JPH07221650A - Method and device for encoding information and method and device for decoding information - Google Patents

Abstract

PURPOSE:To reduce a processing amount at the time of encoding, to simplify constitution and to reduce the cost by performing an actual conversion processing only in a required band and encoding signals based on specified band information or the like. CONSTITUTION:Processing band control information from a terminal 706 is supplied to a processing band control circuit 704 and the processing bands of a frequency component decomposition circuit 701, a normalization and quantization circuit 702 and a code sequence generation circuit 703 are controlled based on the information. Then, the frquency component decomposition circuit 701 performs the processing of only the required band based on the control information sent from the processing band control circuit 704 to the frequency component decomposition circuit 701. Also, the normalization and quantization circuit 702 and the code sequence generation circuit 703 similarly perform only the processing in the required band based on the respective pieces of the control information from the processing band control circuit 704. By performing only the processings in the required band in such a manner, an arithmetic processing amount is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information coding method for coding input digital data by so-called high efficiency coding, and transmitting, recording, reproducing and decoding the input digital data to obtain a reproduced signal. The present invention relates to an apparatus, an information decoding method and an apparatus.

[0002]

2. Description of the Related Art Conventionally, various techniques for high-efficiency coding of signals such as audio and voice have been known. For example, audio signals on the time axis are not divided into blocks and divided into a plurality of frequency bands. Band division coding (sub-band coding: SBC), which is a non-blocking frequency band division method that performs encoding by using a plurality of frequency bands by converting a signal on the time axis into a signal on the frequency axis (spectral conversion). There is a blocking frequency band division method in which each frequency band is divided into, and so-called transform coding and the like. Further, a method of high efficiency coding in which the above band division coding and transform coding are combined is also considered, and in this case, for example, after performing band division by the band division coding, A signal for each band is spectrum-converted into a signal on the frequency axis, and each spectrum-converted band is encoded.

Here, as a band division filter used in the above band division coding, for example, QM
There is an F filter, and this QMF filter is based on the document "Digital Coding of Speech in.
Subbands "(Digital coding of speech in subbands,
RE Crochiere, Bell Syst.Tech. J., Vol.55, No.819
76).

In addition, the document "Polyphase Quadrature Filters-New Band Division Coding Technology" (Po
lyphase Quadrature filters -A new subband coding t
echnique, Joseph H. Rothweiler, ICASSP 83 BOSTON)
Describes an equal bandwidth filter partitioning technique.

Further, as the above-mentioned spectrum conversion,
For example, an input audio signal is divided into blocks in a predetermined unit time (frame), and a discrete Fourier transform (DFT), a cosine transform (DCT), a modified DCT transform (MDCT), etc. are performed for each block to set a time axis as a frequency axis. There is a spectral transformation that transforms. Regarding the MDCT, refer to the document “Time Domain Aliasing.
Subband / Transform Coding with Cancellation-Based Filter Bank Design "
Using Filter Bank Designs Based on Time Domain Ali
asing Cancellation, JPPrincen, ABBradley, Uni
v. of Surrey, Royal Melbourne Inst.ofTech. ICASSP
1987).

As described above, by quantizing the signal divided into each band by the filter and the spectrum conversion, the band in which the quantization noise is generated can be controlled,
By utilizing the properties such as the masking effect, it is possible to perform more efficient audio coding. Further, if the normalization is performed for each band, for example, with the maximum value of the absolute value of the signal component in that band before the quantization is performed here, more efficient encoding can be performed.

Here, as the frequency division width in the case of quantizing each frequency component divided into frequency bands, for example, a bandwidth considering human auditory characteristics is often used. That is, an audio signal may be divided into a plurality of bands (for example, 25 bands) with a bandwidth generally called a critical band in which the bandwidth increases as the frequency band increases. Also, when encoding the data for each band at this time, a predetermined bit allocation for each band, or
Coding by adaptive bit allocation (bit allocation) is performed for each band. For example, when the coefficient data obtained by the MDCT processing is encoded by the bit allocation, the MD of each block is
The MDCT coefficient data for each band obtained by the CT process is encoded with the adaptive allocation bit number. The following two methods are known as bit allocation methods.

For example, the document "Adaptive Transform Coding of Speech Signals,"
IEEE Transactions of Accoustics, Speech, and Signa
l Processing, vol.ASSP-25, No.4, August 1977), bit allocation is performed based on the signal size of each band. In this method, the quantization noise spectrum becomes flat and the noise energy becomes the minimum, but the actual noise feeling is not optimal because the masking effect is not used auditorily.

In addition, for example, the document "Critical band encoder-
Digital Encoding of Perceptual Requirements of the Auditory System "(The critical band coder --digital encodi
ng of the perceptual requirements of the auditory
system, MAKransner MIT, ICASSP 1980) describes a method of performing fixed bit allocation by using the auditory masking to obtain the required signal-to-noise ratio for each band. 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.

In order to solve these problems, all bits that can be used for bit allocation have a fixed bit allocation pattern predetermined for each small block and a bit allocation depending on the signal size of each block. A high-efficiency coding apparatus has been proposed which is used in a divided manner, and the division ratio depends on a signal related to an input signal, and the smoother the spectrum of the signal, the larger the division ratio into the fixed bit allocation pattern. ing.

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, thereby significantly improving the overall signal-to-noise characteristic. can do. In general, human hearing is extremely sensitive to a signal having a steep spectrum component. Therefore, improving the signal-to-noise characteristic by using such a method does not only improve the numerical value in measurement. Not
It is effective for improving the sound quality in terms of hearing.

Many other methods have been proposed for the bit allocation method. Further, if the model relating to hearing is further refined and the performance of the coding apparatus is improved, a more efficient coding can be achieved auditorily. It will be possible.

[0013]

However, in order to realize these encoding and decoding means, a large amount of hardware is required as compared with the case where the sample value of the signal is recorded as it is. In particular, when the signal to be handled covers a wide band including high-frequency components, the number of spectrum components to be handled increases and the sampling frequency also increases, so the required buffer capacity and the amount of arithmetic processing per time are large. Will end up.

On the other hand, these encoding / decoding means are generally realized by a circuit composed of semiconductors. However, the integration and cost of semiconductors are drastically lowered, and at the same time, the sound quality is improved. The required level will increase. For example, when encoding a human voice and recording it efficiently, even if it is required to understand the content in the initial stage, a more faithful presence is required as the technical level rises. Go. Of course, it is possible to increase the standard level by increasing the bandwidth of the signal to be handled according to the improvement of the technical level, but if the standard is changed in this way, the signal between the recorded signal and the decoding device Will be incompatible. In particular, there arises a problem that the decoding means configured based on the old standard cannot reproduce the signal encoded by the new standard.

The present invention has been made in view of such circumstances, and the processing can be simplified according to the quality of the reproduced signal required, and the encoding or the encoding can be performed at low cost or at high speed. It is an object of the present invention to provide an information encoding method and device and an information decoding method and device that can perform decoding.

Another object of the present invention is that the decoding means can reproduce the signal in the band corresponding to the capability from the same recorded code, and the scale corresponding to the purpose,
It is possible to configure a price decoding means, and to expand the band of a signal to be recorded while keeping compatibility with the capability of the popular decoding means.

[0017]

In order to solve the above-mentioned problems, the information coding method according to the present invention performs an actual conversion process only in a necessary band on the basis of designated band information or the like, The signal is encoded.

Further, the information decoding method according to the present invention reproduces a signal by performing conversion processing for actual decoding only in a necessary band based on the information described in the code to be decoded. Is.

Furthermore, in another information decoding method according to the present invention, the decoding means selects a necessary code portion based on a band which the decoding means itself can actually decode from the inputted code. It reproduces a signal having a bandwidth corresponding to the capability.

That is, the information coding method according to the present invention comprises frequency component decomposing means and means for coding the frequency components obtained by the frequency component decomposing means. This is so that the processing of component decomposition may be omitted. An information encoding device to which this method is applied can be configured.

Further, the information decoding method according to the present invention comprises a processing band control means, a frequency component code decoding means, and a waveform signal synthesizing means for synthesizing a waveform signal from the frequency components obtained by the frequency component decoding means. According to the control of the processing band control unit, the waveform signal synthesizing unit may omit the waveform signal synthesizing process for some bands. An information decoding device to which this method is applied can be configured.

Furthermore, another information decoding method according to the present invention is an information selecting means, a frequency component code decoding means,
A waveform signal synthesizing unit for synthesizing a waveform signal from the frequency components obtained by the frequency component decoding unit is provided, and the waveform signal synthesizing unit outputs only a part of information included in the input code string selected by the information selecting unit. The waveform signal synthesizing process is omitted for some bands. An information decoding device to which this method is applied can be configured.

In these methods or devices, it is possible to provide a processing band control means, and control the processing band control means whether or not to omit the processing of frequency component decomposition for the part of the bands. . Further, it is preferable that the band in which the process of frequency component decomposition is omitted is a band on the high frequency side. Further, it is preferable that the frequency decomposing means is composed of a band dividing filter means and a spectrum converting means.

The input signal or the output signal may be an acoustic signal or an image signal.

[0025]

By performing the actual conversion process for encoding or decoding only in the required band, the process is simplified, and the encoding or decoding can be performed at low cost or at high speed. In addition, the decoding means can reproduce the signal in the band corresponding to the capability from the same recorded code, and it is possible to configure the decoding means of the scale and the price corresponding to the purpose according to the purpose. The band of the signal to be recorded can be expanded while maintaining compatibility according to the capability of the popular decoding means.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining an embodiment of an information coding method according to the present invention. In the embodiment shown in FIG. 1, the input signal is a modified discrete cosine transform,
It is decomposed into spectral components obtained by spectral conversion such as so-called MDCT. The respective spectral coefficients are collected for each predetermined band (9 bands b1 to b9 in the example of this figure) and subjected to normalization processing. Here, the normalization processing means dividing each spectral coefficient by the normalizing coefficient determined by the maximum absolute value of the spectral coefficient in each band.

Next, the normalized spectral coefficient for each band is requantized with the given number of bits. The method of giving the number of bits may be constant regardless of the input signal, or may be determined depending on the input signal in consideration of masking and the like. By performing the normalization process, it is possible to efficiently requantize the spectral coefficient in the band composed of only low-frequency components with a small number of bits. The original signal can be compressed by reducing the number of bits for requantization.

FIG. 2 is a block diagram schematically showing a configuration to which the embodiment of the information coding apparatus according to the present invention can be applied. The audio signal input through the input terminal 100 of the encoding device is decomposed into frequency components by the frequency component decomposition circuit 101. This frequency component is subjected to normalization and requantization for each constant band by the normalization quantization circuit 102, and thereafter, the quantization precision information, the normalization coefficient information, the normalization and The quantized frequency component information is converted into a code string and taken out from the output terminal 104.

On the other hand, FIG. 3 shows a block diagram of a schematic configuration to which the embodiment of the decoding apparatus according to the present invention is applied, which corresponds to the encoding apparatus of FIG. Input terminal 2
The code string input to 00 is the output terminal 104 of FIG.
Corresponding to the output from the code string decoding circuit 10
1 separates the quantization precision information, the normalization coefficient information, and the normalized and quantized frequency component information, and sends them to the inverse quantization inverse normalization circuit 202 to generate a frequency component signal. The generated frequency component signal is the waveform signal synthesis circuit 2
03, converted into a waveform signal, and output terminal 204
Will be output.

As a method of decomposing into frequency components, the above-mentioned spectrum conversion means such as DFT, DCT, MDCT or a band division filter may be used, but as shown in FIG. A combination of the division filter and the above-mentioned spectrum conversion may be used.

In the example of FIG. 4, the waveform signal input from the input terminal 300 is divided into four bands by the band division filter circuit 301. Each terminal 331, 33
Signals of bands from lower frequencies are obtained in the order of 2,333,334. These signals have a bandwidth of 1/4 of the input waveform signal of the terminal 300, and the sampling rate of each is 1/4 of the input waveform signal. Therefore, the spectrum conversion circuits 311, 312, 313, and 314 that perform spectrum conversion of these signals are actually 1/4 of those in the case of directly converting the spectrum of the input signal.
The same frequency resolution can be obtained with the conversion length of.
Each spectrum conversion circuit 311, 312, 313, 314
The frequency component output from each output terminal 321, 322,
323 and 324 respectively.

FIG. 5 shows an example of waveform signal synthesizing means corresponding to the frequency component decomposing means of FIG. The input terminals 401, 402, 40 of this waveform signal synthesizing means
3 and 404 are input to the output terminals 32 of FIG. 4, respectively.
It corresponds to the outputs from 1, 322, 323, and 324, respectively.

Here, each inverse spectrum conversion circuit 411,
Output terminals 441, 44 from 412, 413, 414
The sampling rates of the signals in the respective bands obtained at 2, 443 and 444 are the same as the terminals 331, 332 and 33 in FIG.
It is the same as the signal of each band of 3, 334. A waveform signal can be reproduced by synthesizing the signals of the respective bands obtained at these terminals 441, 442, 443, 444 by the band synthesizing filter 421, and the synthesized waveform signal is output from the output terminal 431. Taken out.

FIGS. 6 and 7 show examples of the configurations of the band division filter circuit 301 of FIG. 4 and the band synthesis filter circuit 421 of FIG. 5, respectively. That is, FIG.
In the QMF circuit 501, 511, 512, which divides the input signal from the terminal 500 into a high frequency signal and a low frequency signal.
In combination with, for example, the band division filter circuit 3 of FIG.
01 is configured, and each terminal 521, 522, 523, 52
From 4, the signals in the band from the lower frequency are obtained in this order. Further, in FIG. 7, three IQMF circuits 611, 612, and 621 that combine the signals of the two bands divided by one QMF are combined to configure the band combining filter circuit 421 of FIG. 5, for example. .

As described above, by using the QMF and the IQMF to configure the band division filter means and the band synthesis filter means, it is possible to cancel the influence of aliasing caused by lowering the sampling rate after the band division.

Now, let us consider a case where an audio signal is recorded / reproduced by using the above-mentioned encoding device and decoding device. In many acoustic signals, important signal components are concentrated in a specific band, especially in the low frequency range. Of course, the sound quality is improved by reproducing the higher-frequency signal component,
Although a more realistic sound signal can be obtained, it is possible to understand the content of the speech only by reproducing the low frequency side signal, and it is also possible to enjoy the music with a moderate sound quality.

The above-mentioned encoding / decoding requires a great deal of processing as compared with the case where the waveform signal sample of the original waveform signal is recorded as it is. However, if the sound quality is moderately recorded and expanded easily. Such simple encoding means and decoding means, which are very convenient if they can be reproduced, are particularly useful in the following cases.

The first case is a case where it is known that only the signal on the low frequency side is finally needed at the stage of performing signal compression for a certain application against the above-mentioned reason. In terms of coding, when the band of the input signal is limited in advance, or when the specification is given to the coding means that high-frequency signals can be ignored. And when it comes to decryption,
This is the case when the input code string consists only of information for the low-frequency side signal, or when the decoding means is instructed to ignore the high-frequency signal.

The second case is a case where the band to be reproduced by the decoding means is determined according to the capability of the decoding means.
In this case, the decoding is performed by selecting the information of the band that the decoding means itself can reproduce from the given code string. If this is done, different signals will be reproduced from the same code string depending on the type of decoding means, but these will appear as differences in the sound quality of the reproduced signals. This means that in the process of the cost of the decoding means decreasing with time, it is possible to introduce the decoding means whose sound quality gradually improves without causing compatibility problems. There is.

The method of the present invention for easily realizing the encoding or the decoding of the sound in the band thus limited will be described below with reference to the drawings.

FIG. 8 is a block diagram of an embodiment of an encoding apparatus according to the present invention for dealing with the above first case. The processing band control circuit 704 is provided with processing band control information from the terminal 706, and controls the processing bands of the frequency component decomposition circuit 701, the normalization / quantization circuit 702, and the code string generation circuit 703 based on this information. . The processing band control information from the terminal 706 may be input by the operator of this encoding means, or may be given from, for example, a band limiting filter (not shown in FIG. 8) which supplies an input signal to the terminal 700. good.

The frequency component decomposing circuit 701 has the same structure as the frequency component decomposing circuit 101 of FIG. 2, but only the necessary band is generated based on the control information sent from the processing band control circuit 704 to the frequency component decomposing circuit 101. Perform processing. For example, when a signal in only the band from b1 to b6 in FIG. 1 is encoded, the spectrum conversion means 313, 314 in FIG. 4 for processing a high frequency signal does not perform the process. Further, when the band dividing filter means of FIG. 4 has the configuration of FIG. 6, the processing of the QMF circuit 512 of FIG. 6 is not necessary and is not performed.

The normalization / quantization circuit 702 and the code string generation circuit 703 shown in FIG. 8 similarly perform the processing band control circuit 704.
Only the processing in the required band is performed based on each control information from. By only performing processing in the required band in this way, the amount of calculation processing can be significantly reduced,
The processing can be performed at high speed at low cost, and the power consumed by the circuit can be reduced when the processing is performed by an electric circuit.

It should be noted that this encoding device or method is not necessarily limited to one that processes an input acoustic signal or the like in real time. For example, when the information of the file in which the sample value of the waveform signal is recorded as it is is compressed by the above method and is recorded on the magneto-optical disk or the like, the earlier the processing is, the more convenient the processing is. Doing has a big meaning.

Further, the frequency component decomposing circuit 701 does not necessarily have to have the same structure as that shown in FIGS. 4 and 6, but has a smaller structure from the beginning, for example, the structure shown in FIGS. 11 and 12. May be Figure 11
The band-division filter circuit 801 indicated by (4) inputs the same signal as the band-division filter circuit 301 in FIG. 4, but its output is only the low-frequency side signal and sends them to the spectrum conversion circuits 811, 812. Spectrum conversion circuit 81
Reference numerals 1 and 812 denote the spectrum conversion circuits 311 and 31 of FIG.
The same process as 2 is performed. FIG. 12 shows a configuration example of the band division filter circuit 801. The QMF circuit 821, except that the output of the QMF circuit 821 is only on the low frequency side,
831 performs the same processing as the QMF circuits 501 and 511 of FIG. 6, respectively. In this case, the processing band control circuit 704 of FIG. 8 may not be provided.

FIG. 15 shows an example of a code string for one block formed by performing the coding process in this way. In this example, first, the number of quantization precision information n _Q , for example, a value of n _Q = 6 is recorded, and then the quantization precision information Q and the normalization coefficient information K up to the actually encoded band are recorded. , Spectral coefficient information S is recorded. There are various other methods of recording the coded sequence, for example,
Instead of recording the number of pieces of quantization accuracy information, dummy quantization accuracy information, for example, information that the number of quantization bits is 0 may be recorded in the bands b7, b8, b9.

Next, FIG. 9 is a block diagram of an embodiment of a decoding apparatus according to the present invention for coping with the first case. The code string decoding circuit 711 receives, for example, a code string as shown in FIG. 15 as an input signal, and sends information for restoring the normalized and quantized spectrum coefficient to the dequantization / denormalization circuit 712. At the same time, the number of pieces of quantization precision information is sent to the processing band control circuit 714. The processing band control 714 calculates a band required for processing required for decoding from the number of pieces of quantization precision information, and dequantizes and denormalizes 712.
And the control is performed so that the processing of the waveform signal synthesis circuit 713 is limited to the processing in the required band. Similar to the case of the encoding apparatus shown in FIG. 8, for example, the processing of the inverse spectrum conversion circuits 413 and 414 of FIG. 5 and the IQMF circuit 612 of FIG. 7 can be omitted, and the amount of arithmetic processing can be significantly reduced. Therefore, high-speed processing can be performed at low cost, and electric power consumed by the circuit can be reduced when the electric circuit performs these processes.

Note that this decoding means or method is not necessarily limited to one that processes and outputs an acoustic signal or the like in real time. For example, when the compressed coded file sequence is recorded and the sampled values of the waveform signal are recorded as they are on the magneto-optical disk, the earlier the process is, the more convenient the method of the present invention is. Processing has a big meaning.

Next, FIG. 10 is a block diagram of an embodiment of the decoding means according to the present invention for dealing with the second case. The decoding means of this embodiment accepts, for example, a code string as shown in FIG. 16 as an input.

The waveform signal synthesis circuit 724 of FIG.
3 has the configuration shown in FIG. 3, and the band synthesis filter circuit 851 in FIG. 13 has the configuration shown in FIG. Here, the inverse spectrum conversion circuits 841 and 842 perform the same processing as the inverse spectrum conversion circuits 411 and 412 of FIG. 5, respectively, and the IQMF circuit 861 performs the same processing as the IQMF circuit 611 of FIG. 7. Also, the IQMF circuit 871
Performs the same processing as the IQMF circuit 621 of FIG. 7 using a signal having a value of 0 instead of the input signal from the terminal 642.

Here, the information selection circuit 722 of FIG.
From the output of the code string decoding circuit 721, the information of the band that this decoding device can process is selected. That is, since this decoding means can process only the band from b1 to b6 of FIG. 1, the information selection circuit 722 selectively reverses only the information of the part not shaded in FIG. It is sent to the quantization inverse normalization circuit 723. The dequantization denormalization circuit 723 configures each spectrum coefficient based on these pieces of information, and the waveform signal synthesis circuit 724 converts these spectrum coefficients to synthesize a waveform signal. The processing amount of the waveform signal synthesizing circuit 724 is significantly smaller than that in the case of synthesizing the signals in all bands, and can be configured by the simple means as described above or can be processed at high speed. As in the first case, this decoding means or method is not necessarily limited to the one that processes and outputs the acoustic signal or the like in real time.

As described above, the method of the present invention is effective in both the first case and the second case.
As described above, the effect is great when the band is divided and then the spectrum is converted. For example, as described in Japanese Patent Application Laid-Open No. 5-183442 previously proposed by the applicant of the present application, a fast Fourier transform (FFT) calculation method is used when performing spectrum conversion / inverse spectrum conversion such as MDCT and IMDCT. It is known that these conversions can be realized with a small amount of calculation processing by using.
When performing FFT, for example, as described in the document “Fast Fourier Transform”, E. Oran Bringham, Miyagawa, Imai Translation, Science and Technology Publishing Co., the calculation results in the middle are stored and converted. A work area proportional to the length is required, and the information in the work area is shuffled and processed. For this reason, if spectrum conversion is realized using FFT without band division, a large work area is required, and the effect of reducing arithmetic processing is also
This is smaller than the method of performing spectrum conversion by performing band division that can omit spectrum conversion in a band in which processing is not performed.

The same applies to the case of decoding. Inverse conversion of spectrum-converted spectrum coefficients into a waveform signal after band-splitting results in inverse conversion of spectrum-converted spectrum coefficients into a waveform signal without band-division. The work area is smaller than the above, and the effect of reducing the calculation processing is great. F
In order to perform FT at high speed, it is necessary to make these work areas readable and writable at a sufficiently high speed, but the shorter conversion length means that the necessary work area can be made smaller. This means that the encoding device and the decoding device can be constructed at such a low cost.

FIG. 17 is a processing example of an encoding method for performing processing by using the present invention. In this processing example, it is explicitly shown that only the spectrum conversion portion is processed by the band, but of course, as in the case of the above-mentioned encoding means, the processing is simplified in the band division filter processing of step S11. Is possible.

In FIG. 17, after the band division filter processing is performed in step S11, steps S12 and S1 are performed.
3. In S14, the designated band is larger than Fs / 8 or 2Fs
It is determined whether it is larger than / 8 or larger than 3Fs / 8. Then, when the specified bandwidth is larger than 3Fs / 8 performs orthogonal transform of the band b ₄ ~b ₁ at step S15 to S18, it specifies the bandwidth is large than 2Fs / 8 3Fs
/ 8 or less, the band b _{3 in} steps S16 to S18
Performs a spectrum conversion ~b _1, when the specified band is 2Fs / 8 or less large than Fs / 8 step S17, S1
In step 8, spectrum conversion of bands b ₂ and b ₁ is performed, and when the designated band is Fs / 8 or less, spectrum conversion of band b ₁ is performed in step S18. In the next step S19, the spectrum signal is normalized and quantized, and then the code string is generated in step S20.

Next, FIG. 18 is a processing example of a decoding method for performing the processing by utilizing the present invention. In this processing example, it is explicitly shown that only the inverse spectrum conversion portion is processed by the band, but of course, as in the case of the above-described decoding means, the processing is also performed in the band synthesizing filter processing of step S30. It is possible to simplify.

In FIG. 18, the code string is decoded in step S21, the spectrum signal is dequantized and denormalized in step S22, and then the quantization precision is calculated in steps S23, S24, and S25. It is determined whether the number of information is greater than 4, is greater than 6, or is greater than 8. When the number of pieces of quantization accuracy information is greater than 8, the inverse spectrum conversion of the bands b _{4 to} b ₁ is performed in steps S26 to S29, and when the number of pieces of quantization accuracy information is greater than 6 and is 8 or less, the bands are included in steps S27 to S29. b ₃ performs inverse spectral transform of ~b _1, performs inverse orthogonal transform of the band b _2, b ₁ at step S28, S29. when the number of quantization accuracy information is 6 or less larger than 4, the quantization specified number of information When it is 4 or less, the inverse spectrum conversion of the band b ₁ is performed in step S29. In the final step S30, band synthesis filter processing is performed.

Next, FIG. 19 is a processing example of another decoding method for performing processing by utilizing the present invention. In the example of FIG. 19, the decoding process of the code string is performed in step S31, the necessary information is selected in step S32, and only the information selected here is used in the following process. That is, after performing dequantization and denormalization processing of the spectrum signal in step S33, step S3
4, S35 is performed only inverse spectrum transform for band b _2, b _1, a is performed band synthesis filtering process in step S36.

The case where the MDCT is used as the spectrum conversion has been described above as an example, but the method of the present invention can be applied to the case where the discrete Fourier transform (DFT), the discrete cosine transform (DCT) or the like is used. You can Further, the method of the present invention can be applied to the case of performing band division by a filter and then encoding without using such a special spectrum conversion.

Further, although the case where the low frequency band is taken as the band for the actual processing has been described, in addition to this, for example, only the band where the actual signal level is high is processed. Is also possible. However, in practice, as already described, for example, in a normal acoustic signal, important signal components are distributed on the low frequency side, and a simple processing is performed by making the configuration that only the low frequency side is always processed. The configuration can produce a great effect.

The method of the present invention can of course be applied to multi-channel acoustic signals. Further, in the above description, the case of encoding / decoding an acoustic signal has been described, but the method of the present invention is also effective when processing other types of signals. However, above all, the effect is great when applied to an acoustic signal or an image signal in which important information is concentrated in the low frequency range.

[0063]

As is apparent from the above description, in the information coding method and apparatus according to the present invention, the above-described frequency component decomposition processing is omitted for some bands, and the actual conversion is performed. By performing the processing only in the required band, the processing amount at the time of encoding can be reduced, the configuration can be simplified, and the cost can be reduced.

Further, the information decoding method and apparatus according to the present invention omit the waveform signal synthesizing process for a part of the bands or select the information under the control of the processing band control means. Only part of the information contained in the input code string selected by the means is used, and the waveform signal combining process is omitted for some bands. That is, signal reproduction can be realized by simple processing by performing actual conversion processing only in the required band based on the information described in the code to be decoded. In addition, the decoding means selects a necessary code portion from the input code based on the band that the decoding means can actually decode and reproduces a signal having a bandwidth corresponding to its ability, thereby reducing the cost. It is possible to provide a compatible decoding method.

Therefore, according to the required quality of the reproduced signal, the actual processing for encoding or decoding is performed only in the required band, so that the processing is simplified, at low cost, or at high speed. , Encoding and decoding can be performed. In addition, the decoding means can reproduce the signal in the band corresponding to the capability from the same recorded code, and it is possible to configure the decoding means of the scale and the price corresponding to the purpose according to the purpose. The band of the signal to be recorded can be expanded while maintaining compatibility according to the capability of the popular decoding means.

Further, by setting the band for which processing is omitted to the high frequency side, for example, by always processing only the low frequency side where important signal components are distributed in a normal acoustic signal or image signal, The reduction effect can be enhanced.

[Brief description of drawings]

FIG. 1 is a diagram showing a frequency spectrum for use in explaining an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of an encoding device to which an embodiment of the present invention is applied.

FIG. 3 is a block diagram showing a schematic configuration of a decoding device to which an embodiment of the present invention is applied.

4 is a block circuit diagram showing a schematic configuration of a frequency component decomposition circuit used in the encoding device of FIG.

5 is a block circuit diagram showing a schematic configuration of a waveform signal synthesis circuit used in the decoding device of FIG.

FIG. 6 is a block circuit diagram showing an example of a configuration of a band decomposition filter circuit.

FIG. 7 is a block circuit diagram showing an example of a configuration of a band synthesis filter circuit.

FIG. 8 is a block circuit diagram showing a schematic configuration of an encoding device according to an embodiment of the present invention.

FIG. 9 is a block circuit diagram showing a schematic configuration of a decoding device according to an embodiment of the present invention.

FIG. 10 is a block circuit diagram showing a schematic configuration of a decoding device according to another embodiment of the present invention.

FIG. 11 is a block circuit diagram showing a schematic configuration of a frequency component decomposition circuit used in the encoding device according to the embodiment of the present invention.

FIG. 12 is a block circuit diagram showing an example of a configuration of a band decomposition filter circuit used in an embodiment of the present invention.

FIG. 13 is a block circuit diagram showing a schematic configuration of a waveform signal synthesizing circuit used in the decoding device according to the exemplary embodiment of the present invention.

FIG. 14 is a block circuit diagram showing an example of a configuration of a band synthesizing filter circuit used in the embodiment of the present invention.

FIG. 15 is a diagram showing an example of a code string according to an embodiment of the present invention.

FIG. 16 is a diagram showing another example of a code string according to the embodiment of the present invention.

FIG. 17 is a flowchart schematically showing an example of part of the processing procedure of the encoding method according to the embodiment of the present invention.

FIG. 18 is a flowchart schematically showing an example of part of the processing procedure of the decoding method according to the embodiment of the present invention.

FIG. 19 is a flowchart schematically showing an example of a part of the processing procedure of the decoding method according to another embodiment of the present invention.

[Explanation of symbols]

 101, 701 Frequency component decomposition circuit 102, 702 Normalization / quantization circuit 103, 703 Code string generation circuit 201, 711, 721 Code string decoding circuit 202, 712, 723 Denormalization / dequantization circuit 203, 713, 724 Waveform signal synthesis circuit 704, 714 Processing band control circuit 722 Information selection circuit

Claims (16)

[Claims] 1. A part of performing frequency component decomposition processing for decomposing an input signal into frequency components and processing for encoding frequency components obtained by the frequency component decomposition processing, and omitting the frequency component decomposition processing. A method for encoding information, characterized in that the band of is selectively provided. 2. A processing band control process, wherein control for whether or not to omit the frequency component decomposition process for the partial band is performed by the processing band control process. Information encoding method. 3. The information encoding method according to claim 1, wherein the band in which the processing of the frequency component decomposition is omitted is a band on the high frequency side. 4. The information encoding method according to claim 1, wherein the frequency decomposition processing is performed by a band division filter means and a spectrum conversion means. 5. The information coding method according to claim 1, 2, 3 or 4, wherein the input signal is an acoustic signal. 6. The information encoding method according to claim 1, 2, 3, or 4, wherein the input signal is an image signal. 7. A frequency component decomposing process means for decomposing an input signal into frequency components, and a means for encoding a frequency component obtained by the frequency component decomposing means are provided. An information coding apparatus, wherein a part of the omitted band is selectively provided. 8. The processing band control means comprises a processing band control means, and the processing band control means controls whether or not the processing of frequency component decomposition is omitted for the partial band. Information coding device. 9. A waveform band synthesizing process comprising: a processing band control process; a frequency component code decoding process; and a waveform signal synthesizing process for synthesizing a waveform signal from the frequency components obtained by the frequency component decoding process. The processing is an information decoding method characterized in that, based on the control by the processing bandwidth control processing, the processing of waveform signal synthesis is selectively omitted for some bands. 10. An information selection process, a frequency component code decoding process, and a waveform signal synthesizing process for synthesizing a waveform signal from the frequency components obtained by the frequency component decoding process. Is an information decoding method characterized in that only a part of the information contained in the input code string selected by the above information selecting process is used, and the waveform signal combining process is omitted for a part of the band. 11. The information decoding method according to claim 9, wherein the band in which the waveform signal synthesizing process is omitted is a band on the high frequency side. 12. The information decoding method according to claim 9, 10 or 11, wherein the waveform signal synthesizing process is performed by an inverse spectrum converting unit and a band synthesizing filter unit. 13. The information decoding method according to claim 9, 10, 11 or 12, wherein the output signal is an acoustic signal. 14. The information decoding method according to claim 9, 10, 11 or 12, wherein the output signal is an image signal. 15. A processing band control means, a frequency component code decoding means, and a waveform signal synthesizing means for synthesizing a waveform signal from the frequency components obtained by the frequency component decoding means, the waveform signal synthesizing means. The information decoding apparatus is characterized in that, based on the control of the processing band control means, the waveform signal synthesizing process is selectively omitted for some bands. 16. An information selecting means, a frequency component code decoding means, and a waveform signal synthesizing means for synthesizing a waveform signal from the frequency components obtained by the frequency component decoding means, wherein the waveform signal synthesizing means is provided. , Using only a part of information contained in the input code string selected by the information selecting means,
An information decoding device characterized in that the processing of waveform signal synthesis is omitted for some bands.