JPH11272294A - Encoding method, decoding method, encoder, decoder, digital signal recording method and device, storage medium, and digital signal transmitting method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize efficient coding by considering the difference between the number of two-dimensional blocks having the bit allocation quantity other than a specific value and the value of the number information of two-dimensional blocks specified in several bits in advance, and determining the bit allocation quantity to minimize the difference. SOLUTION: A bit allocation calculating circuit 118 considers the difference between the number of two-dimensional blocks having the bit allocation quantity other than 0 and the value of the number information of two-dimensional blocks specified in several bits in advance, determines the bit allocation quantities for individual bands, and transmits them to adaptive bit allocation coding circuits 106-108. The adaptive bit allocation coding circuits 106-108 re-quantize spectrum data or MDCT coefficient data in response to the bit numbers allocated for split bands in consideration of the block size information, critical band and block floating. Coded data are fetched via output terminals 112, 114, 116.

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 high-efficiency encoding of audio signals, and a few conventional examples will be described below. 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 encoding method,
The signal for each band is orthogonally transformed into a signal in the frequency domain by the above-described transform coding method, and encoding is performed for each band subjected to the orthogonal transformation.

Here, as an example of a band division filter used in the above-mentioned band division coding system, for example, QM
There is a filter such as F (Quadrature Mirror filter). This filter is 1976 RECrochiere
Digital coding of speechin subbands Bell Syst.
Tech. 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
An equal-bandwidth filter splitting method and device such as a quadrature filter is described.

As the above-described orthogonal transform, for example, an input audio signal is divided into blocks in a predetermined unit time (frame), and a fast Fourier transform (FF) is performed for each block.
T), a discrete cosine transform (DCT), a modified DCT transform (MDCT), or the like, to transform the time axis to the frequency axis. For the above MDCT, ICASSP 1987 Subband / Transform
Coding Using Filter Bank Designs Based on Time Dom
ain Aliasing Cancellation JPPrincen ABBradley
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, the audio signal is divided into a plurality of bands (for example, 25 bands) with a bandwidth generally called a critical band (critical band) such that the bandwidth becomes wider as the band becomes higher. When encoding data for each band at this time, a predetermined bit allocation for each band or an adaptive bit allocation for each band is performed. For example, when encoding the MDCT coefficient data obtained by the MDCT processing by the above-described bit allocation, the M
Encoding is performed on the MDCT coefficient data for each band obtained by the DCT process 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-mentioned 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.

[0007] As the above-mentioned bit allocation method, conventionally,
The following two methods are known. That is, IEEE Transacti
ons of Accoustics, Speech, and Signal Processing, vo
In l.ASSP-25, No.4, August 1977, bits are allocated based on the signal magnitude for each band. Also ICASSP
1980 The critical band coder--digital encoding of
the perceptual requirements of the auditory system
At MA Kransner MIT, a method is described in which the required signal-to-noise ratio is obtained for each band and fixed bit allocation is performed using auditory masking.

[0008]

By the way, in the above-mentioned conventional high-efficiency coding method, the coding is actually performed.
When the number information of the two-dimensional block is selected from a predetermined value using several bits and is to be encoded, the number of two-dimensional blocks to be actually encoded and the number of two-dimensional blocks selected as the number information are described above. When the difference from the value of the predetermined number information using the several bits is large, it is actually invalid, that is, it is necessary to encode bit allocation information and the like even for a two-dimensional block that does not need to be encoded. As a result, the coding efficiency becomes poor.

In view of the above, the present invention decomposes an input digital signal into a plurality of frequency band components to obtain signal components in a plurality of two-dimensional blocks relating to time and frequency, and obtains a two-dimensional block relating to time and frequency. For each time, normalized data is obtained by performing normalization based on the signal components in the two-dimensional block, and quantized coefficients representing the characteristics of the signal components in the two-dimensional block are obtained for each two-dimensional block with respect to time and frequency. The bit allocation amount is determined based on the quantization coefficient, the signal component in the block is quantized by the normalized data and the bit allocation amount for each two-dimensional block related to time and frequency, and information is compressed. An encoding method for obtaining information compression parameters for each of them and selecting information on the number of valid two-dimensional blocks from a predetermined value of several bits; Over de method, encoding apparatus, decoding apparatus, a digital signal recording method, a digital signal recording apparatus, a recording medium, the digital signal transmission method, or in the digital signal transmission device, the bit allocation amount is not 0 2
The difference between the number of two-dimensional blocks and the value of the number information of the two-dimensional blocks defined in advance by a few bits is made as small as possible, so that more efficient coding can be realized, and the static characteristics and signal quality can be improved. An object of the present invention is to propose a device capable of achieving effective use of a recording capacity of a recording medium and a transmission capacity of a transmission path.

[0010]

According to 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 time, normalization is performed based on the signal components in the two-dimensional block to obtain normalized data,
For each two-dimensional block relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained, and the bit allocation amount is determined based on the quantization coefficient. In addition to quantizing the signal components in the block based on the coded data and the bit allocation amount and compressing the information, the information compression parameter for each two-dimensional block relating to time and frequency is obtained, and several bits are used for the effective number information of the two-dimensional block. In the encoding method of selecting from a predetermined value using the number of bits, the difference between the number of two-dimensional blocks having a non-zero bit allocation amount and the value of the number information of two-dimensional blocks predetermined with several bits is also taken into consideration. Is determined so as to make the encoding as small as possible, thereby improving the coding efficiency.

According to the encoding method of the present invention, the difference between the value of the number information of the two-dimensional block defined in advance by several bits is also taken into consideration, and the bit allocation amount that minimizes the difference is determined. By doing so, more efficient coding can be realized, and the static characteristics and signal quality can be improved.

[0012]

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. Normalization is performed for each block based on the signal components in the two-dimensional block to obtain normalized data, and quantization coefficients representing the characteristics of the signal components in the two-dimensional block are obtained for each two-dimensional block with respect to time and frequency. A bit allocation amount is determined based on the quantized coefficient, a 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 of obtaining an information compression parameter for each block and selecting information on the number of valid two-dimensional blocks from a predetermined value of several bits, This is an encoding method in which the bit allocation amount is determined in consideration of the difference between the number of two-dimensional blocks whose bit allocation amount is not 0 and the value of the number information of the two-dimensional block defined in advance by several bits. .

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. Normalization is performed based on the signal components in the two-dimensional block to obtain normalized data. For each two-dimensional block related to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained. , And 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. The compression parameter is obtained, and the number information of the two-dimensional blocks to be effective is selected from a predetermined value with several bits, and the time and frequency of the information compression are determined. The signal component of each two-dimensional block, in the decoding method adapted to decoding using information compression parameters for each two-dimensional block with respect to time and frequency, and the number of 2-dimensional block bit allocation amount is not 0,
This is a decoding method in which a bit allocation amount is determined in consideration of a difference from a value of the number information of a two-dimensional block defined in advance by several bits.

According to a third 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, encoding and / or analysis of a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. Orthogonal transformation means for obtaining a signal component for the two-dimensional block, normalized data calculation means for performing normalization based on the signal component in the two-dimensional block for each two-dimensional block relating to time and frequency, and obtaining normalized data. Quantization coefficient calculation 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; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient; Compression encoding means for quantizing the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to frequency and frequency, and compressing the information; Having an information compression parameter determining means for obtaining an information compression parameter for each two-dimensional block and an effective two-dimensional block number information determining means for selecting valid two-dimensional block number information from a predetermined value with several bits In the apparatus, the bit allocation calculating means determines the bit allocation amount in consideration of the difference between the number of two-dimensional blocks having a non-zero bit allocation amount and the value of the number information of the two-dimensional block defined in advance by several bits. This is an encoding device that performs.

According to a fourth 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, and encoding and / or analysis of a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. Orthogonal transformation means for obtaining a signal component for the two-dimensional block, normalized data calculation means for performing normalization based on the signal component in the two-dimensional block for each two-dimensional block relating to time and frequency, and obtaining normalized data. Quantization coefficient calculation 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; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient; Compression encoding means for quantizing the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to frequency and frequency, and compressing the information; Information compression parameter determining means for obtaining an information compression parameter for each two-dimensional block, effective two-dimensional block number information determining means for selecting valid two-dimensional block number information from a predetermined value of several bits, and information compression. Decoding means for decoding the signal component in the two-dimensional block related to time and frequency using the information compression parameter for each two-dimensional block related to time and frequency, wherein the bit allocation calculating means includes: This is a decoding device that determines the bit allocation amount in consideration of the difference between the number of two-dimensional blocks in which is not 0 and the value of the number information of two-dimensional blocks defined in advance by several bits.

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. Normalization is performed based on the signal components in the two-dimensional block to obtain normalized data. For each two-dimensional block related to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained. , And compresses information by quantizing the signal components in the block using normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency, and compressing information for each two-dimensional block relating to time and frequency. A digital signal for recording on a recording medium together with parameters and information on the number of valid two-dimensional blocks selected from a predetermined number of bits. In a recording method, a bit allocation amount is determined in consideration of a difference between the number of two-dimensional blocks having a non-zero bit allocation amount and a value of two-dimensional block number information defined in advance by several bits. This is a signal recording method.

According to a sixth 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, and encoding and / or analysis of time and frequency in a plurality of two-dimensional blocks by orthogonally transforming the signal. Orthogonal transformation means for obtaining a signal component for the two-dimensional block, normalized data calculation means for performing normalization based on the signal component in the two-dimensional block for each two-dimensional block relating to time and frequency, and obtaining normalized data. Quantization coefficient calculation 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; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient; Compression encoding means for quantizing the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to frequency and frequency, and compressing the information; Information compression parameter determining means for obtaining an information compression parameter for each two-dimensional block, and effective two-dimensional block number information determining means for selecting valid two-dimensional block number information from a predetermined number of bits. In a digital signal recording apparatus in which each output of a compression encoding unit, an information compression parameter determining unit, and an effective two-dimensional block number information determining unit is recorded on a recording medium, the bit allocation calculating unit determines that the bit allocation amount is not zero. This is a digital signal recording apparatus which determines a bit allocation amount in consideration of a difference between the number of two-dimensional blocks and the value of the number information of two-dimensional blocks defined in advance by several bits.

According to a seventh 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. Normalization is performed based on the signal components in the two-dimensional block to obtain normalized data. For each two-dimensional block related to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained. , And compresses information by quantizing the signal components in the block using normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency, and compressing information for each two-dimensional block relating to time and frequency. In a recording medium in which parameters and information on the number of valid two-dimensional blocks are selected together with values selected from a predetermined number of bits, The number of two-dimensional blocks amount allocation is not 0, which is a recording medium to perform the determination of the consideration to bit allocation amount to the difference between the value of the number information of pre-defined 2-dimensional block by several bits.

According to an eighth 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. Normalization is performed based on the signal components in the two-dimensional block to obtain normalized data, and for each two-dimensional block relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained. , And compresses information by quantizing the signal components in the block with the normalized data and the bit allocation amount for each two-dimensional block relating to time and frequency, and compressing information for each two-dimensional block relating to time and frequency. A digital signal transmission method for transmitting parameters and information on the number of valid two-dimensional blocks together with one selected from a predetermined number of bits. In addition, the digital signal transmission in which the bit allocation amount is determined in consideration of the difference between the number of two-dimensional blocks whose bit allocation amount is not 0 and the value of the number information of the two-dimensional block defined in advance by several bits. Is the way.

According to a ninth 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, and encoding and / or analysis of a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. Orthogonal transformation means for obtaining a signal component for the two-dimensional block, normalized data calculation means for performing normalization based on the signal component in the two-dimensional block for each two-dimensional block relating to time and frequency, and obtaining normalized data. Quantization coefficient calculation 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; bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient; Compression encoding means for quantizing the signal components in the block by the normalized data and the bit allocation amount for each two-dimensional block relating to frequency and frequency, and compressing the information; Information compression parameter determining means for obtaining an information compression parameter for each two-dimensional block, and effective two-dimensional block number information determining means for selecting valid two-dimensional block number information from a predetermined number of bits. In the 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 bit allocation calculating means determines the number of two-dimensional blocks having a non-zero bit allocation amount. A digital signal transmitting apparatus which determines a bit allocation amount in consideration of a difference from a value of the number information of a two-dimensional block defined in advance by several bits.

[Specific Example of Embodiment of the Invention] Hereinafter, a specific example of an embodiment of the present invention will be described with reference to the drawings. In this specific example, an input digital signal such as an audio PCM signal is subjected to band division coding (SBC: Subband Codin).
g), Adaptive Transform Coding (ATC: Adaptive Transform Co
ding) and adaptive bit allocation techniques. 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 for each frequency band, a signal is orthogonally transformed to obtain a plurality of two-dimensional signals relating to time and frequency. A signal component for encoding and analysis in the block is obtained, and the obtained spectrum data on the frequency axis is converted into a low-frequency band for each so-called critical bandwidth (critical band) in consideration of human auditory characteristics described later.
In the middle and high frequency bands, bits are adaptively allocated and encoded for each band obtained by subdividing the critical bandwidth in consideration of the block floating efficiency. Usually, this block is a quantization noise generating block. Further, in this specific example, the block size (block length) is adaptively changed according to the input signal before the orthogonal transformation.

That is, in FIG. 1, an audio signal of 0 to 22 kHz is input to the input terminal 100 at 44.1 kHz.
Is converted into a digital signal, and an audio PCM signal obtained by subjecting the digital audio signal to pulse code modulation is supplied. This input signal is, for example, a so-called QMF (Quadrature Mirror filter).
The signal is divided into a signal in a band of 0 to 11 kHz and a signal in a band of 11 kHz to 22 kHz by a band dividing filter 101. The signal in the band of 0 to 11 kHz is also applied to a signal of 0 to 5.
The signal is divided into a signal in a band of 5 kHz and a signal in a band of 5.5 kHz to 11 kHz.

11 kHz from the band division filter 101
The signal in the band of ~ 22 kHz is sent to an MDCT (Modified Discrete Cosine Transform) circuit 103 which is an example of an orthogonal transformation circuit. 5. From the band split filter 102
The signal in the band of 5 kHz to 11 kHz is applied to the MDCT circuit 10.
4 from the above-mentioned band division filter 102 to 0
The signals in the 5.5 kHz band are sent to the MDCT circuit 105 to be MDCT processed. In addition,
Each of the MDCT circuits 103, 104, and 105 performs an MDCT process based on the block size (information compression parameter) determined by the block determination circuits 109, 110, and 111 provided for each band.

Here, each of the MDCT circuits 103, 104,
FIG. 2 shows an example of a standard input signal for a block for each band to be supplied to 105. In the example of FIG. 2, each of the three filter output signals has a plurality of orthogonal transform block sizes (information compression parameters) independently for each band, and the time resolution can be switched according to the time characteristics, frequency distribution, and the like of the signal. Like that. When the signal is quasi-stationary in time, the orthogonal transform block size is increased to 11.6 ms, that is, as in the long mode in FIG. 2A, and when the signal is non-stationary, , The orthogonal transform block size is further divided into two and four. As in the short mode (Short Mode) in FIG. 2B, when all are divided into four and 2.9 mS, in the middle mode A (Middle Mode A) in FIG. 2C, and in the middle mode B (Middle Mode B) in FIG. 2D. Partial division into two, 5.8 ms, one part into four, 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 (information compression parameter) is determined by the block size determination circuit 1 in FIG.
09, 110 and 111, and each MDCT circuit 10
3, 104, 105 and a bit allocation calculation circuit (bit allocation calculation circuit) (bit allocation calculation circuit) 118, and are output from output terminals 113, 115, 117 as block size information of the corresponding block.

Referring again to FIG. 1, each MDCT circuit 10
Spectrum data or MDCT coefficient data on the frequency axis obtained by performing MDCT processing in 3, 104 and 105 (signal components in a two-dimensional block related to time and frequency)
, The low band is grouped for each so-called critical band (critical band), and the middle and high bands are divided into the critical bandwidths in consideration of the effectiveness of block floating, and adaptive bit allocation encoding circuits 106, 107, 108, and It is sent to the bit allocation 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. In this critical band (critical band), the higher the band, the wider the bandwidth,
The entire frequency band of 0 to 22 kHz described above is divided into, for example, 25 critical bands.

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

Next, a specific method of the bit allocation performed by the bit allocation calculating circuit (bit allocation calculating circuit) (bit allocation calculating circuit) 118 in FIG. 1 will be described with reference to FIG. FIG. 3 shows an example of the bit allocation calculating circuit 118 in FIG. 1 (bit allocation calculating means).
3 is a block diagram illustrating a schematic configuration of (bit allocation calculating means). 3, an input terminal 301 includes spectrum data or MDCT coefficients (signal components in a two-dimensional block relating to time and frequency) on the frequency axis from the MDCT circuits 103, 104, and 105 in FIG. The above-described block determination circuits 109 and 11 in FIG.
Block size information from 0 and 111 is supplied. Thereafter, in the system of the bit allocation calculation circuit 118 shown in FIG. 1 shown in FIG. 3, processing is performed using constants, weighting functions, and the like, which are adapted to the above-described block size information.

In FIG. 3, spectrum data or MDCT coefficients on the frequency axis input from an input terminal 301 are:
The energy is sent to the energy calculating 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, the number of divisions by unit blocks is represented by 12 blocks (B1 to B12) to simplify the illustration. 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 them, taking a value equal to or greater 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 is numbered using several bits in a form corresponding to the actual value, and the number is represented by R
What is necessary is just to memorize by OM etc. (not shown). Further, as for the scale factor value determined by the above-described method in a certain unit block, the above-described 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 is performed by multiplying the spectrum SB by a predetermined weighting function and adding the result. (Convolution) processing is performed. 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 an output of each of the multipliers. And a sum adder for taking the sum of 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 the 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 an (n-ai) function generation circuit 305 described below.

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

[0035]

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. Note that the above-described inverse convolution processing requires a complicated operation. In this example, however, the inverse convolution is performed using a simplified division circuit 306.

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, the subtraction circuit 309 performs the subtraction operation between the masking spectrum and the spectrum SB, as shown in FIG.
Is masked below the level indicated by the level of the masking spectrum MS.

By the way, at the time of synthesizing by 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 above-mentioned masking spectrum MS can be synthesized. At this minimum audible curve, if the absolute noise level is below this minimum audible curve, the noise will not be heard. This minimum audible curve 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 in such a way that noise near the word length of 4 kHz of the system cannot be heard, for example, the minimum audible curve RC and the masking spectrum MS are combined together to obtain an allowable noise level (quantization coefficient). If it is obtained, the allowable noise level in this case can be up to the shaded portion in FIG. In this example, the 4 kHz level of the above-mentioned minimum audible curve is adjusted to the lowest level corresponding to, for example, 20 bits. FIG. 6 also shows the signal spectrum SS.

Thereafter, in the allowable noise correction circuit 311, the allowable noise level in the output from the subtraction circuit 309 is corrected 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 the noise (allowable noise level) (quantization coefficient) exceeding the level of the above minimum audible curve preferably has 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 (quantization coefficient) in consideration of the above-mentioned equal loudness curve is suitable for human auditory characteristics. By the series of processing up to this point, the allowable noise correction circuit 311 temporarily calculates an allocation bit for each unit block based on various parameters such as the above-described masking and auditory characteristics.

Further, in the allowable noise correction circuit 311,
Since the total number of the allocated bits tentatively calculated for each unit block by the processing up to this point does not generally match the number of available bits determined by the bit rate of the encoding device, this is made to match. Correction operation is being performed. This compensation method is to maintain the relative relationship between the unit blocks of the allocated bits calculated for each unit block, for example, when the total number of the calculated allocated bits is smaller than the number of available bits. Is used to uniformly increase the total number of allocated bits as shown in FIG. 7, and when the total number of the calculated allocated bits is larger than the number of available bits, as shown in FIG. What is necessary is just to reduce the number of bits uniformly. That is, the allowable noise correction circuit 31
1 outputs the allocation bits of each unit block after this correction operation is performed. Note that, although an example in which this compensation operation is performed by the above-described allowable noise correction circuit 311 has been described, in a series of processes in FIG. 3, a fraction adjustment described later will be performed in a final processing stage after this compensation process. Can be performed at a stage prior to the allowable noise correction circuit 311 described above.

Although the total number of allocated bits and the number of usable bits can be made substantially the same by the above-described compensation operation, the bit allocation value of each unit block obtained by the series of processing up to this point is expressed as a real value. Since it is calculated, in practice, it is necessary to convert to an integer by truncation or the like. Also, for a unit block calculated more than the maximum number of bits allowed in the encoding format or a unit block calculated as a negative value by the above-described correction operation, the bit allocation in the range allowed in the encoding format is also considered. It is necessary to convert the value to an integer. Generally,
As a result of this integer conversion operation, the total number of allocated bits and the number of available bits determined by the bit rate do not match again, resulting in a bit surplus or a bit shortage. At this time, if the total number of the calculated allocated bits is smaller than the number of available bits, the bits are surplus, and in order to perform more efficient encoding, the surplus available bits can be used. As long as the assignment operation is required. Conversely, if the total number of the calculated allocated bits is larger than the number of available bits and the number of bits is insufficient, correct encoding cannot be performed, and an operation of reducing the number of allocated bits is required. Hereinafter, an adjustment operation required by conversion to an integer or the like within the range of the encoding format is referred to as a fraction adjustment for convenience of description.

The fraction adjustment circuit 312 in FIG. 3 calculates the maximum possible value in each unit block from the normalized data as the scale factor of each unit block and the bit allocation as the word length, or the maximum signal component in the unit block. Is calculated, and the magnitude of the maximum quantization error is set as the bit necessity of each unit block, and the fraction adjustment operation is performed based on this.

Hereinafter, a method of calculating the maximum quantization error as an index of the bit necessity of each unit block in the fraction adjustment circuit 312 will be described. First, referring to FIG. 9, data obtained by processing an orthogonal transform output spectrum obtained as main information by sub-information, a scale factor indicating a block floating state obtained as sub-information, and a word indicating word length. -An example of encoding by length will be described. FIG. 9 is an example showing a state of a unit block when the bit allocation is 3 bits. The vertical axis indicates the magnitude of the spectrum data or MDCT coefficient with the center being 0, and the horizontal axis indicates the frequency. In this example, a, b, c, d,
There are eight spectral data or MDCT coefficients indicated by e, f, g, and h, each of which has a magnitude in the positive or negative direction from 0. As described above, for the scale factor (normalized data) (information compression parameter) indicating the state of block floating, positive values of several magnitudes are prepared in advance, and spectral data or unit data in a unit block are prepared from among them. The smallest one of the absolute values of the MDCT coefficients that are equal to or greater than the maximum value is adopted as the scale factor of the corresponding unit block. In FIG. 9, the scale factor value is selected by the spectrum a indicating the maximum value of the absolute value. The quantization width in the unit block is determined by the scale factor and the size of the bit allocation. The example of FIG. 9 shows a case where the bit allocation is 3 bits. However, when encoding (quantization) is originally performed with 3 bits, it is possible to express eight values. In the direction, a quantization width of equal division is taken by three values, and a seven-value quantization value is added together with 0, and another code that can be expressed by 3 bits is not used. Here, the quantization value is determined from the scale factor value and the bit allocation value in the unit block, and the spectrum data or M
DCT coefficients are quantized to the nearest quantized value. FIG.
Indicates a value obtained by quantizing each spectral data or MDCT coefficient in a unit block. That is, FIG. 9 shows an example of requantization (normalization and quantization).

In general, when the quantization width in the form as shown in FIG. 9 in which quantization is performed in such a manner as to have equal quantization widths in the positive direction and the negative direction centering on 0 is QV, ,
The quantization width QV of a certain unit block can be obtained by the following expression 2 when the scale factor value of the same unit block is SF and the number of allocated bits is Nb.

[0046]

## EQU2 ## QV = SF / {2 ^(Nb-1) -1} (where Nb ≧ 2)

In this case, the maximum quantization error that can occur in the unit block is half the quantization width QV, that is, QV / 2
Becomes

For a unit block with 0 bit allocation, all spectra or MDs in the unit block are
Since CT data (signal components in a two-dimensional block related to time and frequency) is quantized to 0, the maximum quantization error that can occur in a unit block in this case is:
It is the maximum value of the absolute value of the spectrum or MDCT data in the unit block.

Here, considering the magnitude of the quantization noise of the unit block, strictly speaking, it is necessary to consider the number of spectra contained in the unit block and the magnitude of the actual quantization error. Since calculations are required for the spectrum, the processing is very large and not very practical. However, if there is no significant difference in the number of spectra in the unit block, the larger the maximum quantization error that can occur in the unit block obtained by the method described above, the higher the possibility that the quantization noise will increase. To become
Since the bit necessity can be simply considered to be large and the calculation only needs to be performed for the unit block, the processing can be greatly reduced as compared with the case where the calculation is performed for the entire spectrum.

The fraction adjustment circuit 312 first calculates the maximum quantization error that can occur in each unit block for all unit blocks by using the above-described method, and sets this value as the bit necessity of each unit block. Thereafter, for example, if the total number of the calculated allocated bits is smaller than the number of available bits and a surplus bit occurs, a unit block having the highest bit necessity is detected, and the surplus bit is allocated to the same unit block. . For a unit block to which a surplus bit is newly allocated, the bit necessity is recalculated by the above-described method using the bit allocation value after the surplus bit allocation. Thereafter, the fraction adjustment circuit 312 repeats a series of processes of detecting the unit block having the maximum bit necessity, allocating the surplus bits, and recalculating the bit necessity as long as the surplus bits can be allocated. At this time, the bits having the largest value already allowed in the encoding format are already allocated, and the remaining bits determine the bit allocation of the unit block depending on the number of spectrums in the unit block or the unit block where the bit allocation cannot be increased. If the amount is not enough to increase, the unit block may be excluded from the adjustment operation target.

Here, an example in which the total number of the calculated allocated bits is smaller than the number of available bits and a surplus bit is generated has been described, but the total number of the calculated allocated bits is the total number of available bits. Obviously, when the number of bits is larger than the number and the number of bits is insufficient, an operation reverse to the above-described example, that is, a method of deleting bits from those having a smaller bit necessity is obviously feasible. Also, when deleting bits as necessary,
It is also possible to simply perform processing such as reducing bits from a wide-area unit block.

Thereafter, the output from the fraction adjustment circuit 312,
That is, the bit allocation value after the fraction adjustment of each unit block is sent to the encoding correction circuit 313. In the encoding correction circuit 313, although a unit block adopting the smallest one of the prepared scale factors (normalized data) (information compression parameters) is assigned with two or more bits, Instead, a spectrum or MDCT coefficient (a signal component in a two-dimensional block relating to time and frequency) in a unit block is detected to be quantized to 0, and the bit allocation of the unit block is set to 0.
By doing so, the bits used for encoding the spectral data or MDCT coefficients are omitted, and the bits obtained by the omission are more efficiently allocated.

An example of correction in the coding correction circuit 313 will be described below with reference to FIG. FIG. 10 shows a state of requantization of a certain unit block as in FIG.
The vertical direction indicates the magnitude of the spectrum or MDCT coefficients (signal components in a two-dimensional block relating to time and frequency),
The horizontal direction indicates frequency, and 8 in the unit block.
There are book spectra or MDCT coefficients. In this example, the maximum value of the absolute value of the spectrum or MDCT coefficient in the unit block is smaller than the smallest one among the prepared scale factors (normalized data) (information compression parameters), and the scale of the unit block is reduced. As the factor value, the smallest one among the scale factors prepared in advance is adopted, and the bit allocation is 2 bits, and as shown in FIG. 10, 0, 1 value in the positive direction and 1 value in the negative direction, a total of 3 It is assumed that the value has a quantized value. However, in the case of 2-bit allocation, the maximum value of the absolute value of the spectrum or MDCT coefficient in the unit block as shown in FIG.
If the value is smaller than a half of the quantization width indicated by a dotted line of 0, all spectra or MDCT coefficients in the unit block are quantized to 0. That is, the eight spectra a to h are all encoded with “00”, and at least 16 bits are required for recording the spectra, but the quantization values are all zero. In this case, the sub-information or the like does not record the unit block, that is, by changing the bit allocation to 0 bits, the spectrum or MDCT coefficient values in the unit block can be regarded as all 0s. In the case of the 2-bit allocation described above, exactly the same encoding can be performed without using the 16 bits used for the quantization value “00” of the spectrum or MDCT coefficient. That is, although there is a bit allocation of 2 bits or more in a certain unit block, the spectrum or M
If the quantized values of the DCT coefficients are all 0, the bits used for coding the spectrum or MDCT coefficients are omitted by setting the bit allocation of the corresponding unit block to 0, and the same coding is performed. It is possible to do.

As shown in FIG. 10, even when the allocation is not 2-bit, the smallest one of the prepared scale factors (normalized data) (information compression parameters) is generally adopted as the scale factor value. For the unit block, the maximum value of the absolute value of the spectrum or MDCT coefficient in the unit block is set as SPmax, and the quantization width QV of the unit block obtained by the above expression 2 is used, and the following expression 3 is used. Are all zero in the spectrum or the MDCT coefficients (signal components in the two-dimensional block relating to time and frequency) in the unit block satisfying the condition (1).

[0055]

## EQU3 ## SPmax <QV / 2

The coding correction circuit 313 detects a unit block whose coding can be corrected by using the equation (3) in the manner described above, and corrects the bit allocation to 0, thereby obtaining a new usable bit. be able to.

Also, depending on the encoding format,
For example, in addition to the method of setting bit allocation to 0 with sub information indicating a substantial bit allocation amount, when there is sub information indicating the validity of a unit block, that is, whether or not to record a unit block, the validity of the unit block is If the sub-information indicating the property does not indicate that the unit block is to be encoded, it becomes possible to omit the scale factor, which is the sub-information of the processing block, and the bits of the sub-information used for bit allocation. , In such cases,
By the encoding correction circuit 313 in FIG. 3, it is possible to change the sub information in an adaptive manner, omit bits, and obtain new usable bits.

When the correction by the above-described method is possible, the coding correction circuit 313 redistributes the newly obtained usable bits. It is obvious that an adjustment operation by calculating the bit necessity of a unit block can be used.

The data from the coding correction circuit 313 is transmitted to the coding band adjustment circuit 314. The coding band adjustment circuit 314 is a circuit that adjusts the bit allocation, scale factor, coding band, and the like determined in the process up to the coding correction circuit 313 in consideration of the coding format.

First, 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. 11 represents the number of bytes, and in this example, 212 bytes are used as a unit of one frame.

In the position of 0 byte located at the forefront in FIG. 11, the block determination circuit 109 in FIG.
The block size information of each band determined in 110 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 in the higher frequency range by a series of bit allocation calculation circuits. A lot of bits are allocated to the middle and low frequencies where the influence is large. Also, at the position of this 1 byte, 2 of the bit allocation information
The number of overwritten unit blocks and the number of overwritten unit blocks of scale factor information are recorded. 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. Note that for each piece of information, the correspondence between the code in the prescribed bits and the number of unit blocks is determined in advance as a format.
Specifically, as shown in FIG. 12, three bits out of eight bits at the position of one byte are used as information of 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 on which double writing is performed, and the number of unit blocks on which double writing of scale factor information is performed for the remaining three bits are recorded.

The bit allocation information of the unit block is recorded at the position from the second byte in FIG. For recording bit allocation information, a format is defined in which, for example, four bits are used for one unit block. As a result, bit allocation information for the number of unit blocks actually recorded in FIG. 11 described above is recorded in order from the 0th unit block.

After the data of the bit allocation information recorded by the above-described method, the scale factor information of the unit block is recorded. For the 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. Since how many pieces of spectrum data are present in each unit block is determined in advance in a format, it is possible to correspond to the data by the above-mentioned 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-mentioned double writing of the scale factor information and the double writing of the bit allocation information are performed. In this recording method, the correspondence between the numbers is merely made to correspond to the double-written information shown in FIG.
And recording of bit allocation information.

In FIG. 11, the scale factor double writing and / or the bit allocation double writing are stopped.
That amount may be allocated to the spectrum data area.

For the last two bytes, FIG.
As shown in FIG. 7, the information of the 0th byte and the information of the 1st byte are respectively double-written. The double writing for two bytes is defined as a format, and the double writing of scale factor information and the double writing of bit allocation information are performed.
It is not possible to set the variable amount of overwriting.

With the above-described method, a series of data is recorded in a form as shown in FIG. By the way, when recording is performed by such a method, as shown in FIG. 12, the number of unit blocks to be recorded has a value that is somewhat discrete as shown in FIG. The smallest value that can encode the unit block of the area is selected as the number information. For this reason, for example, when the highest unit block whose bit allocation is not 0 is the 44th unit block and 45 unit blocks from 0th to 44th are to be recorded, the recording shown in FIG. 12 is performed. It is necessary to set the number of unit blocks to 48. At this time, even though the bit allocation of the 45th, 46th, and 47th unit blocks is 0 and it is not necessary to actually record, at least the bit It is necessary to record information as 0. When the bit allocation is 0, a format that does not record the scale factor information is not necessary. However, when the format is not such, the scale of the 45th, 46th, and 47th unit blocks is similarly calculated. It also becomes necessary to record factor information. That is, when the number of unit blocks to be actually recorded does not match the numerical value that can be set by the setting of the number of unit blocks to be recorded shown in FIG.
The recording efficiency is lower than in the case where they match. More specifically, in the case of this format, generally, when the number of unit blocks to be actually recorded matches one of the numbers prescribed in advance by the format shown in FIG. In this case, the recording efficiency becomes worse when the number is slightly larger than any of the predetermined numbers, that is, when the number of unit blocks to be actually recorded is 45 or 49 or the like. When the number of unit blocks to be actually recorded is 46 or the like, the recording efficiency is not good, but the efficiency is better than the case of 45 units. When the recording method itself is considered in this way, there are a unit block number with good recording efficiency and a unit block number with bad recording efficiency, but this point is not taken into consideration in the process up to the encoding correction circuit 313.

In consideration of such circumstances, the coding band adjusting circuit 314 performs the above-mentioned adjustment in consideration of the recording efficiency. An example is described below. The bit allocation value of each unit block is calculated by a series of bit allocation calculation circuits, and the bit allocation value other than the unit block having a value other than 0 and higher than the unit block having the highest number is recorded as 0. Therefore, the number of unit blocks to be recorded is simply determined. Here, the recording band adjustment circuit 314 compares the simply determined number of unit blocks to be recorded with the number prescribed in advance by the format shown in FIG. At this time, if the number of unit blocks to be simply determined is one larger than the number prescribed in advance in the format shown in FIG. 12, it is considered that the recording efficiency is not so good. For example, the bit allocation is changed so as to improve the recording efficiency.
For example, if the number of unit blocks to be simply determined is 45 from the 0th to the 44th, the bit allocation of the 44th unit block is changed to 0, and the 44th from the 0th to the 43rd is changed. I do. Although the data of the forty-fourth unit block is lost due to this change, the bits used for the spectrum data of the forty-fourth unit block can be obtained. Further, in order to record the forty-fourth unit block by changing the above-mentioned bit allocation, it is possible to change the format from the format shown in FIG.
The 46th and 47th bit allocation information and possibly scale factor information can also be obtained.
The acquired bits can be used for the spectrum data of the 44th unit block from the 0th to the 43rd. In the coding band adjustment circuit 314, the number of unit blocks to be recorded determined simply in this way is one larger than the number prescribed in advance by the format shown in FIG. 12, and the bit allocation is other than 0. If it is determined that the highest-order unit block is not a very important element in the value, the bit assignment is changed to a value other than 0 and the highest-order unit block is changed to 0, so that a large number of usable blocks can be used. Try to get a bit. By redistributing the bits to the unit blocks in the middle and low frequencies, it is possible to improve the sound quality in audibility. As for the bit redistribution method, the operation of the fraction adjustment circuit 312 is performed. Whether the operation of changing the bit allocation of the highest-frequency unit block to 0 when the bit allocation is a value other than 0 is possible depends on parameters such as the scale factor value and the maximum value of the spectrum data. The determination is made based on the criteria of the importance of the unit block that is a change candidate. At this time, it is clear that the operation is further refined by increasing the parameters for determination.

This operation can be applied to all cases where the number of unit blocks to be recorded, which is simply determined, is one larger than the number prescribed in advance by the format shown in FIG. In the region of the middle and low frequencies, it has a very large effect on the sense of hearing. Therefore, only the case of the high range is limited.

In the above example, the case where the number of unit blocks to be recorded, which is simply determined, is one larger than the number prescribed in advance by the format shown in FIG. It is apparent that the same change operation can be performed by setting appropriate parameters in the case where there are many or three.

In this example, the method of changing the bit allocation to 0 at the final stage as described above has been described.
The operation performed by the coding band adjustment circuit 314 is a bit allocation adjustment operation in consideration of the relationship between the unit block number generated due to the nature of the recording format and the recording efficiency.
This operation can be realized, for example, at a stage prior to the fraction adjustment circuit 312, in such a manner that the relationship between the unit block number generated due to the nature of the recording format and the recording efficiency corresponds to a numerical value such as a weighting function. is there.

The data output from the coding band adjusting circuit 314 is output from an output terminal 315 as the output of the bit allocation calculating circuit 118 in FIG.

That is, the bit allocation calculation circuit 1 in FIG.
At 18, the data obtained by processing the orthogonal transform output spectrum with the sub-information as the main information by the system shown in FIG. The word length indicating the word length is obtained. Based on this, the adaptive bit allocation coding circuits 106, 107, 1 in FIG.
At 08, requantization is actually performed, and encoding is performed in a form conforming to the encoding format.

FIG. 13 shows a decoding circuit (decoder) for decoding again a signal which has been highly efficiently coded by the system shown in FIG. 1 described above. The quantized MDCT coefficients of each band, that is, the output terminal 11 in FIG.
Data equivalent to the output signals of 2, 114 and 116 are shown in FIG.
3, the block size information used and used, that is, data equivalent to the output signals of the output terminals 113, 115 and 117 in FIG.
It is provided to an input terminal 1308 in FIG. FIG.
In the adaptive bit allocation decoding circuit 1306, the bit allocation is canceled using the adaptive bit allocation information. Next, FIG.
Inverse orthogonal transform (IMDCT) circuit 1303,
At 304 and 1305, the signal on the frequency axis is converted into a signal on the time axis. The signals on the time axis of these subbands are
Band synthesis filter (IQMF) circuit 13 in FIG.
02, 1301, it is decoded into a full band signal.

Next, with reference to FIGS. 14 to 17, the digital signal recording device (method), digital signal reproducing device (method), digital signal transmitting device (method) and digital signal receiving device (method) of the present invention. A specific example of the embodiment will be described. 14 to 17, ENC indicates the encoder of FIG. 1, Tin indicates its input terminal 100,
DEC indicates the decoder of FIG. 13, and Tout indicates its output terminal 1300.

In the recording apparatus shown in FIG. 14, an input digital signal from the input terminal Tin is supplied to the encoder ENC for encoding, and the output of the encoder ENC, that is, FIG.
Output terminals 112, 114, 116 and 1 of the encoders
13, 115, 117 are output from the modulating means MO.
D, and then multiplexes and performs a predetermined modulation, or modulates each output signal and then multiplexes or remodulates.
The modulated signal from the modulating means MOD is recorded on the recording medium M by the recording means (magnetic head, optical head, etc.).

In the reproducing apparatus shown in FIG. 15, a recording medium M shown in FIG.
And the demodulation means DEM demodulates the reproduction signal according to the modulation by the modulation means MOD. A 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 in FIG. 1 is supplied to the input terminal 1307 of the decoder in FIG. 113,
The signals corresponding to the outputs from 115 and 117 are supplied to the input 1308 in FIG.
An output digital signal corresponding to the input digital signal is output.

In the transmitting apparatus shown in FIG. 16, 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 and 117 are connected to the modulating means MO.
D, and then multiplexes and performs a predetermined modulation, or modulates each output signal and then multiplexes or remodulates.
The modulated signal from the modulating means MOD is supplied to the transmitting means TX to perform frequency conversion, amplification, etc., thereby producing a transmission signal.
The transmission signal is transmitted by a transmission antenna ANT-T which is a part of the transmission means TX.

In the receiving apparatus of FIG. 17, the receiving signal from the transmitting antenna ANT-T of FIG. 15 is received by the receiving antenna ANT-R which is a part of the receiving means RX, and the received signal is received by the receiving means RX. , Amplification, inverse frequency conversion, 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 1307 of the decoder in FIG. 13, 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 1308 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 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.
Further, instead of the recording medium, a storage means such as an IC memory or a memory card may be used. The transmission path between the transmitting apparatus and the receiving apparatus may be a wireless transmission path {radio waves, light (infrared rays, etc.)} or a wired transmission path (conductor, optical cable, etc.). For example,
As the input digital signal, a digital audio signal (an audio signal can be a signal of various sounds such as a human voice, a singing voice, and a sound of a musical instrument), a digital video signal, and the like can be used. The present invention can be applied to a digital signal recording / reproducing method (or device), a digital signal transmitting / receiving method (or device), a digital signal receiving method (or device), and the like.

[0083]

According to the first aspect of the present invention described above, 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 to obtain signals relating to time and frequency. For each two-dimensional block, normalization is performed based on the signal components in the two-dimensional block to obtain normalized data. For each two-dimensional block relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained. Asked,
A bit allocation amount is determined based on the quantized coefficient, a 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 block is obtained and the number information of valid two-dimensional blocks is selected from a predetermined value of several bits, the number of two-dimensional blocks having a non-zero bit allocation amount and a few bits Since the bit allocation amount is determined in consideration of the difference from the value of the number information of the predetermined two-dimensional block, the number of two-dimensional blocks whose bit allocation amount is not 0 and the predetermined number of bits are determined. 2
The difference from the value of the number information of the dimensional blocks can be reduced as much as possible to realize more efficient coding, improve static characteristics and signal quality, and improve the recording capacity and transmission path of the recording medium. In this manner, an encoding method capable of effectively utilizing the transmission capacity in the above can be obtained.

According to the 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, and two-dimensional components relating to time and frequency are obtained. Normalization is performed for each block based on the signal components in the two-dimensional block to obtain normalized data, and quantization coefficients representing the characteristics of the signal components in the two-dimensional block are obtained for each two-dimensional block with respect to time and frequency.
A bit allocation amount is determined based on the quantized coefficient, a 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. Obtain the information compression parameter for each block and select the number information of the two-dimensional block to be valid from a value defined in advance by several bits,
In a decoding method in which a signal component of each information-compressed two-dimensional block related to time and frequency is decoded using an information compression parameter for each two-dimensional block related to time and frequency, the two-dimensional bit allocation amount is not 0. Since the bit allocation amount is determined in consideration of the difference between the number of blocks and the value of the number information of the two-dimensional block defined in advance by several bits, the number of two-dimensional blocks whose bit allocation amount is not 0 is determined. And the difference between the value of the number information of the two-dimensional block defined in advance by several bits as small as possible,
It is possible to achieve a more efficient encoding, improve static characteristics and signal quality, and obtain a decoding method capable of effectively utilizing a recording capacity in a recording medium and a transmission capacity in a transmission path. .

According to the third aspect of the present invention described above, band dividing means for dividing an input digital signal into a plurality of frequency band components, and encoding in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. And / or orthogonal transform means for obtaining signal components for analysis;
Normalization data calculating means for performing normalization for each dimension block based on the signal components in the two-dimensional block to obtain normalized data; and characterizing the signal components in the two-dimensional block for each two-dimensional block with respect to time and frequency. Quantization coefficient calculation means for obtaining a quantization coefficient to be represented, bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient, and a block using normalized data and a bit allocation amount for each two-dimensional block relating to time and frequency. Compression encoding means for quantizing the signal components in the information, compressing the information, information compression parameter determining means for obtaining information compression parameters for each two-dimensional block relating to time and frequency, and a few bits of information on the number of valid two-dimensional blocks In the encoding device having effective two-dimensional block number information determining means for selecting from the values specified in advance in Stage, bit allocation amount is not 0 2
Since the bit allocation amount is determined in consideration of the difference between the number of the two-dimensional blocks and the value of the number information of the two-dimensional block defined in advance by several bits, the two-dimensional block in which the bit allocation amount is not 0 is determined. By making the difference between the number and the value of the number information of the two-dimensional block defined in advance by several bits as small as possible, more efficient coding can be realized, and the static characteristics and signal quality can be improved. Thus, it is possible to obtain an encoding device capable of effectively utilizing the recording capacity of the recording medium and the transmission capacity of the transmission path.

According to the fourth aspect of the present invention described above, band dividing means for dividing an input digital signal into a plurality of frequency band components, and encoding in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. And / or orthogonal transform means for obtaining signal components for analysis;
Normalization data calculating means for performing normalization for each dimension block based on the signal components in the two-dimensional block to obtain normalized data; and characterizing the signal components in the two-dimensional block for each two-dimensional block with respect to time and frequency. Quantization coefficient calculation means for obtaining a quantization coefficient to be represented, bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient, and a block using normalized data and a bit allocation amount for each two-dimensional block relating to time and frequency. Compression encoding means for quantizing the signal components in the information, compressing the information, information compression parameter determining means for obtaining information compression parameters for each two-dimensional block relating to time and frequency, and a few bits of information on the number of valid two-dimensional blocks Means for determining the number of effective two-dimensional blocks selected from the values specified in advance, and a two-dimensional block related to the time and frequency of the compressed information. Decoding means for decoding a signal component within the block using information compression parameters for each two-dimensional block relating to time and frequency, wherein the bit allocation calculation means determines the number of two-dimensional blocks having a non-zero bit allocation amount. And the value of the number information of the two-dimensional block defined in advance by several bits in consideration of the bit allocation amount, so that the bit allocation amount is not 0.
The difference between the number of two-dimensional blocks and the value of the number information of the two-dimensional blocks defined in advance by a few bits is made as small as possible, so that more efficient encoding can be realized, and the static characteristics and signal quality can be improved. Thus, it is possible to obtain a decoding device capable of effectively utilizing the recording capacity of the recording medium and the transmission capacity of the transmission path.

According to the fifth 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 two-dimensional components relating to time and frequency are obtained. Normalization is performed for each block based on the signal components in the two-dimensional block to obtain normalized data, and quantization coefficients representing the characteristics of the signal components in the two-dimensional block are obtained for each two-dimensional block with respect to time and frequency.
A bit allocation amount is determined based on the quantized coefficient, a signal component in the block is quantized by the normalized data and the bit allocation amount for each two-dimensional block related to time and frequency, and information is compressed, and a two-dimensional block related to time and frequency is determined. In a digital signal recording method, a two-dimensional block in which a bit allocation amount is not 0, in which a data compression parameter for each and information on the number of valid two-dimensional blocks are selected from a predetermined number of bits and recorded on a recording medium. And the number of
Since the bit allocation amount is determined in consideration of the difference from the value of the number information of the two-dimensional block defined in advance by several bits, the number of two-dimensional blocks in which the bit allocation amount is not 0 and the number of bits are determined. It is possible to realize more efficient encoding by minimizing the difference from the value of the number information of the predetermined two-dimensional block as much as possible, to improve the static characteristics and the signal quality, and to improve the recording on the recording medium. A digital signal recording method capable of effectively utilizing the capacity and the transmission capacity in the transmission path can be obtained.

According to the sixth aspect of the present invention described above, a band dividing means for dividing an input digital signal into a plurality of frequency band components, and encoding in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. And / or orthogonal transform means for obtaining signal components for analysis;
Normalization data calculating means for performing normalization for each dimension block based on the signal components in the two-dimensional block to obtain normalized data; and characterizing the signal components in the two-dimensional block for each two-dimensional block with respect to time and frequency. Quantization coefficient calculation means for obtaining a quantization coefficient to be represented, bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient, and a block using normalized data and a bit allocation amount for each two-dimensional block relating to time and frequency. Compression encoding means for quantizing the signal components within the information, compressing the information, information compression parameter determining means for obtaining information compression parameters for each two-dimensional block relating to time and frequency, and a few bits of information on the number of valid two-dimensional blocks Means for determining the number of effective two-dimensional blocks to be selected from the values specified in advance in (1). In digital signal recording apparatus that records the each output means and the effective two-dimensional block number information determining means to a recording medium, the bit allocation calculating means, and the number of 2-dimensional block bit allocation amount is not 0,
Since the bit allocation amount is determined in consideration of the difference from the value of the number information of the two-dimensional block defined in advance by several bits, the number of two-dimensional blocks in which the bit allocation amount is not 0 and the number of bits are determined. It is possible to realize more efficient encoding by minimizing the difference from the value of the number information of the predetermined two-dimensional block as much as possible, to improve the static characteristics and the signal quality, and to improve the recording on the recording medium. A digital signal recording device capable of effectively utilizing the capacity and the transmission capacity in the transmission path can be obtained.

According to the seventh 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 two-dimensional components relating to time and frequency are obtained. Normalization is performed for each block based on the signal components in the two-dimensional block to obtain normalized data, and quantization coefficients representing the characteristics of the signal components in the two-dimensional block are obtained for each two-dimensional block with respect to time and frequency.
A bit allocation amount is determined based on the quantized coefficient, a signal component in the block is quantized by the normalized data and the bit allocation amount for each two-dimensional block related to time and frequency, and information is compressed, and a two-dimensional block related to time and frequency is determined. The number of two-dimensional blocks having a non-zero bit allocation amount in a recording medium in which the information compression parameter for each and the number of valid two-dimensional block information selected from a predetermined number of bits are recorded. Since the bit allocation amount is determined in consideration of the difference from the value of the number information of the two-dimensional block defined in advance by the bits, the bit allocation amount is 0.
The difference between the number of two-dimensional blocks that are not two-dimensional blocks and the value of the number information of the two-dimensional blocks defined in advance by a few bits is made as small as possible, and more efficient coding can be realized, and the static characteristics and signal quality can be improved. Thus, it is possible to obtain a recording medium capable of improving the recording capacity and effectively utilizing the recording capacity of the recording medium and the transmission capacity of the transmission path.

According to the eighth 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 two-dimensional components relating to time and frequency are obtained. Normalization is performed for each block based on the signal components in the two-dimensional block to obtain normalized data, and quantization coefficients representing the characteristics of the signal components in the two-dimensional block are obtained for each two-dimensional block with respect to time and frequency.
A bit allocation amount is determined based on the quantized coefficient, a signal component in the block is quantized by the normalized data and the bit allocation amount for each two-dimensional block related to time and frequency, and information is compressed, and a two-dimensional block related to time and frequency is determined. In a digital signal transmission method for transmitting information compression parameters for each, and information on the number of valid two-dimensional blocks with a number of bits selected from a predetermined value, the number of two-dimensional blocks having a non-zero bit allocation amount; Since the bit allocation amount is determined in consideration of the difference from the value of the number information of the two-dimensional block defined in advance by several bits, the number of two-dimensional blocks in which the bit allocation amount is not 0 and the number of bits are determined. It is possible to realize a more efficient encoding by minimizing the difference from the value of the number information of the two-dimensional block defined in advance as much as possible, and to realize a static characteristic and a signal. It can improve the quality of, it is possible to obtain a digital signal transmission method capable of performing efficient use of transmission capacity in the recording capacity and the transmission path of the recording medium.

According to the ninth aspect of the present invention described above, band dividing means for dividing an input digital signal into a plurality of frequency band components, and encoding in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal. And / or orthogonal transform means for obtaining signal components for analysis;
Normalization data calculating means for performing normalization for each dimension block based on the signal components in the two-dimensional block to obtain normalized data; and characterizing the signal components in the two-dimensional block for each two-dimensional block with respect to time and frequency. Quantization coefficient calculation means for obtaining a quantization coefficient to be represented, bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient, and a block using normalized data and a bit allocation amount for each two-dimensional block relating to time and frequency. Compression encoding means for quantizing the signal components within the information, compressing the information, information compression parameter determining means for obtaining information compression parameters for each two-dimensional block relating to time and frequency, and a few bits of information on the number of valid two-dimensional blocks Means for determining the number of effective two-dimensional blocks to be selected from the values specified in advance in (1). In the digital signal transmitting apparatus for transmitting each output of the means and the effective two-dimensional block number information determining means, the bit allocation calculating means comprises: a number of two-dimensional blocks having a non-zero bit allocation amount; Since the bit allocation amount is determined in consideration of the difference from the value of the number information, the number of two-dimensional blocks whose bit allocation amount is not 0 and the number information of the two-dimensional block defined in advance by several bits To minimize the difference from the value of, the more efficient coding can be realized, the static characteristics and signal quality can be improved, and the recording capacity of the recording medium and the effective transmission capacity of the transmission path can be improved. A digital signal transmitting device that can be used can be obtained.

[Brief description of the drawings]

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

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

FIG. 3 is a block circuit diagram showing an example of a bit allocation calculating means.

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 illustrating a total amount adjustment operation for uniformly increasing the bit allocation amount.

FIG. 8 is a diagram illustrating a total amount correction operation for uniformly reducing the bit allocation amount.

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

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

FIG. 11 is a diagram showing how data is encoded.

FIG. 12 is a diagram showing details of data of a first byte in FIG. 11;

FIG. 13 is a block diagram showing an example of a high-efficiency compression encoding decoder that can be used for bitrate compression encoding in a specific example of the embodiment of the present invention.

FIG. 14 is a block diagram illustrating an example of a recording apparatus according to a specific example of an embodiment of the present invention.

FIG. 15 is a block diagram illustrating an example of a playback device according to a specific example of the embodiment of the present invention.

FIG. 16 is a block diagram illustrating an example of a transmission device according to a specific example of the embodiment of the present invention.

FIG. 17 is a block diagram illustrating an example of 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, 1
11 block determination circuit, 118 bit allocation calculation circuit, 106, 107, 108 adaptive bit allocation coding circuit, 302 energy calculator per band, 303 convolution filter, 304 adder, 305 function generator, 3
06 divider, 307 synthesizer, 308 subtractor, 3
09 delay circuit, 310 allowable noise corrector, 312 minimum audible curve generator, 313 fraction adjuster, 314 coding corrector, 315 coding band adjuster, 701, 70
Two-band synthesis filter (IQMF), 703, 704, 7
05 Inverse orthogonal transform circuit (IMDCT), 706 adaptive bit allocation decoding circuit, ENC encoder, MOD modulation means, REC recording means, P reproduction means, DEM demodulation means, DEC decoder, TX transmission means, RX reception means.

Claims (9)

[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 two-dimensional block, normalization is performed based on the signal components in the two-dimensional block to obtain normalized data. For each of the two-dimensional blocks relating to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained. Then, a bit allocation amount is determined based on the quantized coefficient, and a signal component in the block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks relating to the time and the frequency to compress the information, and And an information compression parameter for each two-dimensional block related to frequency and frequency, and the number information of valid two-dimensional blocks is selected from a predetermined value of several bits. Number and
An encoding method, wherein the bit allocation amount is determined in consideration of a difference from a value of the number information of the two-dimensional block defined in advance by the several bits. 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 two-dimensional block, normalization is performed based on the signal components in the two-dimensional block to obtain normalized data. Then, a bit allocation amount is determined based on the quantization coefficient, a signal component in the block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to the time and the frequency, and the information is compressed. And information compression parameters for each two-dimensional block relating to frequency and frequency, and the number information of valid two-dimensional blocks is selected from a predetermined value of several bits, and the information is compressed for each two-dimensional block relating to time and frequency. In a decoding method for decoding a signal component using the information compression parameter for each two-dimensional block relating to time and frequency, The number of the above-mentioned two-dimensional blocks in which the allocation amount is not 0;
A decoding method characterized in that the bit allocation amount is determined in consideration of a difference from a value of the number information of the two-dimensional block defined in advance by the several bits. 3. Band splitting means for splitting an input digital signal into a plurality of frequency band components, encoding in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal,
And or orthogonal transformation means for obtaining a signal component for analysis,
Normalization data calculating means for performing normalization based on signal components in the two-dimensional block for each of the two-dimensional blocks relating to time and frequency, and a two-dimensional block for each two-dimensional block relating to the time and frequency Quantization coefficient calculation means for obtaining a quantization coefficient representing the characteristics of the signal components in the bit stream, bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient, and the above-described two-dimensional block for time and frequency. Compression encoding means for quantizing the signal components in the block using the normalized data and the bit allocation amount to compress the information, information compression parameter determining means for obtaining the information compression parameter for each two-dimensional block relating to the time and frequency, and Effective two-dimensional block number information determining means for selecting the number information of two-dimensional blocks to be performed from a predetermined value of several bits. In the encoding device, the bit allocation calculating means may further include a difference between the number of the two-dimensional blocks having a non-zero bit allocation amount and the value of the number information of the two-dimensional blocks defined in advance by the several bits. An encoding device for determining a bit allocation amount. 4. A band dividing means for dividing an input digital signal into a plurality of frequency band components, encoding in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal,
And or orthogonal transformation means for obtaining a signal component for analysis,
Normalization data calculating means for performing normalization based on signal components in the two-dimensional block for each of the two-dimensional blocks relating to time and frequency, and a two-dimensional block for each two-dimensional block relating to the time and frequency Quantization coefficient calculation means for obtaining a quantization coefficient representing the characteristics of the signal components in the bit stream, bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient, and the above-described two-dimensional block for time and frequency. Compression encoding means for quantizing the signal components in the block using the normalized data and the bit allocation amount to compress the information, information compression parameter determining means for obtaining the information compression parameter for each two-dimensional block relating to the time and frequency, and Effective two-dimensional block number information determining means for selecting the number information of two-dimensional blocks to be performed from a predetermined value of several bits, A decoding means for decoding the signal component in the two-dimensional block related to time and frequency using the information compression parameter for each two-dimensional block related to time and frequency. And determining the bit allocation amount in consideration of the difference between the number of the two-dimensional blocks whose bit allocation amount is not 0 and the value of the number information of the two-dimensional block defined in advance by the several bits. Decoding device. 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 two-dimensional block, normalization is performed based on the signal components in the two-dimensional block to obtain normalized data. For each of the two-dimensional blocks related to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained. Then, a bit allocation amount is determined based on the quantized coefficient, and a signal component in the block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to the time and the frequency, and information is compressed. In a digital signal recording method, an information compression parameter for each two-dimensional block relating to frequency and information on the number of valid two-dimensional blocks are recorded on a recording medium together with a value selected from a predetermined number of bits. The number of non-zero two-dimensional blocks;
A digital signal recording method, wherein the bit allocation amount is determined in consideration of a difference from a value of the number information of the two-dimensional block defined in advance by the several bits. 6. A band dividing means for dividing an input digital signal into a plurality of frequency band components, encoding in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal,
And or orthogonal transformation means for obtaining a signal component for analysis,
Normalization data calculating means for performing normalization based on signal components in the two-dimensional block for each of the two-dimensional blocks relating to time and frequency, and a two-dimensional block for each two-dimensional block relating to the time and frequency Quantization coefficient calculation means for obtaining a quantization coefficient representing the characteristics of the signal components in the bit stream, bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient, and the above-described two-dimensional block for time and frequency. Compression encoding means for quantizing the signal components in the block using the normalized data and the bit allocation amount to compress the information, information compression parameter determining means for obtaining the information compression parameter for each two-dimensional block relating to the time and frequency, and Effective two-dimensional block number information determining means for selecting the number information of two-dimensional blocks to be performed from a predetermined value of several bits. In a digital signal recording apparatus in which each output of the compression encoding means, the information compression parameter determining means and the effective two-dimensional block number information determining means is recorded on a recording medium, the bit allocation calculating means comprises: Wherein the bit allocation amount is determined in consideration of a difference between the number of the two-dimensional blocks, in which is not 0, and the value of the number information of the two-dimensional blocks defined in advance by the several bits. Recording device. 7. 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, normalization is performed based on the signal components in the two-dimensional block to obtain normalized data. For each of the two-dimensional blocks related to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained. Then, a bit allocation amount is determined based on the quantized coefficient, and a signal component in the block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to the time and the frequency, and information is compressed. In a recording medium in which the information compression parameter for each two-dimensional block related to frequency and the number information of valid two-dimensional blocks are recorded together with a value selected from a predetermined number of bits, the two-dimensional distribution where the bit allocation amount is not zero The number of blocks,
A recording medium characterized in that the bit allocation amount is determined in consideration of a difference from a value of the number information of the two-dimensional block defined in advance by the several bits. 8. 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, normalization is performed based on the signal components in the two-dimensional block to obtain normalized data. For each of the two-dimensional blocks related to time and frequency, a quantization coefficient representing the characteristic of the signal component in the two-dimensional block is obtained. Then, a bit allocation amount is determined based on the quantized coefficient, and a signal component in the block is quantized by the normalized data and the bit allocation amount for each of the two-dimensional blocks related to the time and the frequency, and information is compressed. In a digital signal transmission method for transmitting an information compression parameter for each two-dimensional block relating to frequency and information on the number of valid two-dimensional blocks with a value selected from a predetermined number of bits, the bit allocation amount is not 0. The number of dimension blocks,
A digital signal transmission method, wherein the bit allocation amount is determined in consideration of a difference from a value of the number information of the two-dimensional block defined in advance by the several bits. 9. A band dividing means for dividing an input digital signal into a plurality of frequency band components, encoding in a plurality of two-dimensional blocks relating to time and frequency by orthogonally transforming the signal,
And or orthogonal transformation means for obtaining a signal component for analysis,
Normalization data calculating means for performing normalization based on signal components in the two-dimensional block for each of the two-dimensional blocks relating to time and frequency, and a two-dimensional block for each two-dimensional block relating to the time and frequency Quantization coefficient calculation means for obtaining a quantization coefficient representing the characteristics of the signal components in the bit stream, bit allocation calculation means for determining a bit allocation amount based on the quantization coefficient, and the above-described two-dimensional block for time and frequency. Compression encoding means for quantizing the signal components in the block using the normalized data and the bit allocation amount to compress the information, information compression parameter determining means for obtaining the information compression parameter for each two-dimensional block relating to the time and frequency, and Effective two-dimensional block number information determining means for selecting the number information of two-dimensional blocks to be performed from a predetermined value of several bits. In the digital signal transmitting apparatus for transmitting each output of the compression encoding unit, the information compression parameter determining unit, and the effective two-dimensional block number information determining unit, the bit allocation calculating unit may be configured such that the bit allocation amount is not zero. A digital signal transmitting apparatus, wherein the bit allocation amount is determined in consideration of a difference between the number of blocks and the value of the number information of the two-dimensional block defined in advance by the several bits.