JP2002229598A - Device and method for decoding stereophonic encoded signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decoding device and a decoding method for a stereophonic encoded signal, which improve deterioration of a stereophonic image. SOLUTION: This device is equipped with harmonic structure analysis parts 5 and 6 which analyze the harmonic structure of unintegrated frequencies and generate a weighting signal for correcting the harmonic structure of integrated frequencies and harmonic structure correction parts 7 and 8 which correct the harmonic structure of the integrated frequencies by using the weighting signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stereo coded signal decoding apparatus for decoding a stereo coded signal, a stereo coded signal decoding method, and a program.

[0002]

2. Description of the Related Art In the field of digital audio in recent years, various audio signal codes enabling high-quality sound storage or transmission at a bit rate lower than one tenth of that of conventional compact discs (CDs). Technology has begun to be widely used. These audio signal encoding techniques include A which is used for a mini disc (MD).
TRAC (Adaptive Transform Acoustic Coding) system and ISO / MPE adopted in digital satellite broadcasting
There are various methods such as MPEG1 and MPEG2 of G.

In an encoding apparatus or an encoding method using these audio signal encoding techniques, first, a time-division sample of an input digital audio signal is subjected to band division filter processing (for example, QMF: Quadrature Mirror Filtration).
ter) and frequency conversion processing (for example, MDCT: Modified Discre
te Transform) and transforms them into subband signals or frequency spectra representing frequency components using a transformation process.

Next, based on human auditory psychological characteristics such as a minimum audible threshold value and simultaneous masking, a quantization bit for a frequency component is allowed by allowing a level of quantization noise that is not perceptually perceptible or hardly perceived. Assign a number.

[0005] Next, the frequency component is quantized by the assigned number of quantization bits. As a result, quantization noise at the time of decoding is not perceived, or is suppressed to a level that is hardly perceived, so that it does not become an obstacle to hearing.

[0006] Finally, a multiplex process is performed to combine the quantized frequency components and auxiliary information such as the number of quantization bits to generate a coded bit string, which is stored or transmitted.

[0007] The stored or transmitted coded bit string is subjected to reverse processing by a decoding device or decoding method to reproduce and output a digital audio signal.

In such an audio signal encoding technique, a technique called stereo encoding (or joint stereo encoding) is used as a method for further improving the encoding efficiency. Stereo encoding is used when the input digital audio signal is a dual stereo signal of two channels or multi channels. The two most common types of stereo coding are mid / side (M / S) stereo coding and intensity stereo coding.

In M / S stereo coding, a mid signal obtained by a sum of stereo signals and a side signal obtained by a difference are generated, and the mid signal and the side signal are encoded instead of the stereo signal. As a result, when the stereo signals are similar with the same code, the amplitude of the side signal is smaller, and when the stereo signals are similar with different codes, the amplitude of the mid signal is smaller. Thus, the coding efficiency can be improved as compared with the case where a stereo signal is coded.

On the other hand, intensity stereo coding generates and codes an integrated signal from a stereo signal. The coded integrated signal may be handled together with left and right codes and auxiliary information indicating amplitude. Thus, since the integrated signal is encoded, the encoding efficiency can be greatly improved as compared with the case where the stereo signal is encoded.

FIG. 6 is a block diagram of an encoding apparatus using intensity stereo encoding.

In FIG. 6, reference numeral 41 denotes a frequency spectrum S of an input digital audio signal SINL (n) of time-series samples.
This is a filter bank for converting to PCL (f). Reference numeral 42 denotes a filter bank for converting the input digital audio signal SINR (n) of the time series sample into a frequency spectrum SPCR (f). 43 is a frequency spectrum SPCL and a frequency spectrum
This is a joint stereo unit that generates an integrated spectrum SPCI (f) based on SPCR (f). 44 is a frequency spectrum SP
CL (f), frequency spectrum SPCR (f) and integrated spectrum SPCI
This is a quantization and multiplexing unit that compiles (f) and collects auxiliary information to generate an encoded bit sequence.

In FIG. 6, the frequency spectrum SPCL
(f) and frequency spectrum SPCR (f) and integrated spectrum SPCI
Bit allocation processing based on human auditory characteristics for calculating the number of quantization bits for quantizing (f) is performed by the quantization and demultiplex unit.

The integrated spectrum SPCI (f) is generated for a frequency spectrum of a high frequency (for example, a frequency of 4 KHz or more). This is because human psychoacoustic characteristics are insensitive to high-frequency phase information.

FIG. 7 is a diagram showing an improvement in coding efficiency by intensity stereo coding.

FIG. 7 shows a case where intensity stereo coding is performed on a frequency spectrum of a high frequency (for example, a frequency of 4 kHz or more). In FIG. 7, (a1) shows the frequency spectrum SPCL (f) of the left channel. (a2)
Shows the frequency spectrum of the right channel in SPCR (f).
(a3) shows the total amount of information when the frequency spectrum (a1) of the left channel and the frequency spectrum (a2) of the right channel are encoded without using intensity stereo encoding. In (a3), SPCL1 is the frequency spectrum SPC
Indicates the amount of information at the time of encoding L (f) (0 <f <4 kHz). SPCL4 is
The information amount at the time of encoding the frequency spectrum SPCL (f) (f> = 4 kHz) is shown. SPCR1 has a frequency spectrum SPCR (f) (0 <f <4 kHz)
Shows the amount of information at the time of encoding. SPCR4 indicates the amount of information at the time of encoding the frequency spectrum SPCR (f) (f> = 4 kHz). That is, the total information amount (a3) when the intensity stereo coding is not used is represented by SPCL1 + SPCL4 + SPCR1 + SPCR4.

On the other hand, (b1) shows the frequency spectrum of the left channel when using intensity stereo coding. The frequency spectrum SPCL1 (f) of (b1) (0 <f <4 kHz) is
This is the same as the frequency spectrum SPCL (f) of (a1) (0 <f <4 kHz). In addition, the frequency spectrum SPCI (f) of (b1) (f> = 4 kHz)
Is an integrated spectrum obtained from the frequency spectrum SPCL (f) (f> = 4 kHz) of (a1) and the frequency spectrum SPCR (f) (f> = 4 kHz) of (a2). (b2) shows the frequency spectrum of the right channel when intensity stereo coding is used. The frequency spectrum SPCR1 (f) of (b2) (0 <f <4 kHz) is
This is the same as the frequency spectrum SPCR (f) (0 <f <4 kHz) of (a1). The frequency spectrum of f> = 4 kHz of (b2) is converted to the frequency spectrum SP of (b1) by intensity stereo coding.
Becomes 0 because it is encoded with CI (f) (f> = 4 kHz). (b3)
Indicates the total amount of information when the frequency spectrum (b1) of the left channel and the frequency spectrum (b2) of the right channel are coded when using intensity stereo coding. In (b3), SPCL1 is the frequency spectrum SPCL1 (f)
Indicates the amount of information at the time of encoding (0 <f <4 kHz). SPCI indicates the amount of information at the time of coding the integrated spectrum SPCI (f) (f> = 4 kHz).
SPCR1 indicates the amount of information at the time of encoding the frequency spectrum SPCR1 (f) (0 <f <4 kHz). That is, the sum (b3) of the information amount when using intensity stereo coding is SPCL1 + SPC
Indicated by I + SPCR1. The total information amount (b3) when using intensity stereo coding can be smaller than the total information amount (a3) when not using intensity stereo coding, and the coding efficiency can be improved. .

FIG. 8 is a block diagram showing a decoding apparatus for decoding a coded bit string generated by using the intensity stereo coding in the coding apparatus shown in FIG.

In FIG. 8, reference numeral 61 denotes an inverse quantified bit stream which is decomposed into a quantized frequency spectrum SPCL1 (f), frequency spectrum SPCR1 (f), integrated spectrum SPCI (f) and auxiliary information. The demultiplexing and dequantizing unit outputs the frequency spectrum SPCL1 (f), the frequency spectrum SPCR1 (f), and the integrated spectrum SPCI (f) after performing the conversion processing. Reference numeral 62 denotes a joint stereo unit that generates the frequency spectrum SPCL2 (f) and the frequency spectrum SPCR2 (f) of the integrated frequency from the integrated spectrum SPCI (f). 63 combines the frequency spectrum SPCL1 (f) and the frequency spectrum SPCL2 (f) to generate a frequency spectrum SPCL (f)
After that, the filter bank converts the output digital audio signal SOUTL (n) of the time series sample. 64 is
Frequency spectrum SPCR1 (f) and frequency spectrum SPCR2 (f)
And a filter bank for converting the frequency spectrum SPCR (f) into a time-series sampled output digital audio signal SOUTR (n).

FIG. 9 is a diagram showing a frequency spectrum of each block in the stereo coded signal decoding apparatus shown in FIG.

In FIG. 9, (a1) is a frequency spectrum SP output from the demultiplexing and inverse quantization unit 61.
CL1 (f) is shown. (a2) shows the frequency spectrum SPCR1 (f) output from the demultiplexing and inverse quantization unit 61. Frequency spectrum SPCL1 (f) and frequency spectrum SPCR
1 (f) is composed of frequency components that are not integrated. (a
3) shows the integrated spectrum SPCI (f) output from the demultiplexing and inverse quantization unit 61. Integrated spectrum S
PCI (f) is composed of integrated frequency components. (b
1) is a frequency spectrum SPCL2 (f) and a frequency spectrum SPCL1 (f) of the integrated frequency of the left channel obtained by the joint stereo unit 62 based on the integrated spectrum SPCI (f).
And shows the frequency spectrum SPCL (f) obtained by combining The frequency spectrum SPCL (f) is output by the filter bang 63 as a digital audio signal SOUTL (n) of time series samples.
Is converted to (b2) is a frequency obtained by combining the frequency spectrum SPCR2 (f) and the frequency spectrum SPCR1 (f) of the integrated frequency of the right channel obtained by the joint stereo unit 62 based on the integrated spectrum SPCR (f). The spectrum SPCR (f) is shown. The frequency spectrum SPCR (f) is converted by the filter bang 63 into an output digital audio signal SOUTR (n) of time series samples.

In FIG. 9, for the sake of simplicity, the joint stereo section 62 is based on the integrated spectrum SPCI (f).
Although the frequency spectrum SPCL2 (f) and the frequency spectrum SPCR2 (f) obtained at are exactly the same frequency spectrum,
The frequency spectrum SPCL2 (f) and the frequency spectrum SPCR are reflected by reflecting the code or amplitude information contained in the auxiliary information.
2 (f) may be different.

[0023]

However, the decoding method or the decoding apparatus for stereo coded signals in the above-mentioned prior art uses the integrated spectrum integrated using intensity stereo coding to integrate the left and right channels. Since the detailed structure of the left and right channels is similar to that of the stereo signal before encoding in order to combine with the frequency spectrum that is not integrated as the converted frequency spectrum, the perceived stereo image is degraded.

For this reason, intensity stereo coding is used only when the number of bits that can be used for encoding is small, or an intensity stereo code is used only when the similarity is large by introducing an algorithm for detecting the similarity between the left and right channels. Can prevent stereo image degradation due to intensity stereo coding, but use intensity stereo coding to improve coding efficiency when the number of bits available for coding is small. In such a case, the perceived stereo image may deteriorate.

Further, in order to avoid such deterioration of the stereo image, code or amplitude information is added to the auxiliary information at the time of encoding, and this information can be used to avoid the deterioration of the stereo image. Since information is added at the time of encoding, the information amount of the intensity stereo encoded signal increases.

That is, in the decoding method or the decoding apparatus for the intensity stereo coded signal in the above-described conventional technique, the decoded stereo signal is more detailed in the left and right channels than the stereo signal before coding. When the structure is similarized and the perceived stereo image is degraded, and when auxiliary information is added to the intensity stereo coded signal to avoid deterioration of the perceived stereo image, the information amount of the intensity stereo coded signal is reduced. There is a problem that becomes large.

The present invention has been made in consideration of the above-described problems, and has been made in consideration of the above-described problems. It is intended to provide a method and a program.

[0028]

In order to solve the above-mentioned problems, a first invention (corresponding to claim 1) has a frequency component equal to or higher than a predetermined frequency generated by intensity stereo coding. Input means for inputting a stereo coded signal in which an integrated spectrum and frequency components lower than the predetermined frequency are multiplexed with each low frequency spectrum corresponding to each channel, and using each low frequency spectrum Frequency spectrum correcting means for obtaining each high frequency spectrum corresponding to each channel having a frequency component equal to or higher than the predetermined frequency by correcting the integrated spectrum, and the low frequency spectrum corresponding to each channel. And a frequency spectrum for obtaining the frequency spectrum of each channel by integrating the high frequency spectrum. And Le derivation means is a stereo coded signal decoding apparatus comprising an audio signal generating means for generating an audio signal of each channel from the frequency spectrum of each channel.

The second invention (corresponding to claim 2)
The frequency spectrum correction means, for each channel, analyzing the low frequency spectrum corresponding to the channel, to generate a harmonic signal corresponding to the channel harmonic structure analysis means, for each channel, for each channel, A stereo coded signal decoding apparatus according to the first aspect of the present invention, further comprising: a harmonic structure correcting unit that obtains the high frequency spectrum corresponding to the channel by applying the weighted signal corresponding to the channel to the integrated spectrum. It is.

The third invention (corresponding to claim 3)
Is the stereo coded signal decoding apparatus according to the second aspect of the present invention, wherein the weighted signal corresponding to the channel is based on an envelope of the low frequency spectrum corresponding to the channel.

The fourth invention (corresponding to claim 4)
The stereo coding according to the second aspect of the present invention, wherein, when generating the weighted signal corresponding to the channel, the frequency spectrum correcting means also uses the low frequency spectrum corresponding to a channel other than the channel. It is a signal decoding device.

The fifth invention (corresponding to claim 5)
Is a weighted signal corresponding to the channel, based on the envelope of the low frequency spectrum corresponding to the channel, based on the reciprocal of the envelope of the low frequency spectrum corresponding to channels other than the channel The stereo coded signal decoding apparatus according to the fourth aspect of the present invention.

Further, a sixth aspect of the present invention (corresponding to claim 6)
In the integrated spectrum having a frequency component equal to or higher than a predetermined frequency generated by intensity stereo coding, and having a frequency component lower than the predetermined frequency, each low frequency spectrum corresponding to each channel is multiplexed. By inputting the stereo coded signal, and correcting the integrated spectrum using each of the low frequency spectrums, having a frequency component equal to or higher than the predetermined frequency, each high frequency spectrum corresponding to each channel is obtained. Stereo coded signal decoding for obtaining the frequency spectrum of each channel by integrating the low frequency spectrum and the high frequency spectrum corresponding to each channel, and generating an audio signal of each channel from the frequency spectrum of each channel. Is the way.

The seventh invention (corresponding to claim 7)
When the high frequency spectrum corresponding to each channel is obtained, the low frequency spectrum corresponding to the channel is analyzed for each channel to generate a weighted signal corresponding to the channel, and for each channel,
The stereo coded signal decoding method according to the sixth aspect of the present invention, wherein the high frequency spectrum corresponding to the channel is obtained by applying the weighted signal corresponding to the channel to the integrated spectrum.

The eighth invention (corresponding to claim 8)
Is the stereo coded signal decoding method according to the seventh aspect of the present invention, wherein the weighting signal corresponding to the channel is based on an envelope of the low frequency spectrum corresponding to the channel.

The ninth invention (corresponding to claim 9)
Is the stereo coded signal decoding method according to the seventh aspect of the present invention, wherein when generating the weighted signal corresponding to the channel, the low frequency spectrum corresponding to a channel other than the channel is also used.

According to a tenth aspect of the present invention (corresponding to claim 10), the weighting signal corresponding to the channel is:
The stereo code according to the ninth aspect of the present invention, which is based on an envelope of the low frequency spectrum corresponding to the channel and based on a reciprocal of an envelope of the low frequency spectrum corresponding to a channel other than the channel. This is a decoded signal decoding method.

An eleventh aspect of the present invention (corresponding to claim 11) is the stereo coded signal decoding apparatus according to the first aspect of the present invention, wherein the frequency is equal to or higher than a predetermined frequency generated by intensity stereo coding. Input means for inputting a stereo-encoded signal in which an integrated spectrum having components and each low-frequency spectrum corresponding to each channel having a frequency component less than the predetermined frequency are input; and each of the low-frequency frequencies Frequency spectrum correcting means for obtaining each high frequency spectrum corresponding to each channel having a frequency component equal to or higher than the predetermined frequency by correcting the integrated spectrum using the spectrum; and The frequency spectrum of each channel by integrating the high frequency spectrum and the high frequency spectrum A frequency spectrum deriving means is a program for causing a computer to function as all or part of the audio signal generating means for generating an audio signal of each channel from the frequency spectrum of each channel.

According to a twelfth aspect of the present invention (corresponding to claim 12), in the stereo coded signal decoding method according to the sixth aspect of the present invention, a frequency higher than a predetermined frequency generated by intensity stereo coding is used. Inputting a stereo coded signal obtained by multiplexing an integrated spectrum having a component, and having a frequency component lower than the predetermined frequency, and each low-frequency spectrum corresponding to each channel; and By correcting the integrated spectrum using, having a frequency component of the predetermined frequency or more, the step of obtaining each high frequency spectrum corresponding to each channel, and the low frequency spectrum corresponding to each channel Obtaining the frequency spectrum of each channel by integrating the high frequency spectrum, From the frequency spectrum of the Yan'neru is a program for executing all or a part of the step of generating an audio signal of each channel to the computer.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description, a coded bit sequence generated by a coding apparatus using intensity stereo coding shown in FIG. 6 or an equivalent coding method is input. FIG. 6 has been described in detail in the related art.

For the sake of simplicity, it is assumed that the frequency at which an integrated spectrum is generated using intensity stereo coding is a frequency of 4 kHz or more (f> = 4 kHz).

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
1 is a block diagram showing a configuration of a stereo coded signal decoding apparatus according to an embodiment of the present invention, wherein 1 performs demultiplexing and dequantization processing on an input coded bit string, and performs frequency spectrum SPCL1 (f) and frequency spectrum SPCR1 (f ) And an integrated spectrum SPCI (f). Reference numeral 2 denotes a joint stereo unit that generates a frequency spectrum SPCL2 (f) and a frequency spectrum SPCR2 (f) of a frequency integrated from the integrated spectrum SPCI (f). 3 is an output digital audio signal of a time series sample after combining the frequency spectrum SPCL1 (f) and the frequency spectrum SPCL3 (f) into a frequency spectrum SPCL (f).
This is a filter bank that performs inverse conversion to SOUTL (n). Reference numeral 4 denotes a filter bank that combines the frequency spectrum SPCR1 (f) and the frequency spectrum SPCR3 (f) into a frequency spectrum SPCR (f), and then inversely converts the output digital audio signal SOUTR (n) of a time-series sample. . 5 is the frequency spectrum
A harmonic structure analysis unit that analyzes the harmonic structure of SPCL1 (f) and outputs a weighted signal WL (f). 6 is the frequency spectrum
A harmonic structure analysis unit that analyzes the harmonic structure of SPCR1 (f) and outputs a weighted signal WR (f). 7 is the frequency spectrum
A harmonic structure correction unit that corrects the harmonic structure of SPCL2 (f) using the weighting signal WL (f) and outputs a frequency spectrum SPCL3 (f). Reference numeral 8 denotes a harmonic structure correction unit that corrects the harmonic structure of the frequency spectrum SPCR2 (f) using the weighting signal WR (f) and outputs the frequency spectrum SPCR3 (f). 10 is
Frequency spectrum SPCL3 (f) and SPCL1 (f)
To generate a frequency spectrum SPCL (f). 11 is a frequency spectrum SPCR3
(F) and SPCR1 (f) are combined to generate a frequency spectrum SPCR (f).

The decoding process performed by the stereo coded signal decoding apparatus shown in FIG. 1 will be described below.

The demultiplexing and inverse quantization unit 1 decomposes the input coded bit string into a quantized frequency spectrum SPCL1 (f), frequency spectrum SPCR1 (f), integrated spectrum SPCI (f) and auxiliary information. Later, the frequency spectrum SPCL1 (f) and the frequency spectrum SP
Output CR1 (f) and integrated spectrum SPCI (f).

The joint stereo unit 2 generates a frequency spectrum SPC of the integrated frequency from the integrated spectrum SPCI (f).
Generate L2 (f) and frequency spectrum SPCR2 (f). For the sake of simplicity, the frequency spectrum SPCL2 (f) and the frequency spectrum SPCR2 (f) are assumed to be the same.

The harmonic structure analyzer 5 has a frequency spectrum SP
It analyzes the harmonic structure of CL1 (f) and outputs a weighted signal WL (f). The frequency spectrum SPCL1 (f) is configured by a frequency spectrum of a frequency that is not integrated (that is, 0 <f <4 kHz).

As a method of analyzing the harmonic structure, for example, there is a method of obtaining an envelope of the frequency spectrum SPCL1 (f) (0 <f <4 kHz). Using the analyzed harmonic structure, a weighting signal WL (f) (f> = 4) that corrects the harmonic structure of the frequency integrated by the intensity stereo coding.
kHz).

As a method of generating the weighted signal WL (f), for example, the envelope (envelope) of the frequency spectrum SPCL1 (f) normalized by the maximum value is integrated with the integrated frequency (that is, from f = 4 kHz to the reproduction band). Up to).

The harmonic structure analyzer 6 performs the same processing as the harmonic structure analyzer 5.

The harmonic structure correcting section 7 converts the harmonic structure of the integrated frequency spectrum SPCL2 (f) into a weighting signal WL.
The frequency spectrum SPCL3 (f) is output after correction using (f).

As a method of correcting the harmonic structure, for example, there is a method of multiplying the frequency spectrum SPCL2 (f) by the weighting signal WL (f).

The harmonic structure corrector 8 performs the same processing as the harmonic structure corrector 7.

The frequency spectrum of a normal audio signal is often a pattern in which the pattern of the envelope of the frequency spectrum in the low-frequency portion is repeated many times in the high-frequency portion. In other words, artificially generated audio signals do not apply to this example, but a wide range of audio signals such as music, animal sounds, human speech, and natural sounds that occur in the natural world, It has been empirically found that the pattern of the envelope of the frequency spectrum of the portion is a pattern that is repeated many times in the high-frequency portion.

As such an example, FIG. 12 shows the frequency spectrum (harmonic structure) of the audio signal of the sound emitted by the harpsichord of the musical instrument. As is clear from FIG. 12, the frequency spectrum (harmonic structure) has a structure composed of the fundamental tone and its overtone, and the pattern of the envelope of the frequency spectrum in the low-frequency part is repeated many times in the high-frequency part. It turns out that it is a pattern.

Therefore, the weighted signal W
L (f) (f> = 4 KHz) is obtained, and this WL (f)
(F> = 4 KHz) to the frequency spectrum SPCL2
By multiplying (f), it is possible to satisfactorily restore SPCL3 (f), which is the harmonic structure of the high-frequency part, with most audio signals. The same applies to SPCR3 (f).

The adder 10 calculates the frequency spectrum
SPCL1 (f) (0 <f <4kHz) and frequency spectrum SPCL3 (f) (f> = 4k
Hz) to obtain a frequency spectrum SPCL (f). Also,
The adding unit 11 combines the frequency spectrum SPCR1 (f) (0 <f <4 kHz) and the frequency spectrum SPCR3 (f) (f> = 4 kHz) to obtain a frequency spectrum SPCR (f).

The filter bank 3 has a frequency spectrum SP
A conversion process is performed on CL (f) to output an output digital audio signal SOUTL (n) of time series samples. The filter bank 4 performs the same processing as the filter bank 3.

FIG. 2 shows the frequency spectrum SPCL1 (f), the frequency spectrum SPCR1 (f), the weighting signal WL (f) and the weighting signal WR (f).

FIG. 3 is a diagram showing a frequency spectrum output from each block of the stereo coded signal decoding apparatus shown in FIG. 1. (A 1) is output from the demultiplexing and inverse quantization unit 1. 13 shows a frequency spectrum SPCL1 (f).
(a2) shows the frequency spectrum SPCR1 (f) output from the demultiplexing and inverse quantization unit 1. (a3) shows the integrated spectrum SPCI (f) output from the demultiplexing and inverse quantization unit 1. (b1) shows a frequency spectrum when the frequency spectrum SPCL2 (f) output from the joint stereo unit 2 and the frequency spectrum SPCL1 (f) are combined. (b2) is the frequency spectrum SPCR2 (f) output from the joint stereo unit 2 and the frequency spectrum SPCR1
6 shows a frequency spectrum when (f) is combined. (c1)
Is the frequency spectrum output from the harmonic structure correction unit 7.
7 shows a frequency spectrum when SPCL3 (f) and frequency spectrum SPCL1 (f) are combined. (c2) shows a frequency spectrum when the frequency spectrum SPCR3 (f) output from the harmonic structure correction unit 7 and the frequency spectrum SPCR1 (f) are combined.

As shown in FIG. 3, by correcting the harmonic structure of the integrated frequency based on the harmonic structure of the non-integrated frequency, the modulation of the integrated frequency by intensity stereo coding is performed. The wave structure can be different for the left and right channels.

As a result, it is possible to improve the stereo image of the output digital audio signal when decoding the coded signal generated by the intensity stereo coding.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
FIG. 9 is a block diagram showing a configuration of a stereo coded signal decoding apparatus according to the embodiment of the present invention, which includes a demultiplexing and inverse quantization processing unit 1, a joint stereo unit 2, a filter bank 3, a filter bank 4, a harmonic structure correction unit 7, The harmonic structure correcting unit 8, the adding unit 10, and the adding unit 11 are the same as each block shown in FIG. 31 is a frequency spectrum SPCL1
(f) is a harmonic structure analysis unit that analyzes the harmonic structure of the frequency spectrum SPCR1 (f) and outputs a weighted signal WL (f) and a weighted signal WR (f).

The decoding process executed by the stereo coded signal decoding apparatus shown in FIG. 4 will be described below.

The demultiplexing and inverse quantization unit 1 decomposes the input coded bit string into a quantized frequency spectrum SPCL1 (f), frequency spectrum SPCR1 (f), integrated spectrum SPCI (f) and auxiliary information. Later, the frequency spectrum SPCL1 (f) and the frequency spectrum SP
Output CR1 (f) and integrated spectrum SPCI (f).

The joint stereo unit 2 has an integrated spectrum
Frequency spectrum SPCL2 of frequency integrated from SPCI (f)
(f) and the frequency spectrum SPCR2 (f) are generated. For the sake of simplicity, the frequency spectrum SPCL2 (f) and the frequency spectrum SPCR2 (f) are assumed to be the same.

The harmonic structure analyzer 31 calculates the frequency spectrum
It analyzes the harmonic structure of SPCL1 (f) and frequency spectrum SPCR1 (f) and outputs weighting signal WL (f) and weighting signal WR (f). Frequency spectrum SPCL1 (f) and frequency spectrum SPCR
1 (f) is the unintegrated frequency (ie 0 <f <4kHz)
Of the frequency spectrum.

As a method of analyzing the harmonic structure, for example, the frequency spectrum SPCL1 (f) (0 <f <4 kHz) and the SPCR1 (f) (0 <f <4 kHz
There is a method of finding the envelope (envelope) of z).
Weighted signals WL (f) (f> = 4kHz) and WR (f) (f> = 4kHz) that use the analyzed harmonic structure to correct the harmonic structure of the frequency integrated by intensity stereo coding Generate

As a method of generating the weighted signal WL (f), for example, a method in which an envelope (envelope) of the frequency spectrum SPCL1 (f) is normalized by a maximum value and an envelope (envelope) of the frequency spectrum SPCR1 (f) are used. The integrated frequency (ie, from f = 4kHz to the reproduction band) obtained by multiplying the reciprocal of by multiplying the result by normalization with the maximum value
There is a method such as repeating between.

As described above, in the present embodiment, unlike the first embodiment, when generating the weighting signal WL (f), the frequency spectrum SPCR1 (f) and the SPCL
Use both envelopes of 1 (f). And WL (f)
Is proportional to the envelope of the frequency spectrum SPCL1 (f) and proportional to the reciprocal of the envelope of the frequency spectrum SPCR1 (f), so that the harmonic structure of the left and right channels is different from that of the first embodiment. It can be.

As a method of generating the weighted signal WR (f), for example, an envelope (envelope) of the frequency spectrum SPCR1 (f) normalized by a maximum value and an envelope (frequency) of the frequency spectrum SPCL1 (f) are used. There is a method of repeating the result obtained by multiplying the reciprocal of the envelope by the maximum value normalized by the maximum value between integrated frequencies (that is, from f = 4 kHz to the reproduction band).

As described above, in the present embodiment, unlike the first embodiment, when generating weighting signal WR (f), frequency spectrum SPCR1 (f) and SPCL
Use both envelopes of 1 (f). And WR (f)
Is proportional to the envelope of the frequency spectrum SPCR1 (f) and proportional to the reciprocal of the envelope of the frequency spectrum SPCL1 (f), so that the harmonic structure of the left and right channels is different from that of the first embodiment. It can be.

The harmonic structure correcting section 7 corrects the harmonic structure of the integrated frequency spectrum SPCL2 (f) using the weighting signal WL (f) and corrects the frequency spectrum SPCL3.
(f) is output. As a method of correcting the harmonic structure, for example, there is a method of multiplying the frequency spectrum SPCL2 (f) by the weighting signal WL (f). The harmonic structure correction unit 8 performs the same processing as the harmonic structure correction unit 7.

The adder 10 calculates the frequency spectrum
SPCL1 (f) (0 <f <4kHz) and frequency spectrum SPCL3 (f) (f> = 4k
Hz) to obtain a frequency spectrum SPCL (f). Also,
The adding unit 11 combines the frequency spectrum SPCR1 (f) (0 <f <4 kHz) and the frequency spectrum SPCR3 (f) (f> = 4 kHz) to obtain a frequency spectrum SPCR (f).

The filter bank 3 has a frequency spectrum SP
A conversion process is performed on CL (f) to output an output digital audio signal SOUTL (n) of time series samples. The filter bank 4 performs the same processing as the filter bank 3.

FIG. 5 shows the frequency spectrum SPCL1 (f), the frequency spectrum SPCR1 (f), the weighting signal WL (f), and the weighting signal WR (f).

A diagram showing the frequency spectrum output from each block of the stereo coded signal decoding apparatus shown in FIG. 4 is the same as FIG.

As shown in FIG. 3, by correcting the harmonic structure of the integrated frequency based on the harmonic structure of the non-integrated frequency, the integrated frequency modulation by intensity stereo coding is performed. The wave structure can be different for the left and right channels.

Thus, it is possible to improve the stereo image of the output digital audio signal when decoding the coded signal generated by the intensity stereo coding.

(Third Embodiment) FIG. 10 is a flowchart showing a method for decoding a stereo coded signal according to a third embodiment of the present invention. And a step of performing an inverse quantization process to output a frequency spectrum SPCL1 (f), a frequency spectrum SPCR1 (f), and an integrated spectrum SPCI (f).
Step 82 is a step of generating a frequency spectrum SPCL2 (f) and a frequency spectrum SPCR2 (f) of the integrated frequency from the integrated spectrum SPCI (f). Step 83
Is a step of analyzing the harmonic structure of the frequency spectrum SPCL1 (f) or the frequency spectrum SPCR1 (f) and outputting a weighting coefficient WL (f) and a weighting coefficient WR (f). Step 84 corrects the harmonic structure of the frequency spectrum SPCL2 (f) or the frequency spectrum SPCR2 (f) using the weighting coefficient WL (f) or the weighting coefficient WR (f), and the frequency spectrum SPCL3 (f) and the frequency spectrum This is the step of outputting SPCR3 (f). Step 85 is the frequency spectrum SPCL
This is a step of combining 1 (f) and the frequency spectrum SPCL3 (f) to obtain a frequency spectrum SPCL (f), and then performing an inverse conversion to an output digital audio signal SOUTL (n) of a time-series sample. Alternatively, step 85 comprises a frequency spectrum SPCR
This is also the step of combining 1 (f) and the frequency spectrum SPCR3 (f) into a frequency spectrum SPCR (f) and then inversely converting it into an output digital audio signal SOUTR (n) of time series samples. Step 86 consists of steps 83 to 85
Is a step of determining a channel in order to repeatedly execute the processing of FIG.

The decoding process executed by the stereo coded signal decoding method shown in FIG. 10 will be described below.

In step 81, the input coded bit string is decomposed into the quantized frequency spectrum SPCL1 (f), frequency spectrum SPCR1 (f), integrated spectrum SPCI (f) and auxiliary information. Frequency spectrum
SPCL1 (f) and frequency spectrum SPCR1 (f) and integrated spectrum
Outputs SPCI (f).

Step 82 is an integrated spectrum SPCI (f)
To generate the integrated frequency spectrum SPCL2 (f) and frequency spectrum SPCR2 (f). For simplicity, the frequency spectrum SPCL2 (f) and the frequency spectrum
SPCR2 (f) is the same.

Step 83 is a processing function FUNC1 [x] (variable
x analyzes the harmonic structure of the frequency spectrum SPCL1 (f) by SPCL1 (f) or SPCR1 (f) and outputs a weighting coefficient WL (f). The frequency spectrum SPCL1 (f) is configured by a frequency spectrum of a frequency that is not integrated (that is, 0 <f <4 kHz). As a method of analyzing the harmonic structure, for example, there is a method of obtaining an envelope of the frequency spectrum SPCL1 (f) (0 <f <4 kHz). Using the analyzed harmonic structure, a weighting coefficient WL (f) (f> = 4) that corrects the harmonic structure of the frequency integrated by the intensity stereo coding.
kHz). As a method of generating the weighting coefficient WL (f), for example, the envelope (envelope) of the frequency spectrum SPCL1 (f) normalized by the maximum value is integrated frequency (that is, from f = 4 kHz to the reproduction band). There is a method such as repeating between.

In step 84, the harmonic structure of the integrated frequency spectrum SPCL2 (f) is weighted by a weighting coefficient WL (f).
And outputs the frequency spectrum SPCL3 (f). As a method of correcting the harmonic structure, for example, there is a method of multiplying the frequency spectrum SPCL2 (f) by a weighting coefficient WL (f). Combining the frequency spectrum SPCL1 (f) (0 <f <4kHz) and the frequency spectrum SPCL3 (f) (f> = 4kHz)
PCL (f). The frequency spectrum SPCR1 (f) (0 <f <4 kHz) and the frequency spectrum SPCR3 (f) (f> = 4 kHz) are combined to form a frequency spectrum SPCR (f).

Step 85 is a processing function FUNC2 [x] (variable
x is the frequency spectrum S by SPCL (f) or SPCR (f)
A conversion process is performed on PCL (f) to output an output digital audio signal SOUTL (n) of time-series samples. In step 86, the channel subjected to the processing of steps 83 to 85 is determined, and the processing of steps 83 to 85 is repeatedly executed for the left and right channels.

Weighting coefficient WL obtained in step 83
(f) and the weighting coefficient WR (f) correspond to the weighting signal WL shown in FIG.
(f) is the same as the weighting signal WR (f).

The diagram showing the frequency spectrum obtained in each step of the method for decoding the stereo coded signal shown in FIG. 10 is the same as FIG.

As shown in FIG. 3, by correcting the harmonic structure of the integrated frequency based on the harmonic structure of the unintegrated frequency, the modulation of the integrated frequency by intensity stereo coding is performed. The wave structure can be different for the left and right channels.

Thus, it is possible to improve the stereo image of the output digital audio signal when decoding the coded signal generated by the intensity stereo coding.

(Fourth Embodiment) FIG. 11 is a flow chart showing a method for decoding a stereo coded signal according to a fourth embodiment of the present invention, wherein steps 81, 82, 84, 85 and 85 are performed. 86 is the same as each step shown in FIG. Step 91 analyzes the harmonic structure of the frequency spectrum SPCL1 (f) and the frequency spectrum SPCR1 (f) to determine the weighting coefficient WL (f) and the weighting coefficient WR (f).
Is a step of outputting.

The decoding process executed by the stereo coded signal decoding method shown in FIG. 11 will be described below.

In step 81, the input coded bit string is decomposed into quantized frequency spectrum SPCL1 (f), frequency spectrum SPCR1 (f), integrated spectrum SPCI (f) and auxiliary information, and then inverse quantization processing is performed. Frequency spectrum
SPCL1 (f) and frequency spectrum SPCR1 (f) and integrated spectrum
Outputs SPCI (f).

Step 82 generates a frequency spectrum SPCL2 (f) and a frequency spectrum SPCR2 (f) of the integrated frequency from the integrated spectrum SPCI (f). For simplicity, the frequency spectrum SPCL2 (f) and the frequency spectrum SP
CR2 (f) is the same.

Step 91 is a processing function FUNC3 [x, y, ch].
(The variable x is SPCL1 (f), the variable y is SPCR1 (f), and the variable ch indicates a channel.) The harmonic structure of the frequency spectrum SPCL1 (f) and the frequency spectrum SPCR1 (f) Analysis is performed to output a weighting coefficient WL (f) and a weighting coefficient WR (f). Frequency spectrum SPCL1 (f) and frequency spectrum SP
CR1 (f) is the non-integrated frequency (ie, 0 <f <4 kHz
z) frequency spectrum. As a method of analyzing the harmonic structure, for example, the frequency spectrum SPCL1 (f) (0 <f
<4kHz) and SPCR1 (f) (0 <f <4kHz)
There is a way to ask. Using the analyzed harmonic structure, a weighting coefficient WL (f) (f> = 4 kHz) for correcting the harmonic structure of the frequency integrated by intensity stereo coding
And WR (f) (f> = 4kHz). As a method of generating the weighting coefficient WL (f), for example, a method in which an envelope of the frequency spectrum SPCL1 (f) is normalized by a maximum value,
After obtaining the reciprocal of the envelope (envelope) of the frequency spectrum SPCR1 (f) and multiplying the result by normalization with the maximum value, the result obtained is the integrated frequency (that is, from f = 4 kHz to the reproduction band). There is a method such as repetition between. As a method for generating the weighting coefficient WR (f), for example, a method in which an envelope of the frequency spectrum SPCR1 (f) is normalized by a maximum value and a method in which the frequency spectrum SPCL1 (f)
The result obtained by multiplying the reciprocal of the envelope (envelope) by the maximum value and the obtained result is repeated between integrated frequencies (that is, from f = 4 kHz to the reproduction band).

In step 84, the harmonic structure of the integrated frequency spectrum SPCL2 (f) is weighted by a weighting factor WL (f).
And outputs the frequency spectrum SPCL3 (f). As a method of correcting the harmonic structure, for example, there is a method of multiplying the frequency spectrum SPCL2 (f) by the weighting signal WL (f). Combining the frequency spectrum SPCL1 (f) (0 <f <4kHz) and the frequency spectrum SPCL3 (f) (f> = 4kHz)
PCL (f). The frequency spectrum SPCR1 (f) (0 <f <4 kHz) and the frequency spectrum SPCR3 (f) (f> = 4 kHz) are combined to form a frequency spectrum SPCR (f).

Step 85 is a step of frequency spectrum SPCL
A conversion process is performed on (f) to output an output digital audio signal SOUTL (n) of a time-series sample.

At step 86, the channel subjected to the processing of steps 83 to 85 is determined, and the processing of steps 83 to 85 is repeatedly executed for the left and right channels.

Weighting coefficient WL obtained in step 91
(f) and the weighting coefficient WR (f) correspond to the weighting signal WL shown in FIG.
(f) is the same as the weighting signal WR (f).

The diagram showing the frequency spectrum obtained in each step of the method for decoding the stereo coded signal shown in FIG. 11 is the same as FIG.

As shown in FIG. 3, by correcting the harmonic structure of the integrated frequency based on the harmonic structure of the non-integrated frequency, the modulation of the frequency integrated by the intensity stereo coding is performed. The wave structure can be different for the left and right channels.

Thus, it is possible to improve the stereo image of the output digital audio signal when decoding the coded signal generated by the intensity stereo coding.

The decoding method for decoding the coded bit string generated from the stereo signal consisting of two channels has been described in the first to fourth embodiments of the present invention. Can be configured based on the above description.

As described above, the apparatus and method for decoding a stereo coded signal according to the present embodiment employs the integrated frequency based on the harmonic structure of the unintegrated frequency in the course of the decoding process. By correcting the harmonic structure, it is possible to improve the stereo image of the output digital audio signal when decoding the coded signal generated by the intensity stereo coding.

Note that the demultiplexing and inverse quantization of the present embodiment are examples of the input means of the present invention, and the harmonic structure analyzing unit and the harmonic structure correcting unit of the present embodiment are different from each other in the present invention. This is an example of the frequency spectrum correction means, the adding section of the present embodiment is an example of the frequency spectrum deriving means of the present invention, and the filter bank of the present embodiment is an example of the audio signal generating means of the present invention. The harmonic structure analyzer of the embodiment is an example of the harmonic structure analyzer of the present invention, and the harmonic structure corrector of the present embodiment is an example of the harmonic structure corrector of the present invention.

The present invention is a program for causing a computer to execute all or some of the functions of the above-described stereo coded signal decoding apparatus of the present invention, and the program operates in cooperation with the computer. It is.

Further, the present invention is a program for causing a computer to execute all or some of the steps of the above-described stereo coded signal decoding method of the present invention, wherein the program operates in cooperation with the computer. It is.

It should be noted that some means of the present invention and some steps of the present invention mean several means or steps of the plurality of means or steps, or one means or one step. It means some functions or some operations in the steps.

The present invention also includes a computer-readable recording medium on which the program of the present invention is recorded.

[0109] An embodiment of the program of the present invention may be a mode in which the program is recorded on a computer-readable recording medium and operates in cooperation with the computer.

[0110] One use form of the program of the present invention may be such that the program is transmitted through a transmission medium, read by a computer, and operates in cooperation with the computer.

The data structure of the present invention includes a database, a data format, a data table, a data list, a type of data, and the like.

The recording medium includes a ROM and the like, and the transmission medium includes a transmission medium such as the Internet, light, radio waves, and sound waves.

As described above, the configuration of the present invention may be realized by software or hardware.

[0114]

As is apparent from the above description, the present invention provides a stereo coded signal decoding apparatus for reducing, suppressing or improving the perceived degradation of a stereo image when decoding an intensity stereo coded signal. ,
A stereo coded signal decoding method and a program can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a stereo coded signal decoding apparatus according to a first embodiment of the present invention.

FIG. 2 (b1) A frequency spectrum SPCL1 output from demultiplexing and dequantization of the stereo coded signal decoding device according to the first embodiment of the present invention.
It is a figure showing (f). (B2) A diagram illustrating a frequency spectrum SPCR1 (f) output from demultiplexing and dequantization of the stereo coded signal decoding device according to the first embodiment of the present invention. (C1) A diagram illustrating a weighting signal WL (f) output from the harmonic structure analysis unit of the stereo coded signal decoding device according to the first embodiment of the present invention. (C2) A diagram illustrating the weighting signal WR (f) output from the harmonic structure analysis unit of the stereo coded signal decoding device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a frequency spectrum output from each processing unit of the stereo coded signal decoding device according to the first embodiment of the present invention. (A1) Demultiplexing and dequantizing unit 1 FIG. 15 is a diagram showing an output frequency spectrum SPCL1 (f). (A2) A diagram illustrating a frequency spectrum SPCR1 (f) output from the demultiplexing and inverse quantization unit 1. (A3) is a diagram illustrating an integrated spectrum SPCI (f) output from the demultiplexing and inverse quantization unit 1. (B1) A diagram showing a frequency spectrum when the frequency spectrum SPCL2 (f) output from the joint stereo unit 2 and the frequency spectrum SPCL1 (f) are combined. (B2) A diagram showing a frequency spectrum when frequency spectrum SPCR2 (f) output from joint stereo unit 2 and frequency spectrum SPCR1 (f) are combined. (C1) A diagram showing a frequency spectrum when the frequency spectrum SPCL3 (f) output from the harmonic structure correction unit 7 and the frequency spectrum SPCL1 (f) are combined. (C2) A diagram showing a frequency spectrum when the frequency spectrum SPCR3 (f) output from the harmonic structure correction unit 7 and the frequency spectrum SPCR1 (f) are combined.

FIG. 4 is a block diagram showing a configuration of a stereo coded signal decoding apparatus according to a second embodiment of the present invention.

FIG. 5 (b1) A frequency spectrum SPCL1 output from demultiplexing and dequantization of the stereo coded signal decoding apparatus according to the second embodiment of the present invention.
It is a figure showing (f). (B2) A diagram illustrating a frequency spectrum SPCR1 (f) output from demultiplexing and inverse quantization of the stereo coded signal decoding device according to the second embodiment of the present invention. (C1) is a diagram illustrating a weighting signal WL (f) output from a harmonic structure analysis unit of a stereo coded signal decoding device according to the second embodiment of the present invention. (C2) A diagram illustrating a weighting signal WR (f) output from the harmonic structure analysis unit of the stereo coded signal decoding device according to the second embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of an apparatus for encoding a two-channel stereo signal using intensity stereo encoding according to the related art and the present embodiment.

FIG. 7 is a diagram showing an improvement in coding efficiency by using intensity stereo coding, and (a1) is a diagram showing a frequency spectrum SPCL (f) of a left channel. (A2) SPCR (f) showing the frequency spectrum of the right channel. (A3) A diagram illustrating the total amount of information when the frequency spectrum of the left channel and the frequency spectrum of the right channel are encoded without using intensity stereo encoding. (B1) is a diagram illustrating a frequency spectrum of a left channel when intensity stereo coding is used. (B2) A diagram illustrating a frequency spectrum of a right channel when intensity stereo coding is used. (B3) A diagram illustrating a total of information amounts when a frequency spectrum of a left channel and a frequency spectrum of a right channel are encoded when intensity stereo encoding is used.

FIG. 8 is a block diagram showing a configuration of a conventional stereo coded signal decoding device.

FIG. 9 is a diagram showing frequency spectra output from the respective processing units of the conventional stereo coded signal decoding device; (a1) frequency spectrum SPCL1 (output from the demultiplexing and inverse quantization unit 61; It is a figure showing f). (A2) A diagram illustrating a frequency spectrum SPCR1 (f) output from the demultiplexing and inverse quantization unit 61. (A3) is a diagram illustrating an integrated spectrum SPCI (f) output from the demultiplexing and inverse quantization unit 61. (B1) The frequency spectrum SPCL2 (f) and the frequency spectrum SPCL1 of the integrated frequency of the left channel obtained by the joint stereo section 62 based on the integrated spectrum SPCI (f).
FIG. 14 is a diagram showing a frequency spectrum SPCL (f) obtained by combining the frequency spectrum SPCL (f) with FIG. (B2) The frequency spectrum SPCR2 (f) and the frequency spectrum SPCR1 of the integrated frequency of the right channel obtained by the joint stereo unit 62 based on the integrated spectrum SPCR (f).
FIG. 13 is a diagram showing a frequency spectrum SPCR (f) obtained by combining the above with (f).

FIG. 10 is a flowchart illustrating a method for decoding a stereo encoded signal according to a third embodiment of the present invention.

FIG. 11 is a flowchart illustrating a method for decoding a stereo encoded signal according to a fourth embodiment of the present invention.

FIG. 12 is a diagram illustrating an example of a frequency spectrum (harmonic structure) of an audio signal.

[Explanation of symbols]

 1,61 Demultiplexing and inverse quantization unit 2,62 Decoding device / joint stereo unit 3,4,63,64 Decoding device / filter bank 5,6,31,32 Harmonic structure analysis unit 7,8 key Wave structure correction unit 41, 44 Encoder / filter bank 43 Encoder / joint stereo unit 44 Quantization and multiplex unit

Claims (12)

[Claims] 1. An integrated spectrum having a frequency component equal to or higher than a predetermined frequency generated by intensity stereo coding, and each low frequency spectrum corresponding to each channel having a frequency component lower than the predetermined frequency. Input means for inputting a multiplexed stereo coded signal; and correcting the integrated spectrum using the low-frequency spectrums, corresponding to each channel having a frequency component equal to or higher than the predetermined frequency. Frequency spectrum correction means for obtaining each high frequency spectrum, frequency spectrum deriving means for integrating the low frequency spectrum and the high frequency spectrum corresponding to each channel to obtain a frequency spectrum for each channel, Audio of each channel from frequency spectrum A stereo coded signal decoding device comprising: an audio signal generation unit that generates a signal. 2. The frequency spectrum correcting means, for each channel, analyzing the low frequency spectrum corresponding to the channel and generating a weighted signal corresponding to the channel; 2. The stereo coded signal decoding apparatus according to claim 1, further comprising: a harmonic structure correcting unit that obtains the high frequency spectrum corresponding to the channel by applying the weighted signal corresponding to the channel to the integrated spectrum. . 3. The stereo coded signal decoding device according to claim 2, wherein the weighting signal corresponding to the channel is based on an envelope of the low frequency spectrum corresponding to the channel. 4. When the frequency spectrum correction unit generates the weighted signal corresponding to the channel,
3. The stereo coded signal decoding apparatus according to claim 2, wherein the low frequency spectrum corresponding to a channel other than the channel is also used. 5. The weighted signal corresponding to the channel is a reciprocal of an envelope of the low frequency spectrum corresponding to a channel other than the channel based on an envelope of the low frequency spectrum corresponding to the channel. The stereo coded signal decoding device according to claim 4, which is based on: 6. An integrated spectrum having a frequency component equal to or higher than a predetermined frequency generated by intensity stereo coding and a low frequency spectrum corresponding to each channel having a frequency component lower than the predetermined frequency. A multiplexed stereo coded signal is input, and the integrated spectrum is corrected by using each of the low-frequency spectra, thereby having a frequency component equal to or higher than the predetermined frequency. A stereo code for obtaining a frequency spectrum, integrating the low frequency spectrum and the high frequency spectrum corresponding to each channel to obtain a frequency spectrum of each channel, and generating an audio signal of each channel from the frequency spectrum of each channel. Signal decoding method. 7. When obtaining the high frequency spectrum corresponding to each channel, the low frequency spectrum corresponding to the channel is analyzed for each channel to generate a weighted signal corresponding to the channel. 7. The stereo encoded signal decoding method according to claim 6, wherein, for each time, the high frequency spectrum corresponding to the channel is obtained by applying the weighted signal corresponding to the channel to the integrated spectrum. 8. The stereo coded signal decoding method according to claim 7, wherein the weighting signal corresponding to the channel is based on an envelope of the low frequency spectrum corresponding to the channel. 9. The stereo coded signal decoding method according to claim 7, wherein when generating the weighted signal corresponding to the channel, the low frequency spectrum corresponding to a channel other than the channel is also used. 10. The weighted signal corresponding to the channel is a reciprocal of an envelope of the low frequency spectrum corresponding to a channel other than the channel based on an envelope of the low frequency spectrum corresponding to the channel. 10. The stereo encoded signal decoding method according to claim 9, wherein the method is based on: 11. The stereo coded signal decoding apparatus according to claim 1, wherein the integrated spectrum has a frequency component equal to or higher than a predetermined frequency generated by intensity stereo coding and a frequency component lower than the predetermined frequency. ,
Input means for inputting a stereo coded signal in which each low-frequency spectrum corresponding to each channel is multiplexed; and correcting the integrated spectrum using each of the low-frequency spectrums, thereby obtaining the predetermined frequency. Frequency spectrum correction means for obtaining each high frequency spectrum corresponding to each channel having the above frequency components, and integrating the low frequency spectrum and the high frequency spectrum corresponding to each channel to obtain the frequency spectrum of each channel A program for causing a computer to function as all or a part of a frequency spectrum deriving unit that calculates the frequency spectrum and an audio signal generating unit that generates an audio signal of each channel from the frequency spectrum of each channel. 12. An integrated spectrum having a frequency component equal to or higher than a predetermined frequency generated by intensity stereo coding and a frequency component lower than the predetermined frequency according to the stereo coded signal decoding method according to claim 6. ,
Inputting a stereo-encoded signal in which each low-frequency spectrum corresponding to each channel is multiplexed, and correcting the integrated spectrum using each of the low-frequency spectra, so that the predetermined frequency or more is corrected. Obtaining the high frequency spectrum corresponding to each channel, and obtaining the frequency spectrum of each channel by integrating the low frequency spectrum and the high frequency spectrum corresponding to each channel. Generating an audio signal of each channel from the frequency spectrum of each channel;