JPH11330974A - Encoding method and device, decoding method and device, digital signal recording method and device, recording medium and digital transmitting method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine the amplitude, in a small-scale process, of signals in a time domain obtained by decoding signals encoded with high efficiency by adding or subtracting the same value of all two-dimensional blocks to/from normalization information defined by a number using several bits of a two-dimensional block and block and performing the level control of the digital signals. SOLUTION: A high frequency encoding device divides digital signals inputted to an input terminal 100 into plural frequency bands by band dividing filters 101 and 102, and also performs orthogonal conversion for each frequency band by orthogonal conversion circuits 103 to 105 to obtain spectrum data on frequency axes. These spectrum data are encoded by adaptive bit allocation encoding circuits 106 to 108 in each so-called critical band width and in consideration of the human aural characteristics in a low frequency area, and at each band defined by fractionizing the critical band width in consideration of the block floating efficiency in medium and high frequency areas respectively. This block is usually is a quantization noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an encoding method,
The present invention relates to a decoding method, an encoding device, a decoding 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 apparatuses for highly 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, and 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: Subband) is one of the non-blocking frequency band division methods in which an audio signal in the time domain is divided into a plurality of frequency bands and encoded without being blocked for each unit time. Coding) 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 coding scheme, the signal for each band is orthogonally transformed into a signal in the frequency domain by the above-described transformation coding scheme, and this orthogonal transformation is performed. Encoding is performed for each band.

Here, as an example of a band division filter used in the above-mentioned band division coding system, for example, QM
There are filters such as F (Quadrature Mirror filter). This filter is 1976 RECrochiere
Digital coding of speechin subbands Bell Syst.Te
ch. J. Vol.55, No.8, 1976. Also, ICASSP 83, BOSTON Polyphase Quadrature filters-
A new subband codingtechnique Joseph H. Rothweiler
Has a polyphase quadrature filter (Polyphase Q
An equal-bandwidth filter splitting method and device, such as a uadrature filter, is described.

As the above-mentioned orthogonal transform, for example, an input audio signal is divided into blocks in a predetermined unit time (frame), and a fast Fourier transform (F
FT), a discrete cosine transform (DCT), a modified DCT transform (MDCT), and the like, to transform the time axis to the frequency axis. Regarding the above MDCT, ICASSP 1987 Subband / Transfor
m Coding Using FilterBank Designs Based on Time Do
main Aliasing Cancellation JPPrincen ABBradle
y Univ. of Surrey 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.
Also, when encoding data for each band at this time,
Encoding by predetermined bit allocation for each band or adaptive bit allocation for each band is performed. For example, when encoding the MDCT coefficient data obtained by the above MDCT processing by the above bit allocation, the MDC for each band obtained by the above MDCT processing for each block is used.
Encoding is performed on the T coefficient data with an adaptive number of allocated bits.

[0006] Further, in encoding for each band, a so-called block floating process for realizing more efficient encoding is performed by normalizing and quantizing each band. For example, when encoding the MDCT coefficient data obtained by the above 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. Thus, more efficient encoding is performed. In normalization, numbering corresponding to information of multiple sizes is specified in advance,
This number is used as normalization information. The information on the magnitude of the normalization prepared in advance is numbered at a constant magnitude ratio.

Conventionally, the following two methods are known as the above-mentioned bit allocation method and the device for the same.

[0008] IEEE Transactions of Accoustics, Speec
h, and Signal Processing, vol.ASSP-25, No.4, August 19
In 77, bit allocation is performed based on the magnitude of the signal for each band. Also ICASSP 1980 The critical band
coder--digital encoding of the perceptual requireme
At the nts of the auditory system MA Kransner MIT,
A method of obtaining a required signal-to-noise ratio for each band and performing fixed bit allocation by using auditory masking is described.

A signal which has been subjected to high-efficiency coding by the above-described method is decoded by the following method. First, a signal subjected to high-efficiency coding is calculated as MDCT coefficient data using bit allocation information, normalization information, and the like for each band. This MDCT coefficient data is subjected to a so-called inverse orthogonal transform, and is converted into data in a time domain. If band division has been performed by a band division filter at the time of encoding, synthesis is further performed using a band synthesis filter. By these operations, the original data in the time domain is decoded.

[0010]

By the way, with respect to a signal in the time domain obtained by decoding a signal which has been subjected to the above-described high-efficiency encoding, the amplitude of the signal, that is, the reproduction level is basically adjusted. Is realized by multiplying, adding, or subtracting a certain amount of value from a signal component in the time domain before encoding or a signal component decoded in the time domain. in this case,
Multiplication using a multiplier, an adder, or a subtractor needs to be performed on the value of each point on the time axis, resulting in an increase in the number of processing steps.

Further, the MDCT in the frequency domain after the orthogonal transform is performed.
A method of adjusting the level using coefficient data is also conceivable, but this method also requires multiplication, addition, or subtraction using a multiplier, an adder, or a subtractor for the number of MDCT coefficients. The processing steps become large.

Further, a signal on which the above-described high-efficiency encoding has been performed is recorded on a certain recording medium, and a magnitude of the amplitude of a signal in a time domain obtained by decoding the recorded signal,
In other words, the same problem occurs when it is desired to change the information so as to change the reproduction level and re-record the information. In particular, when the adjustment is performed in the time domain and the result is to be re-recorded on a recording medium, it is necessary to perform an inverse orthogonal transform, an orthogonal transform, and the like.

Accordingly, an object of the present invention is to realize the adjustment of the magnitude of the amplitude, that is, the reproduction level, of a signal in the time domain obtained by decoding a signal subjected to high-efficiency encoding, with a smaller processing step. Encoding method, decoding method, encoding device, decoding device, digital signal recording method, digital signal recording device, recording medium,
A digital signal transmission method and a digital signal transmission device are proposed.

Another object of the present invention is to record a highly efficient coded signal on a recording medium and decode the recorded signal in a time domain signal to obtain a signal having a large amplitude. In other words, when information is to be changed and re-recorded in such a way as to change the reproduction level, it should be realized with a smaller processing step, and at the same time, to prevent quality deterioration due to operations such as inverse orthogonal transformation and orthogonal transformation. Encoding method, decoding method, encoding device, decoding 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 are proposed.

[0015]

According to the encoding method of the present invention, an input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. For each two-dimensional block, based on the signal components in the two-dimensional block, normalization is performed by selecting, as normalization information, one of several positive values numbered using several bits in advance. The number using the corresponding several bits is used as normalization information, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained for each two-dimensional block related to time and frequency, and based on the quantization coefficient The bit allocation amount is determined, the signal component in the 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 an encoding method in which an information compression parameter for each two-dimensional block relating to the wave number is obtained, and the number information of the two-dimensional blocks to be effective is selected from a predetermined value of several bits, a normalization using a number using several bits of the two-dimensional block The level of the digital signal is adjusted by adding or subtracting the same value for all two-dimensional blocks to the conversion information.

According to the present invention, in the above-described encoding method, the same value is added to or subtracted from all the two-dimensional blocks with respect to the normalized information based on the number using several bits of the two-dimensional block. And adjust the level of the digital signal.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first aspect of the present invention is to decompose an input digital signal into a plurality of frequency band components, obtain signal components in a plurality of two-dimensional blocks relating to time and frequency, and obtain two-dimensional components relating to time and frequency. Based on the signal components in the two-dimensional block for each block, normalization is performed by selecting, as normalization information, one of several positive values numbered using several bits in advance, A number using the corresponding bits is used as normalization information, and a quantization coefficient representing the characteristic of a signal component in the two-dimensional block is obtained for each two-dimensional block related to time and frequency, and bit allocation is performed based on the quantization coefficient. The amount is determined, the signal components in the block are 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 the encoding method in which the information compression parameter for each block is obtained and the number information of the effective two-dimensional block is selected from a predetermined value of several bits, the normalized information by the number using several bits of the two-dimensional block is obtained. On the other hand, this is an encoding method for adjusting the level of a digital signal by adding or subtracting the same value for all two-dimensional blocks.

According to a second aspect of the present invention, an input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Based on the signal components in the dimensional block, normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the corresponding number A number using bits is used as normalization information, a quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained for each two-dimensional block regarding time and frequency, and a bit allocation amount is determined based on the quantization coefficient. Quantizing the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency, and compressing the information. The information compression parameter is obtained, the number information of the effective two-dimensional block is selected from a predetermined value of several bits from a predetermined value, and the signal component of each information-compressed two-dimensional block is converted into the time-frequency related two-dimensional block. In a decoding method in which decoding is performed using an information compression parameter for each dimensional block, the same value is added to all the two-dimensional blocks with respect to the normalized information by a number using several bits of the two-dimensional block, or This is a decoding method for adjusting the level of a digital signal by subtraction.

According to a third aspect of the present invention, there is provided band dividing means for dividing an input digital signal into a plurality of frequency band components, and encoding and / or analysis of a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. Transform means for obtaining a signal component for use, and, for each two-dimensional block related to time and frequency, based on the signal component in the two-dimensional block, among several positive values numbered using several bits in advance. Normalization is performed by selecting one of the
Normalized data calculation means for obtaining a number using the corresponding several bits as normalization information, and a quantization coefficient for obtaining a quantization coefficient representing a characteristic of a signal component in the two-dimensional block for each two-dimensional block relating to time and frequency Calculating means, bit allocation calculating means for determining a bit allocation amount based on the quantized coefficient, and quantizing the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency. Compression encoding means for compressing; information compression parameter determining means for obtaining information compression parameters for each two-dimensional block relating to time and frequency; and validity for selecting information on the number of valid two-dimensional blocks from a predetermined number of bits. In an encoding apparatus having two-dimensional block number information determining means, a number using several bits of a two-dimensional block Against that normalization information, a encoding apparatus having a digital signal level adjusting means by which the same value addition or subtraction for all the 2-dimensional block.

According to a fourth aspect of the present invention, there is provided band dividing means for dividing an input digital signal into a plurality of frequency band components, and encoding and / or analysis of a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. Transform means for obtaining a signal component for use, and, for each two-dimensional block related to time and frequency, based on the signal component in the two-dimensional block, among several positive values numbered using several bits in advance. Normalization is performed by selecting one of the
Normalized data calculation means for obtaining a number using the corresponding several bits as normalization information, and a quantization coefficient for obtaining a quantization coefficient representing a characteristic of a signal component in the two-dimensional block for each two-dimensional block relating to time and frequency Calculating means, bit allocation calculating means for determining a bit allocation amount based on the quantized coefficient, and quantizing the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency. Compression encoding means for compressing; information compression parameter determining means for obtaining information compression parameters for each two-dimensional block relating to time and frequency; and validity for selecting information on the number of valid two-dimensional blocks from a predetermined number of bits. Means for determining the number of two-dimensional block information; In a decoding device having decoding means for decoding by using an information compression parameter for each two-dimensional block related to frequency, the same value is used for all two-dimensional blocks with respect to the normalized information by the number using several bits of the two-dimensional block. Is a decoding device having digital signal level adjusting means by adding or subtracting.

According to a fifth aspect of the present invention, an input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Based on the signal components in the dimensional block, normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the corresponding number A number using bits is used as normalization information, a quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained for each two-dimensional block regarding time and frequency, and a bit allocation amount is determined based on the quantization coefficient. , Quantizes the signal components in the block by the normalized data and the bit allocation amount for each of the two-dimensional blocks relating to time and frequency, and compresses the information. In a digital signal recording method, a parameter and information on the number of valid two-dimensional blocks selected from a predetermined number of bits are recorded on a recording medium. Normalization information by a number using several bits of the two-dimensional block. This is a digital signal recording method for adjusting the level of a digital signal by adding or subtracting the same value for all two-dimensional blocks.

According to a sixth aspect of the present invention, there is provided the digital signal recording method according to the fifth aspect of the present invention, wherein the level-adjusted normalized information is re-recorded on a recording medium.

According to a seventh aspect of the present invention, there is provided band dividing means for dividing an input digital signal into a plurality of frequency band components, and encoding and / or analysis of a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. Transform means for obtaining a signal component for use, and, for each two-dimensional block relating to time and frequency, based on the signal component in the two-dimensional block, out of some positive values numbered using several bits in advance. Normalization is performed by selecting one of the
Normalized data calculation means for obtaining a number using the corresponding several bits as normalization information, and a quantization coefficient for obtaining a quantization coefficient representing a characteristic of a signal component in the two-dimensional block for each two-dimensional block relating to time and frequency Calculating means, bit allocation calculating means for determining a bit allocation amount based on the quantized coefficient, and information by quantizing a signal component in the block by normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency. Compression encoding means for compressing, information compression parameter determining means for obtaining information compression parameters for each two-dimensional block relating to time and frequency, and validity for selecting information on the number of valid two-dimensional blocks from a predetermined value of several bits Compression coding means, information compression parameter determining means, and effective two-dimensional block number determining means. In a digital signal recording apparatus in which each output of the block number information determining means is recorded on a recording medium, the same value is used for all the two-dimensional blocks with respect to the normalized information by the number using several bits of the two-dimensional block. This is a digital signal recording device having digital signal level adjusting means by adding or subtracting.

An eighth aspect of the present invention is the digital signal recording apparatus according to the seventh aspect of the present invention, wherein the normalized information adjusted by the level adjusting means is re-recorded on a recording medium.

According to a ninth aspect of the present invention, an input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Based on the signal components in the dimensional block, normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the corresponding number A number using bits is used as normalization information, a quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained for each two-dimensional block regarding time and frequency, and a bit allocation amount is determined based on the quantization coefficient. , Quantizes the signal components in the block by the normalized data and the bit allocation amount for each of the two-dimensional blocks relating to time and frequency, and compresses the information. A recording medium recorded the number information of the two-dimensional blocks to parameters and effective with those selected from the predefined value by the number bits,
The level of the digital signal is adjusted by adding or subtracting the same value for all the two-dimensional blocks to the normalized information based on the number using several bits of the two-dimensional block. This is a recording medium on which the normalized information of is recorded.

According to a tenth aspect of the present invention, an input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Based on the signal components in the dimensional block, normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the corresponding number A number using bits is used as normalization information, a quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained for each two-dimensional block regarding time and frequency, and a bit allocation amount is determined based on the quantization coefficient. , Quantizes the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency, and compresses the information to obtain information relating to each two-dimensional block relating to time and frequency. In a digital signal transmission method for transmitting a compression parameter and information on the number of valid two-dimensional blocks with a value selected from a predetermined number of bits in a digital signal transmission method, with respect to normalization information by a number using several bits of a two-dimensional block Is a digital signal transmission method for adjusting the level of a digital signal by adding or subtracting the same value for all two-dimensional blocks, and transmitting the digital signal after the level adjustment.

According to an eleventh aspect of the present invention, there is provided band dividing means for dividing an input digital signal into a plurality of frequency band components, and encoding and / or analysis of a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. Transform means for obtaining a signal component for use, and, for each two-dimensional block related to time and frequency, based on the signal component in the two-dimensional block, among several positive values numbered using several bits in advance. A normalized data calculating means for performing normalization by selecting one of the two as normalization information and obtaining a number using the corresponding few bits as the normalization information, and a two-dimensional block for each two-dimensional block relating to time and frequency. Quantization coefficient calculation means for obtaining a quantization coefficient representing the characteristic of a signal component in a block; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient; Compression encoding means for quantizing a signal component in a block with normalized data and a bit allocation amount for each two-dimensional block relating to the number and compressing information, and an information compression parameter for obtaining an information compression parameter for each two-dimensional block relating to time and frequency Determining means for determining the number of effective two-dimensional blocks from a predetermined number of bits of information on the number of valid two-dimensional blocks, the compression encoding means and the information compression parameter determining means; In a digital signal transmitting apparatus for transmitting each output of a two-dimensional block number information determining means, the same value is added to or subtracted from all two-dimensional blocks with respect to normalization information based on a number using several bits of the two-dimensional blocks. Signal level adjustment means and digital signal after level adjustment A digital signal transmitting apparatus and a transmitting unit that.

[Specific Example of Embodiment of the Invention] A specific example of an embodiment of the present invention will be described below with reference to the drawings. In this specific example, an input digital signal such as an audio PCM signal is subjected to high-efficiency encoding using techniques such as band division coding (SBC), adaptive transform coding (ATC), and adaptive bit allocation. This technique will be described with reference to FIG.

In the specific high-efficiency coding apparatus 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, and the obtained spectrum data on the frequency axis is converted. In the low band, adaptively, for each so-called critical bandwidth (critical band) considering human auditory characteristics described later, and in the mid-high band, for each band obtained by subdividing the critical bandwidth in consideration of block flow-taking efficiency. Are assigned to bits and encoded. Usually, this block is a quantization noise generating block. Further, in a specific example of the embodiment of the present invention, the block size (block length) is adaptively changed according to the input signal before the orthogonal transform.

That is, in FIG. 1, when the sampling frequency is 44.1 kHz, for example,
An audio PCM signal of 22 kHz is supplied.
This input signal is reduced to 0 by a band division filter 101 such as a so-called QMF filter (right angle mirror filter).
１１11 kHz band and 11 kHz to 22 kHz band, and signals in the 0 to 11 kHz band
The band division filter 102 such as an MF filter
It is divided into a 5.5 kHz band and a 5.5 kHz to 11 kHz band.

11 from the above-described band division filter 101
A signal in the band of 22 kHz to 22 kHz is an MDCT (Modified Discrete Cosine Transform) which is an example of an orthogonal transform circuit.
The signal in the 5.5 kHz to 11 kHz band from the above-described band division filter 102 is sent to the MDCT circuit 104, and the 0 to 5.5 kHz band signal from the above band division filter 102 is sent to the MDCT circuit 105. By being sent, each is subjected to MDCT processing. Each of the MDCT circuits 103, 104, and 105 includes a block determination circuit 109, 110, 111 provided for each band.
MDCT processing is performed based on the block size (information compression parameter) determined by.

Here, each of the MDCT circuits 103, 104,
FIG. 2 shows a specific example of a standard input signal for a block for each band to be supplied to 105. In the specific example of FIG. 2, each of the three filter output signals has 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 signal. . If the signal is quasi-stationary in time, the orthogonal transform block size is 11.6.
mS, ie, as in the long mode of FIG. 2A,
If the signal is non-stationary, the orthogonal transform block size is further divided into two and four. As shown in the short mode of FIG. 2B, when the whole is divided into four and 2.9 mS, or as in the middle mode A of FIG. 2C and the middle mode B of FIG. Division, 2.9
By setting the time resolution to mS, it is adapted to an actual complicated input signal. It is obvious that the division of the orthogonal transform block size is more effective if a more complicated division is performed if the scale of the processing device permits. The block size is determined by the block size determination circuits 109, 110, and 111 in FIG.
Circuits 103, 104, 105 and bit allocation calculation circuit 1
18 and output from the output terminals 113, 115 and 117 as block size information of the corresponding block.

Referring again to FIG. 1, each MDCT circuit 10
Spectrum data or MDCT coefficient data (signal components in a two-dimensional block related to time and frequency) on the frequency axis obtained by performing MDCT processing in 3, 104, and 105
In the lower band, the critical band is divided for each so-called critical band (critical band), and in the middle and higher bands, the critical bandwidth is subdivided in consideration of the effectiveness of block floating, and the adaptive bit allocation coding circuits 106, 107, 108 and It is sent to the bit assignment calculation circuit 118. The critical band is a frequency band divided in consideration of human auditory characteristics, and has a noise when the pure tone is masked by a narrow band noise of the same strength near the frequency of the pure tone. It is a band. 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. 1 is based on the above-described block size information and spectrum data or MDCT coefficient data.
In consideration of the so-called masking effect and the like, the masking amount and the energy or peak value for each of the divided bands in consideration of the critical band and the block floating described above are calculated. , The number of allocated bits (bit allocation amount) is obtained and transmitted to the adaptive bit allocation coding circuits 106, 107, and 108 in FIG. These adaptive bit allocation encoding circuits 106,
In 107 and 108, each spectrum data or MDCT coefficient data is re-quantized (normalized and quantized) according to the block size information and the number of bits allocated to each divided band in consideration of the critical band and the block floating. ). The data encoded in this manner is output to the output terminals 112 and 11 in FIG.
4 and 116. For convenience of explanation below,
Each of the divided bands that take into account the above-described critical band and block floating, which are units of bit allocation, is referred to as a unit block.

Next, a specific method of the bit allocation performed by the bit allocation calculating circuit (bit allocation calculating means) 118 in FIG. 1 will be described. FIG. 3 is a block circuit diagram showing a schematic configuration of one specific example of the bit allocation calculating circuit 118 in FIG. 1 described above. In FIG. 3, the input terminal 301 is connected to the MDC in FIG.
The spectrum data or MDCT coefficients on the frequency axis from the T circuits 103, 104, and 105 and the block size information from the block determination circuits 109, 110, and 111 in FIG. Thereafter, the bit allocation calculating circuit 118 shown in FIG.
In this system, processing is performed using constants, weighting functions, and the like that are adapted to the above-described block size information (information compression parameters). In FIG. 3, spectrum data or MDC on the frequency axis input from an input terminal 301 is shown.
The T coefficient is sent to the energy calculation circuit 302, and the energy of 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 302, for example, the spectrum of the sum of each band is shown as SB in FIG. However, in FIG. 4, for simplicity of illustration, the number of divisions by the unit block is 12 blocks (B1 to B12).
It is expressed by The energy calculation circuit 302 also determines a scale factor value that is normalized data (information compression parameter) indicating a block floating state of a unit block. Specifically, for example, several positive values are prepared in advance as scale factor value candidates, and a minimum value is selected from among the positive values that are not less than the maximum value of the absolute value of the spectral data or MDCT coefficient in the unit block. Is adopted as the scale factor value of the unit block. The scale factor value may be numbered using several bits in a form corresponding to the actual value, and the number may be stored in a ROM or the like (not shown). For the scale factor value corresponding to the number, for example, 2 dB
It is specified to have a value at intervals of. Here, as for the scale factor value determined by the above-described method in a certain unit block, the above-mentioned number corresponding to the determined value is used as sub-information indicating the scale factor of the unit block.

Next, in order to take into account the so-called masking effect of the above-mentioned spectrum SB obtained by the above-described energy calculation circuit 302, 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 302 for each band, that is, each value of the spectrum SB is sent to the convolution filter circuit 303. The convolution filter circuit 303 includes, for example, a plurality of delay elements for sequentially delaying input data, a plurality of multipliers for multiplying outputs 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 process, the sum of the parts indicated by the dotted lines in FIG. 4 is obtained.

Next, the output of the convolution filter circuit 303 is sent to a subtractor 304. The subtractor 304 is
A level α corresponding to an allowable noise level (quantized coefficient) described later in the convolved region is obtained. The level α corresponding to the permissible noise level (permissible noise level) becomes an allowable noise level for each of the critical bands by performing inverse convolution processing as described later. Level. Here, an allowance function (a function expressing a masking level) for obtaining the level α is supplied to the subtractor 304. The level α is controlled by increasing or decreasing the allowable function. The permissible function is supplied from the (n-ai) function generation circuit 305 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.

[0038]

Α = S− (n−ai)

In the equation (1), n and a are constants and a
> 0, S is the intensity of the convolved spectrum,
(N-ai) in the equation (1) is an allowable function. N as an example
= 38, a = 1 can be used.

In this way, the above-mentioned level α is obtained, and this data is transmitted to the division circuit 306. The division circuit 306 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. Although the above-described inverse convolution processing requires a complicated operation, the inverse convolution is performed using the simplified division circuit 306 in the specific example of the present embodiment.

Next, the above-mentioned masking spectrum is transmitted to the subtraction circuit 309 via the synthesis circuit 308. Here, the output from the above-described energy calculation circuit 302 for each band, that is, the above-described spectrum SB is supplied to the subtraction circuit 309 via the delay circuit 310. Therefore, by performing the subtraction operation of the above-described masking spectrum and the spectrum SB in the subtraction circuit 309, as shown in FIG.
The level below the level indicated by the level of the masking spectrum MS is masked.

By the way, at the time of synthesizing in the synthesizing circuit 308 described above, data indicating a so-called minimum audible curve RC which is a human auditory characteristic as shown in FIG. The masking spectrum MS described above 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 will be different depending on the reproduction volume at the time of reproduction, for example, even if the coding is the same, but in a realistic digital system, for example, when music is entered into 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 the system is used so that noise around 4 kHz of the word length of the system cannot be heard, and an allowable noise level is obtained by synthesizing the minimum audible curve RC and the masking spectrum MS together, In this case, the allowable noise level can be up to the shaded portion in FIG. In the specific example of the present 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. 6 also shows the signal spectrum SS.

Thereafter, the allowable noise correction circuit 311 corrects the allowable noise level in the output from the subtraction circuit 309 based on, for example, information on the equal loudness curve. 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 a pure tone of 1 kHz, and is connected by a curve. 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, at around 4 kHz, even if the sound pressure falls by 8 to 10 dB from the place of 1 kHz, it sounds as large as 1 kHz. It doesn't sound the same size. 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 (allowable quantization coefficient) in consideration of the above-mentioned equal loudness curve is suitable for human auditory characteristics. Through a series of processing up to this point, the allowable noise correction circuit 311 calculates bits to be allocated to each unit block based on various parameters such as the above-described masking and auditory characteristics.

The data output from the allowable noise correction circuit 311 is output from the output terminal 312 as the output of the bit assignment calculation circuit 118 in FIG.

That is, in the bit allocation calculating circuit 118 in FIG. 1, the data obtained by processing the orthogonal transform output spectrum by the sub-information as the main information and the block as the sub-information by the system shown in FIG. The scale factor indicating the floating state and the word length indicating the word length are obtained. Based on these, the adaptive bit allocation encoding 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.

Here, the normalization information adjustment circuit 119 of FIG. 1 will be described. As described above, for the scale factor value which is the normalized data, several positive values are prepared in advance as scale factor value candidates, and the spectrum data in the unit block or the MDC is prepared from among them.
Among the values greater than the maximum value of the absolute value of the T coefficient, the smallest one is adopted as the scale factor value of the unit block, and the scale factor value uses several bits in a form corresponding to the actual value. And the number is used as sub-information indicating the scale factor of the unit block. The scale factor value corresponding to the number is defined to have a value in the order of the number, for example, at an interval of 2 dB. Therefore, for example, by manipulating the number of the sub information indicating the scale factor, it is possible to adjust the level of the unit block by 2 dB. The normalization information adjustment circuit 119 is a circuit that outputs a numerical value for performing this level adjustment. Further, the adder 120,
At 121 and 122, the numerical value from the normalization information adjustment circuit 119 for each band is added to the scale factor value of the unit block. When the numerical value output from the normalization information adjustment circuit 119 is a negative number, the adders 120, 121,
122 acts as a subtractor. That is, the level adjustment of 2 dB can be performed only by adding and subtracting all the same numerical values output from the normalization information adjustment circuit 119 to all the unit blocks. At this time, the addition and subtraction results are restricted so as to be within the range of the scale factor value defined in the format.

Next, an encoding format of data to be actually encoded will be described with reference to FIG. The numerical value shown on the left side of FIG. 7 represents the number of bytes, and in this embodiment, 212 bytes are used as a unit of one frame.

In the position of 0 byte located at the top in FIG. 7, the block determination circuits 109, 1 in FIG.
The block size information (block size mode information) of each band determined in 10 and 111 is recorded.

Information on the number of unit blocks to be recorded is recorded at the position of the next first byte. This is because, for example, the bit allocation becomes 0 and the recording is unnecessary in many cases as it goes to the higher frequency side by a series of bit allocation calculation circuits. Therefore, by setting the number of recordings in a form corresponding to this, the audibility is improved. A lot of bits are allocated to the middle and low frequencies where the influence is large. Also, the number of unit blocks in which the bit allocation information is double-written and the number of the unit blocks in which the scale factor information is double-written are recorded at the position of this 1 byte. Double writing is a method for recording the same data as data recorded at a certain byte position in another location for error correction. The more this double-write information is, the higher the error resistance is, but the less this information is, the more bits that can be used for the spectrum data. For each of the above-mentioned bit allocation information and scale factor information, the number of double-written unit blocks is set independently, and the strength against errors and the number of usable bits for spectrum data are adjusted. ing. For each piece of information, the correspondence between the code in the prescribed bit and the number of unit blocks is determined in advance as a format. Specifically, as shown in FIG. 8, three bits out of eight bits at the position of one byte are used as information on the number of unit blocks to be actually recorded, and two bits out of the remaining five bits are used as bit allocation information. The number of unit blocks for which double writing is being performed.
Record the number of overwritten unit blocks.

At the position from the second byte in FIG. 7, bit allocation information of a unit block is recorded. For recording bit allocation information, for example, 4
Use of bits is defined as a format. As a result, bit allocation information for the number of unit blocks actually recorded in FIG. 7 described above is recorded in order from the 0th unit block.

After the data of the bit allocation information recorded by the above method, the scale factor information of the unit block is recorded. For recording of scale factor information, for example, use of 6 bits for one unit block is defined as a format. Thus, the scale factor information is recorded in the same order as the recording of the bit allocation information, starting from the 0th unit block and by the number of the unit blocks to be actually recorded.

After the scale factor information thus recorded, the spectrum data of the unit block is recorded. The spectrum data is also recorded in order from the 0th unit block by the number of unit blocks to be actually recorded. The number of pieces of spectrum data that exist in each unit block is determined in advance by the format, so that it is possible to correspond to the data by the above-described bit allocation information. It should be noted that recording is not performed for a unit block whose bit allocation is 0.

After this spectrum information, the above-described double writing of the scale factor information and the double writing of the bit allocation information are performed. This recording method is the same as the recording of the scale factor information and the bit allocation information described above, except that the correspondence of the number is made to correspond to the double-written information shown in FIG.

In FIG. 7, the scale factor 2
The overwriting and / or the bit allocation double writing may be stopped, and the portion may be allocated to the spectrum data area.

As for the last two bytes, the information of the 0th byte and the information of the 1st byte are duplicated as shown in FIG. The two-byte double writing is defined as a format, and the scale factor information 2
It is not possible to set the variable amount of double writing as in the case of double writing or double writing of bit allocation information.

That is, the bit allocation calculation circuit 118 in FIG. 1 uses the system shown in FIG. 3 described above to process data obtained by processing the orthogonal transform output spectrum with sub-information as main information and block data as sub-information. The scale factor indicating the floating state and the word length indicating the word length are obtained. Based on these, the adaptive bit allocation encoding circuits 106, 10 in FIG.
In steps 7 and 108, requantization is actually performed, and if necessary, the normalization information is adjusted based on the output from the normalization information adjustment circuit 119, and is encoded in a form conforming to the encoding format.

FIG. 9 shows a decoding circuit for decoding again a signal which has been efficiently coded by the system shown in FIG. 1 described above. Quantized MDCT for each band
The coefficients, that is, the output terminals 112, 114, 1 in FIG.
The data equivalent to the 16 output signals is given to the decoding circuit input terminal 908 in FIG. 9 and used block size information (information compression parameter information), that is, the output signals of the output terminals 113, 115 and 117 in FIG. Data equivalent to is given to the input terminal 910 in FIG. The adaptive bit allocation decoding circuit 906 in FIG. 9 releases bit allocation using adaptive bit allocation information. Next, FIG.
Orthogonal transform (IMDCT: inverse modified discrete cosine transform) circuits 903, 904, 90
At 5, the signal on the frequency axis is converted to a signal on the time axis. The signals on the time axis of these partial bands are represented by a band synthesis filter (inverse band division filter) (IQMF:
The signals are decoded into full-band signals by the inverse right-angle mirror filter circuits 902 and 901.

Here, the normalization information adjustment circuit 911 will be described. Basically, the normalization information adjustment circuit 1 in FIG.
The same operation as 19 is performed. That is, it is a circuit that outputs a numerical value for performing level adjustment by adding and subtracting from the normalized information. An adder 909 adds the numerical value from the normalization information adjustment circuit 911 to the scale factor value of the unit block. When the numerical value output from the normalization information adjusting circuit 911 is a negative number, the adder 909 acts as a subtractor. That is, as in the case of the encoding, the level adjustment by 2 dB can be performed only by adding and subtracting all the same numerical values output from the normalization information adjusting circuit 911 to all the unit blocks. At this time, regarding the addition and subtraction results,
Restriction to be within the range of the scale factor specified in the format. The scale factor value whose level has been adjusted by the adder 909 can be used only for adjusting the level of the decoded signal by being used in the decoding step from 906, and can be used, for example. Reading the scale factor value from the encoded recording medium, outputting the adjusted scale factor value to 907, changing the scale factor value recorded on the recording medium to the adjusted value,
Re-recording is also possible. The information on the recording medium can be changed and re-recorded as necessary. This makes it possible to change the level information of the recording medium with a very simple system.

In the above description, an example in which both the encoding circuit and the decoding circuit have the normalization information adjusting circuit has been described.
Even with the decoding circuit alone, this effect can be fully utilized.

Hereinafter, several examples of level adjustment using the normalization information adjustment circuit will be described. For example, by gradually increasing or decreasing the output value from the normalization information adjustment circuit, a so-called audio signal (audio signal) is obtained.
It is possible to obtain effects such as fade-in and fade-out, which are known by the processing of (1).

Further, by designating a part of the audio signal that is hard to hear due to a low recording level, for example, and adding the output value from the normalization information adjusting circuit to that part, only the level of the relevant part is reduced. It can be larger. Conversely, it is also possible to lower only the level of the corresponding location.

Also, for example, the level of the audio signal of a certain music is analyzed by analyzing the magnitude of the normalized information as a whole, so that a so-called compressor,
It is also possible to obtain an effect such as a limiter.

Next, with reference to FIGS. 10 to 13, a digital signal recording device (method), digital signal reproducing device (method), and digital signal transmitting device (method) including the above-described normalized information adjusting circuit of the present invention. ) And a digital signal receiving device (method) according to an embodiment will be described. Figure 10
In FIG. 13, ENC indicates the encoder of FIG.
in indicates its input terminal 100, DEC indicates the decoder of FIG. 9, and Tout indicates its output terminal 700.

In the recording apparatus of FIG. 10, 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 multiplexes and performs 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. 11, the recording medium M shown in FIG. 10 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 signal corresponding to the demodulated output from the demodulating means DEM, that is, a signal corresponding to the output from the output terminals 112, 114, and 116 of the encoder of FIG. 1 is supplied to the input terminal 908 of the decoder of FIG. 113, 11
Signals corresponding to the outputs from 5, 117 are supplied to an input terminal 910 in FIG. 9 and decoded, and an output digital signal corresponding to the input digital signal is output to an output terminal Tout.

In the transmitting apparatus shown in FIG. 12, 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 and 117 are connected to the modulating means MO.
D, and multiplexes and performs predetermined modulation, or modulates each output signal, and then multiplexes or remodulates. The modulated signal from the modulating means MOD is supplied to the transmitting means TX to perform frequency conversion, amplification and the like to generate a transmitting signal, and the transmitting signal is transmitted by the transmitting antenna ANT-T which is a part of the transmitting means TX. .

In the receiving apparatus of FIG. 13, the receiving signal from the transmitting antenna ANT-T of FIG. 11 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, and the like. The demodulation unit DEM demodulates the received signal from the reception unit RX according to the modulation by the modulation unit MOD. The demodulated output from the demodulating means DEM, that is, the output terminals 112, 114, and 11 of the encoder of FIG.
6 is supplied to the input terminal 908 of the decoder in FIG. 9 and the signal corresponding to the output from the output terminals 113, 115, and 117 of the encoder in FIG. 1 is supplied to the input terminal 910 in FIG. The output digital signal corresponding to the input digital signal is output to the output terminal Tout.

The present invention is not limited to the specific example of the above-described 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 is a magnetic tape. Magnetic disks, magneto-optical disks and the like are possible. Also, instead of a recording medium, an IC memory,
It may be storage means such as a memory card. 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 an 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 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.

[0069]

According to the first aspect of the present invention, an input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency, and two-dimensional components relating to time and frequency are obtained. Based on the signal components in the two-dimensional block for each block, normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, The number using the corresponding few bits is used as normalization information, and a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained for each two-dimensional block relating to time and frequency, and bit allocation is performed based on the quantization coefficient. The amount is determined, the signal components in the block are 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 the encoding method in which the information compression parameter for each block is obtained and the number information of the valid two-dimensional block is selected from a predetermined value of several bits in the encoding method, the normalized information by the number using several bits of the two-dimensional block is used. On the other hand, since the level of the digital signal is adjusted by adding or subtracting the same value for all the two-dimensional blocks, the signal in the time domain obtained by decoding the signal subjected to the high-efficiency encoding is: Adjustment of the magnitude of the amplitude, that is, the reproduction level, can be realized in a smaller processing step, and a highly efficient coded signal is recorded on a certain recording medium, and the recorded signal is decoded. If you want to change the information about the signal in the time domain and change the information so that the playback level changes, Ri together to realize a small step, it is possible to obtain the encoding method capable of realizing the prevention of inverse orthogonal transform, quality deterioration due to the operation of the orthogonal transform or the like.

According to the second aspect of the present invention, the input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Then, based on the signal components in the two-dimensional block, normalization is performed by selecting, as normalization information, one of several positive values that have been numbered using several bits in advance. A number using a few bits is used as normalization information, a quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained for each two-dimensional block relating to time and frequency, and a bit allocation amount is determined based on the quantization coefficient. Is determined, the signal components in the block are quantized by the normalized data and the bit allocation amount for each two-dimensional block related to time and frequency, and information is compressed. The information compression parameter of each block is obtained, and the number information of the two-dimensional block to be effective is selected from a predetermined value of several bits. In a decoding method in which decoding is performed using an information compression parameter for each two-dimensional block related to frequency,
The level adjustment of the digital signal is performed by adding or subtracting the same value for all the two-dimensional blocks to the normalized information based on the number using several bits of the two-dimensional block. In the time domain signal obtained by decoding the converted signal, the magnitude of the amplitude, that is, the adjustment of the reproduction level can be realized in a smaller processing step, and high efficiency coding is performed on a certain recording medium. If the signal in the time domain obtained by recording the recorded signal and decoding the recorded signal is to be re-recorded by changing the information so as to change the magnitude of its amplitude, that is, the reproduction level, It is possible to obtain a decoding method that can be realized with a small processing step and that can prevent deterioration in quality due to operations such as inverse orthogonal transform and orthogonal transform.

According to the third aspect of the present invention, band dividing means for dividing an input digital signal into a plurality of frequency band components,
Orthogonal transform means for orthogonally transforming a signal to obtain signal components for encoding and / or analysis in a plurality of two-dimensional blocks relating to time and frequency, and signal components in the two-dimensional block for each two-dimensional block relating to time and frequency Based on, normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the number using the corresponding several bits is converted to Normalized data calculating means for obtaining as normalized information; quantized coefficient calculating means for obtaining, for each two-dimensional block relating to time and frequency, a quantized coefficient representing a characteristic of a signal component in the two-dimensional block; Bit allocation calculating means for determining the bit allocation amount, and quantizing the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency. Compression encoding means for compressing an information compression parameter determining means for obtaining information compression parameters for each two-dimensional block with respect to time and frequency, 2 as an active
In an encoding apparatus having effective two-dimensional block number information determining means for selecting the number information of two-dimensional blocks from a value defined in advance by several bits, the normalized information by the number using several bits of two-dimensional blocks is completely 2
Since the digital signal level adjusting means is added or subtracted by adding or subtracting the same value with respect to the dimension block, the amplitude of the signal in the time domain obtained by decoding the signal subjected to the high-efficiency encoding, that is, the reproduction level Can be realized with a smaller processing step, and a signal that has been subjected to high-efficiency encoding is recorded on a recording medium, and the amplitude of the signal in the time domain obtained by decoding the recorded signal is obtained. If you want to change and re-record information in a form that changes the size of the playback, that is, the playback level, it is possible to realize it with smaller processing steps and to prevent the quality degradation associated with operations such as inverse orthogonal transform and orthogonal transform. An encoding device that can be realized can be obtained.

According to the fourth aspect of the present invention, band dividing means for dividing an input digital signal into a plurality of frequency band components,
Orthogonal transform means for orthogonally transforming a signal to obtain signal components for encoding and / or analysis in a plurality of two-dimensional blocks relating to time and frequency, and signal components in the two-dimensional block for each two-dimensional block relating to time and frequency Based on, normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the number using the corresponding several bits is converted to Normalized data calculating means for obtaining as normalized information; quantized coefficient calculating means for obtaining, for each two-dimensional block relating to time and frequency, a quantized coefficient representing a characteristic of a signal component in the two-dimensional block; Bit allocation calculating means for determining the bit allocation amount, and quantizing the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency. Compression encoding means for compressing an information compression parameter determining means for obtaining information compression parameters for each two-dimensional block with respect to time and frequency, 2 as an active
Effective two-dimensional block number information determining means for selecting the number information of the two-dimensional block from a predetermined value with several bits, and a signal component in the two-dimensional block related to time and frequency, which is information compressed, and a two-dimensional block related to time and frequency. In a decoding device having decoding means for decoding using each information compression parameter, the same value is added or subtracted for all two-dimensional blocks with respect to normalization information by a number using several bits of a two-dimensional block. The digital signal level adjusting means.
For a signal in the time domain obtained by decoding a signal that has been subjected to high-efficiency encoding, the magnitude of the amplitude, that is, the adjustment of the reproduction level can be realized in a smaller processing step, and the high-efficiency encoding is performed on a certain recording medium. If you want to re-record a signal in the time domain, which is a decoded signal of the recorded signal, and change the information so that the magnitude of the amplitude, that is, the reproduction level, changes, In addition, it is possible to obtain a decoding device that can be realized with smaller processing steps and that can prevent the quality deterioration due to the operations such as the inverse orthogonal transform and the orthogonal transform.

According to the fifth aspect of the present invention, an input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Then, based on the signal components in the two-dimensional block, normalization is performed by selecting, as normalization information, one of several positive values that have been numbered using several bits in advance. The number using several bits to be used as normalization information, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained for each two-dimensional block relating to time and frequency, and the bit allocation amount is determined based on the quantization coefficient. After the decision, the signal components in the block are quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to time and frequency, and the information is compressed.
In a digital signal recording method, information compression parameters for each dimensional block and information on the number of valid two-dimensional blocks are selected from a predetermined number of bits and recorded on a recording medium. Since the level of the digital signal is adjusted by adding or subtracting the same value for all the two-dimensional blocks to the normalized information by the given number, the time domain in which the highly efficient coded signal is decoded Of the signal, the amplitude of the signal, that is, the adjustment of the reproduction level can be realized in a smaller processing step, and a signal that has been subjected to highly efficient encoding is recorded on a certain recording medium, and the recorded signal is recorded. Information about the time-domain signal obtained by decoding the signal is changed in such a way that the magnitude of the amplitude, that is, the reproduction level is changed. If you want re-recorded and changed, with realizing a smaller process, it is possible to obtain a digital signal recording method which can realize the prevention of inverse orthogonal transform, the quality caused by the operation of the orthogonal transform such degradation.

According to the sixth aspect of the present invention, in the digital signal recording method according to the fifth aspect of the present invention, the level-adjusted normalized information is re-recorded on a recording medium, so that a highly efficient coded signal is decoded. For the time domain signal that has been converted, the magnitude of the amplitude, that is, the adjustment of the reproduction level can be realized in a smaller processing step, and the inverse orthogonal transform,
It is possible to obtain a digital signal recording method that can prevent the quality deterioration due to the operation such as the orthogonal transformation.

According to the seventh aspect of the present invention, a band dividing means for dividing an input digital signal into a plurality of frequency band components,
Orthogonal transform means for orthogonally transforming a signal to obtain signal components for encoding and / or analysis in a plurality of two-dimensional blocks relating to time and frequency, and signal components in the two-dimensional block for each two-dimensional block relating to time and frequency Based on, normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the number using the corresponding several bits is converted to Normalized data calculating means for obtaining as normalized information; quantized coefficient calculating means for obtaining, for each two-dimensional block relating to time and frequency, a quantized coefficient representing a characteristic of a signal component in the two-dimensional block; Bit allocation calculating means for determining the bit allocation amount, and quantizing the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency. Compression encoding means for compressing an information compression parameter determining means for obtaining information compression parameters for each two-dimensional block with respect to time and frequency, 2 as an active
Effective two-dimensional block number information determining means for selecting the number information of the two-dimensional blocks from a value predetermined by several bits, each of the compression encoding means, the information compression parameter determining means, and the effective two-dimensional block number information determining means. In a digital signal recording apparatus in which an output is recorded on a recording medium, the same value is added to or subtracted from all the two-dimensional blocks with respect to the normalized information based on the number using several bits of the two-dimensional block. Since the digital signal level adjusting means is provided, the amplitude of the signal in the time domain obtained by decoding the signal subjected to the high-efficiency encoding, that is, the reproduction level can be adjusted in a smaller processing step. At the same time, a high-efficiency coded signal is recorded on a recording medium, and the recorded signal is decoded. For signals in the time domain, when it is desired to change the information to change the magnitude of its amplitude, that is, the reproduction level, and to re-record the information, it is possible to implement the processing in a smaller processing step and perform inverse orthogonal transformation, orthogonal transformation, etc. It is possible to obtain a digital signal recording device that can prevent the quality deterioration due to the calculation.

According to the eighth aspect of the present invention, in the digital signal recording apparatus according to the seventh aspect of the present invention, the normalized information adjusted by the level adjusting means is re-recorded on a recording medium. The amplitude of the signal in the time domain obtained by decoding the decoded signal, that is, the adjustment of the reproduction level can be realized in a smaller processing step, and the operation accompanying the inverse orthogonal transform, orthogonal transform, etc. A digital signal recording device capable of preventing quality deterioration can be obtained.

According to the ninth aspect of the present invention, the input digital signal is decomposed into a plurality of frequency band components 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, based on the signal components in the two-dimensional block, normalization is performed by selecting, as normalization information, one of several positive values that have been numbered using several bits in advance. A number using a few bits is used as normalization information, a quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained for each two-dimensional block relating to time and frequency, and a bit allocation amount is determined based on the quantization coefficient. After the determination, the signal components in the block are quantized by the normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency, and the information is compressed.
Normalization by a number using several bits of a two-dimensional block in a recording medium in which information compression parameters for each dimensional block and information on the number of valid two-dimensional blocks are selected from a predetermined number of bits and recorded. By adding or subtracting the same value for all two-dimensional blocks to the information, the level of the digital signal is adjusted, and the normalized information after the level adjustment is recorded. For a signal in the time domain obtained by decoding the coded signal, the magnitude of the amplitude, that is, the adjustment of the reproduction level can be realized in a smaller processing step, and high-efficiency coding is performed on a certain recording medium. The recorded signal is recorded and the amplitude of the signal in the time domain obtained by decoding the recorded signal, When information is changed in a manner that changes the bell and re-recording is desired, recording that can be achieved with a smaller processing step and that can prevent quality deterioration due to operations such as inverse orthogonal transformation, orthogonal transformation, etc. Medium can be obtained.

According to the tenth aspect of the present invention, an input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Then, based on the signal components in the two-dimensional block, normalization is performed by selecting, as normalization information, one of several positive values that have been numbered using several bits in advance. The number using several bits to be used as normalization information, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained for each two-dimensional block relating to time and frequency, and the bit allocation amount is determined based on the quantization coefficient. Determine, quantize the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block related to time and frequency, and compress the information, and for each two-dimensional block related to time and frequency. In a digital signal transmission method for transmitting an information compression parameter and information on the number of two-dimensional blocks to be valid together with a value selected from a predetermined number of bits, in a digital signal transmission method, normalization information by a number using several bits of a two-dimensional block is used. By adding or subtracting the same value for all two-dimensional blocks,
Since the level of the digital signal is adjusted and the digital signal after the level adjustment is transmitted, the amplitude of the signal in the time domain obtained by decoding the highly efficient encoded signal, that is, the reproduction level Can be realized in a smaller processing step, and a signal that has been subjected to high-efficiency encoding is recorded on a recording medium, and the amplitude of the signal in the time domain obtained by decoding the recorded signal is obtained. If you want to change the information in a way that changes the playback level, that is, change the playback level, re-record it with a smaller processing step, and also prevent the quality degradation associated with operations such as inverse orthogonal transformation and orthogonal transformation. A digital signal transmission method that can be realized can be obtained.

According to the eleventh aspect of the present invention, there is provided a band dividing means for dividing an input digital signal into a plurality of frequency band components,
Orthogonal transformation means for obtaining signal components for encoding and / or analysis in a dimensional block, and numbering using several bits in advance based on the signal components in the two-dimensional block for each two-dimensional block relating to time and frequency. Normalization data calculation means for performing normalization by selecting one of several positive values made as normalization information and obtaining a number using the corresponding several bits as normalization information, Coefficient calculating means for obtaining a quantization coefficient representing a characteristic of a signal component in the two-dimensional block for each two-dimensional block relating to frequency, and bit allocation calculating means for determining a bit allocation amount based on the quantized coefficient; Compression encoding means for quantizing a signal component in the block with normalized data and a bit allocation amount for each two-dimensional block relating to time and frequency and compressing information;
Information compression parameter determining means for obtaining an information compression parameter for each two-dimensional block relating to time and frequency; and effective two-dimensional block number information determining means for selecting valid two-dimensional block number information from a predetermined value of several bits. A digital signal transmitting apparatus for transmitting each output of the compression encoding means, the information compression parameter determining means, and the effective two-dimensional block number information determining means.
The same value is added for all the two-dimensional blocks to the normalized information by the number using several bits of the dimensional block,
Alternatively, the digital signal level adjusting means by subtraction and the transmitting means for transmitting the digital signal after the level adjustment are provided, so that the amplitude of the time domain signal obtained by decoding the highly efficient coded signal is large. Well,
In other words, the adjustment of the reproduction level can be realized in a smaller processing step, and a signal in the time domain obtained by recording a signal with high efficiency encoding on a certain recording medium and decoding the recorded signal is recorded. If you want to change the information to change the magnitude of its amplitude, that is, the reproduction level, and re-record it, you can achieve it in a smaller processing step and also degrade the quality due to operations such as inverse orthogonal transformation and orthogonal transformation. And a digital signal transmission device capable of realizing the prevention.

[Brief description of the drawings]

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

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

FIG. 3 is a block circuit diagram showing an example of a bit allocation operation function.

FIG. 4 is a diagram illustrating spectra of each critical band and a band divided in consideration of block floating.

FIG. 5 is a diagram showing a masking spectrum.

FIG. 6 is a diagram in which a minimum audible curve and a masking spectrum are combined.

FIG. 7 is a diagram showing how data is encoded.

FIG. 8 is a diagram showing details of data of a first byte in FIG. 7;

FIG. 9 is a block circuit diagram showing a specific example of a high-efficiency compression encoding decoder which can be used for bitrate compression encoding in the above embodiment.

FIG. 10 is a block diagram illustrating a recording apparatus according to a specific example of an embodiment of the present invention.

FIG. 11 is a block diagram showing a playback device according to a specific example of the embodiment of the present invention.

FIG. 12 is a block diagram showing a transmission device according to a specific example of the embodiment of the present invention.

FIG. 13 is a block diagram showing a receiving device according to a specific example of the 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, 119 normalization information adjustment circuit, 120, 121,
122 adder (subtractor), 302 energy calculator per band, 303 convolution filter, 304 subtractor, 30
5 function generator, 306 division circuit, 307 minimum audible curve generation circuit, 308 synthesis circuit, 309 subtraction circuit,
310 delay circuit, 311 allowable noise correction circuit, 90
1, 902 band synthesis filter (IQMF), 903,
904, 905 inverse orthogonal transform circuit (IMDCT), 90
6 adaptive bit allocation decoding circuit, 909 adder (subtractor), 911 normalization information adjustment circuit, ENC encoder, MOD modulation means, REC recording means, P reproduction means, DEM demodulation means, DEC decoder, TX transmission means, RX Receiving means.

Claims (11)

[Claims] 1. An input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency.
For each dimension block, based on the signal components in the two-dimensional block,
Normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the number using the corresponding several bits is used as normalization information. A quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained for each of the two-dimensional blocks relating to time and frequency, and a bit allocation amount is determined based on the quantization coefficient; For each time, the information component in the block is quantized by the normalized data and the bit allocation amount to compress the information, and the information compression parameter for the two-dimensional block relating to the time and frequency is obtained, and the number information of the valid two-dimensional block is obtained. Is selected from a predetermined value of several bits in the encoding method. And adjusting the level of the digital signal by adding or subtracting the same value for all two-dimensional blocks. 2. An input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency.
For each dimension block, based on the signal components in the two-dimensional block,
Normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the number using the corresponding several bits is used as normalization information. A quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained for each of the two-dimensional blocks relating to time and frequency, and a bit allocation amount is determined based on the quantization coefficient; In each case, the signal component in the block is quantized by the normalized data and the bit allocation amount to compress the information, and the information compression parameter for each two-dimensional block relating to the time and frequency is obtained, and the number information of the valid two-dimensional block is obtained. Is selected from a value defined in advance by several bits, and the signal component for each two-dimensional block relating to the time and frequency of the information compression is
In the decoding method in which decoding is performed using the information compression parameter for each of the two-dimensional blocks relating to time and frequency, the normalized information by the number using several bits of the two-dimensional block is used for all the two-dimensional blocks. A decoding method characterized in that the level of a digital signal is adjusted by adding or subtracting the same value. 3. A band dividing means for dividing an input digital signal into a plurality of frequency band components, and a signal component for encoding and / or analysis in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. Orthogonal transform means for obtaining, and for each of the two-dimensional blocks relating to time and frequency, one of several positive values that have been numbered using several bits in advance based on the signal components in the two-dimensional block. Normalization data calculation means for performing normalization by selecting as the normalization information and obtaining a number using the corresponding several bits as the normalization information; and for each of the two-dimensional blocks relating to time and frequency, Quantization coefficient calculation means for obtaining a quantization coefficient representing a characteristic of a signal component; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient;
Compression encoding means for quantizing a signal component in the block by the normalized data and the bit allocation amount for each of the two-dimensional blocks relating to time and frequency and compressing the information, and an information compression parameter for each two-dimensional block relating to the time and frequency Information compression parameter determining means for obtaining
In an encoding apparatus having effective two-dimensional block number information determining means for selecting the number information of the two-dimensional block from a value defined in advance by several bits, the normalization information by the number using several bits of the two-dimensional block, An encoding apparatus comprising a digital signal level adjusting means for adding or subtracting the same value for all two-dimensional blocks. 4. A band division means for dividing an input digital signal into a plurality of frequency band components, and a signal component for encoding and / or analysis in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. Orthogonal transform means for obtaining, and for each of the two-dimensional blocks relating to time and frequency, one of several positive values that have been numbered using several bits in advance based on the signal components in the two-dimensional block. Normalization data calculation means for performing normalization by selecting as the normalization information and obtaining a number using the corresponding several bits as the normalization information; and for each of the two-dimensional blocks relating to time and frequency, Quantization coefficient calculation means for obtaining a quantization coefficient representing a characteristic of a signal component; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient;
Compression encoding means for quantizing a signal component in the block by the normalized data and the bit allocation amount for each of the two-dimensional blocks relating to time and frequency and compressing the information, and an information compression parameter for each two-dimensional block relating to the time and frequency Information compression parameter determining means for obtaining
Effective two-dimensional block number information determining means for selecting the number information of the two-dimensional block from a value predetermined by several bits, and a signal component in the two-dimensional block related to the time and frequency of the compressed information, A decoding device for decoding by using an information compression parameter for each two-dimensional block, wherein the same value is added to all the two-dimensional blocks to the normalized information by the number using several bits of the two-dimensional block. Or a digital signal level adjusting means by subtraction. 5. An input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency.
For each dimension block, based on the signal components in the two-dimensional block,
Normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the number using the corresponding several bits is used as normalization information. A quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained for each of the two-dimensional blocks relating to time and frequency, and a bit allocation amount is determined based on the quantization coefficient; For each time, the signal components in the block are quantized by the above-mentioned normalized data and the bit allocation amount, and the information is compressed.
In a digital signal recording method, an information compression parameter for each dimensional block and information on the number of valid two-dimensional blocks are selected from a predetermined number of bits and recorded on a recording medium. A digital signal recording method, wherein the level of a digital signal is adjusted by adding or subtracting the same value for all two-dimensional blocks to the normalized information based on the used number. 6. The digital signal recording method according to claim 5, wherein the level-adjusted normalized information is re-recorded on the recording medium. 7. A band dividing means for dividing an input digital signal into a plurality of frequency band components, and a signal component for encoding and / or analysis in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. Orthogonal transform means for obtaining, and for each of the two-dimensional blocks relating to time and frequency, one of several positive values that have been numbered using several bits in advance based on the signal components in the two-dimensional block. Normalization data calculation means for performing normalization by selecting as the normalization information and obtaining a number using the corresponding several bits as the normalization information; and for each of the two-dimensional blocks relating to time and frequency, Quantization coefficient calculation means for obtaining a quantization coefficient representing a characteristic of a signal component; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient;
Compression encoding means for quantizing a signal component in the block by the normalized data and the bit allocation amount for each of the two-dimensional blocks relating to time and frequency and compressing the information, and an information compression parameter for each two-dimensional block relating to the time and frequency Information compression parameter determining means for obtaining
Effective two-dimensional block number information determining means for selecting the number information of the dimensional blocks from a value prescribed in advance by several bits, the compression encoding means, the information compression parameter determining means, and the effective two-dimensional block number information determining means. In a digital signal recording apparatus in which each output of the means is recorded on a recording medium, the same value is added to all the two-dimensional blocks with respect to the normalized information by the number using several bits of the two-dimensional block, or A digital signal recording device comprising digital signal level adjusting means for performing subtraction. 8. The digital signal recording apparatus according to claim 7, wherein the normalized information adjusted by the level adjusting means is re-recorded on the recording medium. 9. An input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency.
For each dimension block, based on the signal components in the two-dimensional block,
Normalization is performed by selecting one of several positive values that have been numbered using several bits in advance as normalization information, and the number using the corresponding several bits is used as normalization information. A quantization coefficient representing a characteristic of a signal component in the two-dimensional block is obtained for each of the two-dimensional blocks relating to time and frequency, and a bit allocation amount is determined based on the quantization coefficient; For each time, the signal components in the block are quantized by the above-mentioned normalized data and the bit allocation amount, and the information is compressed.
In a recording medium in which information compression parameters for each dimensional block and information on the number of valid two-dimensional blocks selected from a predetermined value of several bits are recorded, a normalization by a number using the several bits of the two-dimensional block is performed. The digital signal level adjustment is performed by adding or subtracting the same value for all two-dimensional blocks to the digitized information, and the normalized information after the level adjustment is recorded. Recording medium. 10. An input digital signal is decomposed into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency. Based on the signal components, normalization was performed by selecting one of several positive values, which were numbered using several bits in advance, as normalization information, and the above-mentioned several bits were used. Using the numbers as normalization information, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained for each of the two-dimensional blocks related to the time and frequency, and a bit allocation amount is determined based on the quantization coefficient. For each two-dimensional block related to time and frequency, signal components in the block are quantized by the above-described normalized data and the bit allocation amount to compress information, and for each two-dimensional block related to time and frequency. In a digital signal transmission method for transmitting an information compression parameter and information on the number of two-dimensional blocks to be enabled together with a value selected from a predetermined number of bits, the normalized information by a number using the bits of the two-dimensional block On the other hand, a digital signal transmission method characterized in that the level of a digital signal is adjusted by adding or subtracting the same value for all two-dimensional blocks, and the digital signal after the level adjustment is transmitted. . 11. Band dividing means for dividing an input digital signal into a plurality of frequency band components, and orthogonally transforming the signal to convert signal components for encoding and / or analysis in a plurality of two-dimensional blocks relating to time and frequency. Orthogonal transformation means for obtaining;
Based on the signal components in the two-dimensional block for each of the two-dimensional blocks relating to time and frequency, one of several positive values that have been numbered using several bits in advance is selected as normalization information. A normalized data calculating means for performing normalization to obtain a number using the corresponding several bits as the normalized information, and representing the characteristics of the signal components in the two-dimensional block for each of the two-dimensional blocks relating to time and frequency. Quantization coefficient calculation means for obtaining a quantization coefficient, bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient, and the above-described normalized data and bit allocation amount for each of the two-dimensional blocks relating to time and frequency. Compression encoding means for quantizing a signal component in the block to compress the information, and an information pressure for obtaining an information compression parameter for each two-dimensional block relating to the time and frequency. A compression deciding means and an information compression parameter deciding means, comprising: a parameter deciding means; and a valid two-dimensional block number information deciding means for selecting the number information of the valid two-dimensional block from a predetermined value with several bits. And a digital signal transmitting device for transmitting each output of the effective two-dimensional block number information determining means, wherein the same value is used for all two-dimensional blocks with respect to normalization information by a number using several bits of the two-dimensional block. A digital signal transmitting apparatus, comprising: digital signal level adjusting means by adding or subtracting; and transmitting means for transmitting the digital signal after the level adjustment.