is also improved by applying universal encoding for reversibly compressing text or the like to the output of the reordering unit 160.

By the above processing, the encoding apparatus shown in FIG.
(E) is output.

On the other hand, in the decoding device shown in FIG. 1, first, the lossless decoding unit 210
The lossless compression code I (e) is decoded by performing processing opposite to 0 (that is, decoding). Next, the reordering unit 220 performs a process reverse to that of the reordering unit 160 to sequentially output digital input signals in frame units. Finally, the frame synthesizing unit 250 reproduces the original digital input signal sequence by sequentially connecting the outputs of the reordering unit 220. By the above processing, the digital input signal sequence is output from the output terminal 260.

§2. Second Embodiment FIG. 4 is a block diagram showing a configuration example of an encoding device and a decoding device according to a second embodiment of the present invention. 4, parts corresponding to the respective parts in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In the encoding apparatus shown in FIG. 4, first, frame dividing section 110 converts a digital input signal sequence from input terminal 100 into a frame unit composed of, for example, 1024 digital input signals (that is, 1024 samples). Divide sequentially. Next, the lossy quantization unit 120 compression-encodes the output of the frame division unit 110. This encoding may be any method suitable for the input signal as long as the original digital input signal can be reproduced to some extent during decoding. For example, if the digital input signal is audio, ITU-T audio coding can be used, if it is music, MPEG or Twin VQ can be used, and if it is video, MPEG can be used.
Note that the output of the irreversible quantization unit 120 is referred to as “irreversible compression code I (n)”.

Next, an inverse quantization unit 130 having the same configuration as the decoder corresponding to the irreversible quantization unit 120 (that is, the inverse quantization unit 230) converts the local reproduced signal from the irreversible compression code I (n). Generate. Then, subtraction section 140 obtains an error signal between the local reproduction signal and the original digital input signal. Normal,
The amplitude of this error signal is much smaller than the amplitude of the original digital input signal. Therefore, it is easier to losslessly compress the error signal than to losslessly compress the digital input signal. If the error signal can be reproduced without distortion, the original digital input signal can be reproduced without distortion by combining the lossless compression-coded error signal and the irreversible compression-coded original digital input signal. Therefore, utilizing this fact (the error signal has a small amplitude and the lossless compression encoding is easy), the lossless encoding unit 150 performs the lossless compression encoding of the error signal.

At this time, in order to increase the efficiency of lossless compression encoding by the lossless encoding unit 150, the reordering unit 160
Reorders the bits of the error signal (ie, bit sequence). Details of the processing by the reordering unit 160 will be described below. FIG. 5 shows the rearranging unit 16 according to the second embodiment.
FIG. 9 is an explanatory diagram illustrating an example of a process 0. In the digital input signal (see A in FIG. 5), positive and negative integers are represented in two's complement representation. FIG. 5B shows an error signal between the digital input signal shown in FIG. 5A and a local reproduction signal corresponding to the digital input signal. The reordering unit 160 converts the error signal (that is, the bit string) from the bit string in the two's complement representation to the bit string in the sign absolute value representation (see C in FIG. 5). Next, the reordering unit 160 decomposes the converted error signal into individual bits. Finally, the reordering unit 160 converts each bit generated by the decomposition into
The bit position of each bit (ie, MSB, second MSB,...)
.., LSB), that is, in the horizontal direction in FIG. 5 (see D in FIG. 5). FIG. 6 is an explanatory diagram illustrating an example of an output of the reordering unit 160 (hereinafter, referred to as a “conversion error signal”) according to the second embodiment. In FIG. 6, each bit string in the horizontal direction (that is, a bit string composed of 1024 bits at the same bit position) is referred to as a “horizontal bit string”. In the above replacement, the value of each error signal does not change at all. However, since the error signal has a small amplitude, in the output of the reordering unit 160, all the upper bits are often "0" as shown in FIG. As a result, the lossless compression encoding efficiency of the error signal increases due to the continuous “0”. It can be said that the reordering is to bit slice the error signal (that is, the bit string in the vertical direction) in the horizontal direction.

Next, the lossless encoding unit 150 performs lossless compression encoding on the output of the reordering unit 160. Lossless encoding unit 1
The details of the processing by 50 will be described below.

First, the lossless encoding unit 150 encodes the horizontal bit strings from the MSB to the j-th MSB (for example, the fourth MSB) by the following methods (1) to (4). If the 1024 bits forming the horizontal bit string are all “0”, the horizontal bit string is encoded to “0”. If one of the 1024 bits forming the horizontal bit string is “1”, the horizontal bit string is expressed as:
The bit string indicating the position of the bit “1” (10 bits as an example) is encoded into a bit string concatenated after “10”. If two of the 1024 bits forming the horizontal bit string are “1”, the horizontal bit string is expressed as:
The bit string indicating the position of the bit being “1” (for example, 10 bits × 2) is encoded into a bit string concatenated after “110”. If three or more of the 1024 bits forming the horizontal bit string are “1”, the horizontal bit string is connected after “111”.

Further, the lossless encoding unit 150 outputs the (j +
1) Encode horizontal bit strings from the MSB to the LSB. In this case, the lossless encoding unit 150 may encode the horizontal bit string by the above-described methods,
Alternatively, after each error signal is recombined for each error signal (that is, in the vertical direction in FIG. 6), encoding may be performed for each error signal using a generally well-known encoding method.

According to the above lossless compression encoding, the MSB
Is "1", the amplitude of the error signal corresponding to the digital input signal is 20 [d
B] It can be expected from FIG. 6 that when the value becomes smaller, "1" hardly exists in the MSB to the third MSB of the error signal. " In this case, by performing the reordering, it is possible to reduce approximately 3/16 of the number of bits of the error signal as compared with the case where the reordering is not performed.

The lossless encoding unit 150 may perform lossless compression encoding using a case where there is a continuous sequence or a case where there is a frequently appearing sequence, in addition to the above-described encoding method. Entropy coding such as Huffman coding or arithmetic coding is an example. The compression efficiency is also improved by applying universal encoding for reversibly compressing text or the like to the output of the reordering unit 160.

By the above processing, the encoding apparatus shown in FIG. 4 performs the irreversible compression code I (n) from the irreversible quantization section 120 and the lossless compression code I (n) from the lossless encoding section 150.
(E) is output.

On the other hand, in the decoding device shown in FIG. 4, the lossless decoding section 210 decodes the lossless compression code I (e). Then, the reordering unit 220 performs an opposite process to the reordering unit 160, thereby sequentially outputting the error signals in frame units. Also, the inverse quantization unit 230
Decodes the lossy compression code I (n). Next, the addition unit 240 outputs the output of the inverse quantization unit 230 and the reordering unit 2
And 30 outputs. Finally, the frame synthesizing unit 25
0 reproduces the original digital input signal sequence by sequentially connecting the outputs of the adder 240. By the above processing, the digital input signal sequence is output to the output terminal 2
It is output from 60.

The irreversible quantization unit 120 in the encoding device shown in FIG. 4 can be constituted by, for example, a transform encoding method. This transform coding method is described in, for example,
No. 44399. This example will be briefly described with reference to FIG. From the output of the frame dividing unit 110, the frame dividing unit 14 calculates the past 2N
Extract a sample. The sequence composed of 2N samples is formed by an LOT (Lapped Orthogonal Transform).
Transform) This is a processing frame. Time window section 15
Apply a time window to the LOT processing frame. On the other hand, the output of the time windowing unit 15 is an Nth-order MDCT (Modified Discrete Cosine) which is a kind of superposition orthogonal transform.
Transform: Modified discrete cosine transform) unit 16
Modified discrete cosine transform is performed on frequency domain coefficients. On the other hand, the output of the time windowing unit 15 is subjected to linear prediction analysis by the linear prediction analysis unit 17. As a result, the P-order prediction coefficient α
0,..., ΑP are obtained. The quantization unit 18 converts the prediction coefficients α0,..., ΑP into, for example, an LSP parameter or a k parameter and then quantizes the prediction coefficients α0,.
Get. Here, "spectrum envelope"
ope) "means the envelope of the amplitude of the MDCT coefficients.

The spectrum shape calculator 21 calculates the spectrum shape of the prediction coefficients α0,..., ΑP. The normalizing unit 22 divides (i.e., normalizes) the spectrum amplitude from the MDCT unit 16 for each corresponding sample using the spectrum outline, thereby obtaining the current frame F.
To obtain the residual coefficient R (F). Here, "residual coefficient (resi
"dual coefficient)" means an MDCT coefficient that has been flattened in a spectral outline. The weight calculation unit 24 multiplies the spectrum outline from the spectrum outline calculation unit 21 and the residual coefficient outline ER (F) from the residual outline calculation unit 23 for each corresponding sample, thereby obtaining a weighting coefficient. , WN (represented by the vector W).
Here, "envelope of residual coeff
“icient)” means an outline obtained by further analyzing the residual coefficient in the frequency axis. And the weight calculator 24
Supplies the weighting coefficient W to the quantization unit 25.

The residual approximate normalizing section 26 divides the residual coefficient R (F) of the current frame F from the normalizing section 22 by the residual coefficient approximate form from the residual coefficient approximate calculating section 23 ( That is, by normalizing), a fine structure coefficient is obtained. here,
"Fine structure coefficient"
This means an MDCT coefficient obtained by further flattening the flattened MDCT coefficient by a residual coefficient outline. Power normalization unit 2
7 is the normalized gain g which is the average value of the amplitude or the square root of the average value of the power.
The result is divided by (F) (that is, normalized), and the result is supplied to the quantization unit 25 as a normalized fine structure coefficient X (F) = (x1,..., XN). The power normalizing section 27 gives the above-mentioned normalized gain g (F) to the inverse normalizing section 31. Also,
The power normalizing unit 27 quantizes the normalized gain g (F), and outputs the result as an index IG.

The quantization unit 25 calculates the normalized fine structure coefficient X
(F) is weighted by a weighting coefficient W, and then vector-quantized to obtain a quantized small series C
(M) is obtained. Here, the quantized small series C (m) is composed of M vectors C (m1), C (m2),.
). The inverse normalization unit 31 inversely normalizes the quantized small series C (m) using the normalization gain g (F) from the power normalization unit 27, and furthermore, the residual coefficient from the residual approximate shape calculation unit 23. Regenerate the quantized residual coefficient Rq (F) by multiplying the approximate shape. The residual approximate shape calculation unit 23 calculates an approximate shape of the quantized residual coefficient Rq (F).

The index IP indicating the quantization value of the linear prediction coefficient, the index IG indicating the quantization value of the power normalization gain of the fine structure coefficient, and the index Im indicating the quantization value of the fine structure coefficient are irreversible. Compression code I
(N) is output from the irreversible quantization unit 120.

In the inverse quantization unit 130, the normalized fine structure coefficient corresponding to the index Im and the normalized gain corresponding to the index IG are input to the power inverse normalization unit 53, respectively. Power inverse normalization unit 53
Obtains a fine structure coefficient by denormalizing the normalized fine structure coefficient with a normalization gain. The residual approximate inverse normalizer 54 calculates the residual approximate E from the residual approximate calculator 55.
Multiply (ie, denormalize) the fine structure coefficient by R 1
Thus, the residual coefficient Rq (F) is reproduced. The residual approximate shape calculation unit 55 calculates the approximate shape of the reproduced residual coefficient Rq (F) in the same manner as the residual approximate shape calculation unit 23 of the irreversible quantization unit 120.

On the other hand, the inverse normalization section 57 multiplies the spectrum outline from the spectrum outline calculation section 21 by the residual coefficient Rq (F) from the residual outline inverse normalization section 54 (ie,
Inverse normalization) reproduces the frequency domain coefficients. The inverse MDCT unit 58 converts the frequency domain coefficient into a time domain signal of 2N samples (hereinafter, referred to as “frame for inverse LOT processing”) by performing an Nth-order inverse modified discrete cosine transform for each frame. The windowing unit 59 applies a time window to the time domain signal for each frame. The frame superposition unit 61 adds the former N samples of the output of the windowing unit 59 (current frame for inverse LOT processing of 2N samples) and the latter N samples of the immediately preceding frame to each other, and obtains the resulting N The sample is output to the subtraction unit 140 as an inverse quantization signal of the current frame.

As an example of the irreversible quantization unit 120,
A configuration for dividing in the frequency domain and performing hierarchical coding will be briefly described with reference to FIG. This configuration is based on the 8-80
No. 096. The highest frequency of the original sound input signal 21 from the frame dividing unit 110 is f4,
The sampling frequency is 2f4. A first sample rate converter 221 serving as a first band selecting means converts a maximum frequency f1 and a sampling frequency 2f1 from the original sound input signal 21.
The first band signal 231 of (where f1 <f2 <f3 <f4) is extracted. The first encoder 241 encodes the first band signal 231 into a first code C1. The first decoder 251 converts the first code C1 into the highest frequency f1.
And it decodes into the decoded signal 121 of sampling frequency 2f1. The first sample rate converter 261 converts the decoded signal 121 into the highest frequency f2 and the sampling frequency 2f2.
To the first converted decoded signal. On the other hand, the sample rate converter 222 which is the second band selecting means outputs the maximum frequency f2 and the sampling frequency 2f from the original sound input signal 21.
2 of the second band signal 232. Second difference circuit 2
82 obtains a second difference signal 292 by subtracting the first transformed decoded signal from the second band signal 232.
The second encoder 242 encodes the second difference signal 292 into a second code C2.

Hereinafter, the same processing is performed. Here, the process of obtaining the third code C3 is described as i = 3 (i = 2, 3,..., N,
In this example, up to 4) will be described as an example. The i-1 (=
2) The decoder 25i-1 (252) outputs the i-1
The (= second) code Ci-1 (= C2) is converted to the highest frequency fi-1 (= f2) and the sampling frequency 2fi-1.
(= 2f2) decoded into the (i-1) th (= second) decoded signal. The adder 60i-1 (= 602) outputs the i-1
By adding the (= second) decoded signal and the (i-2) th (= first) converted decoded signal, an (i-1) th (second) sum signal is obtained. The (i-1) th (= second) sample rate converter 26i
−1 (= 262) is the i−1 (second) sum signal,
Maximum frequency fi (= f3) and sampling frequency 2fi
(= 2f3) into an (i-1) th (= second) transformed decoded signal. On the other hand, the sample rate converter 22i (= 223), which is the i-th (= third) band selecting means, converts the original sound input signal 21 into the i-th signal having the highest frequency fi (= f3) and the sampling frequency 2fi (= 2f3). The (= third) band signal 23i (= 233) is extracted. The i-th (= third) difference circuit 28i (283) converts the i-th (= third) band signal 23i (= 233) to the i-th (= second) signal.
By subtracting the transformed decoded signal, the ith (= third)
The difference signal 293 is obtained. I-th (= third) encoder 24i
(= 243) encodes the ith (= third) difference signal 293 into the ith (= third) code Ci (= C3). Note that the (i−1) th (= second) decoder 25i−1 (= 252)
), Adder 60i-1 (= 602) and i-1.
(= Second) sample rate converter 26i-1 (= 26
2) means the (i-1) th (= second) decoding means 40i-1
(= 402). However, the first decryption means 4
01, since the (i-2) th layer does not exist, the adder 60
0 is omitted. Further, since the band signal of the uppermost layer, in this example, the (i + 1) th (= fourth) band signal 234 is the signal of the highest frequency f4, the sample rate converter 224 as the (i + 1) th band selecting means is omitted.

The irreversible quantization unit 120 shown in FIG.
This can be applied to a case where an input signal band is divided into n sections and encoded. The first to n-th (= fourth) codes C1 to Cn (=
C4) is multiplexed for each frame by the multiplexing circuit, and then output as a lossy code P (n). In this case, the multiplexing circuit is configured to select and output any one of the first to i-th codes. I-th encoder 24i
(I = 1 to n: where n = 4 in FIG. 8) is set so that the compression ratio decreases as i increases.
Broadband, high-quality encoding becomes possible. If this is satisfied, the encoding method of the encoder may be, for example, a transform encoding method.

As a coding method of the first to n-th encoders 241 to 244, a CELP coding method, a transform coding method, or the like can be used, and the first to n-th encoders 241 to 244 use the same coding method. May be used, or different coding methods may be used. The irreversible quantization unit 1 shown in FIG.
An outline of the inverse quantization unit 130 when using No. 20 will be described with reference to FIG. FIG. 9 shows the case where n = 4, that is,
This is a case where the code string C is composed of the first to fourth codes C1 to C4. The code separating means 56 converts the code string C into the 1st to 4th
It is separated into symbols Cl to C4. Then, the first code C1
Is supplied to the first decoder 571, the second code C2 is supplied to the second decoder 572, and the third code C3 is supplied to the third decoder 571.
The fourth code C4 is supplied to the decoder 573, and the fourth code C4 is supplied to the fourth decoder 574. The first decoder 571 decodes the first code C1 into a first decoded signal 581. First
The decoded signal 581 is input to the first sample rate converter 591 as a first decoded output 631. The first sample rate converter 591 outputs a first decoded output 631
Is converted to the first transformed decoded signal 611 of the sampling frequency 2f2.
Convert to On the other hand, the second decoder 572 decodes the second code C2 into a second decoded signal 582. The second adder 622 adds the first transformed decoded signal 611 and the second decoded signal 582 to obtain a second decoded output 632. The second sample rate converter 592 is
The second decoded output 632 is converted to a second converted decoded signal 612 having a sampling frequency of 2f3. Hereinafter, the case of i = 3 will be generalized and described. The i-th (= third) decoder 57i (= 573) outputs the i-th (= third) code Ci.
(= C3) to the i-th (= third) decoded signal 58i (=
583). I-th (= third) adder 62i
(= 623) is the i−1 (= second) transformed decoded signal 6
1i-1 (= 612) and the ith (= third) decoded signal 5
8i (= 583) and the i-th
The (= third) decoded output 63i (= 633) is obtained.
The ith (= third) sample rate converter 59i (= 59)
3) is the ith (= third) decoded output 63i (= 63)
3) is converted to an ith (= third) transformed decoded signal 61i (= 613) having a sampling frequency of 2fi + 1 (= 2f4). The (i + 1) th (= fourth) decoder 57i + 1 (= 5)
74) is the (i + 1) th (= fourth) code Ci + 1 (= C
4) is converted to the (i + 1) th (= fourth) decoded signal 58i + 1
(= 584). The (i + 1) th (= fourth) adder 62i + 1 (= 624) converts the (i) th (= third) transformed decoded signal 61i (= 613) and the (i + 1) th (= fourth)
By adding the decoded signal 58i + 1 (= 584), the (i + 1) th (= fourth) decoded output 63i + 1 is obtained.
(= 634). The (i + 1) th (= fourth) decoded output 63i + 1 (= 634) is supplied to the subtraction unit 140 as a quantized signal.

Next, the experimental results of the second embodiment are shown in FIGS. 3 sampled at 44.1 kHz
Experiments were performed on three different stereo audio signals and three different monaural audio signals sampled at 16 kHz. As the irreversible quantization unit 120,
Twin VQ in the ISO / IEC MPEG-4 scalable profile was used. Irreversible quantization unit 12
The compression unit bit rate of 0 is 16 kbit / s / ch for 44.1 kHz and 8 kbit / s for 16 kHz. By repeatedly using this quantizer, the sum of the data rate of the MPEG compressed signal and the data rate of the error signal is reduced. As a result, the quantization bit rate becomes 44.1 kHz.
For 1 kHz, it was reduced to 1/44 of the original signal, and for 16 kHz, it was reduced to 1/32. The percentage (%) of the total file size is determined by the file size of the error signal and the compression MP
This is the sum with the size of the EG bit stream. The total file size shown in FIGS. 10 and 11 indicates that the original signal size can be reduced to about 70-50%. When the irreversible quantization unit 120 compresses the original signal file size to about 1/10, it can be seen that the total file size is minimized. Also, 44.1k
The Hz stereo has a slightly better compression ratio than the 16 kHz monaural.

§3. Third Embodiment FIG. 12 is a block diagram showing a configuration example of an encoding device and a decoding device according to a third embodiment of the present invention. FIG.
In FIG. 2, portions corresponding to the respective portions in FIGS. 1 and 4 are denoted by the same reference numerals, and description thereof will be omitted. The device shown in FIG. 12 is configured by the selection unit 270 and the switching unit 280 to have either a configuration equivalent to the device according to the first embodiment (see FIG. 1) or a configuration equivalent to the device according to the second embodiment (see FIG. 4). Can be switched.

That is, in the encoding device, the selection unit 270
Receives a digital input signal from the frame division unit 110 on a frame basis, and an error signal corresponding to the digital input signal from the subtraction unit 140 on a frame basis. Then, the selection unit 270 selects and outputs one of the digital input signal and the error signal in a frame unit. In addition, the selection unit 270 generates, for each output (that is, for each frame), selection information indicating whether the output is a digital input signal or an error signal, and adds the selection information to the output. The selection information is stored in the selection unit 2
Instead of being added to the output of the selector 70, it may be separately sent to the switching unit 280 in synchronization with the output of the selector 270. Hereinafter, the output of the selection unit 270 is subjected to the processing described in the first embodiment and the second embodiment (that is, reordering → lossless encoding → lossless decoding → reverse ordering). As a result, the same signal as the output of the selection unit 270 is output from the reordering unit 220 in frame units.

On the other hand, in the decoding device, the switching unit 280
Extracts selection information from the output of the reordering unit 220. The selection information may be received from the selection unit 270 in synchronization with the output of the reordering unit 220. If the selection information indicates that “the output of the reordering unit 220 is a digital input signal”, the switching unit 2
80 sends the output to the frame synthesizing unit 250 as it is. Hereinafter, the output of the switching unit 280 is subjected to the processing (frame synthesis → reproduction signal output) described in the first embodiment. On the other hand, if the selection information indicates that “the output of the reordering unit 220 is an error signal”, the switching unit 280
Sends the output to the frame adder 240. Hereinafter, the output of the switching unit 280 is subjected to the processing described in the second embodiment (addition with the output of the inverse quantization unit 230 → frame synthesis → reproduction signal output).

§4. Fourth Embodiment Before describing the fourth embodiment, problems to be solved by the embodiment will be described. In the irreversible compression part (that is, the irreversible quantization unit 120, the inverse quantization unit 130, and the inverse quantization unit 230) of the second and third embodiments, a known compression format and a decoder are used as they are. There are cases. However, in this case, if the encoding device and the decoding device are realized on different platforms, the local reproduction signal used for generating the error signal (ie, the inverse quantization unit 130)
) And the actual inverse quantized signal (ie, the inverse quantizer 23)
0 output) does not completely match. For example, taking the MPEG audio standard as an example, if the digital input signal is 16 bits, the difference between the reference standard output signal for the interconnection test between the encoder and the decoder and the actual output signal of the decoder is Although it is guaranteed that it falls within “± 1” (that is, an error to the extent that the LSBs do not match), it does not always mean that they completely match. As described above, when the output of the inverse quantization unit 130 and the output of the inverse quantization unit 230 do not match, the error signal generated based on the output of the inverse quantization unit 130 is converted (by the adder 240) into the inverse quantization unit. Adding to the output of 230 does not guarantee that the original digital input signal will be reproduced without distortion.

Therefore, in the fourth embodiment, the inverse quantization unit 1
30. The absolute value portion of the amplitude of the digital input signal is arithmetically shifted upward by the number of bits (tentatively, t bits) based on the difference between the output of the digital input signal 30 and the output of the inverse quantization section 230. Irreversible quantization of the signal. Then, after the irreversibly quantized digital input signal is inversely quantized (by the inverse quantization unit 130 or the inverse quantization unit 230), the absolute value portion of the amplitude of the inversely quantized signal is reduced to t by Bit arithmetic shift (ie, divide by 2t). As a result, the output of the inverse quantization unit 130 and the output of the inverse quantization unit 230 match.

In the case of MPEG audio coding,
The output of the inverse quantization unit 130 and the output of the inverse quantization unit 230 are each ± 1 compared with the original digital input signal.
Error. As a result, the difference between the output of the inverse quantization unit 130 and the output of the inverse quantization unit 230 becomes the maximum value “± 2” when one is “+1” and the other is “−1”. . Therefore, in this embodiment, in order to remove the maximum value of the difference from the digital input signal, t = 3 bits is set, and the digital input signal is arithmetically shifted by 3 bits.
It should be noted that the value of t is not limited to t = 3, but is determined based on the difference between the output of the inverse quantization unit 130 and the output of the inverse quantization unit 230 as described above. You.

FIG. 13 is a block diagram showing a configuration example of an encoding device and a decoding device according to a fourth embodiment of the present invention. 13, parts corresponding to the respective parts in FIGS. 1, 4, and 12 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 13, the frame dividing unit 110
, The reproduced output signal from the frame synthesizing unit 250, and the signals processed by the irreversible quantization unit 120, the inverse quantization unit 130, and the inverse quantization unit 230 are expressed in two's complement. , And the other signals are represented by a sign absolute value expression. Therefore, it is assumed that the conversion from the two's complement representation to the sign absolute value representation and the conversion from the sign absolute value representation to the two's complement representation (not shown in FIG. 13) are appropriately performed. .

In the encoding device shown in FIG. 13, first,
The frame dividing unit 110 converts the digital input signal sequence into
Divide sequentially in frame units. Bit shift unit 290
However, the absolute value part of the amplitude of each digital input signal is arithmetically shifted by t bits upward, and the lower t bits of the absolute value part are set to “0”. The irreversible quantization unit 120
The output of the bit shift unit 290 is subjected to lossy compression encoding. The inverse quantization unit 130 inversely quantizes the output of the irreversible quantization unit 120 to generate a local reproduction signal. The bit shift unit 300 rounds the lower t bits of the absolute value part of the amplitude of the local reproduction signal, and then performs an arithmetic shift by t bits in the lower direction. The subtraction unit 140 obtains an error signal between the output of the frame division unit 110 and the output of the bit shift unit 300. Hereinafter, the reordering unit 160 and the lossless encoding unit 150 perform the same processing on the error signal as the reordering unit 160 and the lossless encoding unit 150 of the second embodiment. Thereby, the lossless encoding unit 150
Outputs a lossless compression code of the error signal.

On the other hand, the lossless encoder 310 losslessly compresses and encodes the upper t bits of the absolute value portion of the amplitude of each digital input signal. Since each digital input signal is represented by a sign absolute value expression, the upper t bits are often “0”. Therefore, the lossless encoding unit 310 can increase the compression efficiency by performing the same encoding processing as the lossless encoding unit 150.

By the above processing, the encoding apparatus shown in FIG. 13 performs the lossy compression code from the lossy quantization section 120, the lossless compression code (of the error signal) from the lossless encoding section 150, and the lossless compression code. The lossless compression code (of the upper t bits of the digital input signal) from the encoding unit 310 is output.

On the other hand, in the decoding device shown in FIG. 13, the lossless decoding unit 210 and the reordering unit 220
Performs the same processing as the lossless decoding unit 210 and the reordering unit 220 of the second embodiment on the lossless compression code (of the error signal) from the lossless encoding unit 150. On the other hand, the inverse quantization section 230 inversely quantizes the output of the irreversible quantization section 120 to generate a local reproduction signal. The bit shift section 320 rounds off the lower t bits of the absolute value portion of the amplitude of the local reproduction signal, and then performs an arithmetic shift by t bits in the lower direction. The adding unit 240 adds the output of the reordering unit 220 and the output of the bit shift unit 320.

On the other hand, the lossless decoding unit 330 losslessly decodes the output of the lossless encoding unit 310, thereby outputting the upper t bits of the absolute value portion of the amplitude of the original digital input signal in frame units. The adding unit 340 connects the output of the lossless decoding unit 330 to the upper bit side of the output of the adding unit 240. Finally, the frame synthesizing unit 250 reproduces the original digital input signal sequence by sequentially connecting the outputs of the adding unit 340. By the above processing, the digital input signal sequence is output from the output terminal 260.

§5. Supplement The functions of each unit described in each of the above embodiments can be realized by causing a computer to decode and execute a program.

The apparatus shown in FIGS. 4, 12, and 13 has only one type of irreversible quantization means (ie, irreversible quantization section 120, inverse quantization section 130, inverse quantization section). However, the present invention is not limited to this, but includes a plurality of types of irreversible quantization methods and a plurality of irreversible quantization conditions. (E.g., a method and conditions corresponding to the inverse quantization executable by the decoding device) are appropriately set (e.g.
(For each frame). In that case,
In the third embodiment, information indicating the selected method and condition may be added to the selection information and sent to the decoding device.

[0055]

According to the present invention, the original digital signal can be completely restored, and at the same time, a high compression rate can be obtained. Further, since the image data is divided on a frame basis, a signal can be completely reproduced even in the middle of a compressed code sequence by using a synchronization word or the like. Conventionally, both the original sound file of music and the compression code file are recorded on a CD-ROM, the compression code file is provided free of charge, and the original sound file is provided only to the person who paid. Have been done. According to the present invention, the compression code and the error signal are recorded, the compression code is provided free of charge, and the paying person can reproduce the original sound by providing the compression code and the error signal. can do. According to this configuration, the data amount of the sum of the compression code and the error signal is significantly smaller than the data amount of the sum of the original sound and the compression code, so that the data can be recorded on a storage medium having a small storage capacity. Although the amount of processing in irreversible quantization and inverse quantization is large, hardware (for example, MPE
G encoding / decoding processor) and various softwares are commercially available and can be obtained at a low price, so that a large amount of processing does not matter.

As described above, according to the present invention, Twin VQ, MP
3, by combining with tone compression encoding such as MPEG-4, highly efficient lossy encoding and distortion-free lossless encoding can coexist without waste. for that reason,
INDUSTRIAL APPLICABILITY The present invention is particularly effective when storing and transmitting musical tone signals, and is applicable to a wide range of applications including network distribution of music and portable music appreciation devices.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of an encoding device and a decoding device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a process of a reordering unit 160 according to the first embodiment.

FIG. 3 is an explanatory diagram illustrating an example of an output of a reordering unit 160 according to the first embodiment.

FIG. 4 is a block diagram illustrating a configuration example of an encoding device and a decoding device according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating an example of processing of a reordering unit 160 according to the second embodiment.

FIG. 6 is an explanatory diagram illustrating an example of an output of a reordering unit 160 according to the second embodiment.

FIG. 7 shows an irreversible quantization unit 120 using a transform coding method.
FIG. 3 is a block diagram illustrating a specific configuration example of the inverse quantization unit 130 and an inverse quantization unit 130;

FIG. 8 shows an irreversible quantization unit 120 using a hierarchical coding method.
3 is a block diagram showing a specific configuration example of FIG.

9 is a block diagram illustrating a specific configuration example of an inverse quantization unit 130 corresponding to the irreversible quantization unit 120 illustrated in FIG.

FIG. 10 is an explanatory diagram showing experimental results of the second embodiment.

FIG. 11 is an explanatory diagram showing experimental results of the second embodiment.

FIG. 12 is a block diagram illustrating a configuration example of an encoding device and a decoding device according to a third embodiment of the present invention.

FIG. 13 is a block diagram illustrating a configuration example of an encoding device and a decoding device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 110: frame division unit 120: irreversible quantization unit 130, 230 ... inverse quantization unit 140: subtraction unit 150, 310 ... lossless encoding unit 160, 220 ... rendition unit 210, 330 ... Lossless decoding units 240, 340 addition unit 250 frame synthesis unit 270 selection unit 280 switching unit 290, 300, 320 bit shift unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akio Kami 2-3-1 Otemachi, Chiyoda-ku, Tokyo Within Nippon Telegraph and Telephone Corporation (72) Inventor Takeshi Mori 2-chome Otemachi, Chiyoda-ku, Tokyo No. 1 Inside Nippon Telegraph and Telephone Corporation (72) Inventor Kazuaki Chikira 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (34)

[Claims] A step of converting a digital input signal into a bit string of a sign absolute value representation for each frame; a step of decomposing the bit string into individual bits; and a step of converting the bits generated by the decomposition into at least one bit position. , A step of connecting in time order and a step of losslessly coding each bit string obtained by the connection. 2. A process of losslessly decoding a lossless encoded sequence for each frame, a process of decomposing each bit string obtained by the lossless decoding into individual bits, and concatenating each bit in the order of bit position at the same time And a step of sequentially connecting the frames obtained by the connection. 3. A step of generating a code sequence by irreversibly quantizing a digital input signal for each frame; a step of generating a quantized signal by quantizing the code sequence for each frame; Calculating an error signal between the signal and the quantized signal; displaying the amplitude value of the error signal in binary and decomposing the bit by bit; connecting adjacent samples of the decomposed binary display signal in chronological order. A lossless encoding method characterized by comprising a step of generating a time series by performing a time series, and a step of generating a losslessly compressed series by performing a lossless compression on the time series. 4. A step of generating a code sequence by irreversibly quantizing a digital input signal for each frame; a step of generating a quantized signal by quantizing the code sequence for each frame; Calculating an error signal between the signal and the quantized signal; selecting and outputting one of the digital input signal and the error signal; A step of generating a time series by connecting adjacent samples of the binary display decomposition signal in chronological order, and a step of generating a lossless compressed sequence by losslessly compressing the time series. A lossless encoding method, comprising: 5. A step of generating a lossless-compressed sequence by reversibly compressing upper t bits of the digital input signal, and converting the remaining bits of the digital input signal to upper bits by t.
Performing a bit arithmetic shift, generating a code sequence by irreversibly quantizing the digital input signal that has been t-bit arithmetically shifted upward in each frame, and dequantizing the code sequence in each frame. Generating an inverse quantized signal by the following method; rounding off the lower t bits of the absolute value portion of the amplitude of the inverse quantized signal; and arithmetically shifting the rounded inverse quantized signal by t bits in the lower direction. A step of calculating an error signal between the input signal and the inversely quantized signal that has been shifted t bits downward in a lower direction; a step of displaying the amplitude value of the error signal in binary and decomposing it for each bit; Generating a time series by connecting adjacent samples of the binary display decomposition signal in chronological order; and losslessly compressing the time series by losslessly compressing the time series. Lossless encoding method characterized by having a process of generating a column. 6. The method of generating a code sequence according to claim 1, wherein one of a plurality of types of irreversible quantization methods is selected and irreversible quantization is performed by the selected method. The lossless encoding method according to any one of claims 3 to 5. 7. The method according to claim 3, wherein the step of generating the code sequence is a step of obtaining the code sequence by encoding the input signal by a transform encoding method. Or the lossless encoding method described in 8. The step of generating the code sequence includes converting the input signal to frequencies f1, f2,..., Fn-1 (f1
<F2 <... <fn-1 <fn; fn is the highest frequency of the input signal) and is a process of encoding by dividing into n sections (n is an integer of 2 or more), A first band selecting step of selecting a first band signal of f1 or less; a first encoding step of generating a first code by encoding the first band signal by a first encoding method; An (i-1) -th band decoding process of obtaining an (i-1) -th decoded signal having a frequency of fi-1 or less from each code (i = 2, 3,..., N) of -i or less; An i-th band selection step of selecting an i-th band signal of the following; an i-th difference step of obtaining an i-th difference signal by subtracting the (i−1) -th decoded signal from the i-th band signal; I-th encoding for generating an i-th code by encoding with an i-th encoding method And obtaining the quantized signal by obtaining an n-th decoded signal having a maximum frequency fn or less from each of the n-th or less codes (i = 2, 3,..., N). The lossless encoding method according to claim 3. 9. The i-th encoding method (i = 1, 2,...,
9. The lossless encoding method according to claim 8, wherein each of n) is a transform encoding method. 10. A method for decoding a digital signal by receiving a code sequence and a lossless compressed sequence, comprising: generating a transform time series by losslessly decoding the lossless compressed sequence for each frame; Arranging the conversion time series in parallel by aligning the first bit for each frame length, and generating a sample sequence as a time series that constitutes each sample by the same bits arranged in parallel, and quantizing the code sequence. A lossless decoding method, comprising: decoding into a signal; and generating the digital signal by adding the time series and the quantized signal. 11. A method for decoding a digital signal by inputting a code sequence and a lossless compressed sequence, comprising: generating a transformed time series by lossless decoding the lossless compressed sequence for each frame; Arranging the conversion time series in parallel by aligning the first bit for each frame length, and generating a sample sequence as a time series that constitutes each sample by the same bits arranged in parallel, and quantizing the code sequence. Decoding the signal, generating the digital signal by adding the time series and the quantized signal, and performing the step of generating the digital signal instead of performing the digital signal with the time series as it is. Performing the reversible decoding. 12. A code sequence, a first lossless compression sequence, and a second
A lossless compressed sequence is input and a digital signal is decoded, wherein a lossless decoding of the first lossless compression sequence for each frame to generate a conversion time series; and Arranging the first bits for each frame length and arranging them in parallel, and generating a sample sequence as a time series that constitutes each sample by the same bits laid out in parallel; and performing t-bit arithmetic operation on the code sequence in the lower direction. Shifting the code sequence, which has been t-bit arithmetically shifted in the lower direction, into a quantized signal; adding the time series and the quantized signal; Lossless decoding for each frame; and linking the losslessly decoded second lossless compressed sequence to the upper bit side of the result of adding the time series and the quantized signal. Combining the lossless decoding method. 13. The method of decoding a code sequence into a quantized signal, wherein one of a plurality of types of inverse quantization methods is selected and decoded by the selected method. 13. The lossless decoding method according to claim 1. 14. The method according to claim 10, wherein the step of decoding the quantized signal is a step of obtaining the quantized signal by decoding the input code sequence by a transform decoding method. The lossless decoding method according to any one of the above. 15. The step of decoding the quantized signal includes the steps of separating the input code sequence into first to m-th codes (m is a natural number of 2 or more), and the i-th code (i = 1, 2). ,..., M) by an i-th decoding method to generate an i-th decoded signal having a frequency of fi or less, and adding the first to m-th decoded signals. 13. The lossless decoding method according to claim 10, further comprising the step of generating the quantized signal. 16. The i-th decoding method (i = 1, 2, 2, 3)
.., M) are conversion decoding methods. 17. A means for converting a digital input signal into a bit sequence of a sign absolute value representation for each frame, a means for decomposing the bit sequence into individual bits, and converting the bits generated by the decomposition into at least one bit position. , A means for linking in order of time, and a means for losslessly coding each bit string obtained by the linking. 18. A means for losslessly decoding a lossless encoded sequence for each frame, a means for decomposing each bit string obtained by lossless decoding into individual bits, and concatenating each bit in the order of bit position at the same time And a means for sequentially connecting the frames obtained by the connection. 19. A means for generating a code sequence by irreversibly quantizing a digital input signal for each frame; means for generating a quantized signal by quantizing the code sequence for each frame; Means for calculating an error signal between the signal and the quantized signal; means for displaying the amplitude value of the error signal in binary and decomposing the bit by bit; connecting adjacent samples of the binary display decomposed signal in time order A lossless encoding apparatus comprising: means for generating a time series by means of the above method; and means for generating a losslessly compressed series by performing a lossless compression on the time series. 20. A means for generating a code sequence by irreversibly quantizing a digital input signal for each frame; means for generating a quantized signal by quantizing the code sequence for each frame; Means for calculating an error signal between the signal and the quantized signal; means for selecting and outputting any one of the digital input signal and the error signal; Means for generating a time series by connecting adjacent samples of the binary display decomposition signal in chronological order, and means for generating a lossless compressed sequence by losslessly compressing the time series. A lossless encoding device comprising: 21. A means for generating a lossless-compressed sequence by reversibly compressing upper t bits of a digital input signal;
Means for performing a bit arithmetic shift, means for generating a code sequence by irreversibly quantizing the digital input signal which has been t-bit arithmetically shifted in the upper direction for each frame, and dequantizing the code sequence for each frame. Means for generating a dequantized signal by means of: a means for rounding off the lower t bits of the absolute value part of the amplitude of the dequantized signal; means for arithmetically shifting the rounded dequantized signal by t bits in the lower direction. Means for calculating an error signal between the input signal and the inversely quantized signal which has been t-bit arithmetically shifted in a lower direction; means for displaying the amplitude value of the error signal in binary and decomposing it for each bit; Means for generating a time series by connecting adjacent samples of the binary display decomposition signal in chronological order; lossless compression by losslessly compressing the time series Lossless encoding apparatus characterized by having a means for generating a column. 22. The means for generating a code sequence selects one of a plurality of types of irreversible quantization methods,
22. The lossless encoding device according to claim 19, wherein irreversible quantization is performed by a selected method. 23. The method according to claim 19, wherein the means for generating the code sequence is means for obtaining the code sequence by coding the input signal by a transform coding method. A reversible encoding device according to any one of the above. 24. The means for generating the code sequence converts the input signal into frequencies f1, f2,..., Fn-1 (fn-1).
1 <f2 <... <fn-1 <fn; fn is a means for dividing and encoding into n sections (n is an integer of 2 or more) of the highest frequency of the input signal; First band selecting means for selecting a first band signal having a frequency equal to or less than f1, first encoding means for generating a first code by encoding the first band signal by a first encoding method, An (i-1) -th band decoding means for obtaining an (i-1) -th decoded signal having a frequency of fi-1 or less from each code (i = 2, 3,..., N) of 1-i or less; I-th band selecting means for selecting the following i-th band signal; i-th difference means for obtaining the i-th difference signal by subtracting the i-1 th decoded signal from the i-th band signal; To generate an i-th code by encoding And a means for obtaining the quantized signal by obtaining an n-th decoded signal having a maximum frequency fn or less from each of the n-th or less codes (i = 2, 3,..., N). The lossless encoding device according to any one of claims 19 to 21. 25. The i-th encoding method (i = 1, 2, 2)
.., N) are all transform coding methods. 26. An apparatus for decoding a digital signal by inputting a code sequence and a lossless compressed sequence, comprising: means for generating a conversion time series by losslessly decoding the lossless compressed sequence for each frame; Means for arranging the conversion time series in parallel by aligning the first bit for each frame length, and generating a sample series constituting a sample as a time series with the same bits arranged in parallel, and quantizing the code series. A lossless decoding device comprising: means for decoding into a signal; and means for generating the digital signal by adding the time series and the quantized signal. 27. An apparatus for decoding a digital signal by receiving a code sequence and a lossless compressed sequence as input, comprising: means for generating a conversion time series by losslessly decoding the lossless compressed sequence for each frame; Means for arranging the conversion time series in parallel by aligning the first bit for each frame length, and generating a sample series constituting a sample as a time series with the same bits arranged in parallel, and quantizing the code series. Means for decoding into a signal, means for generating the digital signal by adding the time series and the quantized signal, instead of executing the means for generating the digital signal, And a means for performing the following. 28. A code sequence, a first lossless compression sequence, and a second
A lossless-compressed sequence for decoding a digital signal, wherein the means for losslessly decoding the first lossless-compressed sequence for each frame to generate a conversion time series; and Means for arranging the first bit for each frame length and arranging them in parallel, and generating, as a time series, a sample sequence constituting each sample by the same bits arranged in parallel; Means for shifting, the means for decoding the code sequence, which has been t-bit arithmetically shifted downward, into a quantized signal, means for adding the time series and the quantized signal, Means for performing lossless decoding for each frame, and linking the second losslessly compressed sequence that has been losslessly decoded to the upper bit side of the addition result of the time series and the quantization signal A lossless decoding device comprising: 29. The method according to claim 26, wherein the means for decoding the code sequence into a quantized signal selects one of a plurality of types of inverse quantization methods and decodes the selected sequence. 29. The lossless decoding device according to claim 28. 30. The apparatus according to claim 26, wherein said means for decoding said quantized signal is means for obtaining said quantized signal by decoding said input code sequence by a transform decoding method. The lossless decoding device according to any one of the above. 31. A means for decoding the quantized signal, means for separating the input code sequence into first to m-th codes (m is a natural number of 2 or more), and the i-th code (i = 1, 2). ,..., M) by an i-th decoding method, thereby adding an i-th decoding means for generating an i-th decoded signal having a frequency of fi or less, and adding the first to m-th decoded signals. 29. The lossless decoding apparatus according to claim 26, further comprising: means for generating the quantized signal. 32. The i-th decoding method (i = 1, 2, 2, 3)
32. The lossless decoding apparatus according to claim 31, wherein each of..., M) is a transform decoding method. 33. A recording medium on which a program for causing a computer to execute each step of the lossless encoding method according to claim 1 is recorded. 34. A recording medium on which a program for causing a computer to execute each step of the lossless decoding method according to claim 2 is recorded.