JP3318824B2 - Digital signal encoding method, digital signal encoding device, digital signal recording method, digital signal recording device, recording medium, digital signal transmission method, and digital signal transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital signal encoding processing method, a digital signal encoding processing device, a digital signal recording method, a digital signal recording device, a recording medium, a digital signal transmission method, and a digital signal transmission device.

[0002]

2. Description of the Related Art There are various conventional methods and devices for efficient encoding of audio signals.
Three examples will be described. The audio signal in the time domain is divided into blocks for each unit time, the signal on the time axis for each block is converted into a signal on the frequency axis (orthogonal transform), divided into a plurality of frequency bands, and encoded for each band. There is a transform coding method which is one of the blocking frequency band division methods. Sub-band coding (SBC), which is one of the non-blocking frequency band division methods for dividing and encoding a time-domain audio signal into a plurality of frequency bands without dividing the signal into unit frequency units. : Subband Codin
g) There is a method. There is also a high-efficiency coding method that combines the above-described band division coding and transform coding. In this case, for example, after performing band division by the above-described band division encoding method, the signal for each band is orthogonally transformed into a signal in the frequency domain by the above-described transformation encoding method, and the orthogonal transformation is performed. Encoding is performed for each band.

Here, as a filter for band division used in the above-described band division encoding method, for example, a quadrature mirror filter (QMF) is used.
rFilter), which is a 1976 RECrochi
ere Digital coding ofspeech in subbands Bell Sys
This is described in t.Tech. J. Vol.55, No.8 1976.
Also, ICASSP 83, BOSTON Polyphase Quadrature filter
sA new subbandcoding technique Joseph H. Rothweil
er has a polyphase quadrature filter (P
An equal bandwidth filter splitting method and apparatus such as QF (Polyphase Quadrature filter) is described.

[0004] The above-mentioned orthogonal transform includes, for example,
The input audio signal is divided into blocks in a predetermined unit time (frame), and a fast Fourier transform (FF) is performed for each block.
T), Discrete Cosine Transform (DCT), Modified D
There is a method of converting a time axis into a frequency axis by performing CT conversion (MDCT) or the like. Regarding the above MDCT, ICASSP 1987 Subband / Transform Coding Using F
ilter Bank DesignsBased on Time Domain Aliasing Ca
ncellation JPPrincen AB BradleyUniv. of Surre
y Royal Melbourne Inst. of Tech.

[0005] Further, as a frequency division width when quantizing each frequency component divided into frequency bands, there is band division in consideration of human auditory characteristics. That is, an audio signal may be divided into a plurality of bands (for example, 25 bands) with a bandwidth generally called a critical band (critical band) such that the bandwidth becomes wider as the band becomes higher.
When encoding data for each band at this time, predetermined bits are allocated to each band, or encoding is performed by adaptive bit allocation to each band. For example, M
When encoding the MDCT coefficient data obtained by the DCT processing by the above-described bit allocation, the MDCT coefficient for each band obtained by the above-described MDCT processing for each block is used.
Coding is performed on the coefficient data with an adaptive number of allocated bits.

Further, when encoding for each band, a so-called block floating (Block Floating) for realizing more efficient encoding is performed by normalizing and quantizing each band. Processing is performed. That is, when encoding the MDCT coefficient data obtained by the above-described MDCT processing, quantization is performed by performing normalization corresponding to the maximum value of the absolute value of the MDCT coefficient described above for each band. Thereby, more efficient encoding is performed.

Conventionally, the following two methods are known as the above-mentioned bit allocation method. IEEE Transactions of Accou
stics, Speech, and Signal Processing, vol.ASSP-25, No.
In 4, August 1977, bits are allocated based on the magnitude of the signal for each band. Also, ICASSP 1980 The cr
itical band coder − digital encoding of the percep
tual requirements of the auditory system MA Kran
The sner MIT describes a method of obtaining a required signal-to-noise ratio for each band and performing fixed bit allocation by using auditory masking.

[0008]

In the above-described conventional high-efficiency coding method, when calculating the bit allocation amount for each band to be quantized, the signal component for each band and the condition for normalization are calculated. In some cases, if bit allocation is not performed to a certain degree or more, all signal components may be quantized to 0. If bit allocation is performed without taking this into account, efficient encoding cannot be performed. Cases arise.

In view of the above, the present invention can prevent the use of extra bits, realize more efficient encoding, improve static characteristics and signal quality, and improve the recording medium. Digital signal encoding processing method that can make effective use of recording capacity and transmission capacity in transmission path,
Digital signal encoding processing device, digital signal recording method,
A digital signal recording device, a recording medium, a digital signal transmission method, and a digital signal transmission device are proposed.

[0010]

SUMMARY OF THE INVENTION A digital signal encoding method according to the present invention divides an input digital signal into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. For each two-dimensional block related to time and frequency, normalization is performed based on the signal components in the two-dimensional block to obtain normalized data.
A quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained for each two-dimensional block, a bit allocation amount is determined based on the quantization coefficient, and normalized data and bit allocation are determined for each two-dimensional block with respect to time and frequency. In a digital signal encoding method in which a signal component in a two-dimensional block is quantized according to the amount and information is compressed, and an information compression parameter for each two-dimensional block is obtained in terms of time and frequency, a digital signal encoding method is used in which For each dimensional block, a minimum bit allocation for quantizing at least one of the two-dimensional block signal components to a value other than 0 is calculated based on the normalized data and the two-dimensional block signal component, and based on the calculation result. When deciding the bit allocation amount, if all the signal components included in the block are quantized to zero, the bit is omitted. Those were Unishi.

[0011] According to the digital signal encoding method of the present invention, for each two-dimensional block relating to the time axis and frequency, the normalized data and the signal component in the two-dimensional block are used.
A minimum bit allocation for quantizing at least one of the signal components in the two-dimensional block to a value other than 0 is calculated, and when determining a bit allocation amount based on the calculation result, all the signal components included in the block are determined. If the data is quantized to zero, bits are omitted.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, an input digital signal such as an audio PCM signal is subjected to band division coding (SBC), adaptive conversion coding, and adaptive adaptive coding.
Transform coding (ATC: Adaptiv T
ransform Coding) Performs high-efficiency coding using the techniques of｝ and adaptive bit allocation. This technique will be described with reference to FIG.

In the specific high-efficiency encoder shown in FIG. 1, an input digital signal is divided into a plurality of frequency bands, and at the same time, orthogonal transform is performed for each frequency band. In the low frequency range, for each so-called critical bandwidth (critical band) in consideration of human hearing characteristics described later, in the middle and high frequency ranges, each critical bandwidth is subdivided in consideration of the block floating efficiency.
Bits are adaptively allocated and encoded. Usually, this block is a quantization noise generating block. Further, in the embodiment of the present invention, the block size (block length) is adaptively changed according to the input digital signal before the orthogonal transform.

That is, in FIG.
Hz audio signal is sampled at a sampling frequency of 44.1 kHz.
The audio PCM signal obtained by the M conversion is supplied to the input terminal 100. The input audio PCM signal is subjected to a band of 0 to 11 kHz and a band of 11 kHz to 22 kHz by a band dividing filter (band dividing means) 101 such as a QMF (quadrature mirror filter).
And divided into bands. Further, the signal in the band of 0 to 11 kHz is similarly divided into a band of 0 to 5.5 kHz and a band of 5.5 kHz by a band division filter (band division means) 102 such as QMF.
Hz to 11 kHz.

11 from the above-mentioned band division filter 101
The signal in the band of kHz to 22 kHz is supplied to an MDCT circuit (modified / discrete cosine transform circuit) (orthogonal transform means) 103 which is an example of an orthogonal transform circuit. The signal in the band of 5.5 kHz to 11 kHz from the band dividing filter 102 is supplied to an MDCT circuit (modified / discrete cosine transform means) (orthogonal transform means) 104. The signals in the band of 0 to 5.5 kHz from the band division filter 102 are supplied to an MDCT circuit (modified / discrete cosine transform means) (orthogonal transform means) 105 to be subjected to MDCT processing. Note that each M
In the DCT circuits 103, 104, and 105, block decision circuits (block decision means) 109, 1 provided for each band are provided.
MD based on the block size (length of processing block) (information compression parameter) determined by 10, 111
CT processing is performed.

As described above, means for dividing an input digital signal into a plurality of frequency bands includes, for example, QM
There is an F filter, which is described in 1976 RECroch
iereDigital Coding of Speech In Subbands Bell Sys
t.Tech. J. Vol.55, No.8, 1976. or,
ICASSP 83, Boston Polyphase Quadrature Filters-ANew
Subband Coding Technique Joseph H. Rothweiler describes an equal bandwidth filter splitting method.
Here, as the above-described orthogonal transform, for example, an input audio signal is divided into blocks in a predetermined unit time (frame), and a fast Fourier transform (FFT), a discrete cosine transform (DCT), a modified DCT transform (MDCT) is performed for each block. By performing such operations, there is an orthogonal transformation in which the time axis is transformed into the frequency axis. IC for MDCT
ASSP 1987 Subband / TransformCoding Using Filter Ban
k Designs Based On Time Domain AliasingCancellatio
n JPPrincen ABBradley Univ. of Surrey Royal Mel
bourneInst. Of Tech.

Here, each of the MDCT circuits 103, 104,
FIG. 2 shows a specific example of a standard input digital signal for a block for each band to be supplied to 105. In the specific example of FIG. 2, the three filter output signals have a plurality of orthogonal transform block sizes independently for each band, and the time resolution can be switched according to the time characteristics, frequency distribution, and the like of the signals. . If the signal is quasi-stationary in time, the orthogonal transform block size is increased to 11.6 mS as in the long mode in FIG. 2A. If the signal is non-stationary, the orthogonal transform block size is further divided into two and four. That is, as shown in the short mode of FIG.
When the time resolution is 9 mS, or as in the middle mode A in FIG. 2C or the middle mode B in FIG. 2D, a part is divided into two, that is, 5.8 mS, and another part is divided into four, that is, 2.
With a time resolution of 9 mS, it is adapted to an actual complex input digital signal. It is clear that the division of the orthogonal transform block size is more effective if more complicated division is performed if the scale of the processing device allows.

The orthogonal transform block size is determined by orthogonal transform block size determining circuits (orthogonal transform block size determining means) 109, 110, and 111, and the result of the determination is determined by each of the MDCT circuits 103, 104, 105 and The information is supplied to the bit allocation calculation circuit 118 and is output to the output terminals 113 and 1 as information on the block size (information on the length of the processing block) (information compression parameter).
15 and 117 are output.

Next, details of the orthogonal transform block size determining circuits 109, 110, and 111 will be described. Here, the orthogonal transform block size determining circuit 109 will be described as an example with reference to FIG. . QMF1 in FIG.
Out of the output 01, the output in the band of 11 kHz to 22 kHz is supplied to the power calculation circuit (power calculation means) 304 via the input terminal 301 in FIG. Further, FIG.
Of the output of the QMF 102 at 5.5 kHz to 1
The output in the 1 kHz band is supplied to the power calculation circuit (power calculation means) 305 via the input terminal 302 in FIG. 3, and the output in the 0 to 5.5 kHz band is output via the input terminal 303 in FIG. (Power calculation means)
306. Note that the block size determination circuits 110 and 111 in FIG.
The operations are the same, except that the signals input to 1, 302, and 303 are different from those of the block size determination circuit 109.

Each block size determining circuit 1 in FIG.
09, 110, 111 input terminals 301, 30 respectively
2 and 303 have a matrix configuration, that is, the input terminal 301 of the block size determination circuit 110 is supplied with the output of the band of 5.5 kHz to 11 kHz from the QMF 102 in FIG. 302
Is supplied with the output of the band of 0 to 5.5 kHz from the QMF 102.

In FIG. 3, each power calculation circuit 304,
Reference numerals 305 and 306 calculate the power of each frequency band by integrating the input time waveform for a certain period of time. At this time, the time width for integration needs to be equal to or smaller than the minimum time block among the orthogonal transform block sizes described above. In addition to the above calculation method, for example, the absolute value of the maximum amplitude or the average value of the amplitude within the minimum time width of the orthogonal transform block size may be used as the representative power.

The output of the power calculating circuit 304 is sent to a change extracting circuit (change extracting means) 308 and a power comparing circuit (power comparing means) 309, and the output of the power calculating circuits (power calculating means) 305 and 306 is sent to the power comparing circuit. 309 respectively. The change extraction circuit 308 obtains a differential coefficient of the power supplied from the power calculation circuit 304 and outputs it as power change information to the block size primary determination circuit (primary block size determination means) 310 and the memory (storage means) 307. Supply. In the memory 307, the power change information supplied from the change extraction circuit (change extraction means) 308 is stored for the maximum time of the orthogonal transform block size or more. This is because the temporally adjacent orthogonal transform blocks mutually influence each other by window processing at the time of orthogonal transform, so that the power change information of the immediately preceding temporally adjacent block is used as the block size primary decision circuit 31.
This is because it is necessary at 0.

The block size primary decision circuit 310 uses the power change information of the block supplied from the change extraction circuit 308 and the power change information of the block immediately before the temporally adjacent block supplied from the memory 307. The orthogonal transform block size of the frequency band is determined from the temporal displacement of the power within the frequency band to be obtained. At this time, if a displacement equal to or greater than a certain value is recognized, a shorter orthogonal transform block size is selected. However, even if the displacement point is fixed, the effect can be obtained. Furthermore, a value proportional to the frequency,
That is, when the frequency is high, a large displacement causes a temporally short block size, and when the frequency is low, it is more effective to determine the temporally short block size with a small displacement as compared to that when the frequency is high. This value desirably changes smoothly, but may be a stepwise change in a plurality of stages. The block size determined as described above is supplied to a block size correction circuit (block size correction means) 311.

On the other hand, a power comparison circuit (power comparison means)
At 309, each power calculation circuit 304, 305, 3
The power information of each frequency band supplied from 06 is compared with the time width at which the masking effect occurs at the same time and on the time axis, and the influence of other frequency bands on the output frequency band of the power calculation circuit 304 is obtained. , To the block size correction circuit 311. Block size correction circuit 31
In 1, the masking information supplied from the power comparison circuit 309 and the delay circuits (delay means) sequentially connected in cascade
(Delay storage means) Primary block size determination circuit (Primary block size determination means) based on past block size information supplied from each tap of 312, 313, 314
Correction is made so that a longer block size is selected based on the block size supplied from 310 and supplied to the delay circuit 312 and the window shape determination circuit (window shape determination means) 315.

The function of the block size correction circuit 311 is that even if a pre-echo is a problem in a specific frequency band, a signal having a large amplitude exists in another frequency band, particularly a band lower than the specific frequency band. The characteristic that the pre-echo does not cause a problem in audibility due to the masking effect or the problem may be reduced. The above-mentioned masking refers to a phenomenon in which a certain signal masks another signal and makes it inaudible due to human auditory characteristics. The masking effect includes a time axis based on an audio signal on a time axis. There are a masking effect and a simultaneous masking effect by a signal on the frequency axis. Due to these masking effects, even if there is noise in the masked portion, this noise will not be heard. For this reason, in an actual audio signal, noise within the masked range is regarded as acceptable noise.

Next, the delay circuits 31 sequentially connected in cascade
The past orthogonal transform block sizes are sequentially stored in 2, 313, and 314, and each tap, that is, the delay circuit 31 is stored.
From the outputs of 2, 313 and 314, the orthogonal exchange block size is supplied to a block size correction circuit 311. At the same time, the output side of the delay circuit 312 is connected to the output terminal 317, and the output side of the delay circuits 312 and 313 is connected to the window shape determination circuit 315. Outputs from the delay circuits 312, 313, and 314 are used by the block size correction circuit 311 to help the block size change in a longer time width to determine the block size of the block. If a short block size is selected, increase the selection of the short block size in time, and if no short block size is selected in the past, select a long block size in the past. It is possible to make decisions such as increasing the number.

This delay circuit includes delay circuits 312, 312 necessary for a window determination circuit 315 and an output terminal 317.
Except for 13, the tap number may be increased or decreased depending on the actual configuration and scale of the device. In the window shape determination circuit 315, the block size correction circuit 31
1, the output of the delay circuit 312, that is, the next block size adjacent to the block in time, ie, the output of the block size and the output of the delay circuit 313, that is, the one that is temporally adjacent to the block. From the previous block size, each MDCT circuit 103, 10 in FIG.
The window shape used in steps 4 and 105 is determined and output to the output terminal 317. The output of the output terminal 316 in FIG. 3, that is, the block size information, and the output of the output terminal 317, that is, the window shape information, are used as the block size determination circuits 109, 110, and 111 in FIG.
Is supplied to each section as the output of

Here, the window shape determined by the window shape determination circuit 315 will be described with reference to FIG. 4 showing the state of the adjacent blocks and the window shape. 4A, 4B, and 4C show windows when the horizontal axis represents time and the vertical axis represents level, respectively, wherein the solid curve is the current window, the broken curve (left side) is the past window, and the broken curve ( (Right) show future windows, respectively.

As can be seen from FIG. 4, the window used for the orthogonal transformation has a portion that overlaps with the temporally adjacent block. In this embodiment, the window overlaps with the center of the adjacent block. Since this is adopted, the shape of the window changes depending on the orthogonal transform size of the adjacent block.

As is clear from the above description, the shape of the window used for the orthogonal transform is determined after the orthogonal transform size of three temporally continuous blocks is determined. Therefore, in the present embodiment, a block of a signal input from the input terminals 301, 302, and 303 differs from a block of a signal output from the output terminals 316 and 317 by one block.

The power calculation circuit 305 in FIG.
Even if the power comparison circuit 306 and the power comparison circuit 309 are omitted, it is possible to configure the block size determination circuits 109, 110, and 111 in FIG. Further, by fixing the shape of the window to the smallest block size that the orthogonal transformation block can take in time, the type is made one, and the delay circuits 312, 313, 314, the block size correction circuit 311 and the window shape shown in FIG. It is also possible to omit the decision circuit 315. In particular,
In an application example in which a delay in the processing time is not desired, the above-described omission causes a configuration with a small delay, which effectively operates.

Returning to FIG. 1, the description will be continued. The spectrum data or MDCT coefficient data (signal components in a two-dimensional block relating to time and frequency) on the frequency axis obtained by performing MDCT processing by each of the MDCT circuits 103, 104, and 105 has a so-called critical band (critical band). ), And in the middle and high frequency bands, the critical bandwidth is subdivided in consideration of the effectiveness of block floating, and the adaptive bit allocation encoding circuit (adaptive bit allocation encoding means) 10
6, 107, 108 and a bit allocation calculation circuit (bit allocation calculation means) 118.

The critical band is a frequency band divided in consideration of human auditory characteristics, and is a noise when a pure tone is masked by a narrow band noise of the same strength near the frequency of a certain pure tone. It is the band that has. This critical band (critical band) has a wider bandwidth as the frequency becomes higher, and the entire frequency band of 0 to 22 kHz is divided into, for example, 25 critical bands.

The bit allocation calculation circuit 118 calculates the critical band and the block floating for each divided band in consideration of the so-called masking effect and the like based on the block size information and the spectrum data or the MDCT coefficient data. The masking amount and the energy or peak value for each of the divided bands are calculated, and the number of bits to be allocated is obtained for each band based on the calculation result, and is supplied to the adaptive bit allocation coding circuits 106, 107, and 108. . These adaptive bit allocation encoding circuits 106, 10
In Steps 7 and 108, each spectrum data or MDCT coefficient data is re-quantized (normalized and quantized) according to the number of bits allocated to each divided band in consideration of the above-described block size information, critical band, and block floating. ). The data encoded in this manner is taken out via the output terminals 112, 114, 116. For the sake of convenience in the following description, each of the above-mentioned divided bands that take into account the critical band and the block floating, which is a unit of bit allocation, will be referred to as a unit block.

Next, specific means of bit allocation performed by the bit allocation calculating circuit 118 in FIG. 1 will be described with reference to FIG. FIG. 5 is a block circuit diagram showing a schematic configuration of a bit allocation calculating means (bit allocation calculating means) which is a specific example of the bit allocation calculating circuit 118 in FIG. In FIG. 5, an input terminal 601 is connected to the MDCT circuit 10 shown in FIG.
The spectrum data or MDCT coefficients on the frequency axis from 3, 104, and 105 and the block size information from the block determination circuits 109, 110, and 111 in FIG. Thereafter, the bit allocation calculation circuit 118 in FIG. 1 shown in FIG. 5 performs processing using a constant, a weighting function, and the like adapted to the above-described block size information.

In FIG. 5, spectrum data or MDCT coefficients on the frequency axis input from an input terminal 601 are:
The energy is supplied to the energy calculation circuit for each band (energy calculation means for each band) 602, and the energy for each unit block is calculated by, for example, calculating the sum of the amplitude values in the unit block. Instead of the energy for each band, a peak value or an average value of the amplitude value may be used. As an output from the energy calculation circuit 602, for example, the spectrum of the sum value of each band is shown in FIG.
Are shown as SB. However, in FIG. 6, the number of divisions by unit blocks is represented by 12 blocks (B1 to B12) to simplify the illustration. Note that the broken line in FIG. 6 indicates the effect of the spectrum SB of the total value of each band on other parts, and corresponds to convolution weighting.

The energy calculation circuit 602 also determines the value of the scale factor (normalized data) (information compression parameter) indicating the block floating state of the unit block. Specifically, for example, several positive values are prepared in advance as candidates for the scale factor value, and the minimum value is selected from among the positive values that are equal to or more than the maximum value of the absolute value of the spectrum data or MDCT coefficient in the unit block. Is adopted as the scale factor value of the unit block. The scale factor value is numbered using several bits in a form corresponding to the actual value, and the number is stored in a ROM or the like (not shown).
May be stored in the memory. Also, the scale factor value determined by the above method in a certain unit block is:
The number assigned using the above-mentioned bits corresponding to the determined value is used as sub-information indicating the scale factor of the unit block.

Next, in order to consider the influence on the so-called masking of the above-mentioned spectrum SB obtained by the above-mentioned energy calculation circuit 602, a convolution (combo) such that the spectrum SB is multiplied by a predetermined weighting function and added. (Reuse) processing. Therefore, the output of the energy calculation circuit 602 for each band, that is, each value of the spectrum SB, is supplied to a convolution filter circuit (convolution filter means) 603. The convolution filter circuit 603 includes, for example, a plurality of delay elements for sequentially delaying input data, a plurality of multipliers for multiplying an output from these delay elements by a filter coefficient (weighting function), and a sum of outputs of the respective multipliers. And a sum adder which takes By this convolution processing, the sum of the parts indicated by the dotted lines in FIG. 6 is obtained.

Next, the output of the above-described convolution filter circuit 603 is output to a subtractor (synthesizer) (synthesis means) (subtraction means) 60.
4 is supplied. The subtracter 604 obtains a level α corresponding to an allowable noise level described later in the convolved region. Note that the level α corresponding to the allowable noise level (quantization coefficient) is determined by performing inverse convolution processing as described later.
This is a level that becomes an allowable noise level (quantization coefficient) for each band of the critical band. Here, the above-described subtractor 604 is supplied with an allowance function (a function expressing a masking level) for obtaining the above-mentioned level α. By increasing or decreasing this tolerance function, the level α
Is controlled. The permissible function is supplied from a (n-ai) function generating circuit {(n-ai) function generating means # 605 as described below.

That is, the level α corresponding to the allowable noise level can be obtained by the following equation (1), where i is a number sequentially given from the lower band of the critical band.

[0041]

Α = S− (n−ai)

In the equation (1), n and a are constants.
a> 0, S is the convolution processed Bark spectrum (Bark
Spectrum), and (n-ai) in Equation 1 is an allowable function. As an example, n = 38 and a = 1 can be used. Note that bark generally means a unit of a critical band. The bark spectrum means that one spectrum is represented for one critical band.

In this way, the above-mentioned level α is obtained, and this data is supplied to a divider (division means) 606. The divider 606 is for performing inverse convolution of the level α in the convolved region. Therefore, by performing the inverse convolution processing, a masking spectrum can be obtained from the level α. That is, this masking spectrum becomes an allowable noise spectrum. Note that the above-described inverse convolution processing requires a complicated operation, but in this embodiment, the inverse convolution is performed using a simplified divider 606.

Next, the above-mentioned masking spectrum is subtracted by a subtracter (subtraction means) via a synthesis circuit (synthesis means) 607.
608. Here, the output from the above-described energy calculation circuit 602 for each band, that is, the above-mentioned spectrum SB is supplied to the subtractor 608 by a delay circuit (delay means).
609. Therefore, this subtractor 6
By performing the subtraction operation between the masking spectrum and the spectrum SB at 08, the spectrum SB is masked at a level equal to or lower than the level of the masking spectrum MS, as shown in FIG.

By the way, at the time of synthesizing by the synthesizing circuit 607, the so-called minimum audible characteristic which is a human auditory characteristic as shown in FIG. 8 supplied from the minimum audible curve generating circuit (minimum audible curve generating means) 612. Data indicating the curve RC and the above-described masking spectrum MS can be synthesized. At this minimum audible curve, if the absolute noise level is below this minimum audible curve, the noise will not be heard. This minimum audible curve is different depending on the reproduction volume at the time of reproduction, for example, even if the coding is the same. However, in a realistic digital system, for example, the music enters the 16-bit dynamic range. Since there is not much difference, if quantization noise in the most audible frequency band around 4 kHz is not heard, for example, it is considered that quantization noise below the level of the minimum audible curve is not heard in other frequency bands. . Therefore, assuming that a method is used in which noise around 4 kHz of the word length of the system is not heard, and an allowable noise level is obtained by synthesizing the minimum audible curve RC and the masking spectrum MS together, The allowable noise level in this case is shown in FIG.
It becomes possible to extend to the part shown by the oblique line in the middle. In this embodiment, the 4 kHz level of the above-described minimum audible curve is adjusted to the lowest level corresponding to, for example, 20 bits. FIG. 8 also shows the signal spectrum SS.

Thereafter, in the allowable noise correction circuit (allowable noise correction means) 610, the allowable noise level in the output from the above-described subtractor 608 based on the information of the equal loudness curve supplied from the correction information output circuit 613, for example. Has been corrected. Here, the equal loudness curve is a characteristic curve relating to human auditory characteristics. For example, the loudness curve is obtained by calculating the sound pressure of sound at each frequency that sounds as loud as the pure tone of 1 kHz, and connecting the curves with each other. Also called a sensitivity curve. Further, this equal loudness curve draws substantially the same curve as the minimum audible curve RC shown in FIG. In this equal loudness curve, for example, around 4 kHz, even if the sound pressure falls by 8 to 10 dB from the place of 1 kHz, 1
It sounds the same size as kHz, and conversely, it does not sound the same at around 50 Hz unless it is about 15 dB higher than the sound pressure at 1 kHz. For this reason, it can be seen that noise exceeding the level of the minimum audible curve (allowable noise level) should have a frequency characteristic given by a curve corresponding to the loudness curve. From this, it can be seen that correcting the above-mentioned allowable noise level in consideration of the above-mentioned equal loudness curve is suitable for human auditory characteristics.

Here, as the correction information output circuit 613,
The adaptive bit allocation encoding circuit 106 in FIG.
The above-described allowable noise level is corrected based on the error information between the detection output of the output information amount (data amount) at the time of quantization in 107 and 108 and the bit rate target value of the final encoded data. It may be. This is because the total number of bits obtained by previously performing temporary adaptive bit allocation for all the bit allocation unit blocks becomes a fixed number of bits (target value) determined by the bit rate of the final encoded output data. In some cases, there is an error, and bit allocation is performed again so that the error is set to zero. That is, when the total number of allocated bits is smaller than the target value, the difference bit number is allocated to each unit block and added. It is to be allocated and cut.

In order to do this, an error of the total number of allocated bits from the above-described target value is detected, and the correction information output circuit 613 corrects each of the allocated number of bits according to the error data. Outputs correction data. Here, when the above-mentioned error data indicates that the number of bits is insufficient, it is possible to consider a case where the above-described data amount is larger than the above-described target value because a large number of bits are used per unit block. it can. Further, when the above-mentioned error data is data indicating the remainder of the number of bits, the case where the number of bits per unit block is small and the amount of data is smaller than the above-described target value may be considered. it can.

Accordingly, the allowable noise level (quantization coefficient) at the output from the subtractor 608 is calculated from the correction information output circuit 613 according to the error data.
For example, the data of the above-described correction value for performing the correction based on the information data of the above-mentioned equal loudness curve is output. The above-described correction value is supplied to the above-described allowable noise correction circuit 610, so that the above-described allowable noise level from the subtracter 608 is corrected. By performing the processing up to the above-described allowable noise correction circuit 610 described above, the data obtained by processing the orthogonal transform output spectrum with the sub-information as the main information and the schedule indicating the state of the block floating as the sub-information. The word length indicating the word factor and word length is obtained.

Here, by performing the processing up to the above-described allowable noise correction circuit 610, data obtained by processing the orthogonal transform output spectrum obtained as main information with sub-information and block floating obtained as sub-information. Scale factor indicating the state of the word and word indicating the word length
A specific example of encoding by length will be described with reference to FIG. FIG. 9 is an example showing a state of a unit block when the bit allocation is 3 bits. The vertical axis indicates the magnitude of the spectrum data or MDCT coefficient with the center at 0,
The horizontal axis indicates frequency. In this example, eight spectral data or MDCT coefficients represented by a, b, c, d, e, f, g, and h exist in the unit block,
Each has a magnitude in the positive or negative direction from 0. As described above, the scale factor indicating the state of the block floating is prepared in advance with positive values of several magnitudes, and among them, a value greater than the maximum value of the absolute value of the spectrum data or MDCT coefficient in the unit block is prepared. Use the smallest value among the values, and use it as the unit block scale factor.

In FIG. 9, the scale factor value is selected based on the spectrum a indicating the maximum absolute value. With this scale factor and the size of the bit allocation,
The quantization width in the unit block is determined. Although the example of FIG. 9 shows a case where the bit allocation is 3 bits, it is possible to express 8 values when encoding (quantizing) with 3 bits, but here, the positive direction and the negative direction are centered around 0. The quantization width of equal division in the direction is taken by three values, and a seven-value quantization value is added together with 0, and another code that can be expressed by 3 bits is not used. Here, the quantization value is determined from the scale factor value and the bit allocation value in the unit block, and the spectral data or MDCT coefficient in the unit block is
It is quantized to the nearest quantization value. The black circles in FIG. 9 indicate the quantized values of the respective spectral data or MDCT coefficients in the unit block.
That is, FIG. 9 shows an example of requantization (normalization and quantization).

In general, the quantization width when performing quantization in such a manner as to have equal quantization widths in the positive direction and the negative direction centering on 0 by the method shown in FIG. ,
The quantization width QV of a certain unit block can be obtained by the following equation (2), where SF is the value of the scale factor of the unit block and Nb is the number of allocated bits.

[0053]

QV = SF / (2 ^(Nb-1) -1) where Nb ≧ 2

By the way, when requantization is performed according to the above procedure, the spectrum or M
If the maximum value of the absolute value of the DCT coefficient is smaller than the smallest one among the prepared scale factors, the smallest one among the previously prepared scale factors is adopted as the scale factor value of the unit block. It will be. As for the unit block employing the smallest one among the scale factors prepared in advance, the spectrum in the unit block or the MD
According to the CT coefficient, the spectrum or MD in a unit block
There is a minimum number of bits required for at least one of the CT coefficients to be quantized to a value other than zero.

In other words, for a unit block employing the smallest scale factor prepared in advance, even if two or more bits are allocated, the number of allocated bits is the minimum required bit. If the number of bits is smaller than the number, all the spectra or MDCT coefficients in the unit block are quantized to 0, even though the bits are allocated. In such a case, it is possible to set the bit allocation to 0, thereby omitting the bits used for coding the spectral data or MDCT coefficients, and performing more efficient allocation. In such a case, the encoding correction circuit 614 in FIG. 5 performs correction for encoding in a more efficient manner.

Hereinafter, the encoding correction circuit 61 in FIG.
The encoding correction in 4 will be described with reference to FIG. FIG. 10 shows a state of requantization of a certain unit block as in FIG.
It indicates the magnitude of the T coefficient, the horizontal direction indicates the frequency, and eight spectra or MDCTs are contained in a unit block.
Coefficient exists. In this example, the maximum value of the absolute value of the spectrum or MDCT coefficient in the unit block is smaller than the smallest one of the prepared scale factors, and the scale factor value of this unit block is the scale factor value of the prepared scale factor. The smallest one is adopted, the bit allocation is 2 bits,
As shown in FIG. 10, it is assumed that there are a total of three quantized values, that is, 0 and one value each in the positive direction and the negative direction. However, in the case of 2-bit allocation, the maximum value of the absolute value of the spectrum or MDCT coefficient in the unit block as shown in FIG.
If the value is smaller than half the value of the quantization width shown by the dotted line in FIG. 2, all the spectra or MDCT coefficients in the unit block are quantized to zero. That is, the eight spectra a to h are all encoded with “00”, and at least 16 bits are required for recording the spectra, but the quantization values are all zero.

In this case, the unit block is not recorded due to the sub-information or the like, that is, by changing the bit allocation to 0 bits, the spectrum or M
Since all DCT coefficient values can be regarded as 0,
Spectrum or MDC in case of 2-bit allocation described above
Exactly the same encoding can be performed without using the 16 bits used for the quantization value “00” of the T coefficient. That is, in a case where the quantization value of the spectrum or MDCT coefficient is all 0 even though there is a bit allocation of 2 bits or more in a certain unit block, the bit allocation of the unit block is set to 0, MDC
It is possible to omit the bits used for encoding the T coefficient and perform exactly the same encoding.

As shown in FIG. 10, even in the case where the allocation is not 2-bit, the spectrum or the spectrum within the unit block is generally used for the unit block in which the smallest scale factor among the prepared scale factors is adopted as the scale factor value. The maximum value of the absolute value of the MDCT coefficient is SPm
Using the quantization width QV of the unit block obtained by the above equation (2) as ax, the quantization value of the spectrum or MDCT coefficient in the unit block satisfying the condition of the following equation (3) is all 0. Become. On the other hand, a QV that does not satisfy the equation (3) can be obtained from Nb in the equation (2), whereby the quantum or the MDCT coefficient in at least one of the spectrum or the MDCT coefficient in the unit block becomes a value other than 0. The minimum required number of bits to be converted can be obtained.

[0059]

## EQU3 ## SPmax <QV / 2

In this embodiment, the encoding correction circuit 614 shown in FIG. 5 detects a unit block satisfying the above-mentioned equation (3) from all the unit blocks, and uses the sub-information of the unit block to Change the bit allocation value to 0 and at least the spectrum or MD in the unit block.
The bits used for encoding the CT coefficients are omitted. Further, depending on the encoding format, for example, in addition to the method of setting the bit allocation to 0 with sub-information indicating a substantial bit allocation amount (information compression parameter), the validity of the unit block, that is, the unit block is recorded. If there is sub-information indicating whether or not to do so, if sub-information indicating the validity of the unit block indicates that coding of the unit block is not performed, it is useful for the scale factor and bit allocation as sub-information of the processing block. It is also possible to omit the bits of the sub information that was used, so even in such a case,
The sub-information is changed to an adaptive form by the encoding correction circuit 614, and bits are omitted.

When the bits used for coding the spectrum or MDCT coefficients in the unit block and the bits used for the sub-information such as the scale factor and the bit allocation can be omitted by the above-described method. Can be used to encode the spectrum or MDCT coefficients of unit blocks other than the omitted unit block according to the omitted bit amounts. In this case, the bit allocation is increased for a unit block newly used for coding a spectrum or MDCT coefficients using bits that could be omitted in the above-described method, and thus the quantization accuracy is improved. Will be.

If there are a plurality of unit blocks in which the above-mentioned bits can be omitted, the bits of a certain omissible unit block are omitted, and the omitted bits are replaced with the other omissible unit blocks. By using the spectrum or MDCT coefficients for coding, it is also possible to have a valid unit block in which the spectrum or MDCT coefficients quantized to a value other than 0 exists. In such a manner, in the encoding correction circuit 614 in FIG. 5, when the above-described bit omission is performed,
After retrieving the state of all unit blocks, allocation is performed for the unit block that is considered to be most effective, and this operation is repeated until the number of omitted bits becomes an amount that cannot be redistributed. At this time, the coding correction circuit 614 uses the conditions of the equations (2) and (3) for the unit block in which the smallest one among the prepared scale factors is adopted as the scale factor value. In order to perform effective coding in which at least one of the spectrums or MDCT coefficients in is quantized to a value other than 0, it is necessary to calculate how many bits are required at least to avoid useless allocation.

As described above, by performing correction by the coding correction circuit 614, more efficient coding is performed, and quantization noise is reduced, thereby improving the sound quality and static characteristics of music data. Will be able to
Also, here, an example is shown in which the correction by the encoding correction circuit 614 is performed in the final stage of the bit allocation calculation means in FIG.
By using the conditions of the equations (2) and (3), the unit block adopting the smallest scale factor value among the prepared scale factors as a scale factor value corresponds to all possible bit assignments in the format. It is possible to calculate in advance the conditions of the spectrum or the MDCT coefficient for performing effective encoding in which at least one of the spectrum or the MDCT coefficient in the unit block is quantized to a value other than 0. For this reason, the calculated amount is stored in a ROM or the like, and the bit allocation calculating means in FIG. 5 performs the bit allocation without waste by referring to the calculated amount at a stage before the encoding correction circuit 614. It is also possible to go.

In general, there are various formats for normalization and quantization in such encoding. However, since at least one of the signal components is quantized to a value other than 0 based on each format, It is obvious that, by calculating the minimum number of bits required and considering this, more efficient encoding can be performed as in the above description.

As described above, in the bit allocation calculating circuit 118 in FIG. 1, the data obtained by processing the orthogonal transform output spectrum as the main information by the sub information by the bit allocation calculating means shown in FIG. Scale factor indicating the state of block floating as
And a word length indicating the word length are obtained.
The adaptive bit allocation coding circuits 106, 10 in FIG.
In steps 7 and 108, requantization is actually performed, and encoding is performed in a form conforming to the encoding format.

Referring to FIG. 11, a description will be given of a decoder for a signal which has been encoded by the encoder shown in FIG. 1 with high efficiency. The quantized MDCT coefficients (two-dimensional blocks in time and frequency) of each band, that is, FIG.
Are supplied to the input terminal 707 in FIG. 11 and used block size information (length of processing block) (information compression parameter), that is, FIG. The data equivalent to the output signals of the output terminals 113, 115, and 117 are supplied to the input terminal 708 in FIG. Adaptive bit allocation decoding circuit (adaptive bit allocation decoding means) 7
In 06, the bit allocation is released using the adaptive bit allocation information. Next, inverse orthogonal transform (IMDCT) circuits (inverse orthogonal transform means) 703, 704, and 705 convert signals on the frequency axis into signals on the time axis. The signals on the time axis of these partial bands are output from the band synthesis filter (IQM
F) The signals are decoded by the circuits (band combining means) 702 and 701 into full-band signals.

Next, with reference to FIGS. 12 to 15, the digital signal recording device (method), digital signal reproducing device (method), digital signal transmitting device (method) and digital signal receiving device (method) of the present invention. An embodiment will be described. 12 to 13, ENC indicates the encoder of FIG. 1, Tin indicates its input terminal 100, DEC indicates the decoder of FIG. 11, and Tout indicates its output terminal 700.
Is shown.

In the recording apparatus of FIG. 12, an input digital signal from the input terminal Tin is supplied to the encoder ENC for encoding, and the output of the encoder ENC, that is, FIG.
Output terminals 112, 114, 116 and 1 of the encoders
13, 115, 117 are output from the modulating means MO.
D, and then multiplexes and performs a predetermined modulation, or modulates each output signal and then multiplexes or remodulates.
The modulated signal from the modulating means MOD is recorded on the recording medium M by the recording means (magnetic head, optical head, etc.).

In the reproducing apparatus shown in FIG. 13, the recording medium M shown in FIG. 12 is reproduced by reproducing means (magnetic head, optical head, etc.) P.
And the demodulation means DEM demodulates the reproduction signal according to the modulation by the modulation means MOD. A demodulation output from the demodulation means DEM, that is, a signal corresponding to the output from the output terminals 112, 114, and 116 of the encoder in FIG. 1 is supplied to the input terminal 707 of the decoder in FIG. 2 and the output terminal of the encoder in FIG. 113, 11
The signals corresponding to the outputs from 5, 117 are input to the input 70 of FIG.
The output digital signal corresponding to the input digital signal is output to an output terminal Tout.

In the transmitting apparatus shown in FIG. 14, the input digital signal from the input terminal Tin is supplied to the encoder ENC for encoding, and the output of the encoder ENC, that is, FIG.
Output terminals 112, 114, 116 and 1 of the encoders
13, 115, 117 are output from the modulating means MO.
D, and then multiplexes and performs a predetermined modulation, or modulates each output signal and then multiplexes or remodulates.
The modulated signal from the modulating unit MOD is supplied to the transmitting unit TX to perform frequency conversion, amplification, etc., to generate a transmitting signal, and the transmitting signal is transmitted to the transmitting antenna A which is a part of the transmitting unit TX.
Transmit by NT-T.

In the reproducing apparatus of FIG. 15, the receiving signal from the transmitting antenna ANT-T of FIG. 15 is received by the receiving antenna ANT-R which is a part of the receiving means RX, and the received signal is received by the receiving means RX. , Amplification, inverse frequency conversion, etc. The demodulation unit DEM demodulates the reception signal from the reception unit RX according to the modulation by the modulation unit MOD. Demodulated output from demodulating means DEM, ie,
A signal corresponding to the output from the output terminals 112, 114 and 116 of the encoder of FIG.
07 and output terminal 1 of the encoder of FIG.
The signals corresponding to the outputs from 13, 115 and 117 are shown in FIG.
Supplied to the input 708 of the terminal and decoded, and the output terminal Tout
Then, an output digital signal corresponding to the input digital signal is output.

The present invention is not limited to the above embodiment, and various modifications and changes can be made. The encoder and the decoder may be separate or integrated. The recording device and the reproducing device may be separate or integrated. The recording medium can be a magnetic tape, a magnetic disk, a magneto-optical disk, or the like.
Further, instead of the recording medium, a storage means such as an IC memory or a memory card may be used. The transmission path between the transmitting apparatus and the receiving apparatus may be a wireless transmission path {radio waves, light (infrared rays, etc.)} or a wired transmission path (conductor, optical cable, etc.). For example,
As the input digital signal, a digital audio signal (an audio signal can be a signal of various sounds such as a human voice, a singing voice, and a sound of a musical instrument), a digital video signal, and the like can be used. The present invention can be applied to a digital signal recording / reproducing method (or device), a digital signal transmitting / receiving method (or device), a digital signal receiving method (or device), and the like.

[0073]

According to the present invention described above, an input digital signal is divided into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency, and each of the two-dimensional blocks relating to time and frequency is obtained. Then, normalization is performed based on the signal components in the two-dimensional block to obtain normalized data, and quantization coefficients representing the characteristics of the signal components in the two-dimensional block are obtained for each two-dimensional block with respect to time and frequency. The bit allocation amount is determined based on the quantization coefficient, the signal component in the two-dimensional block is quantized by the normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency, and information is compressed. In a digital signal encoding method for obtaining an information compression parameter for each two-dimensional block related to the time axis and the frequency, The minimum bit allocation for quantizing at least one of the two-dimensional block signal components to a value other than 0 is calculated based on the digitized data and the two-dimensional block signal components, and the bit allocation amount is determined based on the calculation result. At this time, if all the signal components included in the block are quantized to zero, the bits are omitted, so that
The use of extra bits can be prevented, more efficient encoding can be achieved, the static characteristics and signal quality can be improved, and the effective use of the recording capacity of the recording medium and the transmission capacity of the transmission path can be achieved. You can get what you can do.

Further, according to the present invention described above, the input digital signal is divided into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency, and each of the two-dimensional blocks relating to time and frequency is obtained. , Normalization is performed based on the signal components in the two-dimensional block to obtain normalized data,
For each two-dimensional block relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained, and the bit allocation amount is determined based on the quantization coefficient. In a digital signal encoding processing method in which a signal component in a two-dimensional block is quantized and information-compressed based on encoded data and a bit allocation amount, and an information compression parameter for each two-dimensional block relating to time and frequency is obtained. Signal component condition for at least one of the signal components in the two-dimensional block to be quantized to a non-zero value for the two-dimensional block in which the smallest normalized data is selected from the prepared normalized data Is stored in advance in the memory, and the bit allocation amount is determined based on the signal conditions stored in the memory. Can be used to achieve more efficient encoding, improve static characteristics and signal quality, and make effective use of recording capacity in recording media and transmission capacity in transmission paths. You can get what you can.

[0075]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a specific example of a high-efficiency compression encoding encoder that can be used for bitrate compression encoding according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a structure of an orthogonal transform block at the time of bit compression.

FIG. 3 is a block diagram illustrating a configuration example of a circuit that determines an orthogonal transform block size.

FIG. 4 is a diagram showing a relationship between a change in a temporal length of an orthogonal transform block adjacent in time and a window shape used at the time of orthogonal transform.

FIG. 5 is a block diagram showing an example of a bit allocation operation function.

FIG. 6 is a diagram illustrating spectra of each critical band and a band divided in consideration of block floating.

FIG. 7 is a diagram showing a masking spectrum.

FIG. 8 is a diagram in which a minimum audible curve and a masking spectrum are combined.

FIG. 9 is a diagram illustrating an example of quantization of a signal component in a bit allocation unit block.

FIG. 10 is a diagram illustrating an example in which all signal components are quantized to 0 in a bit allocation unit block.

FIG. 11 is a block diagram showing a specific example of a bitrate compression-encoded signal decoder according to the above embodiment.

FIG. 12 is a block diagram illustrating a recording apparatus according to an embodiment of the present invention.

FIG. 13 is a block diagram illustrating a playback device according to an embodiment of the present invention.

FIG. 14 is a block diagram illustrating a transmission device according to an embodiment of the present invention.

FIG. 15 is a block diagram showing a receiving device according to an embodiment of the present invention.

[Explanation of symbols]

101, 102 band division filter, 103, 104,
105 orthogonal transform circuit (MDCT), 109, 110,
111 block determination circuit, 118 bit allocation calculation circuit, 106, 107, 108 adaptive bit allocation coding circuit, 304, 305, 306 power calculation circuit, 3
07 memory, 308 change extraction circuit, 309 power comparison circuit, 310 block size primary decision circuit, 3
11 Block size correction circuit, 312, 313, 31
4 delay circuit, 315 window shape determination circuit, 60
2 energy calculator per band, 603 convolution filter, 604 adder, 605 function generator, 606 divider, 607 synthesizer, 608 subtractor, 609 delay circuit, 610 allowable noise corrector, 612 minimum audible curve generator, 613: Correction information output unit, 614 Encoding corrector, 701, 702 Band synthesis filter (IQMF), 703, 704, 705 Inverse orthogonal transform circuit (IMDCT), 706 Adaptive bit allocation decoding Circuit, ENC encoder, MOD modulation means, R
EC recording means, P reproduction means, DEM demodulation means, DE
C decoder, TX transmitting means, RX receiving means

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-263926 (JP, A) JP-A-4-104617 (JP, A) JP-A-4-104618 (JP, A) JP-A-4-104617 302533 (JP, A) JP-A-4-302534 (JP, A) JP-A-6-216782 (JP, A) JP-A-8-46518 (JP, A) JP-A-8-125544 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H03M 7/30 G11B 20/10 301

Claims (32)

(57) [Claims] An input digital signal is divided into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency, and a signal in the two-dimensional block is provided for each of the two-dimensional blocks relating to time and frequency. Normalization is performed on the basis of the components to obtain normalized data, and for each of the two-dimensional blocks relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained, and based on the quantization coefficient A bit allocation amount is determined, a signal component in the two-dimensional block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to time and frequency, and information is compressed. A digital signal encoding method for obtaining an information compression parameter for each block, comprising: Based on the data and the signal components in the two-dimensional block, a minimum bit allocation for quantizing at least one of the signal components in the two-dimensional block to a value other than 0 is calculated, and the bit allocation amount is determined based on the calculation result. At this time, if all the signal components included in the block are quantized to zero, bits are omitted from the digital signal encoding processing method. 2. The digital signal encoding method according to claim 1, wherein the omission of the bits sets the bit allocation to zero in sub information indicating a bit allocation amount. 3. The digital signal encoding method according to claim 1, wherein the omission of the bit does not perform the encoding of the block based on sub-information indicating the validity of the unit block. 4. The digital signal encoding method according to claim 1, wherein surplus bits generated by omitting the bits are redistributed to another two-dimensional block. 5. An input digital signal is divided into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Normalization is performed on the basis of the components to obtain normalized data, and for each of the two-dimensional blocks relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained, and based on the quantization coefficient A bit allocation amount is determined, a signal component in the two-dimensional block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to time and frequency, and information is compressed. In a digital signal encoding processing method for obtaining an information compression parameter for each block, a minimum normalization is performed from normalized data prepared in advance. For the two-dimensional block from which the data has been selected, the condition of the signal component in which at least one of the signal components in the two-dimensional block is quantized to a value other than zero is previously stored in a memory, and A digital signal encoding processing method, wherein the bit allocation amount is determined based on stored signal conditions. 6. A band dividing unit for dividing an input digital signal into a plurality of frequency band components, and a signal component in a plurality of two-dimensional blocks relating to time and frequency corresponding to the frequency band components divided by the band dividing unit. And a normalization unit that performs normalization based on the signal components in the two-dimensional block obtained by the orthogonal transformation unit for each of the plurality of two-dimensional blocks related to time and frequency to obtain normalized data. Data calculation means; two for each of a plurality of two-dimensional blocks relating to the time and frequency.
Quantization coefficient calculation means for obtaining a quantization coefficient representing a characteristic of a signal component in a dimensional block; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient calculated by the quantization coefficient calculation means The bit allocation calculating means, for each of the two-dimensional blocks related to the time axis and the frequency, sets at least one of the two-dimensional block signal components to a value other than 0 based on the normalized data and the two-dimensional block signal components. Calculating means for calculating a minimum bit allocation for quantizing to a value; and when determining a bit allocation amount based on a calculation result of the calculating means, all signal components included in the block are quantized to zero. And a control means for setting the bit allocation to zero in the event of occurrence. 7. The digital signal encoding processing apparatus according to claim 6, wherein said control means sets a bit allocation value of the sub information indicating the bit allocation amount to zero. 8. The digital signal encoding processing apparatus according to claim 6, wherein said control means sets the bit allocation to zero based on sub-information indicating the validity of the unit block. 9. The digital signal encoding processing apparatus according to claim 6, wherein surplus bits generated by setting the bit allocation to zero are redistributed to another two-dimensional block. 10. Band dividing means for dividing an input digital signal into a plurality of frequency band components, and signal components in a plurality of two-dimensional blocks relating to time and frequency corresponding to the frequency band components divided by said band dividing means. And a normalization unit that performs normalization based on the signal components in the two-dimensional block obtained by the orthogonal transformation unit for each of the plurality of two-dimensional blocks related to time and frequency to obtain normalized data. Data calculation means; two for each of a plurality of two-dimensional blocks relating to the time and frequency.
A quantization coefficient calculating means for obtaining a quantization coefficient representing a characteristic of a signal component in the two-dimensional block; and a two-dimensional block for selecting a minimum normalized data from the previously prepared normalized data. Memory means for storing in advance a condition of a signal component for at least one of the signal components in the block to be quantized to a value other than zero; and a memory for storing the quantized coefficient calculated by the quantized coefficient calculating means and the memory And a bit allocation calculating means for determining the bit allocation amount based on the signal conditions stored in the digital signal encoding apparatus. 11. An input digital signal is divided into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Normalization is performed on the basis of the components to obtain normalized data, and for each of the two-dimensional blocks relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained, and based on the quantization coefficient A bit allocation amount is determined, a signal component in the two-dimensional block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to time and frequency, and information is compressed. A digital signal recording method for recording on a recording medium together with an information compression parameter for each block, Based on the normalized data and the two-dimensional block signal components, a minimum bit allocation for quantizing at least one of the two-dimensional block signal components to a value other than 0 is calculated. A digital signal recording method comprising omitting bits if all signal components included in the block are quantized to zero at the time of determination. 12. The digital signal recording method according to claim 11, wherein the omission of the bits sets the bit allocation to zero in sub-information indicating a bit allocation amount. 13. The digital signal recording method according to claim 11, wherein the omission of the bit does not encode the block based on sub-information indicating the validity of the unit block. 14. The digital signal recording method according to claim 11, wherein surplus bits generated by omitting the bits are redistributed to another two-dimensional block. 15. An input digital signal is divided into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Normalization is performed on the basis of the components to obtain normalized data, and for each of the two-dimensional blocks relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained, and based on the quantization coefficient A bit allocation amount is determined, a signal component in the two-dimensional block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks relating to the time and the frequency, and information is compressed. In a digital signal recording method in which each information compression parameter is obtained and recorded on a recording medium, the smallest positive data is selected from normalized data prepared in advance. The condition of the signal component for at least one of the signal components in the two-dimensional block to be quantized to a value other than zero for the two-dimensional block from which the quantized data is selected is stored in a memory in advance, and A digital signal recording method, wherein the bit allocation amount is determined based on stored signal conditions. 16. A band dividing means for dividing an input digital signal into a plurality of frequency band components, and signal components in a plurality of two-dimensional blocks relating to time and frequency corresponding to the frequency band components divided by said band dividing means. And a normalization unit that performs normalization based on the signal components in the two-dimensional block obtained by the orthogonal transformation unit for each of the plurality of two-dimensional blocks related to time and frequency to obtain normalized data. Data calculation means; two for each of a plurality of two-dimensional blocks relating to the time and frequency.
Quantization coefficient calculation means for obtaining a quantization coefficient representing a characteristic of a signal component in a dimensional block; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient calculated by the quantization coefficient calculation means The bit allocation calculating means, for each of the two-dimensional blocks related to the time axis and the frequency, sets at least one of the two-dimensional block signal components to a value other than 0 based on the normalized data and the two-dimensional block signal components. Calculating means for calculating a minimum bit allocation for quantizing to a value; and when determining a bit allocation amount based on a calculation result of the calculating means, all signal components included in the block are quantized to zero. A digital signal recording device, comprising: a control unit that sets the bit allocation to zero in a case where the error occurs. 17. The digital signal recording apparatus according to claim 16, wherein said control means sets a bit allocation value of sub information indicating the bit allocation amount to zero. 18. The digital signal recording apparatus according to claim 16, wherein said control means sets bit allocation to zero based on sub-information indicating validity of a unit block. 19. The digital signal recording apparatus according to claim 16, wherein surplus bits generated by setting the bit allocation to zero are redistributed to another two-dimensional block. 20. Band dividing means for dividing an input digital signal into a plurality of frequency band components, and signal components in a plurality of two-dimensional blocks relating to time and frequency corresponding to the frequency band components divided by said band dividing means. And a normalization unit that performs normalization based on the signal components in the two-dimensional block obtained by the orthogonal transformation unit for each of the plurality of two-dimensional blocks related to time and frequency to obtain normalized data. Data calculation means; two for each of a plurality of two-dimensional blocks relating to the time and frequency.
A quantization coefficient calculating means for obtaining a quantization coefficient representing a characteristic of a signal component in the two-dimensional block; and a two-dimensional block for selecting a minimum normalized data from the previously prepared normalized data. A memory means for storing in advance a condition of a signal component for at least one of the signal components in the block to be quantized to a value other than zero; and the quantization coefficient calculated by the quantization coefficient calculation means or the memory And a bit allocation calculating means for determining the bit allocation amount based on the signal condition stored in the digital signal recording device. 21. An input digital signal is divided into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Normalization is performed on the basis of the components to obtain normalized data, and for each of the two-dimensional blocks relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained, and based on the quantization coefficient A bit allocation amount is determined, a signal component in the two-dimensional block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to time and frequency, and information is compressed. In a recording medium on which recording is performed together with an information compression parameter for each block, the normalized data and the normalized data are When calculating the minimum bit allocation for quantizing at least one of the two-dimensional block signal components to a value other than 0 using the signal components within the two-dimensional block, and determining the bit allocation amount based on the calculation result, A recording medium characterized by omitting bits when all signal components included in a block are quantized to zero. 22. An input digital signal is divided into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency, and a signal in the two-dimensional block is provided for each two-dimensional block relating to time and frequency. Normalization is performed based on the components to obtain normalized data, and for each of the two-dimensional blocks related to time and frequency, a quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained. A bit allocation amount is determined, a signal component in the two-dimensional block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks relating to the time and the frequency, and information is compressed. In a recording medium on which recording is performed together with each information compression parameter, a secondary image in which the smallest normalized data is selected from previously prepared normalized data The condition of the signal component for at least one of the signal components in the two-dimensional block to be quantized to a value other than zero is previously stored in the memory, and based on the signal condition stored in the memory, A recording medium, wherein the bit allocation amount is determined by the above method. 23. An input digital signal is divided into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks related to time and frequency, and a signal in the two-dimensional block for each of the two-dimensional blocks related to time and frequency. Normalization is performed on the basis of the components to obtain normalized data, and for each of the two-dimensional blocks relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained, and based on the quantization coefficient A bit allocation amount is determined, a signal component in the two-dimensional block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to time and frequency, and information is compressed. In a digital signal transmission method for obtaining and transmitting an information compression parameter for each block, a normalized data is obtained for each two-dimensional block on the time axis and the frequency. And calculating the minimum bit allocation for quantizing at least one of the two-dimensional block signal components to a value other than 0 using the two-dimensional block signal components, and determining the bit allocation amount based on the above calculation result. A bit is omitted when all signal components included in the block are quantized to zero. 24. The digital signal transmission method according to claim 23, wherein the omission of the bits sets the bit allocation to zero in sub information indicating a bit allocation amount. 25. The digital signal transmission method according to claim 23, wherein the omission of the bit does not perform the encoding of the block based on sub-information indicating the validity of the unit block. 26. The digital signal transmission method according to claim 23, wherein surplus bits generated by omitting the bits are redistributed to another two-dimensional block. 27. An input digital signal is divided into a plurality of frequency bands to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Normalization is performed based on the components to obtain normalized data, and for each of the two-dimensional blocks related to time and frequency, a quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained. A bit allocation amount is determined, a signal component in the two-dimensional block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to time and frequency, and information is compressed. In a digital signal transmission method for obtaining and transmitting an information compression parameter for each block, the smallest normalized data among the normalized data prepared in advance. For the selected two-dimensional block, the condition of the signal component for at least one of the signal components in the two-dimensional block to be quantized to a value other than zero is stored in a memory in advance, and stored in the memory. A digital signal transmission method, wherein the bit allocation amount is determined based on a signal condition. 28. Band dividing means for dividing an input digital signal into a plurality of frequency band components, and signal components in a plurality of two-dimensional blocks relating to time and frequency corresponding to the frequency band components divided by said band dividing means. And a normalization unit that performs normalization based on the signal components in the two-dimensional block obtained by the orthogonal transformation unit for each of the plurality of two-dimensional blocks related to time and frequency to obtain normalized data. Data calculation means; two for each of a plurality of two-dimensional blocks relating to the time and frequency.
Quantization coefficient calculation means for obtaining a quantization coefficient representing a characteristic of a signal component in a dimensional block; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient calculated by the quantization coefficient calculation means The bit allocation calculating means, for each of the two-dimensional blocks related to the time axis and the frequency, sets at least one of the two-dimensional block signal components to a value other than 0 based on the normalized data and the two-dimensional block signal components. Calculating means for calculating a minimum bit allocation for quantizing to a value; and when determining a bit allocation amount based on a calculation result of the calculating means, all signal components included in the block are quantized to zero. And a control unit for setting the bit allocation to zero in the event of occurrence. 29. The digital signal transmission apparatus according to claim 28, wherein said control means sets a bit allocation value of sub information indicating the bit allocation amount to zero. 30. The digital signal transmission apparatus according to claim 28, wherein said control means sets the bit allocation to zero based on sub-information indicating the validity of the unit block. 31. The digital signal transmission apparatus according to claim 28, wherein surplus bits generated by setting the bit allocation to zero are redistributed to another two-dimensional block. 32. Band dividing means for dividing an input digital signal into a plurality of frequency band components, and signal components in a plurality of two-dimensional blocks relating to time and frequency corresponding to the frequency band components divided by said band dividing means. And a normalization unit that performs normalization based on the signal components in the two-dimensional block obtained by the orthogonal transformation unit for each of the plurality of two-dimensional blocks related to time and frequency to obtain normalized data. Data calculation means; two for each of a plurality of two-dimensional blocks relating to the time and frequency.
A quantization coefficient calculating means for obtaining a quantization coefficient representing a characteristic of a signal component in the two-dimensional block; and a two-dimensional block for selecting a minimum normalized data from the previously prepared normalized data. Memory means for storing in advance a condition of a signal component for at least one of the signal components in the block to be quantized to a value other than zero; and a memory for storing the quantized coefficient calculated by the quantized coefficient calculating means and the memory And a bit allocation calculating means for determining the bit allocation amount based on the signal conditions stored in the digital signal transmission device.