JP2000036755A - Method and device for code convesion and program supply medium thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for code conversion which can convert data fast by enabling data conversion between codes of different formats. SOLUTION: A spectrum signal obtained by decoding a 1st code sequence, whis is obtained by encoding a spectrum-converted spectrum signal after a time-series information signal is divided into a 1st band group, is inputted to reverse spectrum converting circuits 1721 to 1724. Signals of two high-frequency bands are put together by a band composing filter 1725 and sent by a forward spectrum converting circuit 1726; and signals from the reverse spectrum converting circuits 1723 and 1724 are sent to a forward spectrum converting circuits 1726 divided into a 2nd band group, and converted to a spectrum signal in spectrum converted form. A band composed of a filter 1725 reconverts part of the spectrum signal to a thinned-out time-series signal, which is converted to a low-frequency side spectrum signal in the high-frequency band, and the converted spectrum signal is encoded into a 2nd code sequence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for performing a process of converting an encoded information signal, and a program supply medium on which a program for performing a process of converting an encoded information signal is recorded. .

[0002]

2. Description of the Related Art There is known a high-efficiency coding method for compressing a data amount of an audio or voice signal without substantially deteriorating the quality of the audio signal. There are various techniques for high-efficiency encoding of signals such as audio or voice. For example, a non-blocking frequency band in which an audio signal or the like on a time axis is divided into a plurality of frequency bands and encoded without being blocked. Band division coding (sub-band coding: SBC), which is a division method, or conversion of a signal on the time axis to a signal on the frequency axis (spectral conversion), and division into a plurality of frequency bands. A block frequency division method to be coded, so-called transform coding, or the like can be used.

Here, as a filter used for band division, for example, a QMF filter (Quadurature Mirror Filtration) is used.
ter), and the document "1976 RECrochiere Digital cod
ingof speech in subbands Bell Syst.Tech.J. Vol.5
5, No. 8 1976 ".

[0004] In the above-mentioned QMF filter, the aliasing component that generates a signal that is decimated to a half rate after band division has the property of canceling each other with the aliasing component that occurs at the time of band synthesis. If the signals in the respective bands are encoded, it is possible to almost eliminate the loss caused by the encoding.

[0005] Further, the literature "ICASSP 83, BOSTON, Polypha"
se Quadrature filters -A new subband coding techni
que Joseph H. Rothweiler ”includes PQF (Polyphase Quadrature Filte), which is an equal bandwidth filter division method.
r) Describes filters. In this PQF filter, the aliasing component generated between the adjacent band and a signal decimated to a rate corresponding to the bandwidth after the band division is different from the aliasing component generated between the adjacent band at the time of band synthesis. There is a property of canceling, and therefore, if the signal of each band is encoded with sufficient accuracy, it is possible to almost eliminate the loss caused by encoding, which is convenient.

[0006] The above-mentioned spectral conversion includes:
For example, an input audio signal is divided into blocks in a predetermined unit time (frame), and a discrete Fourier transform (DFT) and a discrete cosine transform (Discrete Cosine Transform) are performed for each block.
form: DCT), Modified DCT (Modified Dist)
There is a spectrum transformation that transforms a time axis into a frequency axis by performing a crete cosine transform (MDCT) or the like. For the MDCT, see, for example, the document “ICASSP 1987,
Subband / Transform Coding Using Filter Bank Design
s Based on Time Domain Aliasing Cancellation, JP
Princen, ABBradley, Univ. Of Surrey Royal Melb
ourne Inst. of Tech. "

When the above-mentioned DFT or DCT is used as a method of converting a waveform signal into a spectrum, M independent real number data can be obtained by performing conversion using a time block consisting of M samples. In order to reduce the connection distortion between the time blocks, the blocks adjacent to each other are usually overlapped by M1 samples each, so that on average,
In DFT or DCT, M real number data is quantized and encoded for (M-M1) samples.

On the other hand, when the above-mentioned MDCT is used as a method for converting into a spectrum, 2M samples overlapped by M times on both adjacent times,
Since M independent real number data are obtained, on average, M
In DCT, M real number data is quantized and encoded for M samples. For example, the decoding apparatus reconstructs a waveform signal by adding the waveform elements obtained by performing inverse transform in each block from the code obtained by using the MDCT in this way while causing them to interfere with each other. .

[0009] Generally, by extending the time block for conversion, the frequency resolution of the spectrum is increased and energy is concentrated on a specific spectral component. Therefore, by using a MDCT in which the conversion is performed with a long block length by overlapping the adjacent blocks by half each, and the number of obtained spectral signals does not increase with respect to the number of original time samples, Encoding can be performed more efficiently than when the above-described DFT or DCT is used.

[0010] In addition, by providing a sufficiently long overlap between adjacent blocks, it is possible to reduce inter-block distortion of a waveform signal. However, increasing the conversion block length also means that a larger work area is required for conversion, which is an obstacle to reducing the size of the reproducing means and the like. Employing a long block length at a point where it is difficult to raise it leads to an increase in cost.

As described above, by quantizing the signal divided for each band by the filter or the spectrum conversion, the band in which the quantization noise occurs can be controlled.
Furthermore, by utilizing properties such as the masking effect, it is possible to perform audio coding with higher efficiency.

The masking effect means that a loud sound audibly conceals a small sound. By utilizing this effect, the generated quantization noise is audibly concealed by the original signal sound itself. This makes it possible to realize sound quality that is hardly different from the original signal even when compressed. However, in order to use the masking effect effectively, the way of generating the quantization noise must be controlled in the time domain or the frequency domain. For example, in a so-called attack part where the signal magnitude suddenly increases, if quantization noise occurs for several msec or more in a small part of the signal immediately before the signal increases, this quantization noise is not concealed by the signal sound, This causes unpleasant sound quality degradation known as so-called pre-echo. To solve such a problem, for example, a method of switching a block length to be converted into a spectrum signal according to the property of a signal corresponding to the block is used. In addition,
If the normalization is performed for each band before the quantization, for example, with the maximum value of the absolute value of the signal component in the band, more efficient encoding can be performed.

Here, as a frequency division width for quantizing each frequency component, for example, there is a band division in consideration of human auditory characteristics. For example, there is a band division in which an audio signal is divided into a plurality of bands, for example, 25 bands, with a bandwidth that is generally called a critical band (critical band) such that the higher the band becomes, the wider the band becomes.

When encoding data for each band at this time, predetermined bits are allocated to each band, or encoding is performed by adaptive bit allocation (bit allocation) for each band. Done. For example, the above-mentioned MDC
When encoding the coefficient data obtained by the T processing by the bit allocation, the number of bits adaptively allocated to the MDCT coefficient data of each band obtained by the MDCT processing of each block is adjusted. Encoding is performed.

The following two methods are known as the method of bit division.

As a first method, there is a method of allocating bits based on the magnitude of a signal for each band. In this method, the quantization noise spectrum is flattened and the noise energy is minimized. However, since the masking effect is not utilized from the auditory point of view, the actual noise feeling is not optimal. The first method is described in the document "Adaptive Transform Cod
ing of Speech Signals, R. Zelinski and P. Noll, IEEE
Transactions of Acoustics, Speech, and Signal Pro
cessing, vol. ASSP-25, No. 4, August 1977 ".

As a second method, there is a method of obtaining a required signal-to-noise ratio for each band and performing fixed bit allocation by using auditory masking. However, in this method, even when the characteristic is measured with a sine wave input, the characteristic value is not so good because the bit allocation is fixed. For this second method, see the document “ICASSP 198
0, The critical band coder--digital encoding of t
he perceptual requirements of the auditory system,
MAKransner MIT ”.

As a method for solving the problem in each of the above methods, all bits that can be used for bit allocation are
It is divided and used for a fixed bit allocation pattern predetermined for each small block and for performing bit allocation depending on the signal size of each block, and the division ratio is used for a signal (for example, a normal signal) related to an input signal. A highly efficient coding method has been proposed in which the ratio of the signal to a fixed bit allocation pattern is increased as the spectrum of the signal becomes smoother, depending on the signal.

According to this method, when energy is concentrated on a specific spectrum such as a sine wave input, a large number of bits are allocated to a block including the spectrum, so that the overall signal-to-noise characteristic is significantly improved. Can be improved. In general, human hearing is extremely sensitive to signals with sharp spectral components,
Improving the signal-to-noise characteristic by using such a method is effective not only to improve the numerical value in measurement but also to improve the sound quality in terms of hearing.

In addition, a number of other methods have been proposed for the bit allocation method. Further, a model relating to auditory sense is refined, and if the capability of the encoding device is improved, a code that is more efficient in terms of auditory sense is obtained. Becomes possible. In these methods, it is general to obtain a real bit allocation reference value that realizes the signal-to-noise characteristic obtained by calculation as faithfully as possible, and to use an integer value approximating the reference value as the number of allocated bits. .

In constructing an actual code sequence, first, quantization accuracy information and normalization coefficient information are encoded with a predetermined number of bits for each band in which normalization and quantization are performed. This is done by encoding the quantized and quantized spectral signal. In addition, the document "ISO /
“IEC 11172-3: 1993 (E)” describes a high-efficiency coding scheme in which the number of bits representing quantization accuracy information is set differently depending on the band. It is standardized so that the number of bits representing information is reduced.

Conventionally, there has been known a method of determining quantization accuracy information from normalized coefficient information instead of directly encoding the quantization accuracy information by a decoding device.
In this method, since the relationship between the normalization coefficient information and the quantization accuracy information is determined at the time of setting the standard, it will not be possible to introduce quantization accuracy control based on a more advanced auditory model in the future. . Also, if there is a range in the compression rate to be realized, it is necessary to determine the relationship between the normalization coefficient information and the quantization accuracy information for each compression rate.

Each of the above-mentioned methods can be applied to each channel of an audio signal composed of a plurality of channels. For example, the left channel corresponding to the left speaker and the right speaker corresponding to the right speaker are used. It can be applied to each of the R channels. Further, the present invention may be applied to a signal of (L + R) / 2 obtained by adding signals of the L channel and the R channel. Also,
Even with the same two-channel signal, efficient coding may be performed on the (L + R) / 2 signal and the (LR) / 2 signal using the above-described method.

For example, if attention is paid to the fact that the sense of stereo is dominantly affected by the low-frequency side signal, then (LR)
A method of narrowing the band of the / 2 signal to be narrower than the band of the (L + R) / 2 signal is conceivable. When this method is used, it is possible to perform efficient encoding with a smaller number of bits while maintaining a sense of stereo sound.

For example, the quantized spectral signal is
Literature `` DAHuffman: A Method for Construction of Min
imum Redundancy Codes, Proc.IRE, 40, p.1098 (1
952)), a more efficient encoding method is known by encoding using a variable length code.

A method is also conceivable in which a tone component that is particularly important in terms of auditory sense, that is, a signal component in which energy is concentrated around a specific frequency, is separated from the spectral signal and is encoded separately from other spectral components. As a result, it is possible to efficiently encode an audio signal or the like at a high compression ratio with almost no audible deterioration.

As described above, techniques for improving the coding efficiency have been developed one after another. By adopting a standard incorporating a newly developed method, a longer recording time can be achieved or the same recording time can be obtained. Then, it becomes possible to record an audio signal with higher sound quality.

As a method for mapping a time-series audio signal onto the time or frequency domain, a high-efficiency coding method combining the above-described band division coding and transform coding is also considered. For example, it has been proposed that, after performing band division by a band division filter, the signal of each band is spectrally transformed into a signal on the frequency axis, and encoding is performed for each band subjected to the spectrum transformation. .

As described above, the merits of converting the signal into a spectrum signal by MDCT or the like after dividing the signal by the band division filter can include the following points.

First, since the transform block length and the like can be set optimally for each band, the generation of quantization noise in the time / frequency domain can be optimally controlled in terms of hearing.
Sound quality can be improved. In general, MDC
T and other spectral transformations are fast Fourier transforms.
In many cases, processing is performed using a high-speed operation method such as er Transform (FFT). To realize such a high-speed operation method, a memory area having a size proportional to the block length is required. For example, by once performing band division and then performing spectrum conversion on signals decimated in proportion to the bandwidth for each band, the number of samples for spectrum conversion to obtain the same frequency resolution can be reduced. In addition, the memory area required for spectrum conversion can be reduced.

Further, for example, when it is not necessary for a coded signal to have high sound quality, but it is desired to reproduce the coded signal with a decoder having a hardware scale as small as possible, it is necessary to process only low-frequency signal data. It is convenient because it can achieve the purpose.

As described above, the band division filter and the MDCT
Since a compression method using a method of converting into a spectrum signal by combining spectral conversions can be realized on relatively small-scale hardware, for example, it is very convenient as a compression method for a portable recorder. . However, since a large number of multiply-accumulate operations are required to realize the band division filter, the number of arithmetic operations increases.

[0033]

By the way, when a code string transmitted through a communication path having a relatively small transmission capacity is recorded on a recording medium having a relatively large recording capacity, or when the code string is transmitted through a communication path having a large transmission capacity. To transmit the code sequence in a short time,
For high-speed recording on a recording medium having a relatively large recording capacity, it is necessary to employ an encoding method with high encoding efficiency in a communication channel. For this purpose, it is desirable to employ spectrum conversion that can obtain a high frequency resolution and has a long conversion block length.

Further, for a code string to be recorded on a recording medium having a relatively large recording capacity, spectral conversion having a relatively short conversion block length may be adopted so that encoding or decoding can be realized with relatively small hardware. desirable.
In particular, in the case of a recording medium for a portable device, the band is once divided in order to reduce the memory size used for the decoder.
It is convenient to convert it to a spectrum signal. here,
Once the signal transmitted via the communication channel is completely decoded and converted back to a time-series signal, and then encoded into a code sequence for a recording medium, the required code sequence is recorded on the recording medium. However, in this case, it is necessary to perform processing of a band division filter having a large amount of calculation. In particular, when data is transmitted in a short time through a communication path having a large transmission capacity and recorded on a recording medium having a relatively large recording capacity, it is necessary to convert the code string at high speed, but the amount of computation is large. Performing band division processing becomes an obstacle in reducing the time required for recording on a recording medium.

In particular, when converting signals of a plurality of channels, it is necessary to process more signals, so that high-speed conversion is more difficult in the conventional method.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and enables data conversion between codes.
It is an object of the present invention to provide an information encoding method and apparatus, a code conversion method and apparatus, a code conversion control method and apparatus, an information recording method and apparatus, and a program supply medium that can perform data conversion at high speed.

[0037]

According to a code conversion method of the present invention, a first code string obtained by coding a spectrum signal obtained by spectrally converting a time-series information signal into a first band group and then performing spectrum conversion is obtained. An input step of inputting, a decoding step of decoding the input first code string to return to a spectrum signal, and a spectrum in a form in which the decoded spectrum signal is band-divided and converted in a second band group. In order to convert the signal into a signal, in the higher band, a part of the spectrum signal is inversely transformed into a decimated time series signal, and the decimated time series signal is converted into a lower band in the higher band. The above object is achieved by having a spectrum signal conversion step of converting the spectrum signal into a spectrum signal on the side and an encoding step of encoding the converted spectrum signal into a second code string.

This code conversion method omits the processing of band synthesis and band division between two codes that have been band-divided so that the band division width of the high-frequency signal is different and then converted into a spectrum signal.

Further, in order to solve the above-mentioned problem, the code conversion apparatus according to the present invention is configured such that a time-series information signal is band-divided into a first band group, and then the spectrum-converted spectrum signal is encoded. Input means for inputting the first code string, decoding means for decoding the input first code string to return to a spectrum signal, and converting the decoded spectrum signal into a second signal string.
In order to convert to a spectrum signal in the form of band-divided and spectrum-converted in the band group, in the high band side, some spectrum signals are inversely transformed into thinned time-series signals, and the above-described thinning is performed. Spectrum signal converting means for converting the converted time-series signal into a low-frequency spectrum signal in the high-frequency band, and encoding means for encoding the converted spectral signal to form a second code string. .

The transcoder having such a configuration is as follows.
The processing of band synthesis and band division is omitted between the two codes that are band-divided so that the band division width of the high-frequency side signal is different and then converted into a spectrum signal.

Further, in order to solve the above-mentioned problem, the code conversion method according to the present invention converts a time-series information signal into a first band group and then converts a spectrum signal obtained by spectrum conversion with a first block length. An input step of inputting a first code string obtained by encoding, a decoding step of decoding the input first code string to return to a spectrum signal, and converting the decoded spectrum signal into a second band group. In order to convert the spectrum signal into a spectrum signal which is band-divided and spectrum-converted with the second block length, only the low-frequency spectrum signal of the first code string is inversely transformed into a thinned time-series signal, It has a spectrum signal conversion step of converting the thinned time-series signal into a low-frequency side spectrum signal, and an encoding step of encoding the converted spectrum signal.

According to this code conversion method, the spectral conversion of the high-frequency signal is replaced with a spectral conversion having a small number of converted samples.

Further, in order to solve the above-mentioned problems, the code converter according to the present invention divides a time-series information signal into a first band group and then converts a spectrum signal which has been spectrum-converted with a first block length. Input means for inputting a first code string obtained by encoding, decoding means for decoding the input first code string to return to a spectrum signal, and converting the decoded spectrum signal into a second band group In order to convert the spectrum signal into a spectrum signal which is band-divided and spectrum-converted with the second block length, only the low-frequency spectrum signal of the first code string is inversely transformed into a thinned time-series signal, There are spectral signal converting means for converting the decimated time-series signal into a low-frequency-side spectral signal, and coding means for coding the converted spectral signal.

The transcoder having such a configuration is as follows.
The spectral transform of the high-frequency signal is replaced with a spectral transform with a small number of transform samples.

Further, a program supply medium according to the present invention is a program supply medium for supplying an information encoding program to an information processing apparatus in order to solve the above-mentioned problem, wherein the program supply medium is provided by the program supply medium. Inputting a first code string obtained by encoding a spectrum signal obtained by band-dividing a time-series information signal into a first band group and then performing spectrum conversion, and decoding the input first code string A decoding step of converting the decoded spectrum signal into a spectrum signal in a form of being subjected to band division and spectrum conversion in the second band group. A spectrum for inversely converting a spectrum signal into a decimated time-series signal and converting the decimated time-series signal into a low-frequency spectrum signal in the high-frequency band. And No. conversion step, the converted spectrum signal comprising and a coding step of the second code string by encoding.

With this program supply medium, the information processing apparatus can perform band synthesis and band division between two codes that have been band-divided so that the band division width of the high-frequency signal is different and then converted into a spectrum signal. The processing is omitted.

According to another aspect of the present invention, there is provided a program supply medium for supplying an information encoding program to an information processing apparatus, the program being supplied by the program supply medium. Inputting a first code string obtained by coding a spectrum signal obtained by band-dividing the time-series information signal into a first band group and then performing spectrum conversion with a first block length;
A decoding step of decoding the input first code string to return to a spectrum signal, and a spectrum in a form in which the decoded spectrum signal is band-divided by a second band group and spectrum-converted by a second block length. First to convert to a signal
The spectrum signal conversion step of inversely converting only the low-frequency spectrum signal of the code string into a thinned time-series signal, and converting the thinned time-series signal into a low-frequency spectrum signal, And an encoding step for encoding the spectrum signal.

With this program supply medium, the information processing apparatus replaces the spectrum conversion of the high-frequency signal with the spectrum conversion having a small number of conversion samples.

[0049]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment,
The transcoding method and apparatus according to the present invention are applied to a compressed data recording and / or reproducing apparatus that compresses acoustic information and records the compressed information on a recording medium.

Hereinafter, the compressed data recording and / or reproducing apparatus will be described in detail. As shown in FIG. 1, this compressed data recording and / or reproducing apparatus is roughly divided into a recording system for recording and processing compressed data on a magneto-optical disk 1 as a recording medium, and a recording system for recording the compressed data on the magneto-optical disk 1. And a reproducing system for performing a reproducing process of the compressed data.

The compressed data recording system has an input terminal 6 serving as an external input section for analog audio signals.
0, an input terminal 67 serving as an external input section for digital audio signals, a low-pass filter (LPF) 61 for performing low-pass filtering, an A / D converter 62 for converting analog signals to digital signals, and an interface for digital audio signals. A digital input interface circuit 68, an encoder 63 for encoding input signals, a memory 64 for storing data, an encoder 65 for encoding data, and a magnetic head driving circuit 66. The encoding and decoding methods include, for example, ATC (Adapti
ve Transform Coding) is adopted.

The compressed data reproducing system includes decoders 71 and 73 for decoding the compressed data.
It comprises a memory 72 as a data storage unit, a D / A converter 74 for converting a digital signal into an analog signal, a low-pass filter (LPF) 75 for low-pass filtering, and an output terminal 76 as an audio signal output terminal. ing.

The compressed data recording and / or reproducing apparatus includes an optical head for irradiating the magneto-optical disk 1 with a laser beam for reproducing compressed data recorded on the magneto-optical disk 1 or the like. 53, an RF circuit 55 for generating an RF signal, a servo control circuit 56 for performing a servo process constituting a rotation drive system of the magneto-optical disk 1, and a spindle motor 51, and control of each unit constituting the compressed data recording and / or reproducing apparatus. System controller 5 that performs
7. A key input operation unit 58 as an input means and a display unit 59 are provided.

The above-mentioned components constituting the compressed data recording and / or reproducing apparatus will be described in detail. The magneto-optical disk 1 is a recording medium on which compressed data is recorded and reproduced by the compressed data recording and / or reproducing apparatus.

The spindle motor 51 drives the magneto-optical disk 1 to rotate. The optical head 53 and the magnetic head 54 constitute a portion for recording and reproducing data on and from the magneto-optical disk 1.

The optical head 53 includes, for example, a laser light source such as a laser diode, optical components such as a collimator lens, an objective lens, a polarizing beam splitter, and a cylindrical lens, and a photodetector having a light receiving portion having a predetermined pattern. This optical head 53
It is provided at a position facing the magnetic head 54 via the magneto-optical disk 1.

The magnetic head driving section 66 drives the magnetic head 54 and applies a modulation magnetic field in accordance with data recording on the magneto-optical disk 1. That is, when data is recorded on the magneto-optical disk 1, the magnetic head drive circuit 6
6 drives the magnetic head 54 to apply a modulation magnetic field according to the recording data, and the optical head 53 irradiates a target track of the magneto-optical disk 1 with laser light, thereby performing thermomagnetic recording by a magnetic field modulation method. .

The optical head 53 detects the reflected light of the laser beam applied to the target track, detects a focus error by, for example, a so-called astigmatism method, and detects a tracking error by, for example, a so-called push-pull method. Thus, when data is reproduced from the magneto-optical disk 1, the optical head 53 detects the focus error and the tracking error, and at the same time, detects the difference in the polarization angle (Kerr rotation angle) of the laser light reflected from the target track. To generate a reproduction signal.

Therefore, when data is recorded on the magneto-optical disk 1, the modulation magnetic field corresponding to the recording data is recorded while the optical head 53 irradiates the magneto-optical disk 1 rotated by the spindle motor 51 with laser light. Is applied by a magnetic head 54, so-called magnetic field modulation recording is performed, and data is recorded along a recording track of the magneto-optical disk 1. When data is reproduced from the magneto-optical disk 1, the recording tracks of the magneto-optical disk 1 are traced by a laser beam by the optical head 53 and magneto-optically reproduced. The output from the optical head 53 is
It is supplied to the RF circuit 55.

The RF circuit 55 extracts the focus error signal and the tracking error signal from the output of the optical head 53 and supplies the focus error signal and the tracking error signal to the servo control circuit 56.
Feed to 1.

The servo control circuit 56 comprises, for example, a focus servo control circuit, a tracking servo control circuit, a spindle motor servo control circuit, a thread servo control circuit and the like. Here, the focus servo control circuit controls the focus of the optical system of the optical head 53 so that the focus error signal becomes zero. Also,
The tracking servo control circuit performs tracking control of the optical system of the optical head 53 so that the tracking error signal becomes zero. Further, the spindle motor servo control circuit controls the spindle motor 51 so as to rotate the magneto-optical disk 1 at a predetermined rotation speed (for example, a constant linear speed). The thread servo control circuit also controls the optical head 5 at the target track position of the magneto-optical disk 1 specified by the system controller 57.
3 and the magnetic head 54 are moved.

The servo control circuit 56 for performing various control operations sends information indicating the operation state of each unit controlled by the servo control circuit 56 to the system controller 57.

A key input operation unit 58 and a display unit 59 are connected to the system controller 57. The system controller 57 controls a recording system and a reproduction system based on operation input information based on operation input information from the key input operation unit 58.

The system controller 57 traces the optical head 53 and the magnetic head 54 from the recording track of the magneto-optical disk 1 based on the address information of the sector unit to be reproduced based on the header time, the Q data of the subcode, and the like. Recording position and reproduction position on the recording track.

Further, the system controller 57 controls the display section 59 to display the reproduction time based on the data compression ratio of the compressed data recording / reproducing apparatus and the reproduction position information on the recording track.

This reproduction time display is based on the reciprocal of the data compression ratio (absolute time information) with respect to address information (absolute time information) in sector units reproduced from a recording track of the magneto-optical disk 1 by so-called header time or so-called subcode Q data. For example, in the case of 1/4 compression, the actual time information is obtained by multiplying by 4), and this is displayed on the display unit 59.

In recording, if absolute time information is recorded in advance on a recording track of a magneto-optical disk or the like (preformatted), the preformatted absolute time information is read and the data is read. By multiplying the reciprocal of the compression ratio, it is possible to display the current position with the actual recording time.

In the recording system, the analog audio input signal AIN from the input terminal 60 is supplied to the A / D converter 62 via the low-pass filter 61.

The A / D converter 62 quantizes the analog audio input signal AIN. This A / D converter 6
2 is supplied to the ATC encoder 63. Also, the ATC encoder 63 receives a digital audio input signal DIN from an input terminal 67 by a digital input interface circuit 6.
8.

The ATC encoder 63 receives the input signal A
Bit compression (data compression) according to a predetermined data compression ratio is performed on digital audio PCM data of a predetermined transfer rate, which is obtained by quantizing IN by the A / D converter 62. The bit-compressed data (ATC data) in the ATC encoder 63 is input to the memory 64. For example, if the data compression ratio is reduced to 1/8, the data transfer rate here is 1/8 (9.9) of the data transfer rate (75 sectors / second) of the standard CD-DA format.
375 sectors / sec).

The memory 64 is controlled by the system controller 57 to write and read data.
The ATC data supplied from the ATC encoder 63 is temporarily stored, and is used as a buffer memory for recording on the magneto-optical disk 1 as needed.

For example, when the data compression ratio is 1/8, the compressed audio data supplied from the ATC encoder 63 has a data transfer rate of a standard CD-ROM.
DA format data transfer rate (75 sectors / sec)
, Ie, 9.375 sectors / sec., And the compressed data is continuously written to the memory 64.

As for the compressed data (ATC data), it is sufficient to record one sector per eight sectors as described above. However, such recording every eight sectors is practically impossible. Sector continuous recording is performed. This recording is performed in bursts at the same data transfer rate (75 sectors / second) as a standard CD-DA format by using a cluster composed of a predetermined plurality of sectors (for example, 32 sectors + several sectors) as a recording unit through a pause period. It is done on a regular basis. That is, in the memory 64, ATC audio data having a data compression rate of 1/8, which is continuously written at a low transfer rate of 9.375 (= 75/8) sectors / sec according to the bit compression rate, is recorded. The data is read out in bursts at the transfer rate of 75 sectors / second.

For the data to be read and recorded, the overall data transfer rate including the recording pause period is as low as 9.375 sectors / sec. The instantaneous data transfer rate within the time period is the standard 75 sectors / second. Therefore, when the disk rotation speed is a standard CD-D
At the same speed (constant linear speed) as in the A format, recording is performed with the same recording density and storage pattern as in the CD-DA format.

The ATC audio data, ie, recorded data, read from the memory 64 in a burst at the (instantaneous) transfer rate of 75 sectors / second is transferred to the encoder 65.
Supplied to Here, from the memory 64 to the encoder 65
In the data string supplied to the cluster, the unit continuously recorded in one recording is a cluster including a plurality of sectors (for example, 32 sectors) and several sectors for cluster connection arranged before and after the cluster. The cluster connection sector is set to be longer than the interleave length in the encoder 65, so that even if interleaved, data in other clusters is not affected.

The encoder 65 encodes the recording data supplied from the memory 64 in a burst manner as described above for error correction (parity addition and interleave processing) or EFM (Eight to Fourteen Moment).
dulation) Encoding processing is performed. This encoder 65
Is supplied to the magnetic head drive circuit 66.

The magnetic head drive circuit 66 is connected to the magnetic head 54, and applies a modulated magnetic field to the magneto-optical disk 1 in accordance with the recording data.
4 is driven.

The system controller 57 performs the above-described memory control on the memory 64, and continuously records the recording data read out from the memory 64 by the memory control on the recording track of the magneto-optical disk 1. The recording position is controlled as described above. The recording position is controlled by controlling the recording position of the recording data read in a burst from the memory 64 by the system controller 57 and transmitting a control signal designating the recording position on the recording track of the magneto-optical disk 1 to a servo control circuit. 56.

Next, the reproducing system will be described. This reproducing system is for reproducing the recorded data continuously recorded on the recording tracks of the magneto-optical disk 1 by the recording system described above. In the reproducing system of the compressed data recording and / or reproducing apparatus, a reproduction output obtained by tracing a recording track of the magneto-optical disk 1 with a laser beam by the optical head 53 is binarized by the RF circuit 55 and supplied. The decoder 71 is provided. At this time, not only a magneto-optical disk but also a read-only optical disk similar to a so-called CD (Compact Disc) can be read.

The decoder 71 corresponds to the encoder 65 in the above-described recording system, and performs the above-described decoding processing for error correction, EFM decoding processing, and the like on the reproduced output binarized by the RF circuit 55. To reproduce the ATC audio data having the above-mentioned data compression rate of 1/8 at a transfer rate of 75 sectors / sec, which is faster than the normal transfer rate. The reproduction data obtained by the decoder 71 is supplied to the memory 72.

The memory 72 is controlled by the system controller 57 to write and read data.
Reproduced data supplied from the decoder 71 at a transfer rate of 75 sectors / second is written in a burst at the transfer rate of 75 sectors / second. Also, this memory 72
The reproduced data written in a burst at a transfer rate of 5 sectors / second corresponds to a data compression / reduction ratio of 1/8.
It is read continuously at a transfer rate of 75 sectors / sec.

The system controller 57 writes the reproduced data to the memory 72 at a transfer rate of 75 sectors / sec.
Memory control is performed such that data is read continuously at a transfer rate of 375 sectors / second. Also, the system controller 57
Performs the above-described memory control on the memory 72 and controls the reproduction position so that the reproduction data written in a burst from the memory 72 by the memory control is continuously reproduced from the recording track of the magneto-optical disk 1. Do. The reproduction position is controlled by controlling the reproduction position of the reproduction data read in a burst from the memory 72 by the system controller 57 and transmitting a control signal designating the reproduction position on the recording track of the magneto-optical disk 1 or the optical disk 1. This is performed by supplying the signal to the servo control circuit 56. ATC audio data obtained as reproduction data continuously read from the memory 72 at a transfer rate of 9.375 sectors / sec is supplied to an ATC decoder 73.

The ATC decoder 73 corresponds to the ATC encoder 63 of the recording system.
By expanding the data by 8 times (bit expansion), 1
6-bit digital audio data is reproduced. The digital audio data from the ATC decoder 73 is supplied to a D / A converter 74.

The D / A converter 74 includes an ATC decoder 73
Is converted into an analog signal to form an analog audio output signal AOUT. The analog audio signal AOUT obtained by the D / A converter 74 is output from an output terminal 76 via a low-pass filter 75.

With the above configuration, the compressed data recording and / or reproducing apparatus can record and reproduce the compressed data on the magneto-optical disk. This compressed data recording and / or reproducing apparatus realizes highly efficient compression encoding of data.

Next, the high-efficiency compression encoding will be described in detail. High-efficiency compression coding means, for example, compression coding of an input digital signal such as an audio PCM signal at high efficiency using techniques such as band division coding (SBC), adaptive conversion coding (ATC) and adaptive bit allocation. Technology.

FIG. 2 shows an example of the configuration of an encoding means for encoding an acoustic waveform signal. The audio waveform signal encoding means includes a conversion circuit 1101 for band-dividing an input audio signal or the like and performing spectrum conversion, and a signal component encoding circuit 11 for normalizing and quantizing the input signal.
02 and a code sequence generation circuit 110 that generates the signal 103 output from the signal component coding circuit 1102 as a code sequence.
And 3. The audio waveform encoding means converts the input signal waveform 101 into a signal 102 for each signal frequency component by a conversion circuit 1101 and then encodes each signal coded by a signal component encoding circuit 1102.
03, and the signal 103 is generated by the code sequence generation circuit 1103 as a signal 104 as a code sequence.

The conversion circuit 1101 is composed of, for example, band division filters 1201 and 1202 and forward spectrum conversion circuits 1203, 1204 and 1205 as shown in FIG.

The band division filter 1201 outputs the signal 2
01 is divided into two bands. Band splitting filter 120
Signals 211 and 212 divided into two bands by 1
Of these, the signal 211 in the higher band is MDC
The signal is converted into a spectrum signal component 221 by a forward spectrum conversion circuit 1203 such as T.

Further, the signal 212 on the low frequency side is further divided into signals 213 and 214 of two bands by a band dividing filter 1202, and in each band, a forward spectrum conversion circuit 1204, 1
The signal has been converted into a spectral signal component 221 by 205. Note that the signal 201 input to the band division filter 1201 in FIG.
The signal 101 corresponds to the signal 101 input to 1.

The bandwidths of the signals 211 and 212 output from the band division filter 1201 after being divided into bands are
The signal 2 input to the band division filter 1201
01, which is half of the bandwidth of the signal 20.
It has been decimated to 1/2 of 1.

The bandwidths of the signals 213 and 214 which are output from the band dividing filter 1202 after being band-divided are:
The signal 201 input to the band division filter 1201
Of the signal 201, and is thinned out to 1/4 of the signal 201.

The forward spectrum conversion circuit 120
3,1204,1205 are not limited to those configured by the MDCT described above.
And DCT.

As shown in FIG. 4, the signal encoding circuit 1102 comprises a normalizing circuit 1301, a quantization precision determining circuit 1302, and a quantizing circuit 1303.

Each of the forward spectrum conversion circuits 1203, 1
Each signal component 301 output from 204 and 1205 is
The normalization circuit 1301 performs normalization for each predetermined band.

The normalized signal 302 is
The quantization is performed by the quantization circuit 1303 based on the quantization accuracy calculated by the quantization accuracy determination circuit 1302. Here, the quantization circuit 1303 is a signal 303 serving as a control signal output from the quantization accuracy determination circuit 1302.
Controls the quantization accuracy.

In FIG. 4, the signal 301 input to the normalization circuit 1301 and the quantization precision determination circuit 1302
Corresponds to each forward spectrum conversion circuit 120 in FIG.
The signal 304 output from the quantization circuit 1303 in FIG. 4 corresponds to the signal 103 output from the signal component encoding circuit 1102 in FIG. ing.
Here, in FIG. 4, the signal 304 output from the quantization circuit 1303 includes, in addition to the quantized signal component,
Normalization coefficient information and quantization accuracy information are also included.

The signal output from the signal component encoding circuit 1102 configured as shown in FIG. 4 is output as a code string by the code string generation circuit 1103.

As described above, the encoding means of the acoustic waveform configured as described above converts the input signal waveform 101 into
The signal 102 for each signal frequency component is converted by the conversion circuit 1101.
After that, a signal 104 that is a code sequence is generated by the code sequence generation circuit 1103 as the signal 103 coded by the signal component coding circuit 1102.

FIG. 5 shows decoding means for decoding and outputting an audio signal from the code sequence generated by the coding means shown in FIG. This decoding means includes a code string decomposition circuit 1
401, a signal component decoding circuit 1402, and an inverse transform circuit 1
403.

The decoding means comprises a code string decomposition circuit 1401
Thus, the sign of each signal component is extracted from the code string signal 401. The signal component decoding circuit 1402 decodes the signal 403 for each signal component from the code data 402 by the signal component decoding circuit 1402,
03, an acoustic waveform signal 404 is generated.

The signal component decoding circuit 1402 corresponds to the signal component encoding circuit 1102 shown in FIG. 4 and, for example, as shown in FIG.
And an inverse normalization circuit 1552. 6, the input data 551 input to the inverse quantization circuit 1551 and the output data 553 output from the inverse normalization circuit 1552 are the input data 402 input to the signal component decoding circuit 1402 in FIG. It corresponds to the output data 403 output from the signal component decoding circuit 1402, respectively.

The signal component decoding circuit 1 thus configured
402, the input data 511 input as each spectrum signal is subjected to inverse quantization processing of the input data 551 by the inverse quantization circuit 1551, and the inverse normalization circuit 155 is provided.
2 performs inverse normalization on the signal 552 output from the inverse quantization means.

The inverse conversion circuit 1403 corresponds to the conversion circuit 1101 shown in FIG. 3 and, for example, as shown in FIG.
2,1503, and band synthesis filters 1511, 1512
It is composed of This encoding / decomposing circuit 1401
Are the inverse spectrum conversion circuits 1501, 1502, 15
03, the signals 511, 512, and 5 of the respective bands obtained by
13 are synthesized by band synthesis filters 1511 and 1512.

That is, the band synthesis filter 1511
The signals 512 and 513 output from the inverse spectrum conversion circuits 1502 and 1503 are synthesized to output a signal 514, and the band synthesis filter 151
2 synthesizes the signal 511 output from the inverse spectrum conversion circuit 1501 and the signal 514 output from the band synthesis filter 1511 to output a signal 521. Therefore, in FIG.
The signal 501 input to the inverse conversion circuit 1403 in FIG.
3, and a signal 404 output from the inverse conversion circuit 1403
Respectively.

Here, the encoding method will be described with reference to FIG.
This will be described using the encoding means shown in FIG. For example, the signal shown in FIG. 8 is a signal obtained by converting the level of the absolute value of the MDCT spectrum into dB from the spectrum signal obtained by the conversion means shown in FIG.

Here, the input signal is converted into 64 spectral signals for each predetermined time block, and these are converted into eight bands from band [1] to band [8] (hereinafter referred to as a coding unit). ) Are normalized and quantized together. By changing the quantization accuracy for each encoding unit depending on the distribution of the frequency components, it is possible to perform audio-efficient encoding that minimizes deterioration of sound quality.

FIG. 9 shows an example of the configuration of a code string generated by encoding. In this configuration example, data for restoring a spectrum signal of each time block is encoded corresponding to a frame including a predetermined number of bits.

As shown in FIG. 9, at the head (header part) of each frame, first, a synchronization signal and control data such as the number of coding units being coded are coded with a fixed number of bits. The quantization precision data and the normalization coefficient data of each coding unit are respectively coded from the low-frequency side coding unit, and finally, based on the above-described normalization coefficient data and quantization precision data for each coding unit. The normalized and quantized spectral coefficient data is encoded from the low frequency side. The number of bits actually required for restoring the spectrum signal of this time block is determined by the number of coding units being coded and the number of quantization bits indicated by the quantization accuracy information of each coding unit, The amount may be different for each frame.

Further, only the necessary number of bits from the beginning of each frame has significance during reproduction, and the remaining area of each frame becomes a free area, and does not affect the reproduction signal.
As shown in this example, by encoding each time block corresponding to a frame having a fixed number of bits, for example, when this code string is recorded on a recording medium such as a magneto-optical disk, an arbitrary time block Can be easily calculated. This makes it possible to easily realize so-called random access in which reproduction is performed from an arbitrary position. Normally, more bits are effectively used to improve the sound quality so that the empty area of each frame is made as small as possible.

The above is the basic encoding method, but the encoding efficiency can be further improved. For example, by assigning a relatively short code length to high-frequency quantized spectral signals and assigning a relatively long code length to infrequent signals,
Encoding efficiency can be improved.

Further, for example, by increasing the transform block length, the amount of sub-information such as quantization accuracy information and normalization coefficient information can be relatively reduced, and the frequency resolution is increased. Since the precision can be more finely controlled, the coding efficiency can be improved.
Furthermore, it is also possible to consider a method of separating a tone component that is particularly important for hearing from a spectral signal, that is, a signal component in which energy is concentrated around a specific frequency, and encoding it separately from other spectral components. As a result, it is possible to efficiently encode an audio signal or the like at a high compression rate with almost no audible deterioration.

Next, an example of the configuration of the encoding means and the decoding means capable of improving the encoding efficiency will be further described.

FIG. 10 shows the conversion circuit 1101 of FIG.
Is shown. The conversion circuit 1101 has a configuration different from that of FIG.
And forward spectrum conversion circuits 1602, 1603 and 160
4,1605.

The converting means configured as described above divides the signal 601 into four equal bandwidth bands by the band division filter 1601, and outputs the divided signal 6
02, 603, 604, and 605 are subjected to forward spectrum conversion by forward spectrum conversion circuits 1602, 1603, 1604, and 1605, respectively. However, this FIG.
The block length of the forward spectrum conversion by the conversion means shown in FIG. 0 is longer than that of the conversion means shown in FIG. 3, for example, the frequency resolution of the output spectrum signal is doubled.

In the example of the conversion means configured as shown in FIG. 10, the band is divided into four and the signals 602, 60
3, 604 and 605 arrange the time series signals for each band thinned out according to the bandwidth from the high frequency side.
For example, as shown in FIG. 11, the band division filter 1601 is first divided into predetermined bands by a band division filter 1611, and further divided into band division filters 1612, 1
613. Specifically, the signal 611 is first divided into two bands on the low frequency side and the high frequency side by the QMF filter (band division filter 1611) configured as described above, and the divided signals 612 and 613 are Band division filter 1612,
By dividing each band into two bands by 1613, signals 614, 615, 616, and 617 divided into four bands of equal bandwidth are generated.

A so-called band division filter 1601
Can be configured to be divided into four equal-bandwidth bands at once by a PQF filter. In any case, the signals 602, 603, and 603 shown in FIG.
Each of the signals 604 and 605 is thinned out to 信号 of the signal 601, and a high frequency resolution can be obtained while suppressing the amount of buffer memory necessary for the spectrum conversion processing.

FIG. 12 shows an example of the configuration of the inverse conversion circuit 1403 shown in FIG. 5, which is different from that shown in FIG. This inverse conversion circuit 140
3 is an inverse spectrum conversion circuit 1621, 1622, 16
23, 1624, and a band synthesizing filter 1625, and are configured to realize the inverse conversion corresponding to the conversion means of FIG.

The inverse transform means configured as described above converts the signal 621 comprising a code string into each inverse spectrum transform circuit 162
1, 1622, 1623, and 1624, each band is subjected to inverse spectrum conversion processing, and the inversely spectrum-converted signals 622, 623, 624, 62
5 is synthesized by the band synthesis filter 1625,
Output as signal 626.

The band synthesizing filter 1625 can be constituted by a QMF band synthesizing filter, for example, as shown in FIG. This band synthesis filter 16
25, first, the signal 6
31 and the signal 632, and the signal 633 and the signal 634 are combined by the band combining filter 1632,
Then, the signal 635 and the signal 636 generated by being synthesized by the band synthesis filters 1631 and 1632 are output.
Are combined by a band combining filter 1633 to obtain a signal 63
7 is output.

The spectrum signal shown in FIG. 14 is for explaining a method of separating and encoding a signal component having a tone property. Here, a state in which three tone components are separated is shown, and each of these tone components is encoded together with position data on its frequency axis.

In general, in order to prevent the sound quality from deteriorating, it is necessary to quantize the tonal signal components whose energy is concentrated in a small number of spectra with very high precision. Can be quantized with a relatively small number of steps without deteriorating the auditory sound quality. In FIG. 14, for the sake of simplicity, only a relatively small number of spectra are shown, but in an actual tone signal, several spectra in an encoding unit composed of tens of spectra are shown. Since energy is concentrated on the coefficients, the increase in the data amount due to the separation of such tone components is relatively small. By separating the tone components, the coding efficiency can be improved as a whole.

The spectral signal shown in FIG. 14 represents the signal obtained by the conversion means configured as shown in FIG. 10, and is twice as large as the spectral signal shown in FIG. Has frequency resolution. When the frequency resolution is high as described above, the energy is concentrated on a specific spectrum signal, and the method of separating the tone components is more effective.

FIG. 15 shows a configuration example of a code string obtained based on FIG. In the example of the code string shown in FIG. 15, a synchronization signal and control data such as the number of coding units being coded are coded with a predetermined number of bits as a header at the beginning of each frame. The tone component data corresponding to the sex signal component is encoded.

As shown in FIG. 15, regarding the tone component data, first, the number of the tone components is encoded, and then the position information on the frequency axis of each tone component, the quantization accuracy information, the normal The normalized coefficient information and the normalized and quantized spectral coefficient data are encoded. Subsequent to the tone component, data of the remaining signal (noise signal) obtained by subtracting the tone component from the original spectrum signal is encoded. For this, quantization accuracy data and normalization coefficient data of each encoding unit and spectral coefficient data normalized and quantized based on the above-described normalization coefficient data and quantization accuracy data for each encoding unit, Each is encoded from the encoding unit on the lower frequency side. However, here, it is assumed that the spectral coefficient data of the tone signal and the noise signal have been subjected to variable-length encoding.

FIG. 16 shows an example of the configuration of the signal component encoding means in the signal component encoding circuit 1102 shown in FIG. 2, which is configured to separate tone components.

The signal component encoding circuit 1102 includes a tone component separation circuit 1641 and a tone component encoding circuit 1641.
42 and a non-tone component encoding circuit 1643. The tone component encoding circuit 1642 and the non-tone component encoding circuit 1643 are configured, for example, in the same manner as the signal component encoding unit in FIG. Also,
Variable length coding may be performed on the signal quantized as described above.

In the signal generation / encoding circuit 1102, the signal 641 is separated by the tone component separation circuit 1641 into signals 642 and 643. Then, the signal 642 separated by the tone component separation circuit 1641 is subjected to a tone component coding process by the tone coding circuit 1642, and is output as a signal 644. The signal 643 from the tone component separation circuit 1641 is subjected to a non-tone component encoding process in the non-tone component encoding circuit 1643, and is output as a signal 645.

FIG. 17 shows an example of the configuration of the signal component decoding circuit 1402 shown in FIG. 5 when a tone component is separated.

This signal component decoding circuit 1402 comprises a tone component decoding circuit 1661 and a non-tone component decoding circuit 1
662 and a spectrum signal synthesizing circuit 1663. Here, each of the tone component decoding circuit 1661 and the non-tone component decoding circuit 1662 may have the same configuration as the signal component decoding means shown in FIG.

The signal component decoding circuit 1402 generates a signal 663 in which the tone component decoding circuit 1661 has performed a tone component decoding process on the signal 661, and the non-tone component decoding circuit 1662 generates a signal 663. On the other hand, a signal 664 that has been subjected to non-tone component decoding processing is generated, and the spectrum signal synthesis circuit 1663 generates a signal 665 obtained by synthesizing the signal 663 and the signal 664. In the case where the quantized signal has been subjected to the variable-length coding as described above, the signal is decoded before the inverse quantization is performed.

The means for generating a code sequence from an acoustic waveform signal or generating an acoustic waveform signal from a code sequence has been described above.

By the way, the code string obtained as described above often needs to be converted into another code string. For example, when a code string transmitted through a communication path having a relatively small transmission capacity is recorded on a recording medium having a relatively large recording capacity, or when a code string is transmitted in a short time through a communication path having a large transmission capacity. However, when high-speed recording is performed on a recording medium having a relatively large recording capacity, it is necessary to employ an encoding method with high encoding efficiency in transmission over a communication channel. It is desirable to employ a long spectral transform. On the other hand, it is desirable that a code string to be recorded on a recording medium having a relatively large recording capacity employs spectral conversion with a relatively short conversion block length, which can be encoded and decoded with relatively small hardware. In particular, in the case of a recording medium for a portable device, it is convenient that the band is temporarily divided and then converted into a spectrum signal in order to reduce the memory size used for the decoder. Here, once the transmitted signal is completely decoded, converted back to a time-series signal, and then encoded into a code sequence for a recording medium, the required code sequence can be recorded on the recording medium. However, in this case, it is usually necessary to perform processing of a band division filter having a large amount of calculation. In particular, when recording is performed on a recording medium having a relatively large recording capacity by using a communication path having a relatively large transmission capacity for a short time, it is necessary to perform code string conversion at high speed, but the amount of computation is large. Performing band division processing becomes an obstacle in reducing the time required for recording on a recording medium.

In the compressed data recording and / or reproducing apparatus according to the embodiment of the present invention, when a code string used for transmission is converted to another code string, the code string is not completely decoded into a time-series signal. By realizing high-speed code conversion processing, the above-described problem is solved.

The high-speed encoding and conversion processing realized by the compressed data recording and / or reproducing apparatus according to the embodiment of the present invention will be described below.

FIG. 18 shows a case where a code string transmitted through a communication path having a relatively small transmission capacity is recorded on a recording medium having a relatively large recording capacity, or a short time is passed through a communication path having a large transmission capacity. FIG. 2 shows a configuration of a signal transmission and recording unit that transmits a code string and records at a high speed on a recording medium having a relatively large recording capacity. For example, the signal transmission recording means performs processing on a signal output from the encoder 63 in the compressed data recording and / or reproducing apparatus shown in FIG.

This signal transmission recording means is provided by the transmission circuit 190
1, a code conversion circuit 1902, and a recording circuit 1903.

The signal transmission and recording means is configured to divide a time-series information signal into a first band group and then encode a spectrum signal obtained by performing spectrum conversion with a first block length. Input circuit 1901
Code conversion means for converting the first code string into a second code string in a form in which the first code string is band-divided in a second band group and then spectrum-converted and encoded with a second block length. It comprises a circuit 1902 and a recording circuit 1903 for recording the second code string on the magneto-optical disk 1.
Here, signals 901 and 902 correspond to the first code string, and signals 903 and 904 correspond to the second code string.

In this signal transmission recording means, the input signal 901 is input to the transmission means and output as a signal 902. The signal 902 is subjected to code conversion processing by a code conversion circuit 1902 and output as a signal 903. The signal 903 is output as a signal 904 by the recording circuit 1903, and is recorded on a recording medium.

Here, specifically, a code string 901 which is data input to the transmission circuit 1901 is obtained by coding a signal which has been band-divided and converted into a spectrum signal with a relatively long block length. It is. Also, a code string 904
Is equivalent to a signal obtained by encoding a signal converted into a spectrum signal with a relatively short block length after band division, and is recorded on the recording medium of the magneto-optical disk 1 via the recording circuit 1903. You. In addition, contrary to this example,
When recording on a recording medium with a small recording capacity using a communication path with a large transmission capacity, for example, when recording on an expensive semiconductor memory via an optical cable with a large transmission capacity, the code string 901 is A signal converted into a spectrum signal with a relatively short block length after band division is encoded. A code sequence 904 is a signal converted into a spectrum signal with a relatively long block length after band division. May be equivalent to the encoded version.

Further, FIG. 19 shows that, contrary to the above-described example, a code string recorded on a recording medium having a relatively large recording capacity is converted at a high speed and transmitted through a communication path having a relatively small transmission capacity. 2 shows a configuration of a signal reading and transmitting unit when transmitting using a communication path having a large transmission capacity for a short time.

The signal reading and transmitting means includes a reading circuit 1921, a code conversion circuit 1922, and a transmission circuit 1921.
23. In this signal reading means, the input signal 921 is read by the read circuit 1921
Is read out as a signal 922, and this signal 922
Is subjected to code conversion processing by a code conversion circuit 1922 and output as a signal 923, and the signal 923 is
23, and is output as a signal 924 subjected to transmission processing.

Here, specifically, the signal 921 is a code string, which is obtained by coding a signal which has been divided into bands and converted into a spectrum signal with a relatively short block length. This is a code string read out from a recording medium such as a magneto-optical disk via 1921. The code sequence 924 is equivalent to a signal obtained by coding a signal that has been converted into a spectrum signal with a relatively long block length after band division.

Contrary to this example, when a signal encoded and recorded on a recording medium having a small recording capacity is transmitted using a communication path having a large transmission capacity, for example, a signal having a large transmission capacity is transmitted. When transmitting signals recorded in expensive semiconductor memory via an optical cable,
The code string 921 is obtained by coding a signal that has been converted into a spectrum signal with a relatively long block length after band division, and the code string 924 has a spectrum signal with a relatively short block length after band division. May be equivalent to a signal obtained by encoding a signal converted into a signal.

FIG. 20 shows an example of the configuration of a code conversion circuit 1922 for converting a code string into another code string. The code conversion circuit 1922 includes a code string decomposition circuit 1701, a signal component decoding circuit 1702, and a spectrum signal conversion circuit 1703.
, A signal component encoding circuit 1704, and a code string generation circuit 1
705.

Here, the code conversion circuit 1922 converts the time-series information signal into a first band group and then encodes a spectrum signal obtained by performing spectrum conversion with a first block length to obtain a first code string. A code string decomposition circuit 1701 as input means for inputting, a signal component decoding circuit 1702 as decoding means for decoding the input first code string and returning it to a spectrum signal, and a decoded spectrum signal into a second A spectrum signal conversion circuit 1703, which is a spectrum signal conversion means for converting the spectrum signal into a spectrum signal in a form of a spectrum group converted into a spectrum group with a second block length, and a second code sequence by encoding the converted spectrum signal; It comprises a signal component encoding circuit 1704 and a code sequence code sequence generating circuit 1705, which are encoding means. here,
For example, the first block length is longer than the second block length. Further, the compression rate of the first code string is higher than the compression rate of the second code string.

The spectrum signal conversion circuit 17
03 is configured, for example, as shown in FIG.
Accordingly, the encoding unit determines that one band of the second band group of the second code string is equivalent to a combination of two or more bands of the first band group of the first code string. , The spectrum signal conversion circuit 1703 can combine the spectrum signals of the two or more bands of the first band group with the one band of the second band group. .

In the code conversion means configured as described above, the input signal 701 is converted into a code string decomposition circuit 1701.
Is a signal 702 subjected to code decomposition processing by
2 is a signal 703 decoded by the signal component decoding circuit 1702. Then, the signal 703 is output as a signal 704 that has been subjected to the spectrum signal conversion processing by the spectrum signal conversion circuit 1703, and the signal 704 is the signal 7 that has been subjected to the coding processing by the signal component coding circuit 1704.
05 is output as a signal 706 converted into a code string by the code string generation circuit 1705.

More specifically, it is assumed here that the input to the code string decomposition circuit 1701 is the code string shown in FIG. It is assumed here that the output of the code string generation circuit 1705 is the code string in FIG. 9 described above.

The code string decomposition circuit 1701 has the same configuration as the code string decomposition circuit 1401 shown in FIG. The signal component decoding circuit 1702 has the same configuration as that shown in FIG. further,
The signal component encoding circuit 1704 has the same configuration as that shown in FIG. Then, the code string generation circuit 17
05 has the same configuration as the code string generation circuit 1103 shown in FIG.

FIG. 21 shows a configuration example of the spectrum signal converting means shown in FIG. This spectrum signal conversion means includes inverse spectrum conversion circuits 1721 and 172
2, 1723, 1724 and a band synthesis filter 1725
And a forward spectrum conversion circuit (forward spectrum conversion circuit 2)
1726 and forward spectrum conversion circuits (forward spectrum conversion circuits 1) 1727 and 1728.

In this spectrum signal conversion means, the input signal 721 is divided into bands, and inverse spectrum conversion circuits 1721, 1722, 1723, and 1724
Is subjected to an inverse spectrum conversion process. Then, signals 722 and 722 from the inverse spectrum conversion circuits 1721 and 1722 are output.
723 is subjected to band synthesis processing by a band synthesis filter 1725. The signal 726 that is band-synthesized by the band synthesizing filter 1725 and output is subjected to a forward spectrum conversion process in a forward spectrum conversion circuit 1726.

The inverse spectrum conversion circuit 1723,1
The signal 72 subjected to the inverse spectrum conversion processing at 724
4,725 immediately after that, the forward spectrum conversion circuit 17
At 27, 1728, a forward spectrum conversion process is performed.
Output as signal 727.

Here, the inverse spectrum conversion circuit 172
1, 1722, 1723, and 1724 are, for example, inverse spectrum conversion circuits 1621 and 1621 shown in FIG.
It has the same configuration as 1622, 1623, 1624. Further, a forward spectrum conversion circuit (forward spectrum conversion circuit 2)
1726 and forward spectrum conversion circuits (forward spectrum conversion circuits 1) 1727 and 1728 are, for example, forward spectrum conversion circuits 1203, 1204, and 12 shown in FIG.
The configuration is the same as that of the configuration 05.

The band synthesizing filter 1725 is for synthesizing signals of two bands having the same bandwidth on the high frequency side. This band synthesizing filter 1725 may have, for example, the same configuration as the band synthesizing filter 1631 shown in FIG.

As described above, in the code conversion means of FIG. 20 using the spectrum signal conversion means of FIG.
Can be significantly reduced as compared with the conventional method of completely decoding the code string shown in FIG. 9 and re-encoding it into the code string shown in FIG. 9 above. Thereby, high-speed code conversion can be realized.

Here, for example, the code string before conversion by the spectrum signal conversion means is obtained by coding the spectrum signal obtained by the conversion means shown in FIG. 10, and the band division filter 1601 In the case where it is assumed that the converted code string is originally obtained by encoding the spectrum signal obtained by the conversion means shown in FIG. 3, the band division filter shown in FIG. 1201 and 1202 respectively correspond to FIG.
If they are the same as the band division filters 1611 and 1613 of FIG. 1, the band combination filter 1631 of FIG. 13 corresponding to the band division filter 1612 of FIG.

The band synthesizing filter 1725 includes, for example, as shown in FIG.
1732, a high-pass filter 1733, a low-pass filter 1734, and an adding circuit 1735.

Here, the code conversion means having the band synthesizing filter 1725 is configured by applying the code conversion device according to the present invention.

That is, as shown in FIG. 20, an input section for inputting a first code string obtained by encoding a spectrum signal obtained by dividing a time-series information signal into a first band group and then performing spectrum conversion is configured. A code string decomposition circuit 1701
In the code conversion means comprising a code string decomposition circuit 1701 and a signal component decoding circuit 1702 which are decoding means for decoding the input first code string and returning it to a spectrum signal, the spectrum signal conversion circuit 1703 The band synthesis filter 1725 shown in FIG.
Is configured as shown in FIG. By adopting the band synthesis filter configuration as shown in FIG. 22, in order to convert the decoded spectrum signal into a spectrum signal in a form of band division and spectrum conversion in the second band group,
In the high band, a part of the spectrum signal is inversely converted into a decimated time series signal, and the decimated time series signal is converted into a low band spectrum signal in the high band. .
Then, from the band synthesizing filter 1725 of FIG. 21 having the configuration as shown in FIG.
The spectrum signal extracted via 26 is coded into a second code string by a signal component coding circuit 1704 and a code string generation circuit 1705 shown in FIG.

The band synthesizing filter 1725 in FIG.
In the configuration shown in FIG.
1,732 are 0 data interpolation circuits 1731,1
At 732, an interpolation process is performed. Each of the signals 733 and 734 subjected to the 0 data interpolation processing in the 0 data interpolation circuits 1731 and 1732 is converted into a high-pass filter 1733.
And low-pass filter 1734 performs filter processing for each of the high band and the low band, and outputs signals 735 and 736 to adder 1735. In the addition circuit 1735,
The input signals 735 and 736 are subjected to addition processing to obtain a signal 7.
37 is output.

Here, specifically, the 0 data interpolation circuit 1
The high-frequency input signal 731 input to 731 is the same as that in FIG.
21. The low-frequency side input signal 732 input to the 0 data interpolation circuit 1732 is
21 corresponds to the signal 723, and the output signal 737 output from the addition circuit 1735 is the signal 723 in FIG.
Equivalent to 6.

The input signals 731 and 732 on the high frequency side and the low frequency side, which have been decimated by 比較 in comparison with the output signal 737 by the band synthesizing filter 1725, are converted into 0 data interpolation circuits 1731 and 1732, respectively. Are interpolated by a signal having a value of 0 in the high-pass filter 173.
After being filtered by the third or low-pass filter 1734, they are added by the adder 1736 and output as a signal 737.

As the band synthesis filter 1725, a synthesis filter having a shorter tap length may be used in practice. If the tap length, filter coefficient, etc. of the band synthesis filter do not correspond to the band division filter, the original signal is not reproduced even if the band is divided and then synthesized, but as shown in this example, In the case of performing data compression using the property of hearing, if the signal distortion generated due to the filter mismatch is smaller than the amount of quantization noise generated due to the reduction in quantization accuracy,
Actually, it is masked by the signal sound, and the influence on the sound quality deterioration is negligible. In particular, in the case of the example shown in FIG. 21, for example, if the sampling frequency of the original signal is 48 kHz, the signal 726 is a signal in a high band of 12 kHz or more, and has almost no effect on the auditory characteristics and sound quality. Absent. In the above example, the code string before conversion is obtained by coding a spectrum signal divided into four bands by superimposing two stages of QMF. For example, this is divided into bands by PQF. After that, even if the signal is converted into a spectrum signal, the deterioration of the sound quality in the sense of hearing can be suppressed to a small degree due to the masking effect and the like, so that the same QMF filter as described above can be used. .

Further, it is possible to omit the band combining filter 1725. This will be described with reference to FIG. 23, taking a case where the sampling frequency of the original signal is 48 kHz as an example. In FIG. 23, a black circle (●) represents a sampling signal of the signal 732, and a broken line represents the signal 734 obtained by interpolating 0 data.
, And the solid line further represents the signal 736 after it has been passed through the low pass filter 1734. Here, the signal 732 is 1 sampled at 12 kHz.
It corresponds to a signal corresponding to the band from 2 kHz to 18 kHz,
Interpolating data means sampling the signal
This means that the rate is set to 24 kHz and signals in the band indicated by the broken line in FIG. 24 are added. However, 1
Since the human ear is extremely insensitive to sounds of 8 kHz or more, even if the signal in this band is omitted, the effect on the audibility is negligible.

Therefore, the data indicated by the broken line in FIG. 23 is converted into a spectrum signal, and 1
If the frequency of 8 kHz or higher is ignored, the processing of the low-pass filter 1734 shown in FIG. 22 can be omitted.
Also, since the signal of the band of 18 kHz or more is originally ignored, the processing of the 0 data interpolation circuit 1731, the high-pass filter 1733, and the addition circuit 1735 can be omitted, and the band shown in FIG. Synthesis filter 1
725 is not required.

The code conversion means having the spectrum signal conversion means configured as described above is configured by applying the code conversion device according to the present invention. That is, input means for inputting a first code sequence obtained by coding a spectrum signal obtained by band-dividing a time-series information signal into a first band group and then performing spectrum conversion with a first block length; Decoding means for decoding the code string of No. 1 and returning it to a spectrum signal, and converting the decoded spectrum signal into a spectrum signal of a form which is band-divided by the second band group and spectrum-converted by the second block length. For this purpose, only the low-frequency spectrum signal of the first code sequence is inversely transformed into a thinned time-series signal, and the thinned time-series signal is converted into a low-frequency spectrum signal. Means and coding means for coding the converted spectral signal.

FIG. 25 shows an example of the spectrum signal converting means in which the band combining filter is omitted. That is, in this case, the spectrum signal conversion means includes inverse spectrum conversion circuits 1741, 1742, and 1743, a forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1744,
Forward spectrum conversion circuit (forward spectrum conversion circuit 1) 17
45, 1746.

In the spectrum signal conversion means, the input signal 741 is subjected to inverse spectrum conversion processing by the inverse spectrum conversion circuits 1741, 1742, and 1743 for each band. Then, the inverse spectrum conversion circuit 174
Signals 742, 743, and 744 output from 1,1742, and 1743 and subjected to inverse spectrum conversion processing are subjected to forward spectrum conversion processing in forward spectrum conversion circuits 1744, 1745, and 1746, and are output as signals 745.

Here, specifically, for example, the inverse spectrum conversion circuits 1741, 1742, and 1743 respectively include the inverse spectrum conversion circuits 1722 and 1722 shown in FIG.
723 and 1724, and forward spectrum conversion circuits (forward spectrum conversion circuits 1) 1745 and 1746 correspond to, for example, the forward spectrum conversion circuits (forward spectrum conversion circuits 1) 1727 and 1728 shown in FIG. Here, the forward spectrum conversion circuit (forward spectrum conversion circuit 2) 1726 shown in FIG. 21 converts the 4M time-series signals 726 including the overlap into 2M spectrum signals from 12 kHz to 24 kHz. 25, the forward spectrum transform circuit (forward spectrum transform circuit 3) 1744 shown in FIG. 25 converts 2M time-series signals including the overlapped portion, excluding 0 data, into M number of time-series signals from 12 kHz to 18 kHz. , And the amount of arithmetic processing is much smaller.
In fact, for example, when this spectrum conversion is realized by a simple sum-of-products operation, the number of times of sum-of-products can be reduced to approximately 1/4. Higher speed is possible.

It is to be noted that the present invention can also be applied to a case where a code string obtained by directly coding a signal that has been subjected to spectrum conversion without band division is converted. FIG. 26 shows a configuration example of such a spectrum signal conversion means.

This spectrum signal conversion means comprises a low-frequency inverse spectrum conversion circuit 1959 and a low-frequency forward spectrum conversion circuit 1960. In this spectrum signal conversion means, the input signal 941 is subjected to low-frequency inverse spectrum conversion processing by a low-frequency inverse spectrum conversion circuit 1959, and thereafter, the low-frequency forward spectrum conversion circuit 1
In step 960, the signal 942 that has been subjected to the inverse spectrum conversion in the low-band inverse spectrum conversion circuit 1959 is subjected to a forward spectrum conversion process, and is output as a signal 943.

Here, specifically, signal 941 input to low-frequency inverse spectrum conversion circuit 1959 is a spectrum signal equivalent to that obtained by spectral conversion with a long block length, and output from low-frequency forward spectrum conversion circuit 1960. The signal 943 is a spectrum signal equivalent to that obtained by performing spectrum conversion with a short block length. However, signal 943
Is 0 on the high frequency side.

Also, a low-frequency inverse spectrum conversion circuit 1959
Outputs a time series signal 942 decimated according to the bandwidth from the spectrum signal on the low frequency side of the signal 941, and the low-frequency forward spectrum conversion circuit 1960 outputs the time series signal 942 decimated according to the bandwidth. From the signal 942, a signal 943 that is a spectrum signal on the lower frequency side is output.

As in the case of the band on the high frequency side shown in FIG. 25, in the configuration example of the spectrum signal converting means shown in FIG. 26, the processing speed is greatly increased as compared with processing the entire band. Can be achieved. However, in this case, since the thinning of the signal 942, which is a time-series signal, is reduced to １ ／ or less, the bandwidth of the spectrum signal 943 is also reduced to 、 or less. The bandwidth of the spectrum signal cannot be reduced to 3/4.

In FIG. 27, the code converted into the spectrum signal by the conversion means shown in FIG. 3 is converted into the code converted into the spectrum signal by the conversion means shown in FIG. 2 shows an example of the configuration of a spectrum signal converting means to be used.

The spectrum signal conversion means includes an inverse spectrum conversion circuit (inverse spectrum conversion circuit 2) 1861,
Inverse spectrum conversion circuit (Inverse spectrum conversion circuit 1) 18
62, 1863, a band division filter 1864, and forward spectrum conversion circuits 1865, 1866, 1867, 18
68.

In the spectrum signal conversion means, the input signal 861 is subjected to inverse spectrum conversion processing in each of the inverse spectrum conversion circuits 1861, 1862 and 1863 for each band. The signal 862 subjected to the inverse spectrum conversion processing by the inverse spectrum conversion circuit 1861
Is band-divided in a band division filter 1864.

The signals 865 and 866 band-divided by the band division filter 1864 and the signals 863 and 864 subjected to the inverse spectrum transform processing output from the inverse spectrum transform circuits 1862 and 1863 are converted into respective forward spectrum transform circuits 1865. , 1866, 1867, 18
At 68, the signal is forward-spectrum transformed and output as a signal 867.

Here, specifically, the inverse spectrum conversion circuit (inverse spectrum conversion circuit 2) 1861 corresponds to, for example, the inverse spectrum conversion circuit 1501 shown in FIG. The spectrum conversion circuits 1) 1862 and 1863 correspond to, for example, the inverse spectrum conversion circuits 1502 and 1503 similarly shown in FIG. Further, the forward spectrum conversion circuit 1865, 1
866, 1867 and 1868 are, for example, the forward spectrum conversion circuits 1602, 1603 and 16 shown in FIG.
04, 1605 respectively.

In the example shown in FIG. 27, the low-frequency side signal is subjected to inverse spectrum conversion by the inverse spectrum changing circuits 1862 and 1863, and immediately thereafter, the forward spectrum converting circuits 1867 and 1868 perform the forward spectrum conversion for each band. The spectrum has been transformed. As a result, the amount of calculation processing can be reduced as compared with the case where the original time-series signal is completely reproduced. Furthermore, with respect to the band division filter 1864, even if the tap length is relatively short, deterioration of sound quality is negligible, as in the case of the example shown in FIG.

Further, for example, as in the case of FIG.
If coding up to 8 kHz is sufficient, the band division filter 1864 can be omitted. FIG. 28 shows a configuration example of the spectrum signal converting means, and the sampling frequency of the original sound signal is 48 kHz.
5 shows an example of the configuration of the spectrum signal converting means in the case of.

This spectrum signal conversion means is composed of inverse spectrum conversion circuits 1881, 1882, 1883 and forward spectrum conversion circuits 1884, 1885, 1886.

In this spectrum signal conversion means, the input signal 881 is converted into signals 882, 883, and 884 which have been subjected to inverse spectrum conversion by the respective inverse spectrum conversion circuits 1881, 1882, and 1883 for each band, and immediately thereafter, the forward spectrum conversion is performed. Circuits 1884, 1885, 188
6 and output as a signal 885.

More specifically, the inverse spectrum conversion circuits (inverse spectrum conversion circuit 1) 1882 and 1883 are, for example,
The inverse spectrum conversion circuit 1862,1 shown in FIG.
863, and an inverse spectrum conversion circuit (inverse spectrum conversion circuit 3) 1881 also corresponds to the inverse spectrum conversion circuit 1861 shown in FIG. However, regarding the inverse spectrum conversion circuit 1881, the input signal 881 from 12 kHz to 24 kHz is changed from 12 kHz to 18 kHz.
, And a signal decimated to 上 on the time axis is output as an output signal 882. The forward spectrum conversion circuits 1884, 1885, and 1886 are, for example, the forward spectrum conversion circuits 186 shown in FIG.
6, 1867, and 1868.

That is, with the configuration shown in FIG. 28, the spectrum signal
Of the spectrum signals up to 4 kHz, the spectrum signal of 18 kHz or more is subjected to inverse spectrum conversion as 0, but since this signal does not substantially contain a signal component of 18 kHz or more, it is obtained. Even if the signals are simply thinned out, the effect of aliasing can be neglected, and it is not necessary to perform a band division filter.

Note that the inverse spectrum conversion circuit 1881
The half spectrum signal of the inverse spectrum conversion circuit 1861 shown in FIG. 27 is converted into a time-series signal decimated to half the number in the band. The processing is lighter in comparison with the inverse spectrum conversion circuit 1861 shown in FIG. 27, for the same reason as the processing in the forward spectrum conversion circuit 1744 shown in FIG. 25 is lighter.

The above description relates to the conversion of a spectral signal in the case of a monaural signal. However, by applying this to each channel, it is of course possible to cope with a multi-channel signal such as a stereo signal. However, in the case of such a multi-channel signal, using the characteristics of the auditory sense, while suppressing the sound quality deterioration in the auditory sense slightly,
Further, the processing can be simplified and the speed can be increased.

FIG. 29 shows a configuration example of a spectrum signal conversion means for converting a stereo spectrum signal into another spectrum signal at high speed.

This spectrum signal conversion means comprises inverse spectrum conversion circuits 1761, 1762, 1763, 176
4, 1765, 1766, and a time-series signal synthesizing circuit 176.
7, 1768, a forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1769, and a forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1770, 1771, 1772. Note that, in FIG.
1 is an L-channel spectrum signal, and a signal 762
Is the spectrum signal of the R channel.

The code conversion means having the spectrum signal conversion means includes an input means for inputting a first code string obtained by coding a time-series information signal corresponding to a plurality of channels, and an input first code string. And converting means for converting the sequence into a second code sequence having the same high-frequency side as the time-series information signal of a plurality of channels.

In FIG. 29, the input means is an inverse spectrum conversion circuit 1761, 1762, 1763, 176
4, 1765, 1766, and the conversion means are composed of time series signal combining circuits 1767, 1768.

For example, the spectrum signal converting means converts the time-series information signal of a plurality of channels into a first band group and converts the spectrum signal into a first band group.
Means for inputting a first code string obtained by encoding, decoding means for decoding the input first code string and returning it to a spectrum signal, and converting the decoded spectrum signal into a second band group Used as a spectrum conversion means of a code string conversion means having a spectrum signal conversion means for converting into a spectrum signal in a form of divided and spectrum converted, and an encoding means for coding the converted spectrum signal to form a second code string. However, the spectrum signal converting means may convert signals of a plurality of high-frequency channels into the same signal.

In this spectrum signal converting means, the signal 76 which is an input L channel spectrum signal
1 is an inverse spectrum conversion circuit 1761, 17 for each band.
63, 1765, the input signal 762, which is the spectrum signal of the R channel, is supplied to the inverse spectrum conversion circuit 176 for each band.
In 2,1764,1766, inverse spectrum conversion processing is performed.

Then, the inverse spectrum conversion circuit 1761,
The signal 763 inversely transformed in 1762
764 is synthesized in the time domain by the time-series signal synthesizing circuit 1767,
Signals 765 and 766 that have been subjected to inverse spectrum conversion processing in 3,1764 are synthesized in a time domain by a time-series signal synthesis circuit 1768. Each of the signals 769 and 770 generated by being synthesized by the time-series signal synthesizing circuits 1767 and 1768 is converted into a forward spectrum conversion circuit 176.
At 9, 1770, forward spectrum conversion processing is performed.

The inverse spectrum conversion circuit 1765,1
The signal 76 subjected to the inverse spectrum conversion processing at 766
7, 768 is a direct spectrum conversion circuit 17 immediately thereafter.
At 71 and 1772, forward spectrum conversion processing is performed, respectively.

As described above, the spectrum signal converting means appropriately performs inverse spectrum conversion and forward spectrum conversion on the input signals 761 and 762 of a plurality of channels, respectively, to obtain signals 771 and 772 again as a plurality of channel signals. Output.

Here, specifically, the inverse spectrum conversion circuits 1761, 1763, and 1765 and the inverse spectrum conversion circuits 1762, 764, and 1766 are, for example, shown in FIG.
5, the inverse spectrum conversion circuits 1741, 1742,
1743 respectively.

In the example configured as described above, except for the lowest band signal, the L channel signal and the R channel signal are combined in the time domain and then subjected to the forward spectrum conversion. In general, the effect of the high-frequency signal on the sense of stereo is negligible, so that such conversion does not greatly impair the sound quality. By performing such processing, it is possible to reduce the processing amount of the forward spectrum conversion on the high frequency side while maintaining fairly good sound quality, thereby enabling higher-speed conversion. In the above description, the forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1769 and the forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1
770, the output signal of each channel is the same, but as a modified example of this method, the L /
A forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1769 based on the energy ratio of the input spectrum signal of R
And forward spectrum conversion circuit (forward spectrum conversion circuit 1)
The output signal of each channel of 1770 may be weighted to generate a signal of each channel.

In the above description of FIG. 29, a method of processing a plurality of channels based on the conversion method of ignoring the highest band shown in FIG. 25 has been described. The other conversion methods described with reference to FIG. 28 are also applicable.

That is, when the embodiment shown in FIG. 21 is applied, inverse spectrum conversion circuits 1761, 1761
62 is converted to the inverse spectrum conversion circuit 172 in FIG.
1, 1722, and a high-band conversion unit constituted by a band synthesis filter 1725. At this time, the time-series signal synthesizing circuit 1767
A signal from kHz to 24 kHz is synthesized in the time domain.
Note that the forward spectrum conversion circuit (forward spectrum conversion circuit 3)
1769 is replaced by a forward spectrum conversion unit that performs the same processing as the forward spectrum conversion circuit (forward spectrum conversion circuit 2) 1726.

In the case where the embodiment shown in FIG. 27 is applied, inverse spectrum converting means 1761 and 1762 are used.
Is converted to an inverse spectrum conversion circuit (inverse spectrum conversion circuit 2) 1861 and a band division filter 186 in FIG.
4 may be replaced by high-frequency conversion means. At that time, 18kHz to 24kHz
27, that is, the signal 865 in FIG.
Are added to the time-series signal synthesizing means for processing the output corresponding to .times. As the output of the newly added forward spectrum conversion means, L / R output signals are output as signals 771 and 772, respectively. Also, the time-series signal synthesizing circuit 1767 is used for processing the band from 12 kHz to 18 kHz, that is, the output corresponding to the signal 866 in FIG. Note that the forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1769 is replaced by a forward spectrum conversion circuit that performs the same processing as the forward spectrum conversion circuit 1866. Similarly, the inverse spectrum conversion circuits 176 3, 1764, 1765, 1766 and the forward spectrum conversion circuit (forward spectrum conversion circuit 1) 17
Numerals 70, 1771, and 1772 are inverse spectrum conversion circuits 1862, 1862, and 186, respectively, corresponding to FIG.
3, 1863 and forward spectrum conversion circuits 1867, 18
68,1868.

In the case where the embodiment shown in FIG. 28 is applied, inverse spectrum conversion circuits 1761 and 176 are provided.
2, 1763, 1764, 1765, 1766, forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1769, and forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1
770, 1771, and 1772 are inverse spectrum conversion circuits 1881, 1881, and 188, respectively, corresponding to FIG.
2, 1882, 1883, 1883 and forward spectrum conversion circuits 1884, 1885, 1886, 1886.

While FIG. 29 described above combines high-frequency signals in the time domain, FIG. 30 shows an example of the configuration of a spectrum signal conversion means that can combine spectral signals in the frequency domain. Is shown.

The spectrum signal converting means includes spectrum signal synthesizing circuits 1781 and 1782, inverse spectrum converting circuits 1783, 1784, 1785 and 1786, and a forward spectrum converting circuit (forward spectrum converting circuit 3) 1787.
And a forward spectrum conversion circuit (forward spectrum conversion circuit 1)
1788, 1789, and 1790.

In this spectrum signal conversion means, the input signals 781 and 782 are synthesized in each band by spectrum signal synthesizing circuits 1781 and 1782. Then, the spectrum signal synthesizing circuit 1781,
Each signal 783, 784 synthesized in 1782
Are subjected to inverse spectrum conversion processing in inverse spectrum conversion circuits 1783 and 1784 to become signals 785 and 786, and are subjected to forward spectrum conversion processing in forward spectrum conversion circuits 1787 and 1788.

On the other hand, the input signals 781 and 7
For the low band 82, the inverse spectrum conversion circuit 178
5 and an inverse spectrum conversion circuit 1786 performs an inverse spectrum conversion process to obtain a signal 787 and a signal 788. Then, the signal 787 and the signal 788 are subjected to the forward spectrum conversion processing in the forward spectrum conversion circuit 1789 and the spectrum conversion circuit 1790.

Thus, the spectrum signal conversion means
Signals 781 and 782 input as stereo signals are
The inverse spectrum conversion processing and the inverse spectrum conversion processing are appropriately performed and output as signals 789 and 790.

In this spectrum signal conversion means, the processing of the inverse spectrum conversion means is simplified, and the speed can be further increased. However, this configuration cannot be used when the conversion block length differs between L / R channels. Also in this example, L on the high frequency side
A forward spectrum conversion circuit (forward spectrum conversion circuit 3) 178 based on the energy ratio of the input spectrum signal of / R
7 and the forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1788 may weight the output signals of each channel to generate a signal of each channel.

For example, the inverse spectrum conversion unit 176a shown in FIG. 29 and the inverse spectrum conversion unit 1 shown in FIG.
78a can be configured to be switchable. In this way, by configuring the inverse spectrum conversion unit 176a and the inverse spectrum conversion unit 178a so as to be switchable, it becomes possible to execute processing in consideration of processing speed and data accuracy.

Also, in the above description of FIG. 30, a method of processing a plurality of channels based on the conversion method of ignoring the highest band shown in FIG. 25 has been described. The other conversion methods described with reference to FIG. 28 are also applicable.

That is, in the case where the embodiment shown in FIG. 21 is applied, inverse spectrum conversion circuit 1783 is replaced with inverse spectrum conversion circuits 1721 and 172 in FIG.
2 and a high-band converting means constituted by a band synthesizing filter 1725. At this time, the spectrum signal synthesizing circuit 1781
Are synthesized in the frequency domain. The forward spectrum conversion circuit (forward spectrum conversion circuit 3) 178
7 is replaced by a forward spectrum conversion unit that performs the same processing as the forward spectrum conversion circuit (forward spectrum conversion circuit 2) 1726.

In the case where the embodiment shown in FIG. 27 is applied, the inverse spectrum conversion circuit 1783
In this case, it is sufficient to replace each of them by an inverse spectrum conversion circuit (inverse spectrum conversion circuit 2) 1861 and a high-band conversion means including a band division filter 1864. At this time, the forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1787 is a forward spectrum conversion circuit 1866 for processing the band from 12 kHz to 18 kHz, that is, the output corresponding to the signal 866 in FIG.
Forward spectrum conversion means corresponding to
It is replaced by a forward spectrum conversion means corresponding to a forward spectrum conversion circuit 1865 for processing an output corresponding to the highest band which is a 4 kHz band, that is, the signal 865 in FIG. The L / R output signals output from these forward spectrum conversion means are signals 789 and 790, respectively.
Is output as Also, an inverse spectrum conversion circuit 178
4, 1785, 1786 and forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1788, 1789, 1790
Correspond to the inverse spectrum conversion circuit 1 shown in FIG.
862, 1863, 1863 and forward spectrum conversion circuits 1867, 1868, 1868.

In the case where the embodiment shown in FIG. 28 is applied, inverse spectrum conversion circuits 1783 and 178 are provided.
4, 1785, 1786, forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1787, and forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1788, 1789, 1
Reference numeral 790 denotes an inverse spectrum conversion circuit 1881, 1882, 1883, 1883 and a forward spectrum conversion circuit 1884, 1885, 1886, 18 corresponding to FIG.
86.

FIG. 31 shows (L + R) / 2,
Spectral signals 801 and 80 corresponding to (LR) / 2
2 shows a configuration example of a spectrum signal conversion unit that can convert the spectrum signals into different spectral signals 809 and 810 corresponding to L and R, respectively.

This spectrum signal conversion means includes inverse spectrum conversion circuits 1801, 1802, 1803, and 1804.
, A signal combining circuit 1805, 1806, a forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1807, and a forward spectrum conversion circuit (forward spectrum conversion circuit 1) 180
8, 1809 and 1810.

In this spectrum signal conversion means, the input signal 801 is subjected to inverse spectrum conversion processing in each of the inverse spectrum conversion circuits 1801, 1802, and 1803 for each band, and the signal 802 is subjected to inverse spectrum conversion by the inverse spectrum conversion circuit 1804. It is processed. And
The signal 805 subjected to the inverse spectrum conversion processing in the inverse spectrum conversion circuit 1803 is converted into a signal
Signals 806 input to 806 and subjected to inverse spectrum conversion processing in inverse spectrum conversion circuit 1804 are input to signal synthesis circuits 1805 and 1806, respectively.

In the signal synthesizing circuit 1805, the signal 80
5 and a signal 806, and a signal combining circuit 1806 performs a combining process on the signal 805 and the signal 806. The signals 807 and 808 from the signal synthesizing circuits 1805 and 1806 are converted into forward spectrum conversion circuits 1809 and
At 1810, a forward spectrum conversion process is performed.

Here, as for the forward spectrum conversion circuit 1807, the forward spectrum conversion circuit 1 shown in FIG.
A forward spectrum conversion process is performed by a function similar to that of the 787.

Also, the inverse spectrum conversion circuit 1801,1
The signal 80 subjected to the inverse spectrum conversion processing at 802
As for 3,804, the forward spectrum conversion processing is immediately performed in the forward spectrum conversion circuits 1807 and 1808.

As described above, the spectrum signal converting means converts the signals 801 and (LR) / (L + R) / 2 into signals (L + R) / 2.
2 is appropriately subjected to inverse spectrum conversion processing and forward spectrum conversion processing.
It is output as 9,810.

With this configuration, the spectrum signal conversion means performs processing of the band from 12 kHz to 18 kHz by the inverse spectrum conversion circuit 1801 assuming that the original time-series signal is sampled at 48 kHz. The circuit 1802 processes the band from 6 kHz to 12 kHz, and the inverse spectrum conversion circuit 1803,1
According to 804, processing in a band from 0 kHz to 6 kHz is performed.

The signal synthesizing circuit 1805 has (L + R) / 2,
From the (LR) / 2 low-frequency time-series signal, the L-channel low-frequency time-series signal is converted into a signal (L + R) /
The low-frequency time-series signal of the R channel is synthesized from the low-frequency time-series signal of 2, (LR) / 2, respectively. In this configuration example, only the band of 0 kHz to 6 kHz is used for separate L / R signals. A spectrum signal is generated, and on the high frequency side, an L / R identical spectrum signal is generated. That is, a forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1807 and a forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1808
Output the same signal for the L channel and the R channel, respectively.

This utilizes the fact that the effect on the sense of stereo has a large effect on the low-frequency side, as described above. That is, even if the processing is simplified in this way, a relatively good stereo effect is obtained. A feeling can be obtained.

However, it is a matter of course that a more faithful stereo feeling can be obtained by encoding the L / R separate spectrum signals. As a modification, for example, (L +
From the (R) / 2, (LR) / 2 spectrum signals, the energy ratio of the L channel and R channel signals is obtained, and the weighting of the high band L channel and R channel spectrum signals is performed based on the energy ratio. You may do it.

In the above description of FIG. 31, a method of processing a plurality of channels based on the conversion method of ignoring the highest band shown in FIG. 25 has been described. The other conversion methods described with reference to FIG. 28 are also applicable.

That is, in the case where the embodiment shown in FIG. 21 is applied, the inverse spectrum conversion circuit 1801 is replaced with the inverse spectrum conversion circuits 1721 and 172 shown in FIG.
2 and a high-band converting means constituted by a band synthesizing filter 1725.
Note that the forward spectrum conversion circuit (forward spectrum conversion circuit 3)
1807 is replaced by a forward spectrum conversion unit that performs the same processing as the forward spectrum conversion circuit (forward spectrum conversion circuit 2) 1726.

In the case where the embodiment shown in FIG. 27 is applied, inverse spectrum conversion circuit 1801 is
In this case, it is sufficient to replace each of them by an inverse spectrum conversion circuit (inverse spectrum conversion circuit 2) 1861 and a high-band conversion means including a band division filter 1864. At this time, the forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1807 is a forward spectrum conversion circuit 1866 for processing the band from 12 kHz to 18 kHz, that is, the output corresponding to the signal 866 in FIG.
Forward spectrum conversion means corresponding to
It is replaced by a forward spectrum conversion means corresponding to a forward spectrum conversion circuit 1865 for processing an output corresponding to the highest band which is a 4 kHz band, that is, the signal 865 in FIG. The output signals of L / R, which are the outputs of these forward spectrum conversion means, are signals 809 and 810, respectively.
Is output as Also, an inverse spectrum conversion circuit 180
2, 1803, 1804 and forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1808, 1809, 1810
Correspond to the inverse spectrum conversion circuit 1 shown in FIG.
862, 1863, 1863 and forward spectrum conversion circuits 1867, 1868, 1868.

When the embodiment shown in FIG. 28 is applied, inverse spectrum conversion circuits 1801 and 180
2, 1803, 1804, forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1807, and forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1808, 1809, 1
810 are inverse spectrum conversion circuits 1881, 1882, 1883, 1883 and forward spectrum conversion circuits 1884, 1885, 1886, 18 corresponding to FIG.
86.

FIG. 32 shows (L + R) / 2,
Spectral signals 821 and 82 corresponding to (LR) / 2
2 shows an example of the configuration of a spectrum signal conversion unit that can convert the spectrum signals 2 into different spectral signals 832 and 833 corresponding to L and R, respectively.

This spectrum signal conversion means includes inverse spectrum conversion circuits 1821, 1822, 1823, 182
4, 1825 and signal combining circuits 1826, 1827, 1
828, 1829, a forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1830, and a forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1831, 1832, 18
33, 1834.

In this spectrum signal conversion means, the input signal 821 is subjected to inverse spectrum conversion processing in each of the inverse spectrum conversion circuits 1821, 1822, and 1824 for each band, and the signal 822 is inverted in the inverse spectrum conversion circuits 1823 and 1825. The spectrum conversion processing is performed.

The signal 824 subjected to the inverse spectrum conversion processing by the inverse spectrum conversion circuit 1822 is input to the signal synthesis circuits 1826 and 1827, respectively. The signal 826 subjected to the inverse spectrum conversion processing by the inverse spectrum conversion circuit 1824 is Signal synthesis circuit 182
8, 1829, respectively.

The signal 825 subjected to the inverse spectrum conversion processing in the inverse spectrum conversion circuit 1823 is input to signal synthesis circuits 1826 and 1827, respectively.
The signal 827 subjected to the inverse spectrum conversion processing in the inverse spectrum conversion circuit 1825 is converted into a signal
829 respectively.

The signal synthesizing circuits 1826 and 1827 are
The signals 828 and 829 are synthesized by the input signals 824 and 825, respectively, and the signal synthesizing circuits 1828 and 1829 synthesize the signals 826 and 827 to generate the signals 830 and 831. Generate.

Each of the signal synthesizing circuits 1826 and 182
7, 828, 1829;
829, 830, 831 are the forward spectrum conversion circuits 18
At 31, 1832, 1833, and 1834, forward spectrum conversion processing is performed, respectively. The signal 823 that has been subjected to the inverse spectrum conversion processing by the inverse spectrum conversion circuit 1821 is immediately thereafter converted into the forward spectrum conversion circuit 183.
At 0, a forward spectrum conversion process is performed.

As described above, the spectrum signal conversion means appropriately performs the forward spectrum conversion processing and the inverse spectrum conversion processing on the input signals 821 and 822 to obtain the signal 83.
2,833.

Here, the inverse spectrum conversion circuit 1821 shown in FIG. 32 has a 12 kHz to 18 kHz band, the inverse spectrum conversion circuits 1822 and 1823 have a 6 kHz to 12 kHz band, and the inverse spectrum conversion circuits 1824 and 1825 have a 0 kHz band.
From 6 kHz to 6 kHz. The spectrum signal conversion means generates separate L / R spectrum signals in a band from 0 kHz to 12 kHz. As a result, a more faithful stereo feeling can be realized although the amount of calculation processing is increased as compared with the spectrum signal converting means shown in FIG.

In the above description of FIG. 32, a method of processing a plurality of channels based on the conversion method of ignoring the highest band shown in FIG. 25 has been described. The other conversion methods described with reference to FIG. 28 are also applicable.

That is, in the case where the embodiment shown in FIG. 21 is applied, inverse spectrum conversion circuit 1821 is replaced with inverse spectrum conversion circuits 1721 and 172 in FIG.
2 and a high-band converting means constituted by a band synthesizing filter 1725.
Note that the forward spectrum conversion circuit (forward spectrum conversion circuit 3)
Reference numeral 1830 is replaced by a forward spectrum conversion unit that performs the same processing as the forward spectrum conversion circuit (forward spectrum conversion circuit 2) 1726.

When the embodiment shown in FIG. 27 is applied, inverse spectrum conversion circuit 1821 is
In this case, it is sufficient to replace each of them by an inverse spectrum conversion circuit (inverse spectrum conversion circuit 2) 1861 and a high-band conversion means including a band division filter 1864. At this time, the forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1830 is a forward spectrum conversion circuit 1866 for processing the band from 12 kHz to 18 kHz, that is, the output corresponding to the signal 866 in FIG.
Forward spectrum conversion means corresponding to
It is replaced by a forward spectrum conversion means corresponding to a forward spectrum conversion circuit 1865 for processing an output corresponding to the highest band which is a 4 kHz band, that is, the signal 865 in FIG. The output signals of L / R which are the outputs of these forward spectrum conversion means are signals 833 and 833, respectively.
Is output as Also, an inverse spectrum conversion circuit 182
2, 1823, 1824, 1825 and forward spectrum conversion circuits (forward spectrum conversion circuits 1) 1831, 183
2, 1833 and 1834 respectively correspond to the inverse spectrum conversion circuits 1862, 1862, 1863,
1863 and forward spectrum conversion circuits 1867 and 186
7, 1868, 1868.

In the case where the embodiment shown in FIG. 28 is applied, inverse spectrum conversion circuits 1821 and 182
2, 1823, 1824, 1825, a forward spectrum conversion circuit (forward spectrum conversion circuit 3) 1830, and a forward spectrum conversion circuit (forward spectrum conversion circuit 1) 1831, 1
Reference numerals 832, 1833, and 1834 denote inverse spectrum conversion circuits 1881, 1882, and 188, respectively, corresponding to FIG.
2,1883,1883 and forward spectrum conversion circuit 18
84, 1885, 1885, 1886, 1886.

In the above-described method in which high-frequency signals are collectively converted on a plurality of channels, the above-described method is not necessarily performed to convert between code strings equivalent to those obtained by encoding a signal obtained by band-divided and spectrum-converted. However, the present invention is not limited to this. For example, the present invention can also be applied to a case where at least one of the code strings is divided into bands and the time series signals decimated in each band are encoded.

It is also possible to collectively process signals on the high frequency side using a plurality of channels without using a band division filter. FIG. 33 shows an example of the configuration of a spectrum signal conversion means that makes this possible.

This spectrum signal conversion means includes a channel conversion circuit 1962 and an inverse spectrum conversion circuit 1963
, Forward spectrum conversion circuit 1965, low band inverse spectrum conversion circuit 1964, low band forward spectrum conversion circuit 19
66, a channel conversion circuit 1967, a weight calculation circuit 1961, and a high-frequency weighting circuit 1968, 1969.
It is composed of

Here, the code conversion means having the above-mentioned spectrum signal conversion means includes an input means for inputting a first code string obtained by coding a time-series information signal corresponding to a plurality of channels, The first code string is converted to a second code string in which the high-frequency side when the time-series information signals of the plurality of channels are made the same and the same signal is weighted for each channel. And conversion means.

In FIG. 33, the spectrum signal conversion means has an input means of channel conversion circuits 1962 and 1962.
67, an inverse spectrum conversion circuit 1963, a forward spectrum signal conversion circuit 1965, a low band inverse spectrum conversion circuit 196
4 and a low-frequency forward spectrum conversion circuit 1966, and the conversion means for performing the weighting includes high-frequency weighting circuits 1968 and 1969.

In this spectrum signal conversion means,
The input signals 961 and 962 are channel-converted in a channel conversion circuit 1962. The signal 963 that has been channel-converted by the channel conversion circuit 1962 is converted into a signal 965 that has been subjected to inverse spectrum conversion processing by the inverse spectrum conversion circuit 1963, and then subjected to forward spectrum conversion processing by the forward spectrum conversion circuit 1965. Further, the channel conversion circuit 196
The signal 964 output from 2 is converted into a signal 966 that has been subjected to inverse spectrum conversion by the low-band inverse spectrum conversion circuit 1964, and subjected to forward spectrum conversion processing in the low-band forward spectrum conversion circuit 1966.

The channel conversion circuit 1967 performs channel conversion on the signals 967 and 968 output from the forward spectrum conversion circuit 1965 and the low band forward spectrum conversion circuit 1966. Here, the channel-converted signal 9
69, 970 are high-frequency weighting circuits 1968, 196
9 is input. The input signals 961, 9
Reference numeral 62 denotes a weighting coefficient calculated by the weighting coefficient calculation circuit 1961.

The high-frequency weighting circuits 1968 and 1969
The weight coefficient is determined by the signals 971 and 972 composed of the weight coefficients output from the weight coefficient calculation circuit 1961, and the signals 969 and 970 from the channel conversion circuit 1967 are weighted.
The signals are output as signals 973 and 974, respectively.

Here, specifically, signals 961 and 962 input to channel conversion circuit 1962 are L channel and R channel spectrum signals, respectively.
The channel conversion circuit 1962 calculates (L +
An (R) / 2 spectral signal 963 and an (LR) / 2 spectral signal 964 are generated.

Here, the signal of (L + R) / 2 is converted to an inverse spectrum conversion circuit 1963 and a forward spectrum conversion circuit 1963.
65, the entire band of the spectrum signal 967 is sent to the channel conversion circuit 1967, whereas the (LR) / 2 signal is sent to the low-band inverse spectrum conversion circuit 1964, Range order spectrum conversion circuit 196
6, only the low band side processing is performed, and the low band side spectral signal 968 is sent to the channel conversion circuit 1967.

The channel conversion circuit 1967 outputs signals 967,
From 968, the spectral signal 969 of the L channel and R
Generate a spectral signal 970 for the channel,
High frequency weighting circuit 1968, high frequency weighting circuit 1969
Send to

On the other hand, the weighting coefficient calculation circuit 1961
From the original L-channel spectral signal 961 and the original R-channel spectral signal 962, the L-channel high-band weighting coefficients 971 and R based on the L-channel and R-channel energy ratios of the higher-band spectral signal. The high frequency weighting coefficient 972 of the channel is calculated and sent to the high frequency weighting circuit 1968 and the high frequency weighting circuit 1969, respectively.

The high-frequency weighting circuit 1968 and the high-frequency weighting circuit 1969 calculate
The high-frequency signals of the spectral signals of the respective channels are weighted and output as an L-channel spectral signal 973 and an R-channel spectral signal 974. As described above, by performing the weighting process, it is possible to convert a code string at high speed while maintaining a stereo feeling.

In the spectrum signal conversion means shown in FIG. 33, the inverse spectrum conversion circuit 1963 and the forward spectrum conversion circuit 1965 constitute a so-called full spectrum signal conversion circuit 196a. And a low band forward spectrum conversion circuit 1966 is a so-called low band spectrum signal conversion circuit 196.
b.

For example, here, the whole spectrum signal conversion circuit 196a has the same configuration as the spectrum signal conversion means shown in FIG. 21, and the low band spectrum signal conversion circuit 196b is the same as that shown in FIG. Inverse spectrum conversion circuit 1723,1 constituting a spectrum signal conversion part
724 and forward spectrum conversion circuits 1727 and 1728. Furthermore, the whole-band spectrum signal conversion circuit 196a and the low-band spectrum signal conversion circuit 19
6b may have the same configuration as the entire spectrum signal converting means shown in FIG. 25 or the low-frequency side thereof. It is needless to say that the whole-band spectrum signal conversion circuit 196a and the low-band spectrum signal conversion circuit 196b can be configured other than these configurations. For example, the full spectrum signal conversion circuit 196a
A circuit for converting a spectrum signal of the entire band without performing band synthesis and band division, a low-band spectrum signal conversion circuit 1
96b may have the same configuration as in FIG.

When the spectrum signal of the L channel and the spectrum signal of the R channel are converted into the spectrum signal of another L channel and the spectrum signal of the R channel by the above method, the processing of the (LR) / 2 signal is performed in the low band. The amount of computation processing can be reduced as compared with the case where the L-channel spectral signal and the R-channel spectral signal are processed independently, because only the side is required.

In this case, even if the weighting means on the high frequency side is omitted and the output spectrum signal on the high frequency side is the same for the L channel and the R channel, a relatively good stereo feeling can be obtained. It is possible to maintain

FIG. 34 shows the structure of the code conversion means which allows the user to select whether to give priority to the conversion processing speed between codes or to realize higher-quality sound coding after conversion. An example is shown. In this example, whether or not a more faithful stereo feeling is obtained is used as a reference for high sound quality.

This code conversion means includes a code string decomposition circuit 18
41, a signal component decoding circuit 1842, a spectrum signal conversion circuit (spectral signal conversion circuit 1) 1843, a signal component encoding circuit 1845, and a code sequence generation circuit 1846.
, An input circuit 1847, a control circuit 1848, and a spectrum signal conversion circuit (spectrum conversion circuit 2) 1844.

Here, the code conversion means includes a spectrum signal conversion circuit (spectral signal conversion circuit 1) 1843 as a plurality of code conversion processing means for converting the first code string into the second code string, and Based on the conversion circuit (spectral signal conversion circuit 2) 1844 and the selection information (signal 848) which is the input conversion conversion processing speed control information, the spectrum signal conversion circuit (spectral signal conversion circuit 1) 1843 and the spectrum signal conversion And a control circuit 1848 which is a code conversion selecting means for selecting any one of the circuits (spectral signal converting circuit 2) 1844.

In this code conversion means, the input signal 841 is decomposed into a code sequence by a code sequence decomposition circuit 1841, and the decomposed signal 842 is decoded by a signal component decoding circuit 1842. The signal 843 decoded here is converted into a spectrum signal at the corresponding processing speed in the spectrum signal conversion circuit (spectrum signal conversion circuit 2) 1844 or the spectrum signal conversion circuit (spectrum signal conversion circuit 1) 1843. 844 as a signal component encoding circuit 1845
Is input to The signal 844 is output from the signal component encoding circuit 18.
The signal 845 is converted into a signal 845 that has been subjected to the encoding process, and is input to the code string generation circuit 1846.

The spectrum signal conversion circuit 18
44 and 1843 are switched by the control circuit 1848. That is, a control signal 849 is generated by a signal 848 output from the input means in response to the request 847, and the control circuit 1848 controls switching of the spectrum signal conversion circuit 1844 and the spectrum signal conversion circuit 1843 by using this signal. .

Here, specifically, in FIG. 34, the spectrum signal conversion circuit (spectrum signal conversion circuit 1)
Reference numeral 1843 has the same configuration as the spectrum conversion means shown in FIG. 31, and the spectrum signal conversion circuit (spectral signal conversion circuit 2) 1844 has the same configuration as the spectrum conversion means in FIG.

The control circuit 1848 is connected to the input circuit 18
In accordance with the selection information 848 given via 47, it is controlled whether the conversion between spectra is realized by the spectrum signal conversion circuit 1843 or the spectrum signal conversion circuit 1844.

FIG. 35 shows a flowchart for the control means of FIG. 34 to execute the selection process. The selection process of the control means performed here is as described above with reference to FIG.
Are performed based on the signal 848 which is the selection information shown in FIG.

First, in step S101, the code conversion means performs a determination process based on the selection information as to whether or not the request is for a conversion speed-oriented request.

Here, if it is confirmed that the request places importance on the conversion speed, the code conversion means proceeds to step S102.
The spectrum conversion by the spectrum signal conversion circuit 1843 is performed.

If it is confirmed that the request does not place importance on the conversion speed, the code conversion means proceeds to step S103.
The spectrum conversion by the spectrum signal conversion circuit 1844 is performed.

According to the above processing, the user can select whether to give priority to the conversion processing speed between codes or to realize higher-quality sound encoding after conversion.
In addition to this, for example, the type of a band division filter or a band synthesis filter used for code conversion may be selectively switched.
Where the band should be synthesized by the band synthesis filter of
Replacing by processing within a limited band by the band synthesis filter of the MF may be selectively used.

Further, the number of taps may be selectively changed even for the same QMF band synthesis filter. Further, the converted code string may be configured so that the highest reproducible band can be selectively changed instead of the band in which each channel can be reproduced independently.

Also, the selection processing described with reference to FIGS. 34 and 35 can be arbitrarily combined with the conversion processing described with reference to FIGS. It may be configured to be able to do so.

In any of the above cases, it is possible to allow the user to select which of the conversion processing speed between code strings and the reproduced sound quality of the converted code string should be given priority. This is clear from the explanation so far.

In the above, the description has been given of the case where the code transmitted through the communication path is converted into the code for recording on the recording medium. In addition, for example, the code recorded on one recording medium may be replaced with another code. It is needless to say that the present invention can be applied to a case of converting into a code for a recording medium recorded in another format.

[0276] Also, the case where an audio signal is used has been described as an example, but the present invention is directed to a code string obtained by converting an image signal into a spectrum signal by using a band division filter and a spectrum conversion and coding it. It is possible to apply to conversion between.

The various processes executed by the compressed data recording and / or reproducing apparatus may be executed by a program recorded on a recording medium.
That is, for example, an information processing apparatus that performs data processing may execute the above-described processing using a program recorded on a recording medium.

The compressed data recording and / or reproducing apparatus according to the above-described embodiment encodes a spectrum signal obtained by dividing a time-series information signal into a first band group and then performing spectrum conversion with a first block length. The obtained first code sequence is input, the input first code sequence is decoded to return to a spectrum signal, and the decoded spectrum signal is divided into a second band group and divided by a second block length. By converting the spectrum signal into a spectrum signal in the form of spectrum conversion and encoding the converted spectrum signal to form a second code string, the code string can be converted at high speed. Accordingly, for example, a code string transmitted in a short time in a communication path can be rapidly converted to another code string.

[0279] The compressed data recording and / or reproducing apparatus according to the above-described embodiment inputs the first code string obtained by encoding the time-series information signal corresponding to a plurality of channels, and inputs the input first code string. Is converted into a second code sequence having the same high-frequency side as a time-series information signal of a plurality of channels, for example, band-divided into a plurality of channels into spectrum signals. When converting the converted code string, high-frequency components can be collectively processed.

Thus, it is possible to convert a code string composed of a time series information signal composed of a plurality of channels at a high speed. For example, a code string transmitted in a short time on a communication path can be quickly converted to another code string.

The compressed data recording and / or reproducing apparatus according to the above-described embodiment inputs the first code string obtained by coding the time-series information signal corresponding to a plurality of channels, and inputs the first code string. The first code string is converted to a second code string in which the high-frequency side when the time-series information signals of the plurality of channels are made the same and the same signal is weighted for each channel. This makes it possible to collectively process high-frequency components when converting a code string converted into a spectrum signal by band division including a plurality of channels.

Thus, it is possible to convert a code string composed of a time-series information signal composed of a plurality of channels at a high speed. For example, a code string transmitted in a short time on a communication path can be quickly converted to another code string.

In the above-described compressed data recording and / or reproducing apparatus according to the present embodiment, a plurality of code conversion processes for converting the first code string into the second code string can be selected. Based on the converted conversion processing speed control information,
By selecting a plurality of code conversion processes, it is possible to secure a conversion speed that satisfies the request based on the code conversion process speed information requested by the user or the like. At this time, for example, if the first code string is audio information, sound quality can be ensured.

[0284] The compressed data recording and / or reproducing apparatus according to the present embodiment described above converts the time-series information signal to the first data.
A first code string obtained by encoding a spectrum signal that has been subjected to spectrum conversion with a first block length after band division into band groups is input, and the first code string is converted into a second band group. After being band-divided, the spectrum is converted into a second code string in a form of being coded and encoded by a second block length, and the second code string is recorded on a recording medium, so that the long code after band division is obtained. A code string transmitted by encoding a signal converted to a spectrum signal with a block length is converted into a code string equivalent to an encoded signal converted to a spectrum signal with a short block length after band division. Can be recorded on a recording medium.

This makes it possible to convert a code string at a high speed. For example, it is possible to convert a code string transmitted in a short time in a communication path into another code string at a high speed and record it on a recording medium. Becomes possible.

Further, the compressed data recording and / or reproducing apparatus according to the present embodiment described above converts the time-series information signal into the first data.
A first code string obtained by encoding a spectrum signal that has been subjected to spectrum conversion after band division into band groups is input, and the input first code string is decoded and returned to a spectrum signal.
In order to convert the decoded spectrum signal into a spectrum signal of a form which is band-divided and spectrum-converted in the second band group, a time-series signal in which some of the spectrum signals are thinned out in the higher band. By converting the decimated time-series signal into a low-frequency spectrum signal in the high-frequency band, and encoding the converted spectrum signal into a second code sequence. , The code string can be converted at high speed. Accordingly, for example, a code string transmitted in a short time in a communication path can be rapidly converted to another code string.

Also, the compressed data recording and / or reproducing apparatus according to the above-described embodiment is capable of directly converting the time-series information signal or dividing the time-series information signal into the first band group, and then performing spectrum conversion with the first block length. Is input, a first code string obtained by encoding is input, the input first code string is decoded and returned to a spectrum signal, and the decoded spectrum signal is divided into bands directly or in a second band group. In order to convert the spectrum signal into a spectrum signal in a form converted into a spectrum with the second block length, only the spectrum signal on the lower frequency side of the first code string is inversely transformed into a decimated time-series signal, The converted time-series signal is converted into a low-frequency-side spectrum signal, and the converted spectrum signal is encoded, so that the code string can be converted at high speed. Accordingly, for example, a code string transmitted in a short time in a communication path can be rapidly converted to another code string.

[0288]

According to the code conversion method of the present invention, there is provided an input step of inputting a first code string obtained by coding a spectrum signal obtained by band-dividing a time-series information signal into a first band group and then performing spectrum conversion. And a decoding step of decoding the input first code string to return to a spectrum signal, and converting the decoded spectrum signal into a spectrum signal in a form of band division and spectrum conversion in the second band group. Therefore, in the higher band, a part of the spectrum signal is inversely transformed into a decimated time series signal, and the decimated time series signal is converted into the lower band spectrum signal in the higher band. By converting the spectrum signal into a second code string by encoding the converted spectrum signal, the code string can be converted at high speed. Accordingly, for example, a code string transmitted in a short time in a communication path can be rapidly converted to another code string.

[0289] The code conversion apparatus according to the present invention comprises an input means for inputting a first code sequence obtained by coding a spectrum signal obtained by dividing a time series information signal into a first band group and then performing spectrum conversion. And decoding means for decoding the input first code string and returning it to a spectrum signal, and converting the decoded spectrum signal into a spectrum signal in a form which is band-divided and spectrum-converted in the second band group. Therefore, in the higher band, a part of the spectrum signal is inversely transformed into a decimated time series signal, and the decimated time series signal is converted into the lower band spectrum signal in the higher band. , And a coding means for coding the converted spectrum signal into a second code string, thereby enabling high-speed conversion of the code string. Accordingly, for example, a code string transmitted in a short time in a communication path can be rapidly converted to another code string.

Further, the code conversion method according to the present invention is characterized in that the time series information signal is band-divided into a first band group, and then the first code is obtained by coding a spectrum signal obtained by spectrum conversion with a first block length. An input step of inputting a sequence, a decoding step of decoding the input first code string and returning it to a spectrum signal, and dividing the decoded spectrum signal by a second band group into a second block length. In order to convert the spectrum signal into a spectrum signal in the form of spectrum conversion, only the low-frequency side spectrum signal of the first code string is inversely transformed into a decimated time series signal, and the decimated time series signal is converted By having a spectrum signal conversion step of converting the spectrum signal into a low-frequency side spectrum signal and an encoding step of encoding the converted spectrum signal, the code string can be converted at a high speed. Accordingly, for example, a code string transmitted in a short time in a communication path can be rapidly converted to another code string.

Further, the code conversion apparatus according to the present invention provides a first code obtained by coding a spectrum signal obtained by dividing a time-series information signal into a first band group and then performing spectrum conversion with a first block length. Input means for inputting a sequence, decoding means for decoding the input first code string to return to a spectrum signal, and dividing the decoded spectrum signal into a second block length by dividing the decoded spectrum signal into a second band group. In order to convert the spectrum signal into a spectrum signal in the form of spectrum conversion, only the low-frequency side spectrum signal of the first code string is inversely transformed into a decimated time series signal, and the decimated time series signal is converted The provision of the spectrum signal converting means for converting the spectrum signal into a low-frequency side spectrum signal and the coding means for coding the converted spectrum signal enables high-speed conversion of the code sequence. Accordingly, for example, a code string transmitted in a short time in a communication path can be rapidly converted to another code string.

[0292] A program supply medium according to the present invention is a program supply medium for supplying an information encoding program to an information processing apparatus. An input step of inputting a first code string obtained by encoding a spectrum signal that has been subjected to spectral conversion after band division into band groups, and a decoding step of decoding the input first code string and returning it to a spectrum signal , The decoded spectral signal to a second
In order to convert to a spectrum signal in the form of band-divided and spectrum-converted in the band group, in the high band side, some spectrum signals are inversely transformed into thinned time-series signals, and the above-described thinning is performed. A spectrum signal converting step of converting the converted time-series signal into a low-band spectrum signal in the high-band band, and an encoding step of coding the converted spectrum signal to form a second code string. Do it.

With this program supply medium, the information processing apparatus can convert a code string at high speed. Accordingly, for example, a code string transmitted in a short time in a communication path can be rapidly converted to another code string.

A program supply medium according to the present invention is a program supply medium for supplying an information encoding program to an information processing apparatus in order to solve the above-mentioned problem. Inputting a first code string obtained by coding a spectrum signal obtained by band-dividing the time-series information signal into a first band group and then performing spectrum conversion with a first block length;
A decoding step of decoding the input first code string to return to a spectrum signal, and a spectrum in a form in which the decoded spectrum signal is band-divided by a second band group and spectrum-converted by a second block length. First to convert to a signal
The spectrum signal conversion step of inversely converting only the low-frequency spectrum signal of the code string into a thinned time-series signal, and converting the thinned time-series signal into a low-frequency spectrum signal, And an encoding step for encoding the spectrum signal.

With this program supply medium, the information processing apparatus can convert a code string at high speed. Accordingly, for example, a code string transmitted in a short time in a communication path can be rapidly converted to another code string.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a compressed data recording and / or reproducing apparatus as an embodiment to which the present invention is applied.

FIG. 2 is a block diagram showing a configuration of an encoding unit of the compressed data recording and / or reproducing apparatus.

FIG. 3 is a block diagram showing a configuration of a conversion unit applied to the compressed data recording and / or reproducing apparatus.

FIG. 4 is a block diagram showing a configuration of a signal component encoding unit of the compressed data recording and / or reproducing apparatus.

FIG. 5 is a block diagram showing a configuration of a decoding unit of the compressed data recording and / or reproducing apparatus.

FIG. 6 is a block diagram showing a configuration of a signal component decoding means of the compressed data recording and / or reproducing apparatus.

FIG. 7 is a block diagram showing a configuration of an inverse conversion means of the compressed data recording and / or reproducing apparatus.

FIG. 8 is a diagram used for explaining an encoding method by the compressed data recording and / or reproducing apparatus.

FIG. 9 is a diagram showing a code string generated by the encoding by the compressed data recording and / or reproducing apparatus.

FIG. 10 is a block diagram showing a configuration of another conversion unit applied to the compressed data recording and / or reproducing apparatus.

FIG. 11 is a block diagram showing a configuration of another conversion unit applied to the compressed data recording and / or reproducing apparatus.

FIG. 12 is a block diagram showing a configuration of another inverse conversion means applied to the compressed data recording and / or reproducing apparatus.

FIG. 13 is a block diagram showing a configuration of another inverse conversion means applied to the compressed data recording and / or reproducing apparatus.

FIG. 14 is a diagram used to explain another encoding method by the compressed data recording and / or reproducing apparatus.

FIG. 15 is a diagram showing a code string generated by another encoding method of the compressed data recording and / or reproducing apparatus.

FIG. 16 is a block diagram illustrating a configuration of a signal component encoding unit of the compressed data recording and / or reproducing apparatus.

FIG. 17 is a block diagram showing a configuration of another signal component decoding unit applied to the compressed data recording and / or reproducing apparatus.

FIG. 18 is a block diagram illustrating a configuration of a transmission recording unit applied to the compressed data recording and / or reproducing apparatus.

FIG. 19 is a block diagram illustrating a configuration of a signal reading and transmitting unit of the compressed data recording and / or reproducing apparatus.

FIG. 20 is a block diagram illustrating a configuration of a code conversion unit of the compressed data recording and / or reproducing apparatus.

FIG. 21 is a block diagram showing a configuration of a spectrum signal converting means of the compressed data recording and / or reproducing apparatus.

FIG. 22 is a block diagram illustrating a configuration of a band synthesis filter of the compressed data recording and / or reproducing apparatus.

FIG. 23 is a diagram used to explain a spectrum signal conversion method by the compressed data recording and / or reproducing apparatus.

FIG. 24 is a diagram used for explaining a spectrum signal conversion method by the compressed data recording and / or reproducing apparatus.

FIG. 25 is a block diagram showing a configuration of another spectrum signal converting means applied to the compressed data recording and / or reproducing apparatus.

FIG. 26 is a block diagram showing a configuration of another spectrum signal converting means applied to the compressed data recording and / or reproducing apparatus.

FIG. 27 is a diagram showing a configuration of another spectrum signal converting means applied to the compressed data recording and / or reproducing apparatus.

FIG. 28 is a diagram showing a configuration of another spectrum signal converting means applied to the compressed data recording and / or reproducing apparatus.

FIG. 29 is a block diagram showing a configuration of another spectrum signal converting means applied to the compressed data recording and / or reproducing apparatus.

FIG. 30 is a block diagram showing a configuration of another spectrum signal converting means applied to the compressed data recording and / or reproducing apparatus.

FIG. 31 is a block diagram showing a configuration of another spectrum signal converting means applied to the compressed data recording and / or reproducing apparatus.

FIG. 32 is a block diagram showing a configuration of another spectrum signal converting means applied to the compressed data recording and / or reproducing apparatus.

FIG. 33 is a block diagram showing a configuration of another spectrum signal converting means applied to the compressed data recording and / or reproducing apparatus.

FIG. 34 is a block diagram showing a configuration of another code conversion unit applied to the compressed data recording and / or reproducing apparatus.

FIG. 35 is a flowchart used to explain a control method by a code conversion unit of the compressed data recording and / or reproducing apparatus.

[Explanation of symbols]

1701 code string decomposition circuit, 1702 signal component decoding circuit, 1703 spectrum signal conversion circuit, 170
4 signal component encoding circuit, 1705 code string generation circuit, 1725 band synthesis filter, 1731, 17
320 data interpolation circuit, 1733 high-pass filter, 1734 low-pass filter, 1761-17
66 inverse spectrum conversion circuit, 1767, 1768
Time series signal synthesis circuit, 1769-1772 forward spectrum conversion circuit, 1841 code string sentence circuit, 184
2 signal component decoding circuit, 1843, 1844 spectrum signal conversion circuit, 1845 signal component encoding circuit,
1846 code string generation circuit, 1901 transmission circuit,
1902 transcoding circuit, 1903 recording circuit, 1
962 channel conversion circuit, 1963 inverse spectrum conversion circuit, 1965 forward spectrum conversion circuit, 1
965 Low frequency inverse spectrum conversion circuit, 1966 Low frequency forward spectrum conversion circuit, 1968, 1969 High frequency weighting circuit, 1972 Channel conversion circuit

Claims (16)

[Claims] An input step of inputting a first code string obtained by encoding a spectrum signal obtained by band-dividing a time-series information signal into a first band group and then performing spectrum conversion, and an input first code A decoding step of decoding the sequence to return to a spectrum signal; and converting the decoded spectrum signal into a spectrum signal in a form of being subjected to band division and spectrum conversion in the second band group. Inversely transforming some of the spectrum signals into a decimated time-series signal, and a spectrum signal conversion step of converting the decimated time-series signal into a low-band spectrum signal in the high-frequency band, A coding step of coding the converted spectrum signal to form a second code string. 2. The spectrum signal of a part of the high-frequency band is a low-frequency spectrum signal in a high-frequency band of the first code string. The transcoding method described in the above. 3. The high-frequency band division of the first code string is equivalent to the high-frequency band division of the second code string. Code conversion method. 4. The high-frequency band division of the second code sequence is equivalent to a high-frequency band division of the first code sequence. Code conversion method. 5. The transcoding method according to claim 1, wherein said time-series information signal is an audio signal. 6. An input means for inputting a first code sequence obtained by coding a spectrum signal obtained by band-dividing a time-series information signal into a first band group and then performing spectrum conversion, and an input first code Decoding means for decoding the sequence to return the spectrum signal to a spectrum signal; and converting the decoded spectrum signal into a spectrum signal in a form of spectrum division and band conversion by the second band group. Spectral signal converting means for inversely converting a part of the spectrum signal into a decimated time-series signal, and converting the decimated time-series signal into a low-band spectrum signal in the high band. A coding means for coding the converted spectrum signal to form a second code string. 7. The spectrum signal of a part of the high-frequency band is a spectrum signal of a low-frequency part in a high-frequency band of the first code string. A transcoding device according to any one of the preceding claims. 8. The high frequency band division of the first code sequence is equivalent to the high frequency band division of the second code sequence. Transcoding device. 9. The high-frequency band division of the second code string is equivalent to the high-frequency band division of the first code string. Transcoding device. 10. The transcoder according to claim 6, wherein said time-series information signal is an audio signal. 11. An inputting step of inputting a first code string obtained by encoding a spectrum signal obtained by spectrally converting a time-series information signal, and decoding the input first code string to return to a spectrum signal. And converting only the lower-band signal of the decoded spectrum signal into a decimated time-series signal, and converting the decimated time-series signal into a lower-band spectrum signal of the second code string. A code conversion method, comprising: a spectrum signal conversion step of converting; and an encoding step of encoding the converted spectrum signal. 12. The first code string is a code string that has been spectrum-transformed with the first block length, and the second code string is
12. The code conversion method according to claim 11, wherein the code string is a code string that has been spectrum-converted with a second block length different from the first block length. 13. An input means for inputting a first code string obtained by encoding a spectrum signal obtained by spectrally transforming a time-series information signal, and decoding for decoding the input first code string to return to a spectrum signal. Means, and inversely transforms only the low-frequency side signal of the decoded spectrum signal into a decimated time-series signal, and converts the decimated time-series signal into a low-frequency side spectrum signal of the second code string. A code conversion device comprising: a spectrum signal conversion unit for converting; and an encoding unit for encoding the converted spectrum signal. 14. The first code string is a code string that has been spectrum-transformed with the first block length, and the second code string is a second code string.
14. The code conversion apparatus according to claim 13, wherein the code string is a code string that has been spectrum-converted with a second block length different from the first block length. 15. A program supply medium for supplying a code conversion program to an information processing apparatus, wherein the program supplied by the program supply medium is configured to divide a time-series information signal into a first band group and then perform spectrum conversion. An input step of inputting a first code string obtained by encoding the obtained spectrum signal; a decoding step of decoding the input first code string to return to a spectrum signal; In order to convert to a spectrum signal in the form of band-divided and spectrum-converted in the band group, in the high band side, some spectrum signals are inversely transformed into thinned time-series signals, and the above-described thinning is performed. A spectrum signal converting step of converting the converted time-series signal into a spectrum signal of a lower band in the band on the higher frequency side; Program providing medium characterized by comprising and a coding step for. 16. A program supply medium for supplying a code conversion program to an information processing apparatus, wherein the program supplied by the program supply medium is obtained by encoding a spectrum signal obtained by performing spectrum conversion on a time-series information signal. An input step of inputting the first code string, a decoding step of decoding the input first code string to return to a spectrum signal, and a time series in which only the low-frequency side signal of the decoded spectrum signal is decimated. A signal converting step of inversely converting the signal into a signal and converting the decimated time-series signal into a spectrum signal on the lower frequency side of the second code string; and an encoding step of encoding the converted spectrum signal. A program supply medium characterized by comprising: